Journal articles: 'Imido complexes form'

1

Brown, Martyn, and Chet Jablonski. "Synthesis, characterization, and CN bond cleavage of tungsten(VI)arylimido-calix[4]arene complexes." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 463–71. http://dx.doi.org/10.1139/v00-131.

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The tetradentate, partially flattened cone tungsten(VI) imido-calix[4]arene derivative [W(NC6H5)(t-BucalixH)]+Cl, (4), is formed in good yield from reaction of p-tert-butyl-calix[4]arene (t-BucalixH4), and W(NC6H5)Cl4. A reaction mechanism involving a putative, bidentate calixarene intermediate W(NC6H5)(t-BucalixH2)Cl2 (3), which partitions by reversible cleavage of the imido group to give the known tetradentate calixarene complex W(t-Bucalix)Cl2 (2), and elimination of HCl to form the thermodynamic imido product 4 is proposed. A series of iso structural [W(NAr)(t-BucalixH)]+Cl (Ar = C6H5 or o,m,p-C6H4CH3) imido derivatives (47), which adopt a partially flattened cone conformation in solution has been prepared by reaction of dichloride 2 with H2NAr (Ar = C6H5, o,m,p-C6H4CH3). Reaction of W(t-Bucalix)Cl2 with aliphatic amines affords a red product formulated as the nitrido complex, 9, which results from facile cleavage of the imido CN bond.Key words: calix[4]arene complex, imido complex, nitrido complex, CN bond cleavage, conformation, metallocalixarene.

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Desnoyer, Addison N., Weiling Chiu, Candy Cheung, Brian O. Patrick, and Jennifer A. Love. "Oxaziridine cleavage with a low-valent nickel complex: competing C–O and C–N fragmentation from oxazanickela(ii)cyclobutanes." Chemical Communications 53, no. 92 (2017): 12442–45. http://dx.doi.org/10.1039/c7cc07690h.

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3

Tomson, Neil C., Nickolas H. Anderson, Aaron M. Tondreau, Brian L. Scott, and James M. Boncella. "Oxidation of uranium(iv) mixed imido–amido complexes with PhEEPh and to generate uranium(vi) bis(imido) dichalcogenolates, U(NR)2(EPh)2(L)2." Dalton Transactions 48, no. 29 (2019): 10865–73. http://dx.doi.org/10.1039/c9dt00680j.

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4

Ikeda, Hideaki, Kohei Nishi, Hayato Tsurugi, and Kazushi Mashima. "Metathesis cleavage of an NN bond in benzo[c]cinnolines and azobenzenes by triply-bonded ditungsten complexes." Chemical Communications 54, no. 30 (2018): 3709–11. http://dx.doi.org/10.1039/c7cc08570b.

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A metathesis reaction of a WW bond and an NN bond was observed by reacting a W–W triply-bonded W(iii)₂ complex, (^tBuO)₃WW(O^tBu)₃ (1), with benzo[c]cinnoline derivatives to form biphenyl-linked dinuclear (imido)tungsten complexes 2–4.

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Xing, Tian, Mark R. J. Elsegood, Sophie H. Dale, and Carl Redshaw. "Pentamethylcyclopentadienyl Molybdenum(V) Complexes Derived from Iodoanilines: Synthesis, Structure, and ROP of ε-Caprolactone." Catalysts 11, no. 12 (December 20, 2021): 1554. http://dx.doi.org/10.3390/catal11121554.

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The reaction of [Mo(η-C5Me5)Cl4] with the ortho-, meta-, or para-iodo-functionalized anilines 2-IC6H4NH2, 3-IC6H4NH2, 4-IC6H4NH2 yields imido or amine products of the type [Mo(η-C5Me5)Cl2(IC6H4N)] (2-I, 1, 3-I, 3, 4-I, 5) or [Mo(η-C5Me5)Cl4(IC6H4NH2)] (3-I, 2, 4-I, 4), respectively, depending on the reaction stoichiometry/conditions; we were unable to isolate an amine complex of the 2-I derivative. The reaction of [Mo(η-C5Me5)Cl4] with one equivalent of 2-I,4-FC6H3NH2 in the presence of Et3N afforded [Mo(η-C5Me5)Cl2(2-I,4-FC6H3N)]·MeCN (6·MeCN), which, upon exposure to air, afforded the Mo(VI) imido complex [Mo(η-C5Me5)Cl3(2-I,4-FC6H3N)] (7). For comparative studies, the structure of the aniline (C6H5NH2)-derived complex [Mo(η-C5Me5)Cl2(2-C6H3N)] (8) has also been prepared. The molecular structures of 1–8 have been determined and reveal packing in the form of zig-zag chains or ladders. The complexes catalyze, in the presence of benzyl alcohol under N2, the ring-opening polymerization (ROP) of ε-caprolactone affording relatively low molecular weight products. The MALDI-ToF spectra indicate that a number of polymer series bearing a variety of end groups are formed. Conducting the ROPs as melts or under air results in the isolation of higher molecular weight products, again bearing a variety of end groups. Kinetic studies reveal the aniline-derived imido complex 8 performs best, whilst a meta-iodo substituent and a Mo(V) centre are also found to be beneficial. The structures of the side products 2-IC6H4NH3Cl and 3-IC6H4NH3Cl are also reported.

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Ishii, Youichi, Shin'ichi Tokunaga, Hidetake Seino, and Masanobu Hidai. "Synthesis of Tungsten (1-Pyridinio)imido Complexes: Facile N−N Bond Cleavage To Form Pyridine from Coordinated Dinitrogen1." Inorganic Chemistry 35, no. 18 (January 1996): 5118–19. http://dx.doi.org/10.1021/ic960632f.

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7

Moubaraki, Boujemaa, Keith S. Murray, Peter J. Nichols, Scott Thomson, and Bruce O. West. "The synthesis, reactivity and magnetic susceptibilities of Cr(IV)porphyrin imido complexes, CrN(R), and attempts to form heterobinuclear μ-imido compounds with CrN(R)V and CrN(R)Fe bridges." Polyhedron 13, no. 3 (January 1994): 485–95. http://dx.doi.org/10.1016/s0277-5387(00)81665-4.

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8

Leovac, Vukadin, Vladimir Divjakovic, Valerija Cesljevic, and Milena Rakocevic. "Transition metal complexes with thiosemicarbazide-based ligands. Part 51. Square-planer nickel(II)complex with acetylacetone bis(S-n-propylisothiosemicarbazone)(L).Crystal and molecular structure of [." Journal of the Serbian Chemical Society 71, no. 6 (2006): 593–604. http://dx.doi.org/10.2298/jsc0606593l.

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The template reaction of a warm methanolic solution of Ni(OAc)2?4H2O S-n-propylisothiosemicarbazide hydroiodide and acetylacetone yielded the needle- like, brown, diamagnetic complex [Ni(L-H)]I?MeOH, and in the presence of an excess of NH 4NCS, brown, prismatic crystals of the complex [Ni(L-H)]NCS (1), both compounds involving the monoanionic form of the ligand, acetylacetone bis(S-n-propylisothiosemicarbazone), L. Slow recrystallization fromMeOH, EtOH, iPrOH and Me2CO gave the corresponding monosolvent complexes [Ni(L-H)]I?solvent, of which only those involving EtOH and iPrOH were suitable for structural analysis. The crystallographic parameters of [Ni(L-H)]I?EtOH (2) and [Ni(L-H)]I?iPrOH (3) are very similar to each other, showing their structures are isomorphic. The crystal structures of the title compounds consist of the independent ions: NCS-, or I-, and the chemically identical cation [Ni(L-H)]+, where L-H is the monoanion resulting from deprotonation of the acetylacetone moiety, a tetradentate N4 ligand forming a square-planar coordination around a Ni(II) ion. It was found that the isothiosemicarbazide fragment of the ligand has an imido form. The complex cations of the compounds [Ni(L-H)]NCS and [Ni(L-H)]I?EtOH exhibit significant difference only in the conformation of their propyl groups.

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9

Lock, Nina, Julia Matussek, and Dietmar Stalke. "Se-N chemistry: Revisiting an old molecule in the design of novel compounds." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C914. http://dx.doi.org/10.1107/s2053273314090858.

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Chalcogenide chemistry is rich and diverse: The large variety of molecular sulfur and selenium compounds can be ascribed to their multiple stable oxidation states and large radius enabling high coordination. Sulfur-nitrogen chemistry is thoroughly explored and well-understood; polyimido sulfur species S(NR)n with charge m- (n = 2, 3, 4; m = 0, 2) are analogues of SOn molecules (with charge: m-) in which oxygen has been replaced by isovalent NR imido groups [1]. These compounds have been studied in depth and have been demonstrated to be versatile ligand systems which form multifaceted potentially catalytic metal complexes and compounds with lithium organics [2]. Selenium-nitrogen chemistry is comparatively less developed than sulfur-nitrogen chemistry despite of significant contributions to the field [3]. This may be ascribed to the rich redox chemistry of selenium in addition to its ability to polymerize, unfortunately none of these properties are easily controlled. A crucial parameter in the development of sulfur-nitrogen chemistry is attributed to the access to sulfur diimides S(NR)2 and sulfur triimides S(NR)3. Therefore, our starting point in exploring new directions of selenium-nitrogen chemistry was to revisit Se(NtBu)2 (tBu = tertbutyl), which has been used as ligand for metal complexes, but also discussed in large detail with respect to structural geometry and stability. Herein, we are presenting a study of selenium-nitrogen chemistry based on Se(NtBu)2.

