Journal articles: 'Interaction cation-π'

1

Dougherty, Dennis A. "The Cation−π Interaction." Accounts of Chemical Research 46, no. 4 (December 7, 2012): 885–93. http://dx.doi.org/10.1021/ar300265y.

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2

Ma, Jennifer C., and Dennis A. Dougherty. "The Cation−π Interaction." Chemical Reviews 97, no. 5 (August 1997): 1303–24. http://dx.doi.org/10.1021/cr9603744.

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Prampolini, Giacomo, Marco d'Ischia, and Alessandro Ferretti. "The phenoxyl group-modulated interplay of cation–π and σ-type interactions in the alkali metal series." Physical Chemistry Chemical Physics 22, no. 46 (2020): 27105–20. http://dx.doi.org/10.1039/d0cp03707a.

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An extensive exploration of the interaction PESs of phenol and catechol complexes with alkali metal cations reveals a striking effect of –OH substitution on the balance between cation-π and σ-type noncovalent interactions.

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4

Arnal-Herault, Carole, Mihail Barboiu, Eddy Petit, Mathieu Michau, and Arie van der Lee. "Cation–π interaction: a case for macrocycle–cation π-interaction by its ureidoarene counteranion." New Journal of Chemistry 29, no. 12 (2005): 1535. http://dx.doi.org/10.1039/b509240j.

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5

Ortolan, Alexandre O., Giovanni F. Caramori, Gernot Frenking, and Alvaro Muñoz-Castro. "Role of the cation formal charge in cation–π interaction. A survey involving the [2.2.2]paracyclophane host from relativistic DFT calculations." New Journal of Chemistry 39, no. 12 (2015): 9963–68. http://dx.doi.org/10.1039/c5nj02384j.

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6

Said, Musa A., Mohamed R. Aouad, David L. Hughes, Meshal A. Almehmadi, and Mouslim Messali. "Synthesis and crystal structure of a new pyridinium bromide salt: 4-methyl-1-(3-phenoxypropyl)pyridinium bromide." Acta Crystallographica Section E Crystallographic Communications 73, no. 12 (November 3, 2017): 1831–34. http://dx.doi.org/10.1107/s2056989017015481.

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In the cation of the title molecular salt, C15H18NO+·Br−, the pyridinium and phenyl rings are inclined to one another by 11.80 (8)°. In the crystal, the Br−anion is linked to the cation by a C—H...Br hydrogen bond. The cations stack along theb-axis direction and are linked by further C—H...Br interactions, and offset π–π interactions [intercentroid distances = 3.5733 (19) and 3.8457 (19) Å], forming slabs parallel to theabplane. The effects of the C—H...X−interaction on the NMR signals of theortho-andmeta-pyridinium protons in a series of related ionic liquids,viz. 4-methyl-1-(4-phenoxybutyl)pyridin-1-ium salts, are reported and discussed.

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7

Kim, Hee-Joon. "Assembly of Sn(IV)-Porphyrin Cation Exhibiting Supramolecular Interactions of Anion···Anion and Anion···π Systems." Molbank 2022, no. 4 (September 25, 2022): M1454. http://dx.doi.org/10.3390/m1454.

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Trans-diaqua[meso-tetrakis(4-pyridyl)porphyrinato]Sn(IV) dinitrate complexes were assembled in a two-dimensional manner via hydrogen bonding between aqua ligands and pyridyl substituents. Interestingly, this supramolecular assembly was accompanied by unconventional noncovalent interactions, such as anion···anion and anion···π interactions, which were confirmed by X-ray crystallographic analysis. Two nitrate anions close to 2.070 Å were constrained in a confined space surrounded by four hydrogen-bonded Sn(IV)-porphyrin cations. The nitrate anion was also 3.433 Å away from the adjacent pyrrole ring, and the dihedral angle between the two mean planes was estimated to be 7.39°. The preference of the anion···π interaction was related to the electron-deficient π-system owing to the high-valent Sn(IV) center and cationic nature of the porphyrin complex. These two unconventional noncovalent interactions played an important role in the formation of a one-dimensional array with pairs of Sn(IV)-porphyrin cation and nitrate anion.

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Zhu, Yujie, Minmin Tang, Huibin Zhang, Faiz-Ur Rahman, Pablo Ballester, Julius Rebek, Christopher A. Hunter, and Yang Yu. "Water and the Cation−π Interaction." Journal of the American Chemical Society 143, no. 31 (July 30, 2021): 12397–403. http://dx.doi.org/10.1021/jacs.1c06510.

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9

Miao, Junjian, Bo Song, and Yi Gao. "Enhanced Aerogen-π Interaction by a Cation-π Force." Chemistry - A European Journal 22, no. 8 (January 21, 2016): 2586–89. http://dx.doi.org/10.1002/chem.201504210.

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10

Knop, Osvald, T. Stanley Cameron, Pradip K. Bakshi, Antony Linden, and Stephen P. Roe. "Crystal chemistry of tetraradial species. Part 5. Interaction between cation lone pairs and phenyl groups in tetraphenylborates: crystal structures of Me3S+,Et3S+,Me3SO+,Ph2I+, and 1-azoniapropellane tetraphenylborates." Canadian Journal of Chemistry 72, no. 8 (August 1, 1994): 1870–81. http://dx.doi.org/10.1139/v94-238.

