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1
Chopra, Deepak, i Dhananjay Dey. "Computational approaches towards crystal engineering in molecular crystals". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C642. http://dx.doi.org/10.1107/s2053273314093577.
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The investigation of a large number of crystal structures has resulted in the development of the area of crystal engineering, which involves the study of intermolecular interactions in crystalline solids [1]. It is now of importance to understand the nature and energetics associated with different interactions [2] which influence the crystal packing. In this regard, different computational approaches (utilizing PIXEL and TURBOMOLE) have been developed which aid in the understanding of intra- and intermolecular interactions (for example, hydrogen and halogen bonding) in molecular crystals. This approach has been successfully applied in different classes of molecules [3]. These approaches can be combined with topological analysis of the electron density using the quantum theory of atoms in molecules (QTAIM) (in absence of high quality crystals for experimental electron density studies). In order to validate the above-mentioned methodology, we have performed a comprehensive analysis of a series of synthesized fluoro-derivatives of N'-phenylbenzimidamide to gain quantitative insights into different interactions which accompany crystal formation. The packing of the molecules has contributions from strong N-H...N, weak N-H...π [Fig 1], C-H...N, C-H...F, and C-H...π intermolecular interactions along with π-π stacking. In addition to that, ubiquitous H...H contacts are also present in the solid state. This methodology can be extended to include cocrystals, polymorphs (including solvates) and protein-ligand interactions at the active site.
2
Guo, Yanmei, Yunhui Hao, Lei Gao i Hongxun Hao. "Photomechanical Molecular Crystals of an Azopyridine Derivative and Its Zinc(II) Complex: Synthesis, Crystallization and Photoinduced Motion". Crystals 10, nr 2 (6.02.2020): 92. http://dx.doi.org/10.3390/cryst10020092.
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In this work, photomechanical molecular crystals of 4-(4-(6-Hydroxyhexyloxy) phenylazo) pyridine (6cazpy) and its zinc(II) organic complex (complex-I) were synthesized and crystallized. DSC and TGA were used to characterize and compare properties of 6cazpy and its complex-I crystals. Photoinduced motions of 6cazpy crystals and its complex-I crystals were investigated and compared by UV/Vis irradiation. Bending away motions from the light source were observed from both 6cazpy crystals and its complex-I crystals. The bending away motion was attributed to the trans-to-cis photoisomerization of azopyridine derivatives in the crystalline phase. It is worth noting that the photomechanical properties of complex-I were enhanced by the formation of the ligand, which might be caused by the looser packing of molecules inside complex-I crystal. In addition, because of the existence of ligand, which combined two photoactive groups in each complex-I molecule, the isomerization reactions of these two photoactive groups in the molecules can increase the photomechanical movement ability of the crystal. It was also found that the crystal size and shape will affect the photoinduced movement of the crystals. PXRD and AFM were used to investigate the molecular mechanism and the surface topological change upon photoisomerization. The corresponding mechanism was proposed.
3
Tai, Xi Shi, i Lin Tong Wang. "Synthesis, Fluorescence Properties of 2-Acetyl-2'-Chloroacetanilide with Rare Earth Nitrates Complexes". Advanced Materials Research 219-220 (marzec 2011): 574–77. http://dx.doi.org/10.4028/www.scientific.net/amr.219-220.574.
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The reaction of 2-acetyl-2'-chloroacetanilide (L) with rare earth nitrates in CH3CH2OH followed by recrystallization in CH3CH2OH gave rise to colorless block crystals materials. The complexes and ligand were analyzed by FAB, elemental analysis(C, H, N), FT-IR spectra, TG-DTA, molar conductivity and X-ray single crystal diffraction. The fluorescence properties of ligand and the Eu (Ⅲ) complex also have been investigated. The results of crystal structure and spectral data show that the rare earth ions coordinated with oxygen and nitrogen atoms of the ligand, the nitrate and coordinated water molecules. The Eu (Ⅲ) complex material shows characteristic red emissions.
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May, Nóra Veronika, Kevin Nys, H. Y. Vincent Ching, Laura Bereczki, Tamás Holczbauer, Valerio B. Di Marco i Petra Bombicz. "Crystal structures of zinc(II) complexes with β-hydroxypyridinecarboxylate ligands: examples of structure-directing effects used in inorganic crystal engineering". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, nr 2 (27.02.2021): 193–204. http://dx.doi.org/10.1107/s2052520621000299.
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The coordination properties of four hydroxypyridinecarboxylates, designed for the treatment of iron-overloading conditions as bidentate O,O′-donor ligands, have been studied with ZnII in the solid state. The coordination compounds [Zn(A1)2(H2O)2] (1), [Zn(A2)2(H2O)] (2), [Zn(A3)2(H2O)]·2H2O (3) and [Zn2(B1)4(H2O)2]·4H2O (4), where the ligands are 1-methyl-4-oxidopyridinium-3-carboxylate (A1, C7H6NO3), 1,6-dimethyl-4-oxidopyridinium-3-carboxylate (A2, C8H8NO3), 1,5-dimethyl-4-oxido-pyridinium-3-carboxylate (A3, C8H8NO3) and 1-methyl-3-oxidopyridinium-4-carboxylate (B1, C7H6NO3), have been synthesized and analysed by single-crystal X-ray diffraction. The ligands were chosen to probe (i) the electronic effects of inverting the positions of the O-atom donor groups (i.e. A1 versus B1) and (ii) the electronic and steric effects of the addition of a second methyl group in different positions on the pyridine ring. Two axially coordinated water molecules resulting in a six-coordinated symmetrical octahedron complement the bis-ligand complex of A1. Ligands A2 and A3 form five-coordinated trigonal bipyramidal complexes with one additional water molecule in the coordination sphere, which is a rarely reported geometry for ZnII complexes. Ligand B1 shows a dimeric structure, where the two Zn2+ dications have slightly distorted octahedral geometry and the pyridinolate O atom of the neighbouring complex bridges them. The coordination spheres of the Zn2+ dications and the supramolecular structures are discussed in detail. The packing arrangements of 1–3 are similar, having alternating hydrophilic and hydrophobic layers, however the similarity is broken in 4. The obtained coordination geometries are compared with their previously determined CuII analogues. The study of the individual complexes is complemented with a comprehensive analysis of ZnII complexes with oxygen donor ligands with data from the Cambridge Structural Database.
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Pinto, Camila B., Leonardo H. R. Dos Santos i Bernardo L. Rodrigues. "Understanding metal–ligand interactions in coordination polymers using Hirshfeld surface analysis". Acta Crystallographica Section C Structural Chemistry 75, nr 6 (20.05.2019): 707–16. http://dx.doi.org/10.1107/s2053229619005874.
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Properties related to the size and shape of Hirshfeld surfaces provide insight into the nature and strength of interactions among the building blocks of molecular crystals. In this work, we demonstrate that functions derived from the curvatures of the surface at a point, namely, shape index (S) and curvedness (C), as well as the distances from the surface to the nearest external (d e) and internal (d i) nuclei, can be used to help understand metal–ligand interactions in coordination polymers. The crystal structure of catena-poly[[[(1,10-phenanthroline-κ2 N,N′)copper(II)]-μ-4-nitrophthalato-κ2 O 1:O 2] trihydrate], {[Cu(C8H3NO6)(C12H8N2)]·3H2O} n , described here for the first time, was used as a prototypical system for our analysis. Decomposition of the coordination polymer into its metal centre and ligand molecules followed by joint analysis of the Hirshfeld surfaces generated for each part unveil qualitative and semi-quantitative information that cannot be easily obtained either from conventional crystal packing analysis or from Hirshfeld surface analysis of the entire polymeric units. The shape index function S is particularly sensitive to the coordination details and its mapping on the surface of the metallic centre is highly dependent on the nature of the ligand and the coordination bond distance. Correlations are established between the shape of the Hirshfeld surface of the metal and the geometry of the metal–ligand contacts in the crystals. This could be applied not only to estimate limiting coordination distances in metal–organic compounds, but also to help establish structure–property relationships potentially useful for the crystal engineering of such materials.
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Wang, Li Hua, i Peng Fei Li. "Synthesis, Structure, and Catalytic Activity of A New Mn(II) Complex with 1,4-Phenylenediacetic Acid and 1,10-Phenanthroline". Bulletin of Chemical Reaction Engineering & Catalysis 13, nr 1 (2.04.2018): 1. http://dx.doi.org/10.9767/bcrec.13.1.975.1-6.
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A new Mn(II) complex material has been synthesized by one-pot reaction of Mn(CH3COO)2·4H2O, 1,4-phenylenediacetic (H2L), 1,10-phenanthroline (phen), and NaOH in water/ethanol (v:v = 1:1) solution. The structure of Mn(II) complex was determined by elemental analysis, FTIR, and X-ray single-crystal diffraction analysis. The results reveal that Mn(II) complex was constructed by a monodentate 1,4-phenylenediacetate ligand, two phen ligands, a coordinated water molecule, 0.5 uncoordinated 1,4-phenylenediacetate ligand and six uncoordinated water molecules. The complex molecules form 1D chain structure by the π-π interaction of phen molecules. The catalytic activity of Mn(II) complex for coupling of benzaldehyde, phenylacetylene and piperidine in 1,4-dioxane has also been investigated and the maximum yield of propargylamine is up to 72.2 % after 12 h at 120 oC. Copyright © 2017 BCREC Group. All rights reservedReceived: 5th March 2017; Revised: 7th June 2017; Accepted: 12nd July 207; Available online: 22nd January 2018; Published regularly: 2nd April 2018How to Cite: Wang, L.H., Li, P.F. (2018). Synthesis, Structure, and Catalytic Activity of A New Mn(II) Complex with 1,4-Phenylenediacetic Acid and 1,10-Phenanthroline. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1): 1-6 (doi:10.9767/bcrec.13.1.975.1-6)
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Chen, Xiao-Ming. "Crystal Engineering and Applications of Functional Metal-Organic Frameworks". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C16. http://dx.doi.org/10.1107/s2053273314099835.