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10

Jazwinski, S. M. "Participation of ATP in the binding of a yeast replicative complex to DNA." Biochemical Journal 246, no. 1 (August 15, 1987): 213–19. http://dx.doi.org/10.1042/bj2460213.

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The activity that replicates yeast DNA in vitro can be isolated from cells of the budding yeast Saccharomyces in a high-Mr (approximately 2 × 10(6] form. Several lines of evidence indicate that this fraction contains a multiprotein replicative complex. A functional assay has been developed for the analysis of the interaction of the replicating activity with DNA. Binding of the activity required Mg2+, but did not require the addition of ATP or the other ribo- or deoxynucleoside triphosphates. However, the ATP analogues adenosine 5′-[gamma-thio]triphosphate and adenosine 5′-[beta gamma-imido]triphosphate blocked the binding, suggesting that ATP participates in the interaction at some stage. The binding was template (origin)-specific in either the presence or the absence of ATP and the other nucleoside triphosphates; however, ATP stabilized the replicating activity. The preferential inhibition of binding that was observed in the presence of the DNA topoisomerase II inhibitor coumermycin suggests that the requirement for ATP may be at least partially accounted for by the involvement of this enzyme in the initial interaction of the replicating activity with DNA. Finally, the binding was rapid. In contrast, DNA synthesis displayed a lag when assayed directly without first allowing a period for the replicating activity to bind to the DNA. In addition, binding was ‘tight’, as judged by the resistance of the protein–DNA complexes to salt in comparison with the relative sensitivity of binding. The replicating activity was not readily displaced from the complexes by exogenous DNAs, either possessing or lacking yeast origins of replication. The results suggest that the interaction of the replicating activity with the DNA occurs in more than one stage.

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11

Orabi, Adel S. "Preparation and applications of some complexes derived from lanthanon(III) ions with some ligands derived from pyrazole." Macedonian Journal of Chemistry and Chemical Engineering 32, no. 1 (June 15, 2013): 25. http://dx.doi.org/10.20450/mjcce.2013.123.

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The novel complexes derived from some pyrazole derivatives ligands: 2,4-dihydroxybenzylidene-3`-imino-5`-methylpyrazole(L1); salicylidene-3`-imino-5`-methylpyrazole(L2); 2-hydroxynaphthylidene-3`-imino-5`-methylpyrazole(L3) and LaCl3, Ce(NO3)3 and Nd(NO3)3 were prepared and characterized using elemental analysis (C, H, N, M%), mass, FT-IR spectroscopy, electrical conductivity and thermal gravimetric analysis (DTA/TG). The electrical conductivity of 0.001M in DMSO revealed the electrolytic behavior of the all formed complexes as 1:1 (coordination sphere cation : ionization sphere ions) electrolyte for complexes derived from L1 and L2 ligands meanwhile L3 gave 1:2 electrolyte. The thermal analysis (DTA/TG) of the synthesized complexes revealed the presence of two types of water molecules as water of crystallization and coordinated one which act as a ligand. The complexes formed could be formulated as [M(L)2.nH2O].Z.mH2O for L = L1 and L2, [M(L).nH2O].2Z.mH2O for L = L3 (Z = Cl- for M = La(III) and Z = NO3- for M = Ce(III) and Nd(III)). Nd(III)-L3 complexe exhibit promising catalytic activity towards the aerobic oxidation of p-phenylenediamine (PPD) to the corresponding semi-oxidized form (PPD+). The antimicrobial activity of the complexes under investigations was tested and discussed. The simulated molecular structure and the energy of the formed complexes were performed using chem.-office package program. The relation between the spatial arrangement of the formed complexes and its antimicrobial activity was evaluated.

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12

Guillet, Gary L., Skyler L. Pitts, Kirkland W. Sheriff, Donna N. Rucker, and Aaryn L. Rogers. "Synthesis, characterization, and crystal structures of organonickel(II) complexes coordinated to novel 1-bromo-2,6-bis{[(λ5-phosphanylidene)imino]methyl}benzene NCN-pincer ligands." Acta Crystallographica Section C Structural Chemistry 75, no. 10 (September 7, 2019): 1381–88. http://dx.doi.org/10.1107/s2053229619012038.

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A novel family of four 1-bromo-2,6-bis{[(λ5-phosphanylidene)imino]methyl}benzene ligands has been synthesized and characterized. The phosphiniminomethyl substituents are decorated with either three phenyl groups, two phenyl and one cyclohexyl group, one phenyl and two cyclohexyl groups, or three cyclohexyl groups. Each ligand was metallated using zero-valent nickel through an oxidative addition to form a family of organonickel(II) complexes, namely (2,6-bis{[(triphenyl-λ5-phosphanylidene)imino]methyl}phenyl-κ3 N,C 1,N′)bromidonickel(II) dichloromethane hemisolvate, [NiBr(C44H37N2P2)]·0.5CH2Cl2, (2,6-bis{[(cyclohexyldiphenyl-λ5-phosphanylidene)imino]methyl}phenyl-κ3 N,C 1,N′)bromidonickel(II) diethyl ether hemisolvate, [NiBr(C44H49N2P2)]·0.5C4H10O, (2,6-bis{[(dicyclohexylphenyl-λ5-phosphanylidene)imino]methyl}phenyl-κ3 N,C 1,N′)bromidonickel(II), [NiBr(C44H61N2P2)], and (2,6-bis{[(tricyclohexyl-λ5-phosphanylidene)imino]methyl}phenyl-κ3 N,C 1,N′)bromidonickel(II), [NiBr(C44H73N2P2)]. This family of complexes represents a useful opportunity to investigate the impact of incrementally changing the steric characteristics of a complex on its structure and reactivity.

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13

Lecourt, Constance, Warren Madanamoothoo, Vivian Ferreol, Nicolas Bélanger-Desmarais, Lhoussain Khrouz, Jean-Bernard Tommasino, Christian Reber, Cédric Desroches, and Dominique Luneau. "Mononuclear manganese(iii) complexes with reduced imino nitroxide radicals by single-electron transfer and intermolecular hydrogen bonds as an intramolecular structural driving force." Dalton Transactions 48, no. 35 (2019): 13378–87. http://dx.doi.org/10.1039/c9dt02158b.

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One-electron transfer from Mn(ii) ions to an imino nitroxide radical gives mononuclear Mn(iii) complexes of the reduced amino imine-oxide form for which crystal structures evidence hydrogen bonds networks acting as a stabilizing driving-force.

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14

Koch, Daniela, Karlheinz Sünkel, and Wolfgang Beck. "Metallkomplexe mit biologisch wichtigen Liganden, CXI. Phosphan-Gold(I), -Nickel(II) und -Platin(II) Komplexe mit dem Anion von Hydantoin und 3,4-Pyridindicarbonsäureimid/Metal Complexes of Biologically Important Ligands, CXI. Phosphine Gold(I), Nickel(II) and Platinum(II) Complexes with the Anion of Hydantoin and of 3,4 Pyridine Dicarboxylic Imide." Zeitschrift für Naturforschung B 54, no. 1 (January 1, 1999): 96–102. http://dx.doi.org/10.1515/znb-1999-0118.

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The anions of hydantoin (L1) and of the imide of 3,4-pyridine dicarboxylic acid (L2) form the complexes Ph3PAu(L1-H+) (1), Ph3PAu(L2-H+) (2), (nBu3P)2Ni(L1-H+)2 (3) and the ligand bridged compounds Ph3PAu(L2-H+)M(PEt3)Cl2 (M = Pd, Pt, 4, 5). With the neutral ligand L2 the complexes Cp*Ir(Cl)2(L2) (6), (ρ-cymene)Ru(Cl)2 (L2) (7) and (Et3P)(Cl)2Pd(L2) (8) were obtained. Complexes 1, 2 and 6 were characterized by X-ray diffraction.

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Yuan, Yong, Xi-Kun Lu, Gao-Qi Zhou, and Xiao-Yang Qiu. "Syntheses, Characterization, Crystal Structures and Antimicrobial Activity of Schiff Base Copper(II) Complexes Derived from 2-Bromo-6-((2-(isopropylamino) ethylimino)methyl)phenol." Acta Chimica Slovenica 68, no. 4 (December 15, 2021): 1008–15. http://dx.doi.org/10.17344/acsi.2021.7070.

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Three new copper(II) complexes, [Cu(LH)2]Br2 (1), [Cu(LH)2]NCS2 (2), and [Cu(LH)2](NO3)2 (3), where LH is the zwitterionic form of 2-bromo-6-((2-(isopropylamino)ethylimino)methyl)phenol (HL), were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy. The structures of the complexes were further confirmed by single crystal X-ray structure determination. All compounds are mononuclear copper(II) complexes. The Cu atoms in the complexes are coordinated by two imino N and two phenolate O atoms from two LH ligands, forming square planar coordination. The compounds were assayed for their antimicrobial activities.

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16

S. Sharma, S., J. V. Ramani, D. P. Dalwadi, J. J. Bhalodia, N. K. Patel, D. D. Patel, and R. K. Patel. "New Ternary Transition Metal Complexes of 2-{[(2-aminophenyl)imino] methyl}Phenol and Metformin: Synthesis, Characterization and Antimicrobial Activity." E-Journal of Chemistry 8, no. 1 (2011): 361–67. http://dx.doi.org/10.1155/2011/723491.