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Determination of the crystal structures of the tetraphenylborates of the trimethylsulfonium (Me3S+,P21/n), triethylsulfonium (Et3S+,Cmcm), trimethylsulfoxonium (Me3SO+,P21/m), diphenyliodonium (Ph2I+,Pnma), and 1-azoniapropellane (C10H18N+,P21/n) cations has shown that when regions of high local electron density (lone electron pairs) are present in the cation, the cation orients itself so as to minimize the repulsion between the lone pair(s) and the nearest anion phenyl groups, i.e. the cation orientation responds to the lone pair – aromatic π system interaction. This behaviour contrasts with the formation of H …π hydrogen bonds in tetraphenylborates of organic ammonium cations containing N-hydrogens and provides corroborative evidence for our previous finding: (1) given the opportunity, a cation N-hydrogen will form a hydrogen bond to a phenyl group(s) of the anion; (2) the orientation of the cation to form the N—H(N) …π bond is thus a manifestation of a positive hydrogen-bonding tendency rather than a passive response to overall packing requirements in the crystal. The geometries of the above cations are compared to those reported in the literature and those of Me3S+ and Me3SO+ have also been optimized by ab initio (RHF/6-31G*) methods.

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11

Zarić, Snežana D. "Cation–π interaction with transition-metal complex as cation." Chemical Physics Letters 311, no. 1-2 (September 1999): 77–80. http://dx.doi.org/10.1016/s0009-2614(99)00805-2.

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12

Pook, Niels-Patrick. "Supramolecular Structure of Tris(1,10-phenanthroline)zinc(II)-Cation and N,N′,N″-tris(carboxymethyl)-1,3,5-benzenetricarboxamide-Anion: Synthesis, Crystal Structure, Vibrational Spectra, and Theoretical Investigations." Crystals 13, no. 4 (March 27, 2023): 569. http://dx.doi.org/10.3390/cryst13040569.

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The present work reports on the synthesis, structural, spectroscopic, and theoretical studies of a new solid state ionic compound mainly composed of tris(1,10-phenanthroline)zinc(II) cations and N,N′,N″-tris(carboxymethyl)-1,3,5-benzenetricarboxamide anions. Colorless and well-shaped crystals were obtained from an alkaline aqueous methanolic solution, and single-crystal X-ray diffraction revealed a distinct supramolecular network. Powder diffraction techniques and Rietveld analysis confirmed the phase purity of the crystalline probes. The compound crystallizes in the orthorhombic space group Pbca with a cell volume of 9517.0 Å3. The complex cations [Zn(phen)3]2+ are interconnected via π–π-interactions and form a cationic layer network with holes. The organic counterion, as a dianion, forms dimeric units through π–π-interactions and hydrogen bonds, which also form an anionic layer network with honeycomb-like holes through cooperative classical hydrogen bonds of the O∙∙∙H–O and O∙∙∙H–N type with attractive secondary electrostatic interactions. Using the holes, the resulting supramolecular framework can be described as an interpenetrated network of separate anionic and cationic layers linked by further weaker non-covalent interactions such as C–H∙∙∙π and lone-pair∙∙∙π interactions. DFT calculations confirmed the experimentally observed spectroscopic (IR and Raman) findings. For a deeper insight into the structural arrangement in the crystal, the different Hirshfeld surfaces of the cation and anion, the pairwise interaction energies as well as the energy framework were calculated, supporting the dominance of attractive and repulsive electrostatic forces between the ions.

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13

Hausen, H. D., Wolfgang Kaim, Andreas Schulz, Michael Moscherosch, and Jeanne Jordanov. "Erstmaliger Nachweis von π–π Dimerenbildung bei stabilen 1,4-Dialkylchinoxalinium-Radikalkationen. Struktur, Spektroskopie und Magnetismus / First Evidence for π-π-Dimerization of the Stable 1,4-Dialkylquinoxalinium Radical Cations. Structure, Spectroscopy and Magnetism." Zeitschrift für Naturforschung B 48, no. 9 (September 1, 1993): 1181–86. http://dx.doi.org/10.1515/znb-1993-0905.

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Crystal and molecular structure analysis of 1,4-diethylquinoxalinium iodide shows a virtually planar quinoxaline ring with 11 conjugated π-electrons. In contrast to the triiodide of the 1,4,6,7-tetramethyl derivative or to the tetraphenylborate salt of 1,4-diethylquinoxalinium cation radical the iodide exhibits π-π-dimerized radical cations in the solid state with synplanar ethyl groups and a rather small intermolecular distance of about 315 pm between the π-planes of the primarily interacting 1,4-diazine rings. Solid state magnetic measurements between 2 and 300 K show considerably diminished magnetic moments due to partial spin-pairing, and UV/VIS spectroscopic measurements in acetonitrile reflect the π—π-interaction in solution through the appearance of a long-wavelength absorption band.

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14

Canossa, Stefano, Giovanni Predieri, and Claudia Graiff. "Hydrogen bonds and π–π interactions in two new crystalline phases of methylene blue." Acta Crystallographica Section E Crystallographic Communications 74, no. 5 (April 17, 2018): 587–93. http://dx.doi.org/10.1107/s2056989017017881.

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Two unprecedented solid phases involving the 3,7-bis(dimethylamino)phenothiazin-5-ium cation, i.e. methylene blue (MB+ ), have been obtained and structurally characterized. In the crystals of 3,7-bis(dimethylamino)phenothiazin-5-ium chloride dihydrate, C16H18N3S+·Cl−·2H2O (I) and 3,7-bis(dimethylamino)phenothiazinium bisulfite, C16H18N3S+·HSO4 − (II), the cationic dye molecules are planar and disposed in an antiparallel mode, showing π–π stacking interactions, with mean interplanar distances of 3.326 (4) and 3.550 (3) Å in (I) and (II), respectively. In compound (I), whose phase was found affected by merohedral twinning [BASF = 0.185 (3)], the presence of water molecules allows a network of hydrogen bonds involving MB+ as both a donor and an acceptor, whereas in compound (II), the homo-interaction of the anions causes an effective absence of classical hydrogen-bond donors. This substantial difference has important consequences for the stacking geometry and supramolecular interactions of the MB+ cations, which are analysed by Hirshfeld fingerprint plots and subsequently discussed.