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As a new kind of molecular materials composed of metal ions (or clusters) and organic bridging ligands that are interconnected by coordination bonds, porous metal-organic frameworks (MOFs) have many useful characteristics, such as high crystallinity, high porosity, structural diversity, designable frameworks, framework flexibility, as well as unique and modifiable organic pore surface. Therefore, they exhibit very promising potential applications in molecular adsorption/separation, catalysis, and sensors, etc. For example, they can be used for selective adsorption and separation of different gas molecules, such as CO2 and N2, capture of CO2 [2], sensing of small organic molecules and gas molecules, such as O2 and CO2, as well as catalysts and devices for solid-phase microextraction. In this presentation, the design and synthesis, unique pore surface, interesting functionalities will be presented by selected examples, in particular those of metal-azolate frameworks (MAFs) and a few devices useful for practical applications, from our group [1-3]. This work was supported by MoST (973 project) and NSFC.
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Peng, Yun-Dong, Ruo-Yu Li, Peng Li i Yin-Xia Sun. "Insight into Rare Structurally Characterized Homotrinuclear CuII Non-Symmetric Salamo-Based Complex". Crystals 11, nr 2 (26.01.2021): 113. http://dx.doi.org/10.3390/cryst11020113.
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A rare homotrinuclear CuII salamo-based complex [Cu3(L)2(μ-OAc)2(H2O)2]·2CHCl3·5H2O was prepared through the reaction of a non-symmetric salamo-based ligand H2L and Cu(OAc)2·H2O, and validated by elemental analyses, UV-Visible absorption, fluorescence and infrared spectra, molecular simulation and single-crystal X-ray analysis techniques. It is shown that three CuII atoms and two wholly deprotonated ligand (L)2− moieties form together a trinuclear 3:2 (M:L) complex with two coordination water molecules and two bi-dentate briging μ-acetate groups (μ-OAc−). Besides, the Hirshfeld surface analysis of the CuII complex was investigated. Compared with other ligands, the fluorescent strength of the CuII complex was evidently lowered, showing that the CuII ions possess fluorescent quenching effect.
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Bruno, John G. "Potential Use of Antifreeze DNA Aptamers for the Cryopreservation of Human Erythrocytes". Advanced Science, Engineering and Medicine 12, nr 7 (1.07.2020): 870–74. http://dx.doi.org/10.1166/asem.2020.2628.
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This article summarizes proof of concept experiments which clearly demonstrated the ability of DNA aptamers selected against a molecular mimic of early ice crystal nuclei to protect the integrity of human erythrocytes following a slow freeze-thaw cycle. Following 10 cycles of selection and DNA amplification of rare candidate DNA aptamers against a copper-organic ligand complex which holds water molecules in a conformation resembling early ice crystal nuclei, the aptamers were tested for their ability to preserve erythrocyte morphology by phase-contrast microscopy versus controls without aptamers and with the original randomized aptamer DNA library template following slow freezing and storage overnight at -20 °C with slow thawing at 25 °C. Those experiments revealed that a minimum of 32 μg/ml of the final selected aptamer pool of DNA molecules was required to completely protect nearly 100% of the erythrocytes. By contrast, the treatment groups without the aptamers or with the randomized aptamer template DNA at 32 μg/ml produced only fragmented erythrocytes and cellular debris (no intact cells), thus indicating that specifically selected DNA conformations were required to bind and limit the size of forming ice crystals to cryoprotect the erythrocytes.
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Bakheit, Ahmed H., Mohamed W. Attwa, Adnan A. Kadi, Hazem A. Ghabbour i Hamad M. Alkahtani. "Exploring the Chemical Reactivity, Molecular Docking, Molecular Dynamic Simulation and ADMET Properties of a Tetrahydrothienopyridine Derivative Using Computational Methods". Crystals 13, nr 7 (27.06.2023): 1020. http://dx.doi.org/10.3390/cryst13071020.
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This study investigates the crystal structure, physicochemical properties, and pharmacokinetic profile of Ethyl 2-amino-6-methyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate (EAMT) as a potential therapeutic agent. The crystal structure was analyzed using Hirshfeld surface analysis in conjunction with the quantum theory of atoms in molecules (QT-AIM). Non-covalent interactions were evaluated through reduced-density gradient reduction, revealing that the EAMT crystal is stabilized by hydrogen bonds between EAMT molecules in the crystal and between EAMT molecules and water molecules. The molecular electrostatic nature of interactions was examined using MESP, while global and local descriptors were calculated to assess the compound’s reactivity. Molecular docking with the Adenosine A1 receptor was performed and validated through a 50 ns molecular dynamics simulation (MDS). Results suggest that EAMT influences protein structure, potentially stabilizing specific secondary structure elements. The compactness analysis showed a slightly more compact protein conformation and a marginally increased solvent exposure in the presence of the EAMT ligand, as indicated by Rg and SASA values. The total binding free energy (ΔG total) was determined to be −114.56 kcal/mol. ADMET predictions demonstrated EAMT’s compliance with Lipinski’s and Pfizer’s rule of five, indicating good oral availability. The compound may exhibit low-potency endocrine activity. In conclusion, EAMT presents potential as a therapeutic candidate, warranting further exploration of its molecular interactions, pharmacokinetics, and potential safety concerns.
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Lu, Yipin, Renxiao Wang, Chao-Yie Yang i Shaomeng Wang. "Analysis of Ligand-Bound Water Molecules in High-Resolution Crystal Structures of Protein−Ligand Complexes". Journal of Chemical Information and Modeling 47, nr 2 (luty 2007): 668–75. http://dx.doi.org/10.1021/ci6003527.
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Perdih, Franc, Milenko Korica, Lorena Šebalj i Tomislav Balić. "Anion Influence on Supramolecular Interactions in Exo-Coordinated Silver(I) Complexes with N2O2 Schiff Base Macrocycle". Crystals 13, nr 1 (27.12.2022): 50. http://dx.doi.org/10.3390/cryst13010050.
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Silver(I) complexes with aza-oxa macrocyclic Schiff bases L (L = 1,5-diaza-2,4:7,8:16,17-tribenzo-9,15-dioxa-cyclooctadeca-1,5-dien) were prepared by the reaction of the corresponding macrocycle with four different silver salts (AgX; X = ClO4, PF6, SbF6 and BF4). In all four compounds, silver ions are exo-coordinated by two neighboring ligand molecules in linear and T-shaped geometries. Such a coordination mode results in the formation of infinite 1D polymeric chains. Compounds AgLClO4 and AgLBF4 are isostructural, and polymeric chains display 1D zigzag topology. In AgLPF6 there are three symmetrically unique Ag ions in the asymmetric unit of the compound. Two silver ions are linearly coordinated with two neighboring ligand molecules and are part of a discrete polymer chain. The third silver ion is coordinated with two ligand molecules and a methanol molecule in a T-shaped geometry. Such coordination geometry results in the formation of two discrete infinite polymer chains in the crystal structure. In the AgLSbF6 compound, the chain topology is a linear zigzag chain, but in this compound, there is a difference in the orientation of the Ag-N bond. The Ag-N-Ag bonds are in the trans position relative to the plane calculated through the ligand molecule, while the Ag-N bonds are in the cis position in all other compounds. Due to the presence of a bulky SbF6 anion, the ligand molecule is planar compared to other compounds. Considering intermolecular interactions, there is a huge variety of different interactions, mostly depending on the type of anion. A general supramolecular motif in all compounds is best described as 2D sheets of ligand–metal polymers with anions and solvent molecules sandwiched between them. In addition, the obtained compounds were characterized by IR spectroscopy and thermal analysis. The TG analysis indicates a rather surprising and considerable thermal stability of the prepared compounds, with some compounds thermally stable over 300 °C.
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Burlakov, Victor M., i Alain Goriely. "Ligand-Assisted Growth of Nanowires from Solution". Applied Sciences 11, nr 16 (20.08.2021): 7641. http://dx.doi.org/10.3390/app11167641.
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We consider the development of ligand-assisted growth processes for generating shape-anisotropic nanomaterials. Using statistical mechanics, we analyze the conditions under which ligand-assisted growth of shape-anisotropic crystalline nanomaterials from solution can take place. Depending on ligand-facet interaction energy and crystal facet area, molecular ligands can form compact layers on some facets leaving other facets free. The growth process is then restricted to free facets and may result in significant anisotropy in crystal shape. Our study uncovers the conditions for ligand-assisted growth of nanoplatelets and nanowires from isotropic or anisotropic seed nanocrystals of cuboid shape. We show that in contrast to nanoplatelets, ligand-assisted growth of nanowires requires certain anisotropy in the ligand-facet interaction energy.
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Ji, Zhi Xiang, i Peng Fei Li. "Crystal Structure and Catalytic Activity of A Novel Cd(II) Coordination Polymer Formed by Dicarboxylic Ligand". Bulletin of Chemical Reaction Engineering & Catalysis 13, nr 2 (11.06.2018): 220. http://dx.doi.org/10.9767/bcrec.13.2.1178.220-226.