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Complexes of Co(II), Ni(II) and Cu(II) were synthesized from Schiff base 2-{[(2-aminophenyl)imino]methyl}phenol and metformin. The authenticity of the transition metal complexes were characterized by elemental analyses, conductance and magnetic susceptibility measurements, as well as spectroscopic (IR, electronic) and thermal studies. IR spectral studies revealed the existence of the ligands in the amine form in the solid state. The magnetic and electronic spectral studies suggest an octahedral geometry for all the complexes. The metformin acts as a bidentate ligand and Schiff base ofo-phynelendiamine and salicylaldehyde acts as a tridentate ligand. Antimicrobial screening of the Schiff base, metformin and transition metal complexes were determined against the bacteriaEscherichia coliandBacillus megaterium.

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17

Cornelissen, Carsten, Gigi Chan, Jason D. Masuda, and Douglas W. Stephan. "Aluminum pentafluorophenyl–amide complexes." Canadian Journal of Chemistry 85, no. 2 (February 1, 2007): 135–40. http://dx.doi.org/10.1139/v07-003.

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The pentafluoroaryl amine (C6F5)2NH (1) reacts with AlH3·NEtMe2 to give [(C6F5)2N]AlH2·NEtMe2 (2) and [(C6F5)2N]2AlH·NEtMe2 (3). The related fluorinated-aryl amine (C6F5)(n-C4H9)NH (4) also reacts with AlH3·NEtMe2 to give [(C6F5)(n-C4H9)N]3Al·NEtMe2 (5). This latter compound undergoes ligand exchange with PMe3 or N-methylimidazole to form [(C6F5)(n-C4H9)N]3Al·PMe3 (6) and [(C6F5)(n-C4H9)N]3Al·(Me-imid) (7), respectively. The latter amine also reacts with AlMe3, affording [Me2AlN(C6F5)(n-C4H9)]2 (8).Key words: almunium, amides, pentafluorophenylamine.

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18

Lalovic, Mirjana, Vukadin Leovac, Ljiljana Vojinovic-Jesic, Marko Rodic, Ljiljana Jovanovic, and Valerija Cesljevic. "Dioxidovanadium(V) complexes with pyridoxalaminoguanidine: Synthesis, spectral and structural characterization." Journal of the Serbian Chemical Society 78, no. 8 (2013): 1161–70. http://dx.doi.org/10.2298/jsc130326038l.

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Three square-pyramidal complexes of dioxidovanadium(V) with pyridoxalaminoguanidine (PLAG), of the formulas NH4[VO2(PLAG?2H)]?H2O (1), VO2(PLAG?H) (2) and K[VO2(PLAG?2H)]?H2O (3) have been synthesized and characterized by IR and UV-Vis spectral analysis and in case of 1 and 3 by X-ray crystallography as well. The reaction of aqueous ammoniacal solution of NH4VO3 and PLAG resulted in formation of 1, which in MeOH undergoes spontaneous transformation into 2, which, in turn, in the reaction with KOH transforms into 3. In these complexes PLAG is coordinated in a common tridentate ONN mode, via phenoxide oxygen atom and nitrogen atoms of azomethine and imino groups of the aminoguanidine fragment. In all previously characterized complexes PLAG was coordinated in neutral form. However, here we have proven that this ligand can be coordinated in both mono- (2) and doubly deprotonated form (1 and 3) as well. [Projekat Ministarstva nauke Republike Srbije, br. 172014].

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19

Volkenandt, Senta, Frank Beierlein, and Petra Imhof. "Interaction of Thymine DNA Glycosylase with Oxidised 5-Methyl-cytosines in Their Amino- and Imino-Forms." Molecules 26, no. 19 (September 22, 2021): 5728. http://dx.doi.org/10.3390/molecules26195728.

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Thymine DNA Glycosylase (TDG) is an enzyme of the base excision repair mechanism and removes damaged or mispaired bases from DNA via hydrolysis of the glycosidic bond. Specificity is of high importance for such a glycosylase, so as to avoid the damage of intact DNA. Among the substrates reported for TDG are mispaired uracil and thymine but also formyl-cytosine and carboxyl-cytosine. Methyl-cytosine and hydroxylmethyl-cytosine are, in contrast, not processed by the TDG enzyme. We have in this work employed molecular dynamics simulations to explore the conformational dynamics of DNA carrying a formyl-cytosine or carboxyl-cytosine and compared those to DNA with the non-cognate bases methyl-cytosine and hydroxylmethyl-cytosine, as amino and imino tautomers. Whereas for the mispairs a wobble conformation is likely decisive for recognition, all amino tautomers of formyl-cytosine and carboxyl-cytosine exhibit the same Watson–Crick conformation, but all imino tautomers indeed form wobble pairs. The conformational dynamics of the amino tautomers in free DNA do not exhibit differences that could be exploited for recognition, and also complexation to the TDG enzyme does not induce any alteration that would indicate preferable binding to one or the other oxidised methyl-cytosine. The imino tautomers, in contrast, undergo a shift in the equilibrium between a closed and a more open, partially flipped state, towards the more open form upon complexation to the TDG enzyme. This stabilisation of the more open conformation is most pronounced for the non-cognate bases methyl-cytosine and hydroxyl-cytosine and is thus not a likely mode for recognition. Moreover, calculated binding affinities for the different forms indicate the imino forms to be less likely in the complexed DNA. These findings, together with the low probability of imino tautomers in free DNA and the indifference of the complexed amino tautomers, suggest that discrimination of the oxidised methyl-cytosines does not take place in the initial complex formation.

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20

Ejidike, Ikechukwu P., and Peter A. Ajibade. "Synthesis, Characterization, Antioxidant, and Antibacterial Studies of Some Metal(II) Complexes of Tetradentate Schiff Base Ligand: (4E)-4-[(2-{(E)-[1-(2,4-Dihydroxyphenyl)ethylidene]amino}ethyl)imino]pentan-2-one." Bioinorganic Chemistry and Applications 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/890734.

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Co(II), Ni(II), Cu(II), and Zn(II) complexes of (4E)-4-[(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)imino]pentan-2-one have been synthesized and characterized by elemental analyses, molar conductance, electronic and IR spectral studies, and XRD. FTIR confirmed the ligand coordinates the metal ion to form mononuclear complex via the oxygen and nitrogen atoms of the phenolic group and azomethine group, respectively. Tetrahedral geometry is proposed for Co(II) complex and square-planar geometry for Ni(II) and Cu(II) complexes. The antibacterial studies of the compounds were determined and they show that the metal complexes are more active than the free ligands. The antioxidant activity by DPPH and ABTS method was examined and it shows Cu(II); IC50= 2.31 ± 1.54 µM for DPPH and Co(II); IC50= 1.83 ± 1.08 µM for ABTS were the most active.

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21

Ventura, Dominic L., William W. Brennessel, and William S. Durfee. "Crystal structures of {1,1,1-tris[(salicylaldimino)methyl]ethane}gallium as both a pyridine solvate and an acetonitrile 0.75-solvate and {1,1,1-tris[(salicylaldimino)methyl]ethane}indium dichloromethane solvate." Acta Crystallographica Section E Crystallographic Communications 76, no. 5 (April 3, 2020): 615–20. http://dx.doi.org/10.1107/s2056989020004375.

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The sexadentate ligand 1,1,1-tris[(salicylideneamino)methyl]ethane has been reported numerous times in its triply deprotonated form coordinated to transition metals and lanthanides, yet it has been rarely employed with main-group elements, including in substituted forms. Its structures with gallium and indium are reported as solvates, namely, ({[(2,2-bis{[(2-oxidobenzylidene)amino-κ2 N,O]methyl}propyl)imino]methyl}phenololato-κ2 N,O)gallium(III) pyridine monosolvate, [Ga(C26H24N3O3)]·C5H5N, the acetonitrile 0.75-solvate, [Ga(C26H24N3O3)]·0.75C2H3N, and ({[(2,2-bis{[(2-oxidobenzylidene)amino-κ2 N,O]methyl}propyl)imino]methyl}phenololato-κ2 N,O)indium(III) dichloromethane monosolvate, [In(C26H24N3O3)]·CH2Cl2. All three metal complexes are pseudo-octahedral and each structure contains multiple weak C—H...O and/or C—H...N intermolecular hydrogen-bonding interactions. The syntheses and additional characterization in the forms of melting points, high-resolution mass spectra, infra-red (IR) spectra, and 1H and 13C NMR spectra are also reported.

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22

Radanović, Mirjana M., Ljiljana S. Vojinović-Ješić, Miodrag G. Jelić, Elias Sakellis, Berta Barta Holló, Vukadin M. Leovac, and Marko V. Rodić. "Synthesis, Structures, and Photoluminescence of Two Novel Zinc(II) Compounds Containing 2-Acetylpyridine-aminoguanidine." Inorganics 10, no. 10 (September 20, 2022): 147. http://dx.doi.org/10.3390/inorganics10100147.

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In the reaction of zinc(II) sulfate and the chloride salt of 2-acetylpyridine-aminoguanidine, two types of complex were obtained, i.e., [Zn(H2O)6](H2L)2(SO4)3·3H2O and [Zn(L)H2O(SO4)]·H2O, depending on the presence of LiOAc as the deprotonating agent. The physicochemical, structural, and photoluminescence properties of the complexes were examined. In the first complex, obtained in the absence of LiOAc, the Schiff base had the role of a counter-ion in its doubly protonated form, while in the presence of LiOAc, upon deprotonation, coordination takes place, and thus the Schiff base acts as a tridentate N3 ligand. In the latter complex, the ligand is coordinated through pyridine, azomethine, and the imino nitrogen of the aminoguanidine residue, leading to formation of two fused five-membered chelate rings. Both the examined complexes, as well as the ligand itself, show high photoluminescence.