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15

Yourdkhani, Sirous, Michał Chojecki, and Tatiana Korona. "Substituent effects in the so-called cation⋯π interaction of benzene and its boron–nitrogen doped analogues: overlooked role of σ-skeleton." Physical Chemistry Chemical Physics 21, no. 12 (2019): 6453–66. http://dx.doi.org/10.1039/c8cp04962a.

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By decomposing IQA atom–atom interaction energies to σ and π contributions, we have shown that the substituent effect in cation⋯π interactions is a nonlocal classical effect in which σ-polarization plays an important role.

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16

Govindan, E., Subramani Thirumurugan, Ayyakannu Sundaram Ganeshraja, Krishnamoorthy Anbalagan, and A. SubbiahPandi. "Bis(1,10-phenanthrolin-1-ium) tetrachloridozincate monohydrate." Acta Crystallographica Section E Structure Reports Online 70, no. 2 (January 18, 2014): m53. http://dx.doi.org/10.1107/s1600536814000208.

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In the crystal structure of the title compound, (C12H9N2)2[ZnCl4]·H2O, the two independent 1,10-phenanthrolinium cations are bridged by the water molecule and the tetrahedral tetrachloridozincate anionviaN—H...O, O—H...Cl and N—H...Cl hydrogen bonds, forming chains along [100]. The chains are linkedviaC—H...Cl hydrogen bonds and a number of π–π interactions [centroid–centroid distances vary from 3.5594 (14) to 3.7057 (13) Å], forming a three-dimensional network. In each 1,10-phenanthrolinium cation, there is a short N—H...N interaction.

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17

Zuo, Minghui, Haiyu Wang, Jie Xu, Lingling Zhu, and Shuxin Cui. "Crystal structure of poly[(2,2′-bipyridine-κ2N,N′)tetrakis(μ-cyanido-κ2N:C)dinickel(II)]." Acta Crystallographica Section E Crystallographic Communications 71, no. 6 (May 28, 2015): 709–11. http://dx.doi.org/10.1107/s2056989015009706.

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The polymeric title complex, [Ni2(CN)4(C10H8N2)]n, was obtained serendipitously under hydrothermal conditions. The asymmetric unit consists of one half of an [Ni(CN)4]2−anion with the Ni2+cation situated on an inversion centre, and one half of an [Ni(2,2′-bpy)]2+cation (2,2′-bpy is 2,2′-bipyridine), with the second Ni2+cation situated on a twofold rotation axis. The two Ni2+cations exhibit different coordination spheres. Whereas the coordination of the metal in the anion is that of a slightly distorted square defined by four C-bound cyanide ligands, the coordination in the cation is that of a distorted octahedron defined by four N-bound cyanide ligands and two N atoms from the chelating 2,2′-bpy ligand. The two different Ni2+cations are alternately bridged by the cyanide ligands, resulting in a two-dimensional structure extending parallel to (010). Within the sheets, π–π interactions between pyridine rings of neighbouring 2,2′-bpy ligands, with a centroid-to-centroid distance of 3.687 (3) Å, are present. The crystal packing is dominated by van der Waals forces. A weak C—H...N interaction between adjacent sheets is also observed.

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18

Yamada, Shinji. "Intramolecular cation–π interaction in organic synthesis." Organic & Biomolecular Chemistry 5, no. 18 (2007): 2903. http://dx.doi.org/10.1039/b706512b.

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19

Takemura, Hiroyuki, Hiroaki Nakamichi, and Katsuya Sako. "Pyrene–azacrown ether hybrid: cation–π interaction." Tetrahedron Letters 46, no. 12 (March 2005): 2063–66. http://dx.doi.org/10.1016/j.tetlet.2005.01.141.

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20

Estarellas, Carolina, Antonio Frontera, David Quiñonero, and Pere Deyà. "Can lone pair-π and cation-π interactions coexist? A theoretical study." Open Chemistry 9, no. 1 (February 1, 2011): 25–34. http://dx.doi.org/10.2478/s11532-010-0127-7.

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AbstractThe interplay between two important noncovalent interactions involving different aromatic rings is studied by means of ab initio calculations (MP2/6-31++G**) computing the non-additivity energies. In this study we demonstrate the existence of cooperativity effects when cation-π and lone pair-π interactions coexist in the same system. These effects are studied theoretically using energetic and geometric features of the complexes. In addition we use Bader’s theory of atoms-in-molecules and Molecular Interaction Potential with polarization (MIPp) partition scheme to characterize the interactions. Experimental evidence for this combination of interactions has been obtained from the Cambridge Structural Database.

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21

Zawari, Mahsa, Maryam Haghighizadeh, Maryam Derakhshandeh, Zahra Barmaki, Nabieh Farhami, and Majid Monajjemi. "Cation–π Interaction with Graphene for Cyclic Cationic Polypeptide Compounds." Journal of Computational and Theoretical Nanoscience 12, no. 12 (December 1, 2015): 5472–78. http://dx.doi.org/10.1166/jctn.2015.4551.

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22

Belmont-Sánchez, Jeannette Carolina, Noelia Ruiz-González, Antonio Frontera, Antonio Matilla-Hernández, Alfonso Castiñeiras, and Juan Niclós-Gutiérrez. "Anion–Cation Recognition Pattern, Thermal Stability and DFT-Calculations in the Crystal Structure of H2dap[Cd(HEDTA)(H2O)] Salt (H2dap = H2(N3,N7)-2,6-Diaminopurinium Cation)." Crystals 10, no. 4 (April 15, 2020): 304. http://dx.doi.org/10.3390/cryst10040304.