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A new Cd(II) coordination polymer, {[Cd3(L)2(DMF)2(H2O)2]·H2O}n (H2L = 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylic acid) was synthesized by one-pot synthesis method from 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylic acid, NaOH, DMF, and Cd(NO3)2·4H2O. Its structure was determined by elemental analysis and single crystal X-ray diffraction. Structural analysis shows that three Cd(II) ions are all six-coordinated with four oxygen atoms of four 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylate ligands and two O atoms from two DMF molecules (Cd1) or two oxygen atoms of two coordinated H2O molecules (Cd2 and Cd3) to form an octahedral coordination geometry. The Cd(II) coordination polymer displays a 1D chained structure by the bridging carboxylate groups from 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylate ligands. The conversion of benzaldehyde is 90.9%, which is 40~50% higher than those of the other three aldehydes (4-methylbenzaldehyde, p-methoxybenzaldehyde and 3-chlorobenzaldehyde), so the Cd(II) coordination polymer catalyst shows better catalytic activity for the coupling reaction of benzaldehyde, phenylacetylene, and piperidine than the other three aldehydes. Copyright © 2018 BCREC Group. All rights reservedReceived: 25th April 2017; Revised: 11st September 2017; Accepted: 1st November 2017; Available online: 11st June 2018; Published regularly: 1st August 2018How to Cite: Ji, Z.X., Li, P.F. (2018). Crystal Structure and Catalytic Activity of A Novel Cd(II) Coordination Polymer Formed by Dicarboxylic Ligand. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2): 220-226 (doi:10.9767/bcrec.13.2.1178.220-226)
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Müller-Buschbaum, Klaus. "3D-[Pr(Im)3(ImH)]@ImH: Ein dreidimensionales Netzwerk mit vollständiger Stickstoffkoordination aus einer Imidazolschmelze / 3D-[Pr(Im)3(ImH)]@ImH: A Three-Dimensional Network with Complete Nitrogen Coordination Obtained from an Imidazole Melt". Zeitschrift für Naturforschung B 61, nr 7 (1.07.2006): 792–98. http://dx.doi.org/10.1515/znb-2006-0704.
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The reaction of a melt of unsubstituted imidazole with praseodymium metal yields bright green crystals of 3D-[Pr(Im)3(ImH)]@ImH. Imidazolate ligands coordinate η1 via both N atoms their 1,3 positioning within the heterocycle being responsible for the connection of praseodymium atoms. A 3-dimensional network is formed with imidazole molecules from the melt intercalated in the crystal structure. The imidazole molecules can be released and temperature dependent reversibly be exchanged with gas molecules including argon. Thus the solvent free high temperature synthesis of rare earth elements with amine melts can also be utilized for “crystal engineering” and the synthesis of compounds with material science aspects. Furthermore 3D-[Pr(Im)3(ImH)]@ImH is the first unsubstituted imidazolate of the lanthanides.
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Guo, Jiajia, Wenli Cao, Shuailei Li, Kanghua Miao, Jirong Song i Jie Huang. "Synthesis and crystal structure of a two-dimensional sodium coordination polymer of 4,4′-(diazenediyl)bis(1H-1,2,4-triazol-5-one)". Acta Crystallographica Section C Structural Chemistry 72, nr 2 (27.01.2016): 166–69. http://dx.doi.org/10.1107/s2053229616001509.
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The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-μ-aqua-[μ4-4,4′-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na2(C4H2N8O2)(H2O)4]n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4′-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolide) (ZTO2−) ligand is located on an inversion centre. The asymmetric unit consists of one Na+cation, half a bridging ZTO2−ligand and two bridging water ligands. Each Na+cation is coordinated in a trigonal antiprismatic fashion by six O atoms,i.e.two from two ZTO2−ligands and the remaining four from bridging water ligands. The Na+cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO2−ligands are on adjacent apices of the trigonal antiprism, rather than being in ananticonfiguration. All water and ZTO2−ligands act as bridging ligands between metal centres. Each Na+metal centre is bridged to a neigbouring Na+cation by two water molecules to give a one-dimensional [Na(H2O)2]nchain. The organic ZTO2−ligand, an O atom of which also bridges the same pair of Na+cations, then crosslinks these [Na(H2O)2]nchains to form two-dimensional sheets. The two-dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.
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Karwan, Omer Ali, Ali Mohamad Hikmat, Thomas Gerber i Eric Hosten. "Zinc(II) Complex Containing Oxazole Ring: Synthesis, Crystal Structure, Characterization, DFT Calculations, and Hirshfeld Surface Analysis". Acta Chimica Slovenica 69, nr 4 (15.12.2022): 906–12. http://dx.doi.org/10.17344/acsi.2022.7682.
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A new complex of Zn(II), with 5-chloro-2-methylbenzoxazole ligand (L), has been synthesized by the reaction of zinc dichloride with the ligand (L= C8H6ClNO) in ethanol solution: dichloridobis(5-chloro-2-methyl-1,3-benzoxazole)-zinc(II), C16H12Cl4N2O2Zn. The synthesized complex has been fully characterized by elemental analysis, molar conductivity, FT‑IR, UV‑Vis, and single-crystal X-ray diffraction (XRD). The XRD analysis reveals that the complex has a 1:2 metal-to-ligand ratio. The zinc(II) complex has a distorted tetrahedral geometry with two coordinated nitrogen atoms from the ligand. Density Functional Theory (DFT) calculations were performed at the B3LYP level of theory using the LANL2DZ basis set for metal complex and the 6–31G(d) basis set for non-metal elements to determine the optimum geometry structure of the complex, and the calculated HOMO and LUMO orbital energies were presented. A natural bond orbital (NBO) analysis was carried out on the molecules to analyze the atomic charge distribution before and after the complexation of the ligand. The Hirshfeld surface mapped over dnorm, shape index, and curvature exhibited strong H... Cl/Cl...H and H...H intermolecular interactions as the principal contributors to crystal packing.
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Li, Ruo-Yan, Xiao-Xin An, Juan-Li Wu, You-Peng Zhang i Wen-Kui Dong. "An Unexpected Trinuclear Cobalt(II) Complex Based on a Half-Salamo-Like Ligand: Synthesis, Crystal Structure, Hirshfeld Surface Analysis, Antimicrobial and Fluorescent Properties". Crystals 9, nr 8 (6.08.2019): 408. http://dx.doi.org/10.3390/cryst9080408.
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An unexpected trinuclear Co(II) complex, [Co3(L2)2(μ-OAc)2(CH3OH)2]·2CH3OH (H2L2 = 4,4′-dibromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) constructed from a half-Salamo-based ligand (HL1 = 2-[O-(1-ethyloxyamide)]oxime-4-bromophenol) and Co(OAc)2·4H2O, has been synthesized and characterized by elemental analyses, infrared spectra (IR), UV-Vis spectra, X-ray crystallography and Hirshfeld surface analysis. The Co(II) complex contains three Co(II) atoms, two completely deprotonated (L2)2− units, two bridged acetate molecules, two coordinated methanol molecules and two crystalline methanol molecules, and finally, a three-dimensional supramolecular structure with infinite extension was formed. Interestingly, during the formation of the Co(II) complex, the ligand changed from half-Salamo-like to a symmetrical single Salamo-like ligand due to the bonding interactions of the molecules. In addition, the antimicrobial activities of HL1 and its Co(II) complex were also investigated.
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Lu, Xin-Hua, i Kai-Long Zhong. "A new three-dimensional manganese(II) coordination polymer based on the 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene ligand". Acta Crystallographica Section C Structural Chemistry 72, nr 11 (24.10.2016): 895–900. http://dx.doi.org/10.1107/s2053229616015965.
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The self-assembly of coordination polymers and the crystal engineering of metal–organic coordination frameworks have attracted great interest, but it is still a challenge to predict and control the compositions and structures of the complexes. Employing multidentate organic ligands and suitable metal ions to construct inorganic–organic hybrid materials through metal–ligand coordination and hydrogen-bonding interactions has become a major strategy. Recently, imidazole-containing multidentate ligands that contain an aromatic core have received much attention. A new three-dimensional MnIIcoordination polymer based on 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene, namely poly[(ethane-1,2-diol-κO)(μ-sulfato-κ2O:O′){μ3-1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene-κ3N:N′:N′′}manganese(II)], [Mn(SO4)(C18H18N6)(C2H6O2)]n, was synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal structural analysis shows that there are two kinds of crystallographically independent MnIIcentres, each lying on a centrosymmetric position and having a similar six-coordinated octahedral structure. One is coordinated by four N atoms from four 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene (timb) ligands and two O atoms from two different bridging sulfate anions. The second is surrounded by two timb N atoms and four O atoms, two from sulfate anions and two from two ethane-1,2-diol ligands. The tripodal timb ligand bridges neighbouring MnIIcentres to generate a two-dimensional layered structure running parallel to theabplane. Adjacent layers are further bridged by sulfate anions, resulting in a three-dimensional structure with3,4,6-ctopology. Thermogravimetric analysis of the title polymer shows that it is stable up to 533 K. The first weight loss between 533 and 573 K corresponds to the release of coordinated ethane-1,2-diol molecules, and further decomposition occurred at 648 K.
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Tai, Xi Shi. "Synthesis, Structural Characterization and Luminescence Property of Ring-Like Zinc(II) Complex of N-Paratoluensulfonyl-Glycine Acid and 1,10-Phenanthroline". Advanced Materials Research 321 (sierpień 2011): 127–30. http://dx.doi.org/10.4028/www.scientific.net/amr.321.127.