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Wang, Fu-Ming, Li-Jie Li, Guo-Wei Zang, Tong-Tong Deng, and Zhong-Lu You. "Synthesis, Characterization, Crystal Structures, and Urease Inhibition of Copper(II) and Zinc(II) Complexes Derived from Benzohydrazones." Acta Chimica Slovenica 67, no. 4 (December 15, 2020): 1155–62. http://dx.doi.org/10.17344/acsi.2020.6056.

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A new copper(II) complex [Cu(L1)(NCS)(CH3OH)] (1) and a new zinc(II) complex [ZnCl2(HL2)] · CH3OH (2), derived from 4-bromo-N’-(pyridin-2-ylmethylene)benzohydrazide (HL1) and 4-methoxy-N’-(pyridin-2-ylmethylene)benzohydrazide (HL2), were prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy and single crystal X-ray diffraction. The hydrazone HL1 coordinates to the Cu atom in enolate form, while the hydrazone HL2 coordinates to the Zn atom in carbonyl form. Single crystal structural analyses indicate that the hydrazones coordinate to the metal atoms through the pyridine N, imino N, and enolate/carbonyl O atoms. The Cu atom in complex 1 is in square pyramidal coordination, and the Zn atom in complex 2 is in trigonal-bipyramidal coordination. The inhibitory effects of the complexes on Jack bean urease were studied, which show that the copper complex has strong activity on urease.

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24

Bera, Manindranath. "Synthesis, characterisation and activity in catalytic epoxidation of olefins of new dinuclear nickel(ll) complexes." Journal of Chemical Research 2009, no. 8 (August 2009): 527–32. http://dx.doi.org/10.3184/030823409x12491271131153.

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Two new dinuclear nickel(ll) compounds of formula [Nill2(μ-L1)2](CIO4)2·MeCN (1·MeCN) and [NiII2(μ-L2)2](CIO4)2 (2) where HL1 and HL2 stand for 3-(2-(dimethylamino)ethylimino)butan-2-one oxime and 1-(2-(dimethylamino)ethyl-imino)-1-phenylpropan-2-one oxime respectively, have been synthesised. Single crystal X-ray analyses of the complexes reveal that the nickel(ll) ions are in square-planar N3O environments and form six-membered (NiNO)2 metallacycles. Cyclic voltammetric measurements of 1·MeCN and 2 in MeCN solution show quasirreversible one-electron oxidations at E1/2 = 0.566 V and 0.603 V ( vs Fc+/Fc), respectively, attributed to NiIIINiII/NiII2 redox couples. Additional reversible NiIII2/NiIIINiII redox responses were observed at relatively higher potential near E1/2 = 0.832 V and 0.850 V ( vs Fc+/Fc), respectively, for 1·MeCN and 2. Complexes 1·MeCN and 2 display intense charge-transfer bands at ∼390 and ∼345 nm in the visible region. Chemical oxidation of complex 1·MeCN by sodium hexachloroiridate(IV) hexahydrate generates red Ni2III species with characteristic new bands at ∼520 and 427 nm in the visible region as well as the characteristic EPR signals at 77 K with g⊥ > gII. Similar phenomena were observed for complex 2 upon chemical oxidation. The dinickel(ll) complexes are catalytically active for epoxidation of olefins using iodosylbenzene as the terminal oxidant.

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Prokopowicz, Małgorzata, Adam Jarmuła, Yannick Casamayou-Boucau, Fiona Gordon, Alan Ryder, Justyna Sobich, Piotr Maj, et al. "Advanced Spectroscopy and APBS Modeling for Determination of the Role of His190 and Trp103 in Mouse Thymidylate Synthase Interaction with Selected dUMP Analogues." International Journal of Molecular Sciences 22, no. 5 (March 6, 2021): 2661. http://dx.doi.org/10.3390/ijms22052661.

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A homo-dimeric enzyme, thymidylate synthase (TS), has been a long-standing molecular target in chemotherapy. To further elucidate properties and interactions with ligands of wild-type mouse thymidylate synthase (mTS) and its two single mutants, H190A and W103G, spectroscopic and theoretical investigations have been employed. In these mutants, histidine at position 190 and tryptophan at position 103 are substituted with alanine and glycine, respectively. Several emission-based spectroscopy methods used in the paper demonstrate an especially important role for Trp 103 in TS ligands binding. In addition, the Advanced Poisson–Boltzmann Solver (APBS) results show considerable differences in the distribution of electrostatic potential around Trp 103, as compared to distributions observed for all remaining Trp residues in the mTS family of structures. Together, spectroscopic and APBS results reveal a possible interplay between Trp 103 and His190, which contributes to a reduction in enzymatic activity in the case of H190A mutation. Comparison of electrostatic potential for mTS complexes, and their mutants, with the substrate, dUMP, and inhibitors, FdUMP and N4-OH-dCMP, suggests its weaker influence on the enzyme–ligand interactions in N4OH-dCMP-mTS compared to dUMP-mTS and FdUMP-mTS complexes. This difference may be crucial for the explanation of the ”abortive reaction” inhibitory mechanism of N4OH-dCMP towards TS. In addition, based on structural analyses and the H190A mutant capacity to form a denaturation-resistant complex with N4-OH-dCMP in the mTHF-dependent reaction, His190 is apparently responsible for a strong preference of the enzyme active center for the anti rotamer of the imino inhibitor form.

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26

Kocak, Cagdas, Gorkem Oylumluoglu, Adem Donmez, M. Burak Coban, Ugur Erkarslan, Muhittin Aygun, and Hulya Kara. "Crystal structure and photoluminescence properties of a new monomeric copper(II) complex: bis(3-{[(3-hydroxypropyl)imino]methyl}-4-nitrophenolato-κ3 O,N,O′)copper(II)." Acta Crystallographica Section C Structural Chemistry 73, no. 5 (April 25, 2017): 414–19. http://dx.doi.org/10.1107/s2053229617005976.

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Copper(II)–Schiff base complexes have attracted extensive interest due to their structural, electronic, magnetic and luminescence properties. The title novel monomeric CuII complex, [Cu(C10H11N2O4)2], has been synthesized by the reaction of 3-{[(3-hydroxypropyl)imino]methyl}-4-nitrophenol (H2 L) and copper(II) acetate monohydrate in methanol, and was characterized by elemental analysis, UV and IR spectroscopies, single-crystal X-ray diffraction analysis and a photoluminescence study. The CuII atom is located on a centre of inversion and is coordinated by two imine N atoms, two phenoxy O atoms in a mutual trans disposition and two hydroxy O atoms in axial positions, forming an elongated octahedral geometry. In the crystal, intermolecular O—H...O hydrogen bonds link the molecules to form a one-dimensional chain structure and π–π contacts also connect the molecules to form a three-dimensional structure. The solid-state photoluminescence properties of the complex and free H2 L have been investigated at room temperature in the visible region. When the complex and H2 L are excited under UV light at 349 nm, the complex displays a strong green emission at 520 nm and H2 L displays a blue emission at 480 nm.

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27

Basaran, Ismet, Md Mhahabubur Rhaman, Douglas R. Powell, and Md Alamgir Hossain. "Crystal structure of bis(bis{(E)-[(6-{(E)-[(4-fluorobenzyl)imino]methyl}pyridin-2-yl)methylidene](4-fluorophenyl)amine}nickel(II)) tetrabromide nonahydrate." Acta Crystallographica Section E Crystallographic Communications 71, no. 12 (November 21, 2015): m226—m227. http://dx.doi.org/10.1107/s2056989015021519.

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In the title complex, [Ni(C21H17F2N3)2]2Br4·9H2O, there are two independent metal complexes per asymmetric unit and two ligands per metal complex. The structural features (bond lengths and angles) of the two complexes are almost identical. In each complex, the nickel(II) ion is coordinated in an octahedral environment by six N atoms from two chelating (9E)-N-({6-[(E)-(4-fluorobenzylimino)methyl]pyridin-2-yl}methylene)(4-fluorophenyl)methanammine ligands. The Ni—N bond lengths range from 1.973 (2) to 2.169 (2) Å, while the chelate N—Ni—N angles range from 77.01 (10) to 105.89 (9)°. Additionally, there are four bromide anions and nine solvent water molecules within the asymmetric unit. The water molecules form a hydrogen-bonded network, displaying C—H...O, C—H...Br, O—H...Br, O—H...O and O—H...F interactions into layers parallel to (111). In each unit, the fluorophenyl rings of one ligand are stacked with the central ring of the other ligandviaπ–π interactions, with the closest centroid-to-plane distances being 3.445 (5), 3.636 (5), 3.397 (5) and 3.396 (5) Å.

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Rzaev, Zakir M. O., Güneri Akovali, E. Yu Kuliyeva, and N. Yu Lezgiev. "Complex-radical copolymerization of vinylcyclohexyl ketones with maleic anhydride and N-p-tolylmaleimide." Eurasian Chemico-Technological Journal 1, no. 1 (April 14, 2016): 17. http://dx.doi.org/10.18321/ectj343.