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The proton transfer between equimolar amounts of [Cd(H2EDTA)(H2O)] and 2,6-diaminopurine (Hdap) yielded crystals of the out-of-sphere metal complex H2(N3,N7)dap[Cd(HEDTA)(H2O)]·H2O (1) that was studied by single-crystal X-ray diffraction, thermogravimetry, FT-IR spectroscopy, density functional theory (DFT) and quantum theory of “atoms-in-molecules” (QTAIM) methods. The crystal was mainly dominated by H-bonds, favored by the observed tautomer of the 2,6-diaminopurinium(1+) cation. Each chelate anion was H-bonded to three neighboring cations; two of them were also connected by a symmetry-related anti-parallel π,π-staking interaction. Our results are in clear contrast with that previously reported for H2(N1,N9)ade [Cu(HEDTA)(H2O)]·2H2O (EGOWIG in Cambridge Structural Database (CSD), Hade = adenine), in which H-bonds and π,π-stacking played relevant roles in the anion–cation interaction and the recognition between two pairs of ions, respectively. Factors contributing in such remarkable differences are discussed on the basis of the additional presence of the exocyclic 2-amino group in 2,6-diaminopurinium(1+) ion.

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23

Masoodi, Hamid Reza, and Sotoodeh Bagheri. "Interplay between π···π stacking and cation···π interaction: a theoretical NMR study." Journal of the Iranian Chemical Society 12, no. 10 (May 28, 2015): 1883–92. http://dx.doi.org/10.1007/s13738-015-0663-3.

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24

Najafpour, M. Mahdi, and Vickie McKee. "Guanidinum diphenylphosphinate monohydrate." Acta Crystallographica Section E Structure Reports Online 62, no. 4 (March 15, 2006): o1365—o1368. http://dx.doi.org/10.1107/s1600536806007860.

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Hydrogen bonding in the title structure, CH6N3 +·C12H10O2P−·H2O or [C(NH2)3]+[Ph2PO2]−·H2O, results in a bilayer architecture, which also involves π–π stacking interactions between pairs of guanidinium ions. All the cation H atoms are involved in hydrogen bonds, five to O atoms of the anion or solvent water and the sixth in an N—H...π interaction with a neighbouring phenyl ring.

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25

Mucelini, Johnatan, Ina Østrøm, Alexandre O. Ortolan, Karla F. Andriani, Giovanni F. Caramori, Renato L. T. Parreira, and Kenneth K. Laali. "Understanding the interplay between π–π and cation–π interactions in [janusene–Ag]+ host–guest systems: a computational approach." Dalton Transactions 48, no. 35 (2019): 13281–92. http://dx.doi.org/10.1039/c9dt02307k.

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26

Alirezapour, Fahimeh, and Azadeh Khanmohammadi. "The effect of cation–π interactions on the stability and electronic properties of anticancer drug Altretamine: a theoretical study." Acta Crystallographica Section C Structural Chemistry 76, no. 10 (September 28, 2020): 982–91. http://dx.doi.org/10.1107/s2053229620012589.

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The present work utilizes density functional theory (DFT) calculations to study the influence of cation–π interactions on the electronic properties of the complexes formed by Altretamine [2,4,6-tris(dimethylamino)-1,3,5-triazine], an anticancer drug, with mono- and divalent (Li+, Na+, K+, Be2+, Mg2+ and Ca2+) metal cations. The structures were optimized with the M06-2X method and the 6-311++G(d,p) basis set in the gas phase and in solution. The theory of `Atoms in Molecules' (AIM) was applied to study the nature of the interactions by calculating the electron density ρ(r) and its Laplacian at the bond critical points. The charge-transfer process during complexation was evaluated using natural bond orbital (NBO) analysis. The results of DFT calculations demonstrate that the strongest/weakest interactions belong to Be2+/K+ complexes. There are good correlations between the achieved densities and the amounts of charge transfer with the interaction energies. Finally, the stability and reactivity of the cation–π interactions can be determined by quantum chemical computation based on the molecular orbital (MO) theory.

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27

Ahern, Christopher A., Amy L. Eastwood, Henry A. Lester, Dennis A. Dougherty, and Richard Horn. "A Cation–π Interaction between Extracellular TEA and an Aromatic Residue in Potassium Channels." Journal of General Physiology 128, no. 6 (November 27, 2006): 649–57. http://dx.doi.org/10.1085/jgp.200609654.

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Open-channel blockers such as tetraethylammonium (TEA) have a long history as probes of the permeation pathway of ion channels. High affinity blockade by extracellular TEA requires the presence of an aromatic amino acid at a position that sits at the external entrance of the permeation pathway (residue 449 in the eukaryotic voltage-gated potassium channel Shaker). We investigated whether a cation–π interaction between TEA and such an aromatic residue contributes to TEA block using the in vivo nonsense suppression method to incorporate a series of increasingly fluorinated Phe side chains at position 449. Fluorination, which is known to decrease the cation–π binding ability of an aromatic ring, progressively increased the inhibitory constant Ki for the TEA block of Shaker. A larger increase in Ki was observed when the benzene ring of Phe449 was substituted by nonaromatic cyclohexane. These results support a strong cation–π component to the TEA block. The data provide an empirical basis for choosing between Shaker models that are based on two classes of reported crystal structures for the bacterial channel KcsA, showing residue Tyr82 in orientations either compatible or incompatible with a cation–π mechanism. We propose that the aromatic residue at this position in Shaker is favorably oriented for a cation–π interaction with the permeation pathway. This choice is supported by high level ab initio calculations of the predicted effects of Phe modifications on TEA binding energy.

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Mishra, Brijesh Kumar, Vivek Kumar Bajpai, V. Ramanathan, Shridhar Gadre, and N. Sathyamurthy. "Cation-π interaction: to stack or to spread." Molecular Physics 106, no. 12 (June 2008): 1557–66. http://dx.doi.org/10.1080/00268970802175290.