Pełny tekst źródłaStreszczenie:
A novel ring-like zinc (II) complex of N-paratoluensulfonyl-glycine acid and 1,10-phenanthroline was synthesized and characterized by elemental analysis, IR spectrum and molar conductivity. The crystal structure of Zn (II) was determined by X-ray single crystal diffraction. The results show that each zinc (II) atoms is in a distorted trigonal bipyramidal geometry and form 16-membered chelate ring with the tridentate ligand. Intermolecular weak interactions in complex link molecules into a one-dimensional infinite chain supramolecular structure. The luminescence property of the complex was investigated in solid.
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Al-Rasheed, Hessa H., Matti Haukka, Saied M. Soliman, Abdullah Mohammed Al-Majid, M. Ali, Ayman El-Faham i Assem Barakat. "Synthesis and Solid-State X-Ray Structure of the Mononuclear Palladium(II) Complex Based on 1,2,3-Triazole Ligand". Crystals 12, nr 10 (21.09.2022): 1335. http://dx.doi.org/10.3390/cryst12101335.
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Herein, we described the synthesis and X-ray crystal structure of the new [Pd(3)2Cl2] complex with 1,2,3-triazole-based ligand (3). In the unit cell, there are two [Pd(3)2Cl2] molecules, and the asymmetric unit comprised half of this formula due to the presence of an inversion symmetry element at the Pd(II) center. The monoclinic unit cell volume is 1327.85(6) Å3, with crystal parameters of a = 10.7712(2) Å, b = 6.8500(2) Å, and c = 18.2136(6) Å, while β = 98.851(2)°. The structure comprised two trans triazole ligand units coordinated to the Pd(II) ion via one of the N-atoms of the triazole moiety. In addition, the Pd(II) is further coordinated with two trans chloride groups, where each of the trans bonds is equidistant. The crystal structure of the [Pd(3)2Cl2] complex was compared with that for free triazole ligand 3. It was found that the coordinated ligand showed less twist around the C–N bond compared to free triazole ligand 3. The molecular packing of the latter is found controlled by short O…H, N…H, C…N, and C…C interactions in addition to the short Cl…F interhalogen and π–π interactions. H…H (23.5%), Cl…H (14.4%), N…H (14.3%), and O…H (11.2%) are the most dominant contacts. In the [Pd(3)2Cl2] complex, no significant interhalogen or π–π interactions were detected. In this case, Cl…H (31.1%), H…H (16.7%), O…H (11.6%), and F…H (9.7%) are the most dominant contacts.
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Masaryk, Lukáš, Ján Moncol, Radovan Herchel i Ivan Nemec. "Halogen Bonding in New Dichloride-Cobalt(II) Complex with Iodo Substituted Chalcone Ligands". Crystals 10, nr 5 (30.04.2020): 354. http://dx.doi.org/10.3390/cryst10050354.
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The synthesis and properties of new chalcone ligand 4I-L ((2E)-1-[4-(1H-imidazol-1-yl)phenyl]-3-(4-iodophenyl)prop-2-en-1-one) and tetracoordinate Co(II) complex [Co(4I-L)2Cl2], (1a), are reported in this article. Upon recrystallization of 1a, the single crystals of [Co(4I-L)4Cl2]·2DMF·3Et2O (1b) were obtained and crystal structure was determined using X-ray diffraction. The non-covalent interactions in 1b were thoroughly analyzed and special attention was dedicated to interactions formed by the peripheral iodine substituents. The density functional theory (DFT), atoms in molecule (AIM) and noncovalent interaction (NCI) methods and electronic localization function (ELF) calculations were used to investigate halogen bond formed between the iodine functional groups and co-crystallized molecules of diethyl ether.
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Burrows, Andrew D. "The Design and Applications of Multifunctional Ligands". Science Progress 85, nr 3 (sierpień 2002): 199–217. http://dx.doi.org/10.3184/003685002783238799.
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The properties of a metal coordination complex are determined as much by the ligand set – the molecules and ions coordinated to the metal centre – as by the nature of the metal itself. The design and use of new ligands is consequently a major part of chemical research. This review considers the role of multifunctional ligands in three separate and distinct areas of chemistry. In homogeneous catalysis, the role of hybrid and hemilabile ligands is considered, and the introduction of functionalities designed to overcome problems of separation, either by tethering or solubilising, is discussed. In supramolecular chemistry, functionalities enabling the recognition and sensing of cations and anions are examined. In addition, ligands containing two or more faces are discussed for their role in metallodendrimer formation and self-assembly reactions, and the use of bifunctional ligands in crystal engineering is addressed. The application of metal complexes in medicine is examined by consideration of cis-platin and its derivatives as antitumour agents. Imaging agents are also discussed with the uses of gadolinium MRI contrast agents and γ-emitting technetium complexes highlighted.
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Zhao, Xiao-Jun, Su-Zhen Bai i Ling-Wei Xue. "Tetranuclear Copper(II) Complexes Derived from 5-Bromo- 2-((2-(2-hydroxyethylamino)ethylimino)methyl)phenol: Synthesis, Characterization, Crystal Structures and Catalytic Oxidation of Olefins". Acta Chimica Slovenica 69, nr 4 (15.12.2022): 787–95. http://dx.doi.org/10.17344/acsi.2022.7530.
Pełny tekst źródłaStreszczenie:
An acetate bridged tetranuclear copper(II) complex, [Cu4L2(μ2-η1:η1-CH3COO)6(CH3OH)2] (1), and a chloride, phenolate and azide co-bridged tetranuclear copper(II) complex, [Cu4L2Cl2(μ-Cl)2(μ1,1-N3)2]2CH3OH (2), where L is the deprotonated form of the Schiff base 5-bromo-2-((2-(2-hydroxyethylamino)ethylimino)methyl)phenol (HL), have been synthesized and characterized by elemental analysis, IR and UV spectra, and single crystal X-ray diffraction. Single crystal X-ray analysis revealed that the Cu atoms in both complexes are in square pyramidal geometry. In complex 1, two [CuL] units and [Cu2(μ2-η1:η1-CH3COO)4] core are linked through two acetate ligands. In complex 2, [Cu2LCl(μ-Cl)] units are linked together by two end-on azido ligands. The Schiff base ligand coordinates to the Cu atoms through four N and O donor atoms. The molecules of both complexes are linked through hydrogen bonds to generate three dimensional networks. The catalytic property of the complexes for epoxidation reactions of some alkenes was studied using tert-butylhydroperoxide as the terminal oxidant under mild conditions in acetonitrile.
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Trofimova, Olesya Y., Arina V. Maleeva, Kseniya V. Arsenyeva, Anastasiya V. Klimashevskaya, Il’ya A. Yakushev i Alexandr V. Piskunov. "Glycols in the Synthesis of Zinc-Anilato Coordination Polymers". Crystals 12, nr 3 (10.03.2022): 370. http://dx.doi.org/10.3390/cryst12030370.
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We report the synthesis, structural investigation, and thermal behavior for three zinc-based 1D-coordination polymers with 3,6-di-tert-butyl-2,5-dihydroxy-p-benzoquinone, which were synthesized in the presence of different glycols. The interaction of zinc nitrate with glycols, followed by using the resulting solution in solvothermal synthesis with the anilate ligand in DMF, makes it possible to obtain linear polymer structures with 1,2-ethylene or 1,2-propylene glycols coordinated to the metal. The reaction involving 1,3-propylene glycol under similar conditions gives a crystal structure that does not contain a diol. The crystal and molecular structures of the synthesized compounds were determined using single crystal by X-ray structural analysis. The influence of glycol molecules coordinated to the metal on the thermal destruction of synthesized compounds is shown.
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Sivagami, S., R. Rathna, S. Nagavignesh, N. V. Ghone i M. Sivanandham. "In silico binding analysis of human CD40 ligand mimetic molecule, 3-(dimethylamino)-1-phenyl-1-propanone hydrochloride (3-DPH), with CD40 receptor molecules of various mammalian species". Journal of Environmental Biology 42, nr 2 (1.03.2021): 186–91. http://dx.doi.org/10.22438/jeb/42/2/mrn-1440.
Pełny tekst źródłaStreszczenie:
Aim: To investigate the binding of human CD40 ligand (CD40L) mimetic molecule, 3-(dimethylamino)-1-phenyl-1-propanone hydrochloride (3-DPH), with CD40 receptor (CD40R) molecules of Homo sapiens, Cavia porcellus, Cricetulus griseus, Macaca mulatta, Mus musculus, Oryctolagus cuniculus, Papio anubis and Rattus norvegicus species using bioinformatics tool. Methodology: Three-dimensional structures of CD40Rs and CD40Ls for various mammalian species were generated using the published crystal structure of human CD40 receptor-ligand complex by homology modelling using SWISS-MODEL tool. Furthermore, human CD40L mimetic molecule, 3-DPH was docked against the generated CD40R of various mammalian species using AUTODOCK 4.2. Results: Docking studies revealed that documented HIS78 and GLN79 residues of human CD40R were the key interaction residues, which interacted with human CD40L and 3-DPH. The CD40Rs of H. sapiens, C. porcellus, C. griseus, M. mulatta, M. musculus, O. cuniculus, P. anubis, and R. norvegicus bind with 3-DPH with a binding energy -4.67, -5.22, -5.19, -4.62, -4.85, -4.63, -4.51, and -4.86 kcal/mol, respectively. Interpretation: Molecular docking studies provide crucial insight into the binding affinity and interaction of 3-DPH at the active site of CD40R of the respective mammalian species. O. cuniculus and M. musculus species were found to be appropriate animal models for further evaluation of the therapeutic effect of human CD40L mimetic molecule Key words: 3-DPH, Animal model, CD40R, CD40L, Homo sapeins, Molecular docking
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Jeon, Moncol, Mazúr, Valko i Choi. "Synthesis, Crystal Structure, Spectroscopic Properties, and Hirshfeld Surface Analysis of Diaqua [3,14-dimethyl-2,6,13,17 tetraazatricyclo(16.4.0.07,12)docosane]copper(II) Dibromide". Crystals 9, nr 7 (28.06.2019): 336. http://dx.doi.org/10.3390/cryst9070336.