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<p>Some features of the formation and photochemical reactions of cyclohexylketone containing macromolecules including copolymers of vinylcyclohexyl ketone (VCHK) and its derivatives (V-a-Cl-CHK and V- d-C1-CHK) with maleic anhydride (MA) and N-p-tolylmaleimide (TMI) have been revealed. It has been established that keto-enol tautomerism is the only reaction realized in the vinylcyclohexylketone molecules having mobile hydrogen atom at a -position in the cyclohexane ring, enol form of which is formed by charge-transfer complexes with anhydride or imide of maleic acid as acceptor monomers. The kinetic parameters of these reactions, including complex-formation and copolymerization constants, as well as the ratios of chain growth rates for the participation of monomeric charge-transfer complexes and free monomers, are all determined. It is shown that an alternative copolymerization is realized with the monomer systems containing VCHK and V- d -C1-CHK, which are carried out through a complex-mechanism due to the keto-enol tautomerism; while random copolymer enriched with vinyl ketone units is formed with the system containing oc-substituted VCHK. It is found that characteristics of photochemical reactions of alternating copolymer synthesized depend on the type of substitutation in the vinyl ketone molecule; unlink VCHK-MA(TMI) and V-d-C1-CHK-MA(TMI) copolymers case which easily crosslink upon UVirradiation, and the N-substituted derivatives of these copolymers which decompose under similar condition.</p>

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29

Esmaeilzadeh, J., Z. Mardani, K. Moeini, C. Carpenter-Warren, A. M. Z. Slawin, and J. D. Woollins. "Coordination of an amino alcoholic Schiff base ligand toward the zinc(II) ion: spectral, structural, theoretical, and docking studies." Журнал структурной химии 63, no. 2 (2022): 233. http://dx.doi.org/10.26902/jsc_id88425.

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A new zinc(II) complex of 2-(((2-((2-hydroxyethyl)amino)ethyl)imino)methyl)phenol (L), [Zn(Lz)Br2] (1), is prepared and identified by elemental analysis, FTIR and 1H NMR spectroscopy, and single crystal X-ray diffraction. The X-ray structure analysis of 1 reveals a tetrahedrally coordinated zinc(II) complex containing the NO-donor amino alcoholic Schiff base ligand and two bromo ligands. After complexation, the ligand (L) converts to its zwitterionc form (Lz) of phenol → phenolate; amine → ammonium. In this structure, hydrogen bonds between amine and alcohol units form different types of hydrogen bond motifs, including R21(7), R22(7), R22(10), R44(24), R44(30), R66(38), and R66(44). In addition to the hydrogen bonds in this crystal network, there are π—π stacking interactions between the phenyl ring and the imine group. The ability of the ligand and its isostructural complexes [Zn(Lz)Br2] (1), [Zn(Lz)Cl2] (2), and [Zn(Lz)I2] (3) to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, and B-DNA) is investigated by docking studies. The results show that in some cases, the studied compound can interact with proteins and DNA better than doxorubicin. The charge distribution pattern of the ligand and complex 1 is studied by the NBO analysis.

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30

Esmaeilzadeh, J., Z. Mardani, K. Moeini, C. Carpenter-Warren, A. M. Z. Slawin, and J. D. Woollins. "Coordination of an amino alcoholic Schiff base ligand toward the zinc(II) ion: spectral, structural, theoretical, and docking studies." Журнал структурной химии 63, no. 2 (2022): 233. http://dx.doi.org/10.26902/jsc_id88425.

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A new zinc(II) complex of 2-(((2-((2-hydroxyethyl)amino)ethyl)imino)methyl)phenol (L), [Zn(Lz)Br2] (1), is prepared and identified by elemental analysis, FTIR and 1H NMR spectroscopy, and single crystal X-ray diffraction. The X-ray structure analysis of 1 reveals a tetrahedrally coordinated zinc(II) complex containing the NO-donor amino alcoholic Schiff base ligand and two bromo ligands. After complexation, the ligand (L) converts to its zwitterionc form (Lz) of phenol → phenolate; amine → ammonium. In this structure, hydrogen bonds between amine and alcohol units form different types of hydrogen bond motifs, including R21(7), R22(7), R22(10), R44(24), R44(30), R66(38), and R66(44). In addition to the hydrogen bonds in this crystal network, there are π—π stacking interactions between the phenyl ring and the imine group. The ability of the ligand and its isostructural complexes [Zn(Lz)Br2] (1), [Zn(Lz)Cl2] (2), and [Zn(Lz)I2] (3) to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, and B-DNA) is investigated by docking studies. The results show that in some cases, the studied compound can interact with proteins and DNA better than doxorubicin. The charge distribution pattern of the ligand and complex 1 is studied by the NBO analysis.

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31

Khalaf, Mai M., Hany M. Abd El-Lateef, Mohamed Gouda, Fatma N. Sayed, Gehad G. Mohamed, and Ahmed M. Abu-Dief. "Design, Structural Inspection and Bio-Medicinal Applications of Some Novel Imine Metal Complexes Based on Acetylferrocene." Materials 15, no. 14 (July 12, 2022): 4842. http://dx.doi.org/10.3390/ma15144842.

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Some novel imine metal chelates with Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ cations were produced from 2-acetylferrocene and 3-aminophenol. The new acetylferrocene azomethine ligand ((Z)-cyclopenta-1,3-dien-1-yl(2-(1-((3-hydroxyphenyl)imino)ethyl)cyclopenta-2,4-dien-1-yl)iron) and its metal ion chelates were constructed and elucidated using FT-IR, UV/Vis, 1HNMR, DTA/TGA, CHNClM studies, mass spectrometry and SEM analysis. According to the TGA/DTG investigation, the ferrocene moiety spontaneously disintegrates to liberate FeO. The morphology of the free acetylferrocene azomethine via SEM analysis was net-shaped with a size of 64.73 nm, which differed in Cd(II) complex to be a spongy shape with a size of 42.43 nm. The quantum chemical features of the azomethine ligand (HL) were computed, and its electronic and molecular structure was refined theoretically. The investigated acetylferrocene imine ligand behaves as bidinetate ligand towards the cations under study to form octahedral geometries in case of all complexes except in case of Zn2+ is tetrahedral. Various microorganisms were used to investigate the anti-pathogenic effects of the free acetylferrocene azomethine ligand and its metal chelates. Moreover, the prepared ligand and its metal complexes were tested for anticancer activity utilizing four different concentrations against the human breast cancer cell line (MCF7) and the normal melanocyte cell line (HBF4). Furthermore, the binding of 3-aminophenol, 2-acetylferrocene, HL, Mn2+, Cu2+, and Cd2+ metal chelates to the receptor of breast cancer mutant oxidoreductase was discovered using molecular docking (PDB ID: 3HB5).

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32

Yahsi, Yasemin, Hatice Ozbek, Muhittin Aygun, and Hulya Kara. "Crystal structure and photoluminescence properties of a new CdIIcoordination polymercatena-poly[bis[4-bromo-2-({[2-(pyrrolidin-1-yl)ethyl]imino}methyl)phenolato-κ3N,N′,O]di-μ3-chlorido-di-μ2-chlorido-bis(methanol-κO)tricadmium(II)]." Acta Crystallographica Section C Structural Chemistry 72, no. 5 (April 18, 2016): 426–31. http://dx.doi.org/10.1107/s2053229616005180.

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Schiff base–metal complexes have been used widely as catalysts for many organic reactions, such as ring-opening polymerization and oxidation. In view of the importance of CdIIcoordination polymers and in an effort to enlarge the library of such complexes, the title novel polymeric CdIItridentate Schiff base complex, [Cd3(C13H16BrN2O)2Cl4(CH4O)2]n, has been synthesized and characterized by elemental analyses, UV and IR spectroscopies, and single-crystal X-ray diffraction. The complex crystallizes in the triclinicP\overline{1} space group with two symmetry-independent CdIIatoms, one of which lies on an inversion centre, and analysis of the crystal structure shows that both CdIIatoms are six-coordinated; the environment around one CdIIatom can be described as distorted octahedral, while that around the second CdIIatom is octahedral. The CdIIatoms are linked by chloride ligands to form a one-dimensional coordination polymer. The nonbonding intermolecular Cd...Cd distances are 3.7009 (4) and 4.3563 (5) Å. Furthermore, the photoluminescence properties of the complex have been investigated and it displays a strong red emission in the solid state at room temperature.

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33

Povidaichik, Mariana, Oleksandr Shalimov, Mykhailo Onysko, and Petro Onysko. "SYNTHESIS OF SALTS OF N-ALLYLTRICHLOROACETAMIDINIUM HEXAHALOGENOTELLURATE." Ukrainian Chemistry Journal 88, no. 9 (October 28, 2022): 34–40. http://dx.doi.org/10.33609/2708-129x.88.09.2022.34-40.

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Amidines with a trichloromethyl group exhibit the properties of inotropic agents, which are used as scaffolds in synthesizing aza-heterocycles and ligands for complex formation. Functionalized amidines show anticancer, and antidiabetic activity, and are antihypertensive and antiparasitic agents. The synthesis of new functional derivatives of such amidines is definitely an urgent task. The introduction of an alkenyl substituent and several nucleophilic centers in the amidine creates prerequisites for electrophilic cyclization. This work aims to study the reactions of N-allyl-N-methyl-N'-(trimethylsilyl)-2,2,2-trichloroethanimidamide with tellurium halides. The starting N-allyl-N-methyl-N'-(trimethylsilyl)-2,2,2-trichloroethanimidamide was synthesized from N-allyl-N-methyl-2,2,2-trichloroethanimidamide by the action of trimethylsilyl chloride in the presence of triethylamine base. The reaction of N-allyl-N-methyl-N'-(trimethylsilyl)-2,2,2-trichloroethanimidamide with tellurium dioxide in hydrohalic acid was carried out while cooling to 0°C. Elemental analysis confirms that the electrophilic reagent is in its acidic form in the complex. The 1H NMR spectra of the obtained complexes indicate the absence of EVC - the spin pattern of the proton signals of the allylic substituent, characteristic of the starting compounds, is preserved, but the signals are shifted by 0.3–0.6 ppm. The absence of proton signals of the trimethyl salt substituent indicates the removal of imide protection under these conditions. The presence of a broadened singlet in a weak field indicates the presence of acidic protons. Apparently, protonation does not take place on the alkenyl multiple bonds, but, presumably, on the imide nitrogen atom. Based on elemental analysis, the composition of the formed complex was determined: N-allyl-N-methyl-2,2,2-trichloroethanimidamidine: hexahalogenotelluric acid as 1:0.5, which contains 4 or 3 water molecules. So the interaction of N-allyl-N-methyl-N'-(trimethylsilyl)-2,2,2-trichloroethanimidamide with tellurium tetrahalides in a strongly acidic environment, tellurium- or proton-induced cyclization does not occur, but hexahalogenotellurate N-allyl-N-methyl-2,2,2-trichloroethaneimidamidinium regardless of the polarity of the solvent.