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Shi, Zhengshuang, C. Anders Olson, and Neville R. Kallenbach. "Cation−π Interaction in Model α-Helical Peptides." Journal of the American Chemical Society 124, no. 13 (April 2002): 3284–91. http://dx.doi.org/10.1021/ja0174938.

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30

Mohajeri, A., and E. Karimi. "AIM and NBO analyses of cation–π interaction." Journal of Molecular Structure: THEOCHEM 774, no. 1-3 (November 2006): 71–76. http://dx.doi.org/10.1016/j.theochem.2006.07.013.

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31

Kennedy, C. Rose, Song Lin, and Eric N. Jacobsen. "The Cation-π Interaction in Small-Molecule Catalysis." Angewandte Chemie International Edition 55, no. 41 (June 22, 2016): 12596–624. http://dx.doi.org/10.1002/anie.201600547.

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32

Bakshi, Pradip K., T. Stanley Cameron, and Osvald Knop. "Crystal chemistry of tetraradial species. Part 8. Mix and match: cation geometry, ion packing, hydrogen bonding, and π–π interactions in cis-2,2′-bipyridinium(1+) and 1,10-phenanthrolinium(1+) tetraphenylborates — and what about proton sponges?" Canadian Journal of Chemistry 74, no. 2 (February 1, 1996): 201–20. http://dx.doi.org/10.1139/v96-023.

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The crystal structures at −20 °C of cis-2,2′-bipyridinium(1+) (BPTB, P21/n, a = 9.249(3), b = 14.093(7), c = 20.285(3) Å, β = 92.86(2)°, Z = 4) and 1,10-phenanthrolinium(1+) (PTB, P21/c, a = 11.194(2), b = 13.837(3), c = 18.303(3) Å, β = 107.82(1)°, Z = 4) tetraphenylborates have been determined. Inasmuch as 1,10-phenanthroline is an aromatically bridged cis-2,2′-bipyridine, monoprotonation results, in both systems, in the formation of an intra-cation N—H … N′ hydrogen bond, the geometric and spectroscopic properties of which we have investigated. The cation skeleton in PTB is planar to 0.03(2) Å; in BPTB the dihedral angle between the two cation ring planes is 5.2°. In the pale yellow PTB there are significant π–π stacking interactions that persist into solution. The effect of protonation on the geometry of the 2,2′-bipyridine and 1,10-phenanthroline systems is examined in considerable detail and compared with the corresponding effects in the paraquat(2+) and similar cations. On both geometric and spectroscopic (infrared spectra between 10 and 295 K) evidence, the N—H … N′ hydrogen-bonding interaction is stronger in BPTB; in PTB this interaction is among the weakest reported in crystals, the ν(NH) stretching frequency at 10 K being as high as 3279 cm−1. A detailed comparison of the geometries of the intra-cation N—H … N′ bonds in BPTB and PTB with those in classical and modified proton-sponge cations has led to the formulation of criteria useful in predicting the occurrence of proton-sponge-like properties. Key words: bipyridinium ions, hydrogen bonding, phenanthrolinium ions, proton sponges, tetraphenylborates.

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Kasprzak, Artur, and Hidehiro Sakurai. "Site-selective cation–π interaction as a way of selective recognition of the caesium cation using sumanene-functionalized ferrocenes." Dalton Transactions 48, no. 46 (2019): 17147–52. http://dx.doi.org/10.1039/c9dt03162f.

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34

Sarmah, Nabajit, and Pradip Kr Bhattacharyya. "Behaviour of cation–pi interaction in presence of external electric field." RSC Advances 6, no. 102 (2016): 100008–15. http://dx.doi.org/10.1039/c6ra21334k.

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35

JEONG, K. S., S. H. PARK, J. H. KIM, and Y. L. CHO. "ChemInform Abstract: Cation-π Interaction Between Synthetic Hosts and Alkali Metal Cations." ChemInform 28, no. 33 (August 3, 2010): no. http://dx.doi.org/10.1002/chin.199733218.

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36

White, Frankie, and Richard E. Sykora. "Crystal structure of bis(2,2′:6′,2′′-terpyridine-κ3N,N′,N′′)nickel(II) dicyanidoaurate(I)." Acta Crystallographica Section E Structure Reports Online 70, no. 12 (November 19, 2014): 519–21. http://dx.doi.org/10.1107/s1600536814024672.

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The title compound, [Ni(C15H11N3)2][Au(CN)2]2, is an ionic compound composed of bis(2,2′:6′,2′′-terpyridine)nickel(II) dications and dicyanidoaurate(I) anions in a 1:2 ratio. The two tridentate terpyridine ligands define the coordination of the Ni2+cation, resulting in a nearly octahedral coordination sphere, although there is not any imposed crystallographic symmetry about the Ni2+site. The two nearly linear dicyanidoaurate(I) anions [C—Au—C = 179.0 (2) and 178.2 (2)°] contain a short aurophilic interaction of 3.1017 (3) Å. The structure does not demonstrate any π–π stacking. Non-classical C—H...N interactions between the cations and anions build up a three-dimensional network.

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37

Mahanta, Sanjeev Pran, Biswajyoti Dutta, Pradip K. Bhattacharyaa, and Kusum K. Bania. "Cation–π interaction in cofacial molecular dyads: a DFT and TDDFT study." RSC Advances 6, no. 68 (2016): 63827–36. http://dx.doi.org/10.1039/c6ra10368e.

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38

Kavitha, Channappa N., Manpreet Kaur, Brian J. Anderson, Jerry P. Jasinski, and H. S. Yathirajan. "1-Piperonylpiperazinium picrate." Acta Crystallographica Section E Structure Reports Online 70, no. 2 (January 29, 2014): o208—o209. http://dx.doi.org/10.1107/s1600536814001524.