Pełny tekst źródłaStreszczenie:
A newly prepared Cu(II) complex salt, Cu(L1)(H2O)2Br2, where L1 is 3,14-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12) docosane, is characterized by elemental and crystallographic analyses. The Cu(II) center is coordinated by four nitrogen atoms of macrocyclic ligand and the axial position by two water molecules. The macrocyclic ligand adopts an optimally stable trans-III conformation with normal Cu–N bond lengths of 2.018 (3) and 2.049 (3) Å and long axial Cu1–O1W length of 2.632 (3) Å due to the Jahn–Teller effect. The complex is stabilized by hydrogen bonds formed between the O atoms of water molecules and bromide anions. The bromide anion is connected to the neighboring complex cations and water molecules through N–H···Br and O–H···Br hydrogen bonds, respectively. The g-factors obtained from the electron spin resonance spectrum show the typical trend of g∥ > g⊥ > 2.0023, which is in a good accordance to the dx2-y2 ground state. It reveals a coordination sphere of tetragonal symmetry for the Cu(II) ion. The infrared and electronic absorption spectral properties of the complex are also discussed. Hirshfeld surface analysis represents that the H···H, H···Br/Br···H and H···O/O···H contacts are the major molecular interactions in the prepared complex.
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Hasi, Qi-Meige, Yan Fan, Chen Hou, Xiao-Qiang Yao i Jia-Cheng Liu. "Two new two-dimensional coordination polymers based on isophthalate and a flexibleN-donor ligand containing benzimidazole and pyridine rings: synthesis, crystal structures and a solid-state UV–Vis study". Acta Crystallographica Section C Structural Chemistry 72, nr 10 (2.09.2016): 724–29. http://dx.doi.org/10.1107/s2053229616012912.
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In coordination chemistry and crystal engineering, many factors influence the construction of coordination polymers and the final frameworks depend greatly on the organic ligands used.N-Donor ligands with diverse coordination modes and conformations have been employed to assemble metal–organic frameworks. Carboxylic acid ligands can deprotonate completely or partially when bonding to metal ions and can also act as donors or acceptors of hydrogen bonds and are thus good candidates for the construction of supramolecular architectures. Two new transition metal complexes, namely poly[diaqua(μ4-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(μ2-isophthalato)dicobalt(II)], [Co(C8H4O4)(C34H28N6O2)0.5(H2O)]n, (1), and poly[diaqua(μ4-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(μ2-isophthalato)dicadmium(II)], [Cd(C8H4O4)(C34H28N6O2)0.5(H2O)]n, have been constructed using a symmetricN-donor ligand and a carboxylate ligand under hydrothermal conditions. X-ray crystallographic studies reveal that complexes (1) and (2) are isostructural, both of them exhibiting three-dimensional supramolecular architectures built by hydrogen bonds in which the coordinated water molecules serve as donors, while the O atoms of the carboxylate groups act as acceptors. Furthermore, (1) and (2) have been characterized by elemental, IR spectroscopic, powder X-ray diffraction (PXRD) and thermogravimetric analyses. The UV–Vis absorption spectrum of complex (1) has also been investigated.
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Benmansour, Samia, Antonio Hernández-Paredes, Kilian Defez-Aznar i Carlos J. Gómez-García. "Two-Dimensional Lattices with Lanthanoids, Anilato Ligands and Formamide". Crystals 13, nr 6 (11.06.2023): 939. http://dx.doi.org/10.3390/cryst13060939.
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Here, we illustrate the use of formamide (fma) and anilato-type ligands to build two-dimensional lattices with lanthanoids. Thus, we describe the synthesis and crystal structure of four lattices formulated as [Ln2(C6O4X2)3(fma)6]·6fma with Ln/X = La/Cl (1), La/Br (2), Eu/Cl (3), and Eu/Br (4), where C6O4X22− = dianion of 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone with X = Cl (chloranilato) and X = Br (bromanilato). Single crystal X-ray analysis shows that the four compounds crystallize in the triclinic P-1 space group and present two-dimensional, very distorted hexagonal lattices with the lanthanoids ions in the vertex coordinated by three anilato ligands forming the sides of the distorted hexagons that appear as rectangles. The rectangles are disposed parallel to their long sides in a brick wall fashion. The nona-coordination of the lanthanoids is completed by three formamide molecules. These layered compounds include three additional formamide molecules per lanthanoid atom, located in the interlayer space inside the channels formed by the eclipsed packing of the layers. We discuss the differences observed among these compounds due to the change of the lanthanoid ion (La and Eu) and of the substituent group X in the anilato ligand (Cl and Br).
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Danilescu, Olga, Paulina N. Bourosh, Oleg Petuhov, Olga V. Kulikova, Ion Bulhac, Yurii M. Chumakov i Lilia Croitor. "Crystal Engineering of Schiff Base Zn(II) and Cd(II) Homo- and Zn(II)M(II) (M = Mn or Cd) Heterometallic Coordination Polymers and Their Ability to Accommodate Solvent Guest Molecules". Molecules 26, nr 8 (16.04.2021): 2317. http://dx.doi.org/10.3390/molecules26082317.
Pełny tekst źródłaStreszczenie:
Based on solvothermal synthesis, self-assembly of the heptadentate 2,6-diacetylpyridine bis(nicotinoylhydrazone) Schiff base ligand (H2L) and Zn(II) and/or Cd(II) salts has led to the formation of three homometallic [CdL]n (1), {[CdL]∙0.5dmf∙H2O}n (2) and {[ZnL]∙0.5dmf∙1.5H2O}n (3), as well as two heterometallic {[Zn0.75Cd1.25L2]∙dmf∙0.5H2O}n (4) and {[MnZnL2]∙dmf∙3H2O}n coordination polymers. Compound 1 represents a 1D chain, whereas 2–5 are isostructural and isomorphous two-dimensional structures. The entire series was characterized by IR spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction and emission measurements. 2D coordination polymers accommodate water and dmf molecules in their cage-shaped interlayer spaces, which are released when the samples are heated. Thus, three solvated crystals were degassed at two temperatures and their photoluminescent and adsorption–desorption properties were recorded in order to validate this assumption. Solvent-free samples reveal an increase in volume pore, adsorption specific surface area and photoluminescence with regard to synthesized crystals.
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Ni, Sheng Liang, Yue Meng i Pei Song Tang. "Synthesis and Crystal Structure of [Zn(C14H12N2)(HCO2)2]•2H2O". Advanced Materials Research 279 (lipiec 2011): 174–78. http://dx.doi.org/10.4028/www.scientific.net/amr.279.174.
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Reactions of a freshly prepared Zn(OH)2-2x(CO3)x×yH2O precipitate, formic acid with 2,9’-dimethyl-1,10’-phenanthroline in CH3OH/H2O afforded [Zn(C14H12N2)(HCO2)2]·2H2O. The title compound was structurally characterized by X-ray diffraction methods. It consists of complex molecules [Zn(C14H12N2)(HCO2)2] in which Zn atoms are hexa-coordinated by two N atoms of one phenanthroline ligand and four O atoms of two bidentate formate groups. In the crystal, molecules are connected by O–H···O hydrogen bonds forming layers parallel to (010), and the resulting layers are further linked 3D framework along [100] by π-π packing interactions.
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Jiang, Jian, Peng Liang, Huiyuan Yu i Zhonglu You. "Synthesis, Crystal Structures and Urease Inhibition of Mononuclear Copper(II) and Nickel(". Acta Chimica Slovenica 69, nr 3 (26.09.2022): 629–37. http://dx.doi.org/10.17344/acsi.2022.7513.
Pełny tekst źródłaStreszczenie:
Three mononuclear copper(II) and nickel(II) complexes, [Cu(L1)(NCS)(CH3OH)] (1), [Cu(L2)(NCS)] (2) and [Ni(L2) (N3)] (3), where L1 and L2 are the monoanionic forms of the Schiff bases N’-(pyridin-2-ylmethylene)picolinohydrazide (HL1) and 4-methyl-2-(((pyridin-2-ylmethyl)imino)methyl)phenol (HL2), have been prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy, as well as single crystal X-ray diffraction studies. The Cu atom in complex 1 is in a square pyramidal coordination, with the three N atoms of the ligand L and the N atom of the thiocyanate ligand in the basal plane, and with the methanol O atom at the apical position. The Cu and Ni atoms in complexes 2 and 3 are in square planar coordination, with the three donor atoms of the Schiff base ligands and the terminal N atoms of thiocyanate and azide ligands. Complexes 1 and 2 inhibit the Jack bean urease with IC50 value of 0.33 ± 0.12 and 0.39 ± 0.10 μmol L–1, respectively. Molecular docking study was performed to investigate the interaction between the complexes and the enzyme.
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Martinez-Martin, Paloma, Josefina Perles i Juan Carlos Rodriguez-Ubis. "Crystal Structure Dependence of the Energy Transfer from Tb(III) to Yb(III) in Metal–Organic Frameworks Based in Bispyrazolylpyridines". Crystals 10, nr 2 (27.01.2020): 69. http://dx.doi.org/10.3390/cryst10020069.