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34

Neri, Paola. "Enhancer Deregulation in Myeloma." Blood 132, Supplement 1 (November 29, 2018): SCI—38—SCI—38. http://dx.doi.org/10.1182/blood-2018-99-109523.

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Abstract The complexity of gene expression regulation is the result of a composite interplay between promoters, enhancers and other cis-acting regulatory elements bound by transcription factors (TFs) that controls the transcriptional activity of genes. Primary tumor cells, in comparison to their healthy counterparts, are known to display altered enhancer repertoires that are associated with tumor-specific transcription. Large groups of transcriptional enhancers cluster together to form super-enhancers (SEs). These elements have been shown to control genes that are important for maintaining cell identity but are also frequently associated with oncogenes as well as translocations that result in aberrant gene expression in cancer. Immunoglobulin (IGH, IGL, IGK) and non-immunoglobulin (PVT1, FAM46C, DUSP22, etc.) enhancers hijacking by variable genes (MYC, MAF, CCND1/2/3, MMSET, IRF4) is a recognized oncogenic driver event in multiple myeloma (MM). However, the identity of the TFs or transcriptional regulatory complexes binding and regulating the activity of these enhancers remains to be fully elucidated and may yield valuable therapeutic targets. In this regard, the bromodomain and extra-terminal (BET) inhibitors have emerged as promising molecules for the treatment of hematologic malignancies. BET family proteins are chromatin adaptors, functionally linked to important pathways for cellular viability and cancer signaling. In particular, BRD4 has a direct role in the transcription regulation of different genes involved in the cell cycle progression and cellular viability. The BET inhibitor JQ1 selectively inhibits BRD4 by competitively binding to the acetyl-lysine recognition pocket of BET bromodomains from chromatin leading to the inhibition of MYC transcription in a dose- and time-dependent manner. Thus, BRD4 has been recently described as a therapeutic target for MM, among other hematologic diseases. Constitutive activation of MYC signaling is detected in more than 60% of patient-derived MM cells and can be involved in the pathogenesis of MM through different mechanisms. One of the most common somatic genomic aberrations in early and late-stage MM is rearrangement or translocation of MYC. Regardless of whether MYC rearrangements occur at early or late stages of MM pathogenesis, MYC rearrangements may provide one of several critical events contributing to increased autonomy and a more aggressive phenotype. Moreover promiscuous rearrangements of the MYC locus are known to hijack enhancers and super-enhancers to dysregulate MYC expression in MM and are involved in its pathogenesis. The development of the immunomodulatory drugs (IMiDs) has contributed significantly to improve the outcomes of MM patients. They possess pleiotropic anti-MM properties and through CRBN binding they induce Ikaros and Aiolos ubiquitylation and proteasomal degradation with an ensuing transcriptional repression of MYC and IRF4, two essential factors for myeloma cells survival. However, is not clear how IKZF1/IKZF3 regulate MYC transcription and how myeloma cells acquire resistance to IMIDs, "beyond CRBN". In addition, acquired resistance to IMIDs and the loss of the transcriptional repression of MYC are nearly universal and occur in spite of sustained IKZF1/3 degradation suggesting that transcriptional rewiring may be sustaining hijacked enhancers activity and transcription of driver oncogenes. In this contest we have recently demonstrated that IMiDs are repressors of IKZF1/3-depedent oncogenic enhancers. Transcriptional plasticity with expression of extra-lineage TFs such as the ETS family member ETV4 sustains oncogenic enhancers in MM overcoming IKAROS and AIOLOS dependency and promoting IMiDs resistance. Therefore defining TFs occupancy and their circuitry at enhancers identifies "non-canonical" (aberrant) myeloma TFs dependency that may be linked to potential therapeutic targets. Disclosures Neri: Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

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35

Abrahão, Ana Beatriz Ramos Moreira, Jonas Frank Reis, Samia Danuta Brejão, Vinícius Garcia Ribeiro, Michelle Leali Costa, and Edson Cocchieri Botelho. "Avaliação dos parâmetros tempo, corrente e pressão na soldagem por resistência elétrica de compósitos PEI/fibras contínuas: influência na resistência mecânica." Matéria (Rio de Janeiro) 20, no. 2 (June 2015): 530–43. http://dx.doi.org/10.1590/s1517-707620150002.0053.

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Atualmente, muitos componentes destinados à indústria aeronáutica, que anteriormente utilizavam compósitos com matriz termorrígida, vêm sendo substituídos por aqueles que apresentam matriz termoplástica, devido principalmente às melhores propriedades mecânicas obtidas, possibilidade de reaproveitamento do mesmo e a facilidade na fabricação de peças grandes e complexas, que serão integradas para formar o componente final desejado, assim como a sua temperatura de serviço mais elevada. Entretanto, um dos principais problemas da utilização de compósitos poliméricos em aplicações estruturais consiste em sua união efetiva para a integração de componentes. Nos últimos anos, a soldagem por resistência elétrica vem sendo considerada como uma das mais promissoras técnicas para a união de compósitos, pois se trata de um processo com pouca preparação de superfície e com qualidade aceitável no setor industrial. O principal objetivo deste trabalho consiste no estudo de parâmetros de soldagem por resistência elétrica para o compósito polimérico PEI poli (éter-imida) reforçado com fibras de carbono e de vidro (sistema híbrido) para aplicações aeronáuticas. As amostras do compósito foram soldadas e submetidas ao ensaio de lap shear para obtenção de tensão de ruptura ao cisalhamento de juntas simples. A partir deste ensaio foram estabelecidas as variáveis mais adequadas para utilização neste processo. O método utilizado foi um planejamento experimental fatorial completo que permitiu, com um número menor de experimentos, explorar todo o espaço experimental de interesse, estabelecendo os valores mais adequados de corrente elétrica, pressão e tempo para o processo de soldagem estudado.

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Pickardt, Joachim, and Britta Kühn. "Metallkomplexe mit Guanidinderivaten als Liganden: Kristallstrukturen von [Zn(cnge)2(SCN)2] · 2H2O und Zn(eoge)Br2 (enge = Cyanoguanidin; eoge = 1-Ethoxyiminomethylguanidin) / Metal Complexes with Guanidine Derivatives as Ligands: Crystal Structures of [Zn(cnge)2(SCN)2]·2H2O und Zn(eoge)Br2 (cnge = Cyanoguanidine; eoge = 1-Ethoxyim inom ethylguanidine)." Zeitschrift für Naturforschung B 51, no. 10 (October 1, 1996): 1469–72. http://dx.doi.org/10.1515/znb-1996-1018.

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Crystals of |Zn(cnge)2(SCN)2]-2H2O (1) were obtained by evaporation of an aqueous solution of Z n(SO4)·7H2O , KSCN, and cyanoguanidine. Crystals of Zn(eoge)Br2 (2) were obtained by reaction of ZnBr2 and cyanoguanidine in ethanol/water. Both compounds are monoclinic, space group C2/c, 1: Z = 4, a = 1919.6(7), b = 467.3(2), c = 1838.5(6) pm, β = 112.99(3)°, 2: Z = 8, a = 1799.5(6), b = 878.7(2), c = 1367.2(5) pm, β = 101.52(3)°. In 1 each Zn is bonded to two cyanoguanidine molecules and via the N atoms to two NCS groups. Intermolecular hydrogen bonds lead to chains along the a-axis, and these chains are again connected via hydrogen bonds to the two crystal water molecules. In the course of the formation of 2, the cyanoguanidine reacted with the ethanol to form 1-ethoxyiminomethylguanidine. This ligand forms chelate rings with the Zn atoms, which are tetrahedrally coordinated by the two imino N atoms of the ligand and by two bromine atoms.

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37

Shteinberg, Leon. "INFLUENCE OF SUBSTITUTES ON THE RATE OF THE REACTION OF ORTHOSUBSTITUTED BENZOIC ACIDS WTH ANILINE, CATALYZED BY POLYBUTOXYTITANATES." Ukrainian Chemistry Journal 87, no. 3 (April 23, 2021): 18–40. http://dx.doi.org/10.33609/2708-129x.87.03.2021.18-40.