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In the cation of the title salt [systematic name: 4-(2H-1,3-benzodioxol-5-ylmethyl)piperazin-1-ium 2,4,6-trinitrophenolate], C12H17N2O2+·C6H2N3O7−, the piperazine ring adopts a slightly disordered chair conformation. The piperonyl ring system and the piperazine ring are twisted with respect to each other with an N—C—C—C torsion angle of 40.7 (2)°. In the anion, the dihedral angles between the mean planes of the nitro substituentsorthoto the phenolate O atom and the mean plane of the phenyl ring are 28.8 (9) and 32.2 (8)°. In contrast, the nitro group in theparaposition lies much closer to the aromatic ring plane, subtending a dihedral angle of 3.0 (1)°. In the crystal, the cations and anions interact through N—H...O hydrogen bonds and a weak C—H...O interaction. Weak C—H...O interactions are also observed between the anions, formingR22(10) graph-set ring motifs. In addition, a weak centroid–centroid π–π stacking interaction between the aromatic rings of the cation and the anion, with an intercentroid distance of 3.7471 (9) Å, contributes to the crystal packing, resulting in a two-dimensional network along (10-1).

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39

Mague, Joel T., Erin Larrabee, David Olivier, Francesca Vaccaro, Kevin E. Riley, and Lynn V. Koplitz. "Crystal structures of the hexafluoridophosphate salts of the isomeric 2-, 3- and 4-cyano-1-methylpyridinium cations and determination of solid-state interaction energies." Acta Crystallographica Section E Crystallographic Communications 74, no. 9 (August 24, 2018): 1322–29. http://dx.doi.org/10.1107/s2056989018011003.

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The synthesis and crystal structures of the isomeric molecular salts 2-, 3- and 4-cyano-1-methylpyridinium hexafluoridophosphate, C7H7N2 +·PF6 −, are reported. In 2-cyano-1-methylpyridinium hexafluoridophosphate, C—H...F hydrogen bonds form chains extending along the c-axis direction, which are associated through C—H...F hydrogen bonds and P—F...π(ring) interactions into stepped layers. For 3-cyano-1-methylpyridinium hexafluoridophosphate, corrugated sheets parallel to [001] are generated by C—H...F hydrogen bonds and P—F...π(ring) interactions. The sheets are weakly associated by a weak interaction of the cyano group with the six-membered ring of the cation. In 4-cyano-1-methylpyridinium hexafluoridophosphate, C—H...F hydrogen bonds form a more open three-dimensional network in which stacks of cations and of anions are aligned with the b-axis direction. Dispersion-corrected density functional theory (DFT-D) calculations were carried out in order to elucidate some of the energetic aspects of the solid-state structures. The results indicate that the distribution of charge within a molecular ionic cation can play a large role in determining the strength of a cation–anion interaction within a crystal structure. Crystals of 2-cyano-1-methylpyridinium hexafluoridophosphate are twinned by a 180° rotation about the c* axis. The anion in 3-cyano-1-methylpyridinium hexafluoridophosphate is rotationally disordered by 38.2 (1)° in an 0.848 (3):0.152 (3) ratio.

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40

Razzoqova, Surayyo, Batirbay Torambetov, Matluba Amanova, Shakhnoza Kadirova, Aziz Ibragimov, and Jamshid Ashurov. "Crystallization, structural study and analysis of intermolecular interactions of a 2-aminobenzoxazole–fumaric acid molecular salt." Acta Crystallographica Section E Crystallographic Communications 78, no. 12 (November 30, 2022): 1277–83. http://dx.doi.org/10.1107/s2056989022011185.

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The new organic salt, 2-aminobenzoxazol-3-ium 3-carboxyprop-2-enoate, C7H7N2O+·C4H3O4 −, of the two bioactive compounds 2-aminobenzoxazole and fumaric acid, crystallizes in the orthorhombic space group Pbca using classical evaporation of their solution in water. The usual topological analysis revealed four classical (N—H...O and O—H...O) and two non-classical (C—H...O) hydrogen bonds in the structure. Stacking was found as well for a pair of 2-aminobenzoxazolium cations. A Hirshfeld surface analysis including the two-dimensional fingerprint plots was performed to define the residual π–π interactions and to quantify the influences of different types of interactions by means of topological analysis. Analysis of the pairwise interaction energies was used to prove the formation of the corrugated paired layers of cation–anion dimers parallel to the plane (001) as a basic structural motif in the topological, as well as in the energetic structure of the crystal. It showed that the layers are connected by the hydrogen bonds inside and by stacking and π–π interactions and general dispersion between them.

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41

Lummis, Sarah C. R. "Locating GABA in GABA receptor binding sites." Biochemical Society Transactions 37, no. 6 (November 19, 2009): 1343–46. http://dx.doi.org/10.1042/bst0371343.

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The Cys-loop family of ligand-gated ion channels contains both vertebrate and invertebrate members that are activated by GABA (γ-aminobutyric acid). Many of the residues that are critical for ligand binding have been identified in vertebrate GABAA and GABAC receptors, and specific interactions between GABA and some of these residues have been determined. In the present paper, I show how a cation–π interaction for one of the binding site residues has allowed the production of models of GABA docked into the binding site, and these orientations are supported by mutagenesis and functional data. Surprisingly, however, the residue that forms the cation–π interaction is not conserved, suggesting that GABA occupies subtly different locations even in such closely related receptors.

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Koteswara Rao, Vandavasi, Tausif Siddiqui, Matthias Zeller, and Sherri R. Lovelace-Cameron. "Adenin-1-ium hydrogen isophthalate dimethylformamide monosolvate." Acta Crystallographica Section E Structure Reports Online 70, no. 2 (January 18, 2014): o166—o167. http://dx.doi.org/10.1107/s1600536813034971.