Pełny tekst źródłaStreszczenie:
Luminescent mixed lanthanide metal−organic framwork (MOF) materials have been prepared from two polyheterocyclic diacid ligands, 2,6-bis(3-carboxy-1-pyrazolyl)pyridine and 2,6-bis(4-carboxy-1-pyrazolyl)pyridine. The crystal structures of the two organic molecules are presented together with the structures for the MOFs obtained by hydrothermal synthesis either with Yb(III) or mixed Tb(III)/Yb(III) ions. Different coordination architectures result from each ligand, revealing also important differences between the lanthanides. The mixed lanthanide metal−organic frameworks also present diverse luminescent behavior; in the case of 2,6-bis(4-carboxy-1-pyrazolyl)pyridine, where no coordinated water is present in the metal environment, Tb(III) and Yb(III) characteristic emission is observed by excitation of the bispyrazolylpyridine chromophore.
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Thoelen, Felix, i Walter Frank. "Crystal engineering with short-chained amphiphiles: decasodium octa-n-butanesulfonate di-μ-chlorido-bis[dichloridopalladate(II)] tetrahydrate, a layered inorganic–organic hybrid material". Acta Crystallographica Section E Crystallographic Communications 75, nr 5 (2.04.2019): 557–61. http://dx.doi.org/10.1107/s2056989019004201.
Pełny tekst źródłaStreszczenie:
In the course of crystal-engineering experiments, crystals of the hydrated title salt, Na10[Pd2Cl6](C4H9SO3)8·4H2O, were obtained from a water/2-propanol solution of sodium n-butanesulfonate and sodium tetrachloridopalladate(II). In the crystal, sodium n-butanesulfonate anions and water molecules are arranged in an amphiphilic inverse bilayered cationic array represented by the formula {[Na10(C4H9SO3)8(H2O)4]2+} n . Within this lamellar array: (i) a hydrophilic layer region parallel to the bc plane is established by the Na+ cations, the H2O molecules (as aqua ligands in κNa,κNa′-bridging coordination mode) and the O3S– groups of the sulfonate ions, and (ii) hydrophobic regions are present containing all the n-butyl groups in an almost parallel orientation, with the chain direction approximately perpendicular to the aforementioned hydrophilic layer. Unexpectedly, the flat centrosymmetric [Pd2Cl6]2− anion in the structure is placed between the butyl groups, within the hydrophobic regions, but due to its appropriate length primarily bonded to the hydrophilic `inorganic' layer regions above and below the hydrophobic area via Pd—Clt...Na- and Pd—Clt...H—O(H)—Na-type (Clt is terminal chloride) interactions. In addition to these hydrogen-bonding interactions, both aqua ligands are engaged in charge-supported S—O...H—O hydrogen bonds of a motif characterized by the D 4 3(9) graph-set descriptor within the hydrophilic region. The crystal structure of the title compound is the first reported for a metal n-butanesulfonate.
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Liu, Yang, Yong-Lan Feng i Wei-Wei Fu. "A two-dimensional zinc(II) coordination polymer based on mixed dimethyl succinate and bipyridine ligands: synthesis, structure, thermostability and luminescence properties". Acta Crystallographica Section C Structural Chemistry 72, nr 4 (16.03.2016): 308–12. http://dx.doi.org/10.1107/s2053229616003211.
Pełny tekst źródłaStreszczenie:
From the viewpoint of crystal engineering, the construction of crystalline polymeric materials requires a rational choice of organic bridging ligands for the self-assembly process. Multicarboxylate ligands are of particular interest due to their strong coordination activity towards metal ions, as well as their various coordination modes and versatile conformations. The structural chemistry of dicarboxylate-based coordination polymers of transition metals has been developed through the grafting of N-containing organic linkers into carboxylate-bridged transition metal networks. A new luminescent two-dimensional zinc(II) coordination polymer containing bridging 2,2-dimethylsuccinate and 4,4′-bipyridine ligands, namely poly[[aqua(μ2-4,4′-bipyridine-κ2N:N′)bis(μ3-2,2-dimethylbutanedioato)-κ4O1,O1′:O4:O4′;κ5O1:O1,O4:O4,O4′-dizinc(II)] dihydrate], {[Zn2(C6H8O4)2(C10H8N2)(H2O)]·2H2O}n, has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction and elemental, IR and thermogravimetric analyses. In the structure, the 2,2-dimethylsuccinate ligands link linear tetranuclear ZnIIsubunits into one-dimensional chains along thecaxis. 4,4′-Bipyridine acts as a tethering ligand expanding these one-dimensional chains into a two-dimensional layered structure. Hydrogen-bonding interactions between the water molecules (both coordinated and free) and carboxylate O atoms strengthen the packing of the layers. Furthermore, the luminescence properties of the complex were investigated. The compound exhibits a blue photoluminescence in the solid state at room temperature and may be a good candidate for potential hybrid inorganic–organic photoactive materials.
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Soliman, Saied M., Jamal Lasri, Matti Haukka, Essam N. Sholkamy, Hessa H. Al-Rasheed i Ayman El-Faham. "Synthesis, X-ray Crystal Structure and Antimicrobial Activity of Unexpected Trinuclear Cu(II) Complex from s-Triazine-Based Di-Compartmental Ligand via Self-Assembly". Crystals 9, nr 12 (9.12.2019): 661. http://dx.doi.org/10.3390/cryst9120661.
Pełny tekst źródłaStreszczenie:
The synthesis and X-ray crystal structure of the trinuclear [Cu3(HL)(Cl)2(NO3)(H2O)5](NO3)2 complex of the s-triazine-based di-compartmental ligand, 2-methoxy-4,6-bis(2-(pyridin-2-ylmsethylene)hydrazinyl)-1,3,5-triazine (H2L), are presented. The Cu1 and Cu2 are penta-coordinated with CuN3ClO coordination environment, distorted square pyramidal coordination geometry while Cu3 is hexa-coordinated with CuN2O4 coordination sphere, and distorted octahedral geometry. The complex crystallized in the primitive P-1 triclinic crystal system with two molecular units per unit cell. Its packing is dominated by the O–H (35.5%) and Cl–H (8.8%) hydrogen bonding interactions as well as the π–π stacking (2.3%) and anion–π-stacking interactions (3.7%). The different coordination interactions were analyzed using atoms in molecules (AIM) theory, and the number of charge transferences from the ligand group to Cu(II) were determined using natural bond orbital calculations. The effect of the free ligand and its Cu(II) complex on the tested pathogenic microbes (Staphylococcus aureus, S. epidermidis, Enterococcus faecalis, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa) and one fungal isolate (Candida albicans) is presented. Both have wide spectrum antimicrobial activity against the selected microorganism. It is observed that the free ligand at 180 µg/mL was more effective than its Cu(II) complex and showed close results compared to the positive control gentamicin. At higher concentrations (1 mg/mL), the Cu(II) complex was found to be more active against S. epidermidis, E. coli and C. albicans than the lower concentration. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values are also lower for the Cu(II) complex than the free ligand.
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Srivastava, Devyani, Om Prakash, Gabriele Kociok-Köhn, Abhinav Kumar, Abdullah Alarifi, Naaser A. Y. Abduh, Mohd Afzal i Mohd Muddassir. "Centrosymmetric Nickel(II) Complexes Derived from Bis-(Dithiocarbamato)piperazine with 1,1′-Bis(diphenylphosphino)ferrocene and 1,2-Bis(diphenylphosphino)ethane) as Ancillary Ligands: Syntheses, Crystal Structure and Computational Studies". Crystals 13, nr 2 (17.02.2023): 343. http://dx.doi.org/10.3390/cryst13020343.
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Two Ni(II) complexes with the formula [{Ni(dppf)}2{(L1)2}](PF6)2 (Ni-I) and [{Ni(dppe)}2{(L1)2}](PF6)2 (Ni-II) were prepared by reacting [Ni(dppf)Cl2] and [Ni(dppe)Cl2] (dppf = 1,1′-Bis(diphenylphosphino)ferrocene; dppe = 1,2-Bis(diphenylphosphino)ethane) with secondary amine piperazine derived ligand disodium bis-(dithiocarbamate)piperazine ((piper(dtc)2 = L1) and counter anion PF6−. These complexes were characterized by elemental analyses, FT-IR, 1H, 13C and 31P NMR, UV-Vis. spectroscopy and single crystal X-ray diffraction. The X-ray analyses reveal centrosymmetric structures where each Ni(II) centre adopts distorted square planar geometry defined by two sulfur centres of dithiocarbamate ligand and two phosphorus centres of dppf and dppe ligands in Ni-I and Ni-II, respectively. The supramolecular framework of both Ni-I and Ni-II are sustained by C-H⋯π and C-H⋯F interactions, and they also display interesting intramolecular C-H⋯Ni anagostic interactions. Further, the nature of these interactions are studied using Hirshfeld surface analyses, DFT and quantum theory of atoms in molecules (QTAIM) calculations. Additionally, non-covalent interaction (NCI) plot analyses were conducted to gain additional insight into these non-covalent interactions. This work is vital in a new approach towards the rational designing of the centrosymmetric molecules with interesting architectures.
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Yapryntsev, A. D., A. E. Baranchikov, A. V. Churakov, G. P. Kopitsa, A. A. Silvestrova, M. V. Golikova, O. S. Ivanova, Yu E. Gorshkova i V. K. Ivanov. "The first amorphous and crystalline yttrium lactate: synthesis and structural features". RSC Advances 11, nr 48 (2021): 30195–205. http://dx.doi.org/10.1039/d1ra05923h.