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The polybutoxytitanates catalysis of aniline acylation by orthosubstituted benzoic acids leads to the production of substituted benzanilides. Catalytic rate constants of the second order reaction (the first with respect to aniline and ortho-substituted benzoic acid; boiling ortho=xylene, 145°C) correlate well according to the Hammett and Bronsted equations with straight line segments with ρ=1.93 and α=0.66, in contrast to the reaction of aniline with meta- and parasubstituted benzoic acids and substituted anilines with benzoic acid. This dependence drops out 2=nitrobenzoic and 1=naphthoic acids, which have relatively low reactivity and the greatest steric hindrances both for nucleophilic attack by aniline and for possible coordination with catalytically active centers of the corresponding ortho-substituted titanium polybutoxybenzoates formed in situ. Based on these data, the previously proposed mechanism of bifunctional catalysis due to titanium polybutoxybenzoates and their complexes with meta- and parasubstitutedbenzanilides was supplemented by the possibility of the steric inhibition of reaction by the most bulky substituents and chelate structures formation of orthosubstituted benzoic acids and their anilides with individual titanium atoms of the catalyst, as well as the simultaneous H-bonding of the amino group hydrogen atoms of aniline, which leads to its activation to a nucleophilic attack, with a carbonyl group and an orthopositioned substituent of the orthobenzoate ligand in the coordination sphere of titanium. Taking into account such chelation and steric barriers, as well as inhibition of acid catalysis due to the formation of the imide form of anilides, containing electron-withdrawing substituents, the equations for the rate constants of the catalytic reaction of ortho-substituted benzoic acids with aniline are derived, corresponding to the experimentally obtained Hammett dependence.

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Al-Sheakh, Loai, Sebastian Fritsch, Andreas Appelhagen, Alexander Villinger, and Ralf Ludwig. "Thermodynamically Stable Cationic Dimers in Carboxyl-Functionalized Ionic Liquids: The Paradoxical Case of “Anti-Electrostatic” Hydrogen Bonding." Molecules 27, no. 2 (January 7, 2022): 366. http://dx.doi.org/10.3390/molecules27020366.

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We show that carboxyl-functionalized ionic liquids (ILs) form doubly hydrogen-bonded cationic dimers (c+=c+) despite the repulsive forces between ions of like charge and competing hydrogen bonds between cation and anion (c+–a−). This structural motif as known for formic acid, the archetype of double hydrogen bridges, is present in the solid state of the IL 1−(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC−CH2−py][NTf2]. By means of quantum chemical calculations, we explored different hydrogen-bonded isomers of neutral (HOOC–(CH2)n–py+)2(NTf2−)2, single-charged (HOOC–(CH2)n–py+)2(NTf2−), and double-charged (HOOC– (CH2)n−py+)2 complexes for demonstrating the paradoxical case of “anti-electrostatic” hydrogen bonding (AEHB) between ions of like charge. For the pure doubly hydrogen-bonded cationic dimers (HOOC– (CH2)n−py+)2, we report robust kinetic stability for n = 1–4. At n = 5, hydrogen bonding and dispersion fully compensate for the repulsive Coulomb forces between the cations, allowing for the quantification of the two equivalent hydrogen bonds and dispersion interaction in the order of 58.5 and 11 kJmol−1, respectively. For n = 6–8, we calculated negative free energies for temperatures below 47, 80, and 114 K, respectively. Quantum cluster equilibrium (QCE) theory predicts the equilibria between cationic monomers and dimers by considering the intermolecular interaction between the species, leading to thermodynamic stability at even higher temperatures. We rationalize the H-bond characteristics of the cationic dimers by the natural bond orbital (NBO) approach, emphasizing the strong correlation between NBO-based and spectroscopic descriptors, such as NMR chemical shifts and vibrational frequencies.

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39

Falk, G., and J. E. Walker. "DNA sequence of a gene cluster coding for subunits of the F0 membrane sector of ATP synthase in Rhodospirillum rubrum. Support for modular evolution of the F1 and F0 sectors." Biochemical Journal 254, no. 1 (August 15, 1988): 109–22. http://dx.doi.org/10.1042/bj2540109.

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A region was cloned from the genome of the purple non-sulphur photobacterium Rhodospirillum rubrum that contains genes coding for the membrane protein subunits of the F0 sector of ATP synthase. The clone was identified by hybridization with a synthetic oligonucleotide designed on the basis of the known protein sequence of the dicyclohexylcarbodi-imide-reactive proteolipid, or subunit c. The complete nucleotide sequence of 4240 bp of this region was determined. It is separate from an operon described previously that encodes the five subunits of the extrinsic membrane sector of the enzyme, F1-ATPase. It contains a cluster of structural genes encoding homologues of all three membrane subunits a, b and c of the Escherichia coli ATP synthase. The order of the genes in Rsp. rubrum is a-c-b'-b where b and b' are homologues. A similar gene arrangement for F0 subunits has been found in two cyanobacteria, Synechococcus 6301 and Synechococcus 6716. This suggests that the ATP synthase complexes of all these photosynthetic bacteria contain nine different polypeptides rather than eight found in the E. coli enzyme; the chloroplast ATP synthase complex is probably similar to the photosynthetic bacterial enzymes in this respect. The Rsp. rubrum b subunit is modified after translation. As shown by N-terminal sequencing of the protein, the first seven amino acid residues are removed before or during assembly of the ATP synthase complex. The subunit-a gene is preceded by a gene coding for a small hydrophobic protein, as has been observed previously in the atp operons in E. coli, bacterium PS3 and cyanobacteria. A number of features suggest that the Rsp. rubrum cluster of F0 genes is an operon. On its 5′ side are found sequences resembling the -10 (Pribnow) and -35 boxes of E. coli promoters, and the gene cluster is followed by a sequence potentially able to form a stable stem-loop structure, suggesting that it acts as a rho-independent transcription terminator. These features and the small intergenic non-coding sequences suggest that the genes are cotranscribed, and so the name atp2 is proposed for this second operon coding for ATP synthase subunits in Rsp. rubrum. The finding that genes for the F0 and F1 sectors of the enzyme are in separate clusters supports the view that these represent evolutionary modules.

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40

Drapak, Iryna, Borys Zimenkovsky, Lina Perekhoda, Мargarita Suleyman, Hanna Yeromina, Natalia Skaletska, Natalya Seredynska, and Anatoly Demchenko. "Search for angiotensin II receptor antagonists among 4-aryl-n-(aryl)-3-(prop-2-en-1-yl)-2,3-dihydro-1,3-thiazol-2-imine derivatives." Pharmacia 66, no. 4 (December 31, 2019): 181–86. http://dx.doi.org/10.3897/pharmacia.66.e36808.

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The aim of study was to find potential antihypertensive and cardiotropic drugs among new 4-aryl-N-(aryl)-3-(prop-2-en-1-yl)-2,3-dihydro-1,3-thiazol-2-imines. Materials and methods: The target compounds were synthesized by condensation asymmetrical substituted thioureas with α-bromo-4-R1-acetophenones in ethanol medium. The structure and purity of the compounds synthesized were confirmed by 1H, 13C NMR-spectroscopy and elemental analysis. Docking studies of synthesized compounds to the active site of angiotensin receptor ІІ (PDB ID: 3R8A) were performed in order to find its potential inhibitors and to select promising compounds for experimental screening. Pharmacological studies of the influence on the cardiovascular system were performed. Results: The results of docking studies indicate a high affinity of all tested substances to the selected biotarget. The thermodynamic probability of binding of synthesized substances to protein 3R8A was confirmed by negative values of scoring functions. Hydrobromide of 4-(4-methoxyphenyl)-N-phenyl-3-(prop-2-en-1-yl)-2,3-dihydro-1,3-thiazol-2-imine 3(1) and hydrobrmide of 4-(4-methoxyphenyl)-N-(4-bromphenyl)-3-(prop-2-en-1-yl)-2,3-dihydro-1,3-thiazol-2-imine 3(3), which have the highest negative values of scoring functions, are recommended for in vivo pharmacological studies. Based on a complete analysis of the geometric location of the synthesized compounds (ligands) in the active site of the angiotensin II receptor, it was found that the complexes are formed with the involvement of Nitrogen atom of imino group, the 1,3-thiazole ring, the phenyl and alkyl moieties of the molecule form hydrogen bonds, intermolecular electrostatic and donor-acceptor interactions. The conducted pharmacological studies of the influence on the cardiovascular system have allowed to confirm the presence of antihypertensive effect inherent in compounds of this series (except for compound 3(2)). The most effective antihypertensive effect, which is similar in duration and strength of the effect of valsartan, was the effect of compound 3(5). Conclusions: In order to expand the arsenal of biologically active substances of cardiotropic action a systematic series of new 4-aryl-N-(aryl)-3-(prop-2-en-1-yl)-2,3-dihydro-1,3-thiazol-2-imine derivatives were synthesized. The structure and purity of the compounds synthesized were confirmed by 1H, 13C NMR-spectroscopy and elemental analysis. Based on the results of docking studies using Autodock 4.2.6 software, selected compounds with the best affinity for protein biomes (PDB codes: 3R8A) are promising for experimental studies of hypotensive and cardiotropic activity. The most effective antihypertensive effect, which is similar in duration and strength of the effect of valsartan, was the effect of compound 3(5). A comparative analysis of the results of molecular docking and in vivo results suggests that there is a positive correlation between scoring protein inhibition and experimental data.

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Chen-Glasser, Melodie, Lydia Meyer, Sean Skweres, Jason Morgan Porter, and Steven C. DeCaluwe. "An FTIR Study of Electrolyte Dynamics in Lithium-Air Batteries." ECS Meeting Abstracts MA2022-01, no. 1 (July 7, 2022): 113. http://dx.doi.org/10.1149/ma2022-011113mtgabs.