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In the title proton-transfer organic salt, C5H6.3N5+·C8H4.7O4−·C3H7NO, the adeninium moiety is protonated at the N atom in the 1-position of the 6-amino-7H-purin-1-ium (adeninium) cation. In the solid state, the second acidic proton of isophthalic acid is partially transferred to the imidazole N atom of the adeninium cation [refined O—HversusN—H ratio = 0.70 (11):0.30 (11)]. Through the partially transferred proton, the adeninium cation is strongly hydrogen bonded (N—H...O/O—H...N) to the isophthalate anion. This strong interaction is assisted by another N—H...O hydrogen bond originating from the adeninium NH2group towards the isophthalate keto O atom, with anR22(8) graph-set motif. This arrangement is linkedviaN—H...O hydrogen bonds to the O atoms of the carboxylate group of an isophthalate anion. Together, these hydrogen bonds lead to the formation criss-cross zigzag isophthalate...adeninium chains lying parallel to (501) and (50-1). The adeninium cations and the isophthalate anions are arranged in infinite π stacks that extend along thec-axis direction [interplanar distance = 3.305 (3) Å]. Molecules are inclined with respect to this direction and within the stacks they are offset by ca. half a molecule each. Combination of the N—H...O and O—H...N hydrogen bonds with the π–π interactions forms infinitely stacked isophthalate...adeninium chains, thus leading to a two-dimensional supramolecular structure with parallel interdigitating layers formed by theπstacked isophthalate...adeninium chains. The DMF molecules of crystallization are bonded to the adeninium cations through strong N—H...O hydrogen bonds and project into the lattice space in between the anions and cations. There are also C—H...O hydrogen bonds present which, combined with the other interactions, form a three-dimensional network. The crystal under investigation was found to be split and was handled as if non-merohedrally twinned.

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Nishikawa, Michihiro, Kotaro Mutsuura, and Taro Tsubomura. "Crystal structure of bis[μ-1,4-bis(diphenylphosphanyl)butane-κ2P:P′]bis[(3,4,7,8-tetramethyl-1,10-phenanthroline-κ2N,N′)copper(I)] bis(hexafluoridophosphate) dichloromethane disolvate." Acta Crystallographica Section E Crystallographic Communications 72, no. 11 (October 11, 2016): 1554–56. http://dx.doi.org/10.1107/s2056989016015553.

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The dication of the title compound, [Cu2(C28H28P2)2(C16H16N2)2](PF6)2·2CH2Cl2, has crystallographically imposed inversion symmetry. The copper(I) cation is coordinated in a distorted tetrahedral geometry by two N atoms of a chelating 3,4,7,8-tetramethyl-1,10-phenanthroline ligand and two P atoms of two bridging 1,4-bis(diphenylphosphanyl)butane ligands, forming a 14-membered ring. An intramolecular π–π interaction stabilizes the conformation of the dication. In the crystal, dications are linked by π–π interactions involving adjacent phenanthroline rings, forming chains running parallel to [111]. Weak C—H...F hydrogen interactions are also observed.

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Oliveira, Boaz G. "The covalence and infrared spectra of cationic hydrogen bonds and dihydrogen bonds." Journal of Theoretical and Computational Chemistry 13, no. 07 (November 2014): 1450060. http://dx.doi.org/10.1142/s0219633614500606.

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A theoretical study of hydrogen bonds and dihydrogen bonds formed by ethyl cation, hydrocarbons and magnesium hydride is presented with calculations performed at the BHandHLYP/6-31G(d,p) level of theory. The structural results and IR analyses demonstrated great insights, mainly the strengthening and weakness of the CC bond of the ethyl cation and π or pseudo-π bonds, respectively. The interaction strength was measured through the supermolecule as well as by means of additional approaches. The QTAIM calculations were applied to characterize not only the intermolecular interactions but specifically the covalent character in the H + ⋯ π, H + ⋯ pseudo-π and H + ⋯ H contacts. The NBO calculations were useful to interpret the polarization on the CC bond and whether this effect is related with the bond length reduction as well as increase of charge density and frequency shifts.

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45

Prasad, N. L., M. S. Krishnamurthy, and Noor Shahina Begum. "Crystal structure of 2-acetyl-5-(3,4-dimethoxyphenyl)-6-ethoxycarbonyl-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidin-8-ium chloride." Acta Crystallographica Section E Crystallographic Communications 71, no. 10 (September 17, 2015): o764—o765. http://dx.doi.org/10.1107/s2056989015016229.

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The title molecular salt, C21H25N2O5S+·Cl−, crystallizes with two ion pairs in the asymmetric unit. The cations have similar conformations (r.m.s. overlay fit = 0.40 Å), with one of them showing disorder of the terminal methyl group of the ester in a 0.72 (2):0.28 (2) ratio. In the first cation, the 3,4-dimethoxy-substituted phenyl ring subtends a dihedral angle of 88.38 (7)° with the pyrimidine ring and 6.79 (8)° with the thiazole ring. The equivalent data for the second cation are 89.97 (3) and 6.42 (7)°, respectively. The pyrimidine ring adopts a sofa conformation in each cation. In the crystal, the components are linked by N—H...Cl hydrogen bonds, generating isolated ion pairs. The ion pairs are are linked by C—H...O interactions, generating a three-dimensional network. In addition, a weak C—H...π interaction is observed.

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Ederer, Jakub, Petra Ecorchard, Michaela Šrámová Slušná, Jakub Tolasz, Darina Smržová, Simona Lupínková, and Pavel Janoš. "A Study of Methylene Blue Dye Interaction and Adsorption by Monolayer Graphene Oxide." Adsorption Science & Technology 2022 (August 9, 2022): 1–16. http://dx.doi.org/10.1155/2022/7385541.