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The synthesis and crystal structure of the first molecular yttrium lactate complex, Y(Lac)3(H2O)2, is reported, where the coordination sphere of yttrium is saturated with lactate ligands and water molecules, resulting in a neutral moiety.
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Altowyan, Mezna Saleh, Eman M. Fathalla, Dalia Hawas, Jörg H. Albering, Assem Barakat, Morsy A. M. Abu-Youssef, Saied M. Soliman, Taher S. Kassem i Ahmed M. A. Badr. "Synthesis, X-ray, Hirshfeld, and AIM Studies on Zn(II) and Cd(II) Complexes with Pyridine Ligands". Crystals 12, nr 5 (22.04.2022): 590. http://dx.doi.org/10.3390/cryst12050590.
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The synthesis and crystal structures of three heteroleptic complexes of Zn(II) and Cd(II) with pyridine ligands (ethyl nicotinate (EtNic), N,N-diethylnicotinamide (DiEtNA), and 2-amino-5-picoline (2Ampic) are presented. The complex [Zn(EtNic)2Cl2] (1) showed a distorted tetrahedral coordination geometry with two EtNic ligand units and two chloride ions as monodentate ligands. Complexes [Zn(DiEtNA)(H2O)4(SO4)]·H2O (2) and [Cd(OAc)2(2Ampic)2] (3) had hexa-coordinated Zn(II) and Cd(II) centers. In the former, the Zn(II) was coordinated with three different monodentate ligands, which were DiEtNA, H2O, and SO42−. In 3, the Cd(II) ion was coordinated with two bidentate acetate ions and two monodentate 2Ampic ligand units. The supramolecular structures of the three complexes were elucidated using Hirshfeld analysis. In 1, the most important interactions that governed the molecular packing were O···H (15.5–15.6%), Cl···H (13.6–13.8%), Cl···C (6.3%), and C···H (10.3–10.6%) contacts. For complexes 2 and 3, the H···H, O···H, and C···H contacts dominated. Their percentages were 50.2%, 41.2%, and 7.1%, respectively, for 2 and 57.1%, 19.6%, and 15.2%, respectively, for 3. Only in complex 3, weak π-π stacking interactions between the stacked pyridines were found. The Zn(II) natural charges were calculated using the DFT method to be 0.8775, 1.0559, and 1.2193 for complexes 1–3, respectively. A predominant closed-shell character for the Zn–Cl, Zn–N, Zn–O, Cd–O, and Cd–N bonds was also concluded from an atoms in molecules (AIM) study.
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Sakaguchi, Kazuha, Biao Zhou, Yuki Idobata, Hajime Kamebuchi i Akiko Kobayashi. "Syntheses, Structures, and Physical Properties of Neutral Gold Dithiolate Complex, [Au(etdt)2]·THF". Crystals 10, nr 11 (4.11.2020): 1001. http://dx.doi.org/10.3390/cryst10111001.
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In order to develop new types of single-component molecular conductors with novel electronic structures and physical properties, the neutral gold dithiolate complex with an etdt (= ethylenedithiotetrathiafulvalenedithiolate) ligand, [Au(etdt)2] was prepared. However, unlike the reported single-component molecular metals, the neutral gold complex [Au(etdt)2]·THF (2) contains a solvent molecule of tetrahydrofuran (THF). The crystals of 2 form a two-dimensional conducting layer structure, which are separated by the terminal ethylene groups and THF molecules. The fairly high room-temperature conductivity of 0.2 S/cm and semiconducting behavior with a low activation energy of 0.1 eV of 2, is consistent with the result of the density functional theory band structure calculations. The observed non-magnetic behavior of 2 is caused from the dimeric structure of [Au(etdt)2] molecules.
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Kanelidis, Ioannis, i Tobias Kraus. "The role of ligands in coinage-metal nanoparticles for electronics". Beilstein Journal of Nanotechnology 8 (7.12.2017): 2625–39. http://dx.doi.org/10.3762/bjnano.8.263.
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Coinage-metal nanoparticles are key components of many printable electronic inks. They can be combined with polymers to form conductive composites and have been used as the basis of molecular electronic devices. This review summarizes the multidimensional role of surface ligands that cover their metal cores. Ligands not only passivate crystal facets and determine growth rates and shapes; they also affect size and colloidal stability. Particle shapes can be tuned via the ligand choice while ligand length, size, ω-functionalities, and chemical nature influence shelf-life and stability of nanoparticles in dispersions. When particles are deposited, ligands affect the electrical properties of the resulting film, the morphology of particle films, and the nature of the interfaces. The effects of the ligands on sintering, cross-linking, and self-assembly of particles in electronic materials are discussed.
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D’Vries, Richard F., Germán E. Gomez i Javier Ellena. "Highlighting Recent Crystalline Engineering Aspects of Luminescent Coordination Polymers Based on F-Elements and Ditopic Aliphatic Ligands". Molecules 27, nr 12 (14.06.2022): 3830. http://dx.doi.org/10.3390/molecules27123830.
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Three principal factors may influence the final structure of coordination polymers (CPs): (i) the nature of the ligand, (ii) the type and coordination number of the metal center, and (iii) the reaction conditions. Further, flexible carboxylate aliphatic ligands have been widely employed as building blocks for designing and synthesizing CPs, resulting in a diverse array of materials with exciting architectures, porosities, dimensionalities, and topologies as well as an increasing number of properties and applications. These ligands show different structural features, such as torsion angles, carbon backbone number, and coordination modes, which affect the desired products and so enable the generation of polymorphs or crystalline phases. Additionally, due to their large coordination numbers, using 4f and 5f metals as coordination centers combined with aliphatic ligands increases the possibility of obtaining different crystal phases. Additionally, by varying the synthetic conditions, we may control the production of a specific solid phase by understanding the thermodynamic and kinetic factors that influence the self-assembly process. This revision highlights the relationship between the structural variety of CPs based on flexible carboxylate aliphatic ligands and f-elements (lanthanide and actinides) and their outstanding luminescent properties such as solid-state emissions, sensing, and photocatalysis. In this sense, we present a structural analysis of the CPs reported with the oxalate ligand, as the one rigid ligand of the family, and other flexible dicarboxylate linkers with –CH2– spacers. Additionally, the nature of the luminescence properties of the 4f or 5f-CPs is analyzed, and finally, we present a novel set of CPs using a glutarate-derived ligand and samarium, with the formula [2,2′-bipyH][Sm(HFG)2 (2,2′-bipy) (H2O)2]•(2,2′-bipy) (α-Sm) and [2,2′-bipyH][Sm(HFG)2 (2,2′-bipy) (H2O)2] (β-Sm).
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Delgado-Martínez, Patricia, Luis Moreno-Martínez, Rodrigo González-Prieto, Santiago Herrero, José L. Priego i Reyes Jiménez-Aparicio. "Steric, Activation Method and Solvent Effects on the Structure of Paddlewheel Diruthenium Complexes". Applied Sciences 12, nr 3 (19.01.2022): 1000. http://dx.doi.org/10.3390/app12031000.
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Conventional heating and solvothermal synthetic methods (with or without microwave activation) have been used to study the reaction of o-, m- and p-methoxybenzoic acid with [Ru2Cl(μ-O2CMe)4]. The tetrasubstituted series [Ru2Cl(µ-O2CC6H4-R)4], with R = o-OMe, m-OMe and p-OMe, has been prepared by the three procedures. Depending on the synthetic method and the experimental conditions, three compounds have been isolated (1a, 1b, 1c) with the o-methoxybenzoate ligand. However, with the m- and p-methoxybenzoate ligands, only the complexes 2 and 3 have been obtained, respectively. Compound 1a, with stoichiometry [Ru2Cl(µ-O2CC6H4-o-OMe)4]n, shows a polymeric structure with the chloride ions bridging the diruthenium units to form linear chains. Compounds 2 and 3, with the same stoichiometry, predictably form zig-zag chains in accordance with their insolubility and their magnetic measurements. Compound 1b, [Ru2Cl(µ-O2CC6H4-o-OMe)4(EtOH)], is a discrete molecular species with a chloride ion and one ethanol molecule occupying the axial positions of the dimetallic unit. Compound 1c is a cation-anion complex, [Ru2(µ-O2CC6H4-o-OMe)4(MeOH)2][Ru2Cl2(µ-O2CC6H4-o-OMe)4]. The cationic complex has two solvent molecules at the axial positions whereas the anionic complex has two chloride ligands at these positions. Complexes have been characterized by elemental analyses, mass spectrometry and IR and UV-vis-NIR spectroscopies. A magnetic study of complexes 1a, 1b, 2 and 3 have also been carried out. The crystal structure of compounds 1b and 1c have been solved by single X-ray crystal methods.
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Mirtamizdoust, Babak, Amirhossein Karamad, Negin Rahmani, Younes Hanifehpour i Sang Woo Joo. "Synthesis, Characterization and DFT Calculation of Naphthalene-Based Crystal Structure with Pyridylimine-Binding Units". Crystals 13, nr 7 (19.07.2023): 1129. http://dx.doi.org/10.3390/cryst13071129.
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This study focuses on the synthesis, characterization, and properties of a yellowish, prism-shaped ligand, N,N′-(naphthalene-1,5-diyl) bis(1-(pyridin-2-yl) methanimine). The ligand was synthesized through refluxing 1,5-diaminonaphthalene and pyridine-2-carbaldehyde in extra-pure ethanol, employing X-ray diffraction on single crystal. The crystal is structured with two pyridylimine-binding units linked to a naphthalene. The crystal has a P21/c space group in a monoclinic system. The structure was confirmed through an infrared examination. Computational spectroscopy and theoretical methods were used to investigate the ligand HOMO, LUMO, and charge distribution. Additionally, a Hirshfeld analysis was performed to investigate noncovalent interactions in the crystalline form. The results showed that dispersion forces (H···H) were the primary factor contributing to the arrangement of the ligand molecule, accounting for 45.3% of the total interactions in the absence of hydrogen bonding. Overall, this study provides valuable insights into the synthesis, characterization, and properties of this unique ligand.