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Lithium-oxygen (Li-O2) batteries are widely studied for their potential to improve the energy density for electric vehicles; however, the high reactivity of cell components limits extended cyclability of the batteries. Some of this degradation can be attributed to the formation of O2-, which reacts with the electrolyte and Li+ to form irreversible biproducts. These complexes have been detected on the cathode of Li-O2 cells by Raman spectroscopy and FTIR after cycling in TEGDME, a popular electrolyte solvent for Lithium-Air batteries [1, 2]. FTIR has potential to quantify electrolyte speciation as a function of battery operation, but there has been little direct FTIR study of the TEGDME-LiTFSI electrolyte. In the past FTIR of electrolytes has allowed insightful operando analysis, where the ratio of peaks impacted by lithium and those which are not can be used to track the lithium concentration during battery operation [3]. Most FTIR studies of LiO2 focus on the cathode. The present work characterizes well-defined standard systems, providing a similar quantitative basis for understanding dynamic electrolyte evolution in operating Li-O2 batteries. This presentation will describe how the FTIR can track the electrolyte species composition. Figure 1 shows the FTIR spectra of TEGDME-LiTFSI and TEGDME-LiNO3 for different concentrations. By comparing these two systems, the TEGDME peaks associated with Li+ and TFSI- can be independently identified, enabling precise quantification of the electrolyte ion concentration. The partnered peaks at 1080 cm-1 and 1100 cm-1 show evidence influence of Li+, as the peak at 1080 cm-1 increases while the other decreases. A variety of peaks associated with TFSI- can be seen at 740, 786, 1180, 1327, and 1352 cm-1. At high molarities there is a wavelength shift near the 1327 cm-1 wavelength which indicates a configuration change in S=O bond [4, 5]. The examination of control electrolyte systems lays groundwork for future FTIR studies of lithium-air system and operando experiments can used to inform Lithium-Air cell design. [1] A. Chamaani, M. Safa, N. Chawla, M. Herndon and B. El-Zahab, "Stabilizing effect of ion complex formation in lithium–oxygen battery electrolytes," J. Electroanal. Chem., vol. 815, pp. 143-150, 2018. [2] S. Fruenberger, Y. Chen, N. E. Drewett, L. J. Hardwick, F. Barde and P. G. Bruce, "The Lithium–Oxygen Battery with Ether-Based Electrolytes," Angew. Chem. Int. Ed., vol. 2011, pp. 8609-8613, 2011. [3] L. Meyer, D. Curran, B. Ryan, S. Shriram and J. Porter, "Operando Measurements of Electrolyte Li-ion Concentration during fast charging with FTIR/ATR," J. Electrochem. Soc., vol. 169, no. 9, p. 090502, 2021. [4] M. Herstedt, M. Smirnov, P. Johansson, M. Chami, J. Grondin, L. Servant and J. C. Lasseguess, "Spectroscopic characterization of the conformational states of the bis(trifluoromethanesulfonyl)imide anion (TFSI−)," J. Raman Spectrosc., vol. 36, pp. 762-770, 2005. [5] L. Aguilera, S. Xiong, J. Scheers and M. Aleksandar, "A structural study of LiTFSI–tetraglyme mixtures: From diluted solutions to solvated ionic liquids," J. Mol. Liq, vol. 210, pp. 238-242, 2015. Figure 1

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42

Anyfanti, Goulielmina, Antonio Bauzá, Lorenzo Gentiluomo, João Rodrigues, Gustavo Portalone, Antonio Frontera, Kari Rissanen, and Rakesh Puttreddy. "Short X···N Halogen Bonds With Hexamethylenetetraamine as the Acceptor." Frontiers in Chemistry 9 (April 29, 2021). http://dx.doi.org/10.3389/fchem.2021.623595.

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Hexamethylenetetramine (HMTA) and N-haloimides form two types of short (imide)X···N and X–X···N (X = Br, I) halogen bonds. Nucleophilic substitution or ligand-exchange reaction on the peripheral X of X–X···N with the chloride of N-chlorosuccinimide lead to Cl–X···N halogen-bonded complexes. The 1:1 complexation of HMTA and ICl manifests the shortest I···N halogen bond [2.272(5) Å] yet reported for an HMTA acceptor. Two halogen-bonded organic frameworks are prepared using 1:4 molar ratio of HMTA and N-bromosuccinimide, each with a distinct channel shape, one possessing oval and the other square grid. The variations in channel shapes are due to tridentate and tetradentate (imide)Br···N coordination modes of HMTA. Density Functional Theory (DFT) studies are performed to gain insights into (imide)X···N interaction strengths (ΔEint). The calculated ΔEint values for (imide)Br···N (−11.2 to −12.5 kcal/mol) are smaller than the values for (imide)I···N (−8.4 to −29.0 kcal/mol). The DFT additivity analysis of (imide)Br···N motifs demonstrates Br···N interaction strength gradually decreasing from 1:1 to 1:3 HMTA:N-bromosuccinimide complexes. Exceptionally similar charge density values ρ(r) for N–I covalent bond and I···N non-covalent bond of a (saccharin)N–I···N motif signify the covalent character for I···N halogen bonding.

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Shri, Fatime Satar. "Microwave assisted synthesis and identification of new Azo-Schiff bases with N,O Donor atoms and their Ni(II) and Cu(II) complexes." International journal of health sciences, August 13, 2022, 8326–38. http://dx.doi.org/10.53730/ijhs.v6ns5.10548.

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The present paper describes the synthesis of two Azo-Schiff base named (2-(((2-aminophenyl)imino)methyl)-6-ethoxy-4-((Z)-phenyldiazenyl) phenol, 2-((Z)-((4-aminobutyl)imino)methyl)-6-ethoxy-4-((Z)-phenyldiazenyl)phenol) by diazotization reaction of the synthesized (3-Ethoxy-2-hydroxy benzaldehyde) with aniline compound to gave Al- Azo – aldehyde and reacted with (O-phenylenediamine or1,4-butanediamine) to gave Azo-Schiff bases compounds. All new synthesized derivatives (ligands and complexes with Ni(II) and Cu(II)) were identified by melting points, FT-IR, 1H-NMR, Mass, molar conductivity and magnetic susceptibility. The ligands are coordinate to metal ion by nitrogen atom of azomethine and oxygen atom of hydroxyl group to form Ni(II) complex with square planer geometry and Cu(II) complex with octahedral geometry.

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Kadhim, Sroor M., and Saad M. Mahdi. "Preparation and Characterization of New (Halogenated Azo-Schiff) Ligands with Some of their Transition Metal Ions Complexes." Iraqi Journal of Science, August 31, 2022, 3283–99. http://dx.doi.org/10.24996/ijs.2022.63.8.4.

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Two new halogenated azo-Schiff ligands were prepared in two steps. The first step included a condensation between 4-amino acetophenone and 2-fluoro-4-bromo aniline to give the corresponding Schiff base. In the second step, the diazonium salt of this Schiff base reacted with 2-naphthol and 4,5-diphenylimidazole to form two new azo-Schiff base derivatives as ligands; (3-((E)-(4-((E)-1-((4-bromo-2-fluorophenyl) imino)ethyl) phenyl) diazenyl) naphthalen-2-ol (HSBAN) (L1) and ((E)-N-(4-bromo-2-fluorophenyl)-1-(4-((E)-(4,5-diphenyl-1H-imidazol-2-yl)diazenyl) phenyl) ethan-1-imine) (HSBAI) (L2), respectively. These new ligands were characterized by mass spectrometry, FT-IR, 1H NMR, UV-Visible spectroscopy and elemental microanalysis (CHN). Five divalent transition metal ion complexes (Co, Ni, Cu, Cd, and Hg) were prepared and characterized, beyond the determination of the optimal condition (concentration, pH value, and the mole ratio M:L) using UV-visible studies. Additionally, complementary techniques, such as atomic absorption, electrical conductivity and magnetic susceptibility, were performed to deduce their geometries. The comprehensive study suggested an octahedral geometry for all complexes except Cd and Hg complexes of the first ligand.

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Wyszko, Eliza, Mariusz Popenda, Dorota Gudanis, Joanna Sarzyńska, Agnieszka Belter, Patrick Perrigue, Paweł Skowronek, Katarzyna Rolle, and Jan Barciszewski. "The model structure of the hammerhead ribozyme formed by RNAs of reciprocal chirality." Bioscience Reports, December 22, 2020. http://dx.doi.org/10.1042/bsr20203424.

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RNA-based tools are frequently used to modulate gene expression in living cells. However, the stability and effectiveness of such RNA-based tools is limited by cellular nuclease activity. One way to increase RNA’s resistance to nucleases is to replace its D-ribose backbone with L-ribose isomers. This modification changes chirality of an entire RNA molecule to L-form giving it more chance of survival when introduced into cells. Recently, we have described the activity of left-handed hammerhead ribozyme (L-Rz, L-HH) that can specifically hydrolyze RNA with the opposite chirality at a predetermined location. To understand the structural background of the RNA specific cleavage in a heterochiral complex, we used circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy as well as performed molecular modelling and dynamics simulations of homo- and heterochiral RNA complexes. The active ribozyme-target heterochiral complex showed a mixed chirality as well as low field imino proton NMR signals. We modelled the three dimensional structures of the oligoribonucleotides with their ribozyme counterparts of reciprocal chirality. L- or D-ribozyme formed a stable, homochiral helix 2, and two short double heterochiral helixes 1 and 3 of D- or L-RNA strand thorough irregular Watson-Crick base pairs. The formation of the heterochiral complexes is supported by the result of simulation molecular dynamics. These new observations suggest that L-catalytic nucleic acids can be used as tools in translational biology and diagnostics.

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Journal articles on the topic 'Imido complexes form'

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