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The graphene oxide (GO) interaction with methylene blue (MB) cationic dye was studied in an aqueous solution at different pH during MB adsorption. The mutual interaction of MB with GO surface was studied and evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The π-π and electrostatic interaction of MB with GO surface are the main types of interactions, and the XRD data show the monomeric arrangement of MB cation with GO. The GO surface functional groups and point of zero charge (PZC) were determined by acid-base titration. Suitability of zeta-potential measurement and acid-base titration method was briefly discussed. The quality of prepared GO was evaluated by Raman spectroscopy, XRD, and atomic force microscope (AFM). The experimental adsorption equilibrium data were analyzed using Langmuir, Langmuir-Freundlich, Freundlich, and Temkin isotherms. The GO maximum adsorption capacity increases with higher pH, that is ascribed to the facile interaction of negatively charged GO with positively charged MB structure.

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47

Lu, Xi, Changyuan He, Zhiwei Gao, Wenzheng Ban, Chong Chen, Chaomei Zhou, Yingchun Gu, and Sheng Chen. "Mussel-inspired cationic chitosan-based flocculants with floc enlarging capacity for efficient removal of anionic dye." Materials Express 13, no. 4 (April 1, 2023): 670–78. http://dx.doi.org/10.1166/mex.2023.2380.

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Biomass-based flocculants have been widely studied and applied to wastewater treatment due to their environmental friendliness. However, these flocculants tend to generate flocs with small size and lead to difficult solid-liquid separation after the flocculation. The key to solving the floc size problem is enhancing intermolecular or intramolecular interaction forces by changing the molecular structure and functional groups of flocculants. Herein, we developed a mussel-inspired cationic biomass flocculant by functionalizing chitosan (CS) with cation component acryloyloxyethyltrimethyl ammonium chloride (DAC) and mussel-inspired monomer N-2-(3, 4-dihydroxyphenethyl) acrylamide (DAA) through free radical polymerization. The prepared flocculant could provide multiple interaction forces such as electrostatic interaction, cation-π interaction, π −π stacking, and hydrogen bonding to pollutants. As a result, the spent CS-g-p (DAC-co-DAA) flocculant generate dye-containing flocs with dramatically increased size when compared with its counterpart CS-g-pDAC without catechol groups and are capable to realize more than 95% removal efficiency towards organic dyes such as MB and CR over a broad pH range from 3 to 9. This study provides some insights in how to apply this mussel-inspired strategy to develop environmentally friendly biomass-derived flocculants with floc enlarging capacity to treat organic wastewaters in wide pH range.

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Närhi, Sari M., Raija Oilunkaniemi, and Risto S. Laitinen. "Triphenyltelluronium(IV) bromide acetone hemisolvate." Acta Crystallographica Section E Structure Reports Online 69, no. 11 (October 19, 2013): o1666. http://dx.doi.org/10.1107/s160053681302816x.

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The asymmetric unit of the title compound, 2C18H15Te+·2Br−·C3H6O or Ph3TeBr·0.5Me2CO, contains two crystallographically independent triphenyltelluronium cations, two bromide anions, and one disordered [site-occupancy ratio = 0.581 (7):0.419 (7)] solvent molecule. Interionic Te...Br interactions connect the cations and anions into a tetrameric step-like structure. The primary coordination spheres of both Te atoms are TeC3trigonal pyramids: three short secondary tellurium–bromine interactions expand the coordination geometry of one of the Te atoms to an octahedron. While the other Te atom shows only two Te...Br secondary bonding interactions, it is also six-coordinated due to a Te...π interaction [3.769 (2) Å] with one of the phenyl rings of the adjacent cation.

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Dong, Wen-Shuai, Lu Zhang, Wen-Li Cao, Zu-Jia Lu, Qamar-un-Nisa Tariq, Chao Zhang, Xiao-Wei Wu, Zong-You Li, and Jian-Guo Zhang. "Synthesis, Crystal Structure, and Characterization of Energetic Salts Based on 3,5-Diamino-4H-Pyrazol-4-One Oxime." Molecules 28, no. 1 (January 3, 2023): 457. http://dx.doi.org/10.3390/molecules28010457.

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In order to broaden the study of energetic cations, a cation 3,5-diamino-4H-pyrazol-4-one oxime (DAPO) with good thermal stability was proposed, and its three salts were synthesized by a simple and efficient method. The structures of the three salts were verified by infrared spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction. The thermal stabilities of the three salts were verified by differential scanning calorimetry and thermos-gravimetric analysis. DAPO-based energetic salts are analysed using a variety of theoretical techniques, such as 2D fingerprint, Hirshfeld surface, and non-covalent interaction. Among them, the energy properties of perchlorate (DAPOP) and picrate (DAPOT) were determined by EXPLO5 program combined with the measured density and enthalpy of formation. These compounds have high density, acceptable detonation performance, good thermal stability, and satisfactory sensitivity. The intermolecular interactions of the four compounds were studied by Hirshfeld surface and non-covalent interactions, indicating that hydrogen bonds and π–π stacking interactions are the reasons for the extracellular properties of perchlorate (DAPOP) and picrate (DAPOT), indicating that DAPO is an optional nitrogen-rich cation for the design and synthesis of novel energetic materials with excellent properties.

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Kim, Sangsik, Ali Faghihnejad, Yongjin Lee, YongSeok Jho, Hongbo Zeng, and Dong Soo Hwang. "Cation–π interaction in DOPA-deficient mussel adhesive protein mfp-1." Journal of Materials Chemistry B 3, no. 5 (2015): 738–43. http://dx.doi.org/10.1039/c4tb01646g.

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Journal articles on the topic 'Interaction cation-π'

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