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Wu, Dong-Fang, Kiyonori Takahashi, Masaru Fujibayashi, Naoto Tsuchiya, Goulven Cosquer, Rui-Kang Huang, Chen Xue, Sadafumi Nishihara i Takayoshi Nakamura. "Fluoride-bridged dinuclear dysprosium complex showing single-molecule magnetic behavior: supramolecular approach to isolate magnetic molecules". RSC Advances 12, nr 33 (2022): 21280–86. http://dx.doi.org/10.1039/d2ra04119g.
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(Na+)(benzo[18]crown-6) forms a bamboo-like supramolecular architecture within the crystal. Dinuclear Dy complexes with polyoxometalate ligands embedded between bamboo nodes exhibited a clear single-molecule magnet (SMM) response.
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Altowyan, Mezna Saleh, Jörg H. Albering, Assem Barakat, Saied M. Soliman i Morsy A. M. Abu-Youssef. "Synthesis, Supramolecular Structural Investigations of Co(II) and Cu(II) Azido Complexes with Pyridine-Type Ligands". Crystals 13, nr 2 (17.02.2023): 346. http://dx.doi.org/10.3390/cryst13020346.
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Two new Co(II) and Cu(II) azido complexes with 4-picoline (4-Pic) and pyridine-2-carboxaldoxime (HAld) were synthesized by self-assembly of the organic ligand and the M(II) nitrate in the presence of azide as a co-ligand. Their structures were determined to be [Co(4-Pic)4(H2O)(N3)]NO3*H2O*4-Pic (1) and [Cu(HAld)(Ald)(N3)] (2) using X-ray single crystal diffraction. In complex 1, the coordination geometry is a slightly distorted octahedron with a water molecule and azide ion located trans to one another. On the other hand, complex 2 has a distorted square pyramid CuN5 coordination sphere with N-atoms of the organic ligand as a basal plane and azide ion as apical. All types of intermolecular contacts and their contributions in the molecular packing were analyzed using Hirshfeld analysis. The intermolecular contacts, H…H (53.9%), O…H (14.1%), N…H (11.0%) and H…C (18.8%) in 1, and H…H (27.4%), N…H (27.7%), O…H (14.7%) and H…C (13.6%) in 2 have the largest contributions. Of all the contacts, the O…H, N…H and C…C interactions in 2 and the O…H, N…H and H…C in 1 are apparently shorter than the van der Waals radii sum of the interacting atoms. Atoms in molecules (AIM) topological parameters explained the lower symmetry of the coordinated azide in 1 than 2.
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Nikiforova, Marina E., Dmitriy S. Yambulatov, Yulia V. Nelyubina, Petr V. Primakov, Olga B. Bekker, Konstantin B. Majorov, Maxim A. Shmelev, Andrey V. Khoroshilov, Igor L. Eremenko i Irina A. Lutsenko. "Current Design of Mixed-Ligand Complexes of Magnesium(II): Synthesis, Crystal Structure, Thermal Properties and Biological Activity against Mycolicibacterium Smegmatis and Bacillus Kochii". Crystals 13, nr 9 (27.08.2023): 1306. http://dx.doi.org/10.3390/cryst13091306.
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The interaction of Mg2+ with 2-furoic acid (HFur) and oligopyridines, depending on the synthesis conditions, leads to the formation of mixed-ligand complexes [Mg(H2O)4(phen)]·2HFur·phen·H2O (1), [Mg(NO3)2(phen)2] (2) and [Mg3(Fur)6(bpy)2]·3CH3CN (3); these structures were determined with an SC X-ray analysis. According to the X-ray diffraction data, in complex 1, obtained in ambient conditions, the magnesium cation coordinated four water molecules and one phenanthroline fragment, while in complexes 2 and 3 (synthesized in an inert atmosphere), the ligand environment of the complexing agent was represented by neutral oligopyridine molecules and acid anions. The thermal behavior of 1 and 2 was studied using a simultaneous thermal analysis (STA). The in vitro biological activity of complexes 1–3 was studied in relation to the non-pathogenic Mycolicibacterium smegmatis and the virulent strain Mycobacterium tuberculosis H37Rv.
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Wang, Ai, i Ulli Englert. "N—H...X (X = Cl and Br) hydrogen bonds in three isomorphous 3,5-dichloropyridinium salts". Acta Crystallographica Section C Structural Chemistry 73, nr 10 (25.09.2017): 803–9. http://dx.doi.org/10.1107/s2053229617013201.
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Specific short contacts are important in crystal engineering. Hydrogen bonds have been particularly successful and together with halogen bonds can be useful for assembling small molecules or ions into crystals. The ionic constituents in the isomorphous 3,5-dichloropyridinium (3,5-diClPy) tetrahalometallates 3,5-dichloropyridinium tetrachloridozincate(II), (C5H4Cl2N)2[ZnCl4] or (3,5-diClPy)2ZnCl4, 3,5-dichloropyridinium tetrabromidozincate(II), (C5H4Cl2N)2[ZnBr4] or (3,5-diClPy)2ZnBr4, and 3,5-dichloropyridinium tetrabromidocobaltate(II), (C5H4Cl2N)2[CoBr4] or (3,5-diClPy)2CoBr4, arrange according to favourable electrostatic interactions. Cations are preferably surrounded by anions and vice versa; rare cation–cation contacts are associated with an antiparallel dipole orientation. N—H...X (X = Cl and Br) hydrogen bonds and X...X halogen bonds compete as closest contacts between neighbouring residues. The former dominate in the title compounds; the four symmetrically independent pyridinium N—H groups in each compound act as donors in charge-assisted hydrogen bonds, with halogen ligands and the tetrahedral metallate anions as acceptors. The M—X coordinative bonds in the latter are significantly longer if the halide ligand is engaged in a classical X...H—N hydrogen bond. In all three solids, triangular halogen-bond interactions are observed. They might contribute to the stabilization of the structures, but even the shortest interhalogen contacts are only slightly shorter than the sum of the van der Waals radii.
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García-García, Amalia, Andoni Zabala-Lekuona, Ainhoa Goñi-Cárdenas, Javier Cepeda, José M. Seco, Alfonso Salinas-Castillo, Duane Choquesillo-Lazarte i Antonio Rodríguez-Diéguez. "Magnetic and Luminescent Properties of Isostructural 2D Coordination Polymers Based on 2-Pyrimidinecarboxylate and Lanthanide Ions". Crystals 10, nr 7 (2.07.2020): 571. http://dx.doi.org/10.3390/cryst10070571.
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A couple of isostructural coordination polymers with the general formula [Ln4(pymca)4(AcO)8]n have been obtained from reactions between pyrimidine-2-carboxylate (pymca) ligand and rare-earth ions (Ln = Dy (1), Nd (2)). These two-dimensional compounds have been characterized and the crystal structures have been solved by single-crystal X-ray diffraction technique, resulting in layers along the bc plane based on pymca and acetate anions that act as bridging ligands between metal atoms. Given that pymca and acetate anions possess carboxylate and hetero-nitrogen groups, it is possible to build a coordination polymer whose metal centers have a nine coordination. Furthermore, static and dynamic magnetic measurements of compound 1 reveal the lack of single molecule-magnet (SMM) behavior in this system due to the following two effects: (i) the ligand field does not stabilize magnetic ground states well separated from excited states, and (ii) anisotropy axes are not collinear, according to results with Magellan software. On another level, luminescent properties of compounds 1 and 2 are attributed to singlet π-π* transitions centered on pymca ligand as corroborated by time-dependent density functional theory (TD-DFT) calculations.
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Tiekink, Edward. "Exploring the Topological Landscape Exhibited by Binary Zinc-triad 1,1-dithiolates". Crystals 8, nr 7 (14.07.2018): 292. http://dx.doi.org/10.3390/cryst8070292.
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The crystal chemistry of the zinc-triad binary 1,1-dithiolates, that is, compounds of xanthate [−S2COR], dithiophosphate [−S2P(OR)2], and dithiocarbamate [−S2CNR2] ligands, is reviewed. Owing to a wide range of coordination modes that can be adopted by 1,1-dithiolate anions, such as monodentate, chelating, μ2-bridging, μ3-bridging, etc., there exists a rich diversity in supramolecular assemblies for these compounds, including examples of zero-, one-, and two-dimensional architectures. While there are similarities in structural motifs across the series of 1,1-dithiolate ligands, specific architectures are sometimes found, depending on the metal centre and/or on the 1,1-dithiolate ligand. Further, an influence of steric bulk upon supramolecular aggregation is apparent. Thus, bulky R groups generally preclude the close approach of molecules in order to reduce steric hindrance and therefore, lead to lower dimensional aggregation patterns. The ligating ability of the 1,1-dithiolate ligands also proves crucial in determining the extent of supramolecular aggregation, in particular for dithiocarbamate species where the relatively greater chelating ability of this ligand reduces the Lewis acidity of the zinc-triad element, which thereby reduces its ability to significantly expand its coordination number. Often, the functionalisation of the organic substituents in the 1,1-dithiolate ligands, for example, by incorporating pyridyl groups, can lead to different supramolecular association patterns. Herein, the diverse assemblies of supramolecular architectures are classified and compared. In all, 27 structurally distinct motifs have been identified.