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1.
Mathieu Guerain Patrick Derollez Luisa Roca-Paixo Catherine Dejoie Natlia T. Correia Frdric Affouard 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(3):225-230
The crystal structure of a new cocrystal of carbamazepine (systematic name: 5H‐dibenzo[b,f]azepine‐5‐carboxamide, C15H12N2O) and dl ‐tartaric acid (C4H6O6), obtained by liquid‐assisted grinding, was solved by powder X‐ray diffraction (PXRD). The high‐resolution PXRD pattern of this new phase was recorded at room temperature thanks to synchrotron experiments at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated by a Monte‐Carlo simulated annealing method. The final structure was obtained through Rietveld refinement and an energy minimization simulation was used to estimate the H‐atom positions. The stability of the proposed structure as a function of temperature was also assessed from molecular dynamics simulations. The symmetry is monoclinic (space group P21/c) and contains eight molecules per unit cell, namely, four dl ‐tartaric acid and four carbamazepine molecules. 相似文献
2.
Legrand YM Gilles A Petit E van der Lee A Barboiu M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(36):10021-10028
Cyclobutadiene ( CBD ), the smallest cyclic hydrocarbon bearing conjugated double bonds, has long intrigued chemists because of its chemical characteristics. The question of whether the molecule could be prepared at all has been answered, but the parent compound and its unperturbed derivatives have eluded crystallographic characterization or synthesis “in water”. Different approaches have been used to generate and to trap cyclobutadiene in a variety of confined environments: a) an Ar matrix at cryogenic temperatures, b) a hemicarcerand cage enabling the characterization by NMR spectroscopy in solution, and c) a crystalline guanidinium–sulfonate–calixarene G4C matrix that is stable enough to allow photoreactions in the solid state. In the latter case, the 4,6‐dimethyl‐α‐pyrone precursor, Me21 , has been immobilized in a guanidinium–sulfonate–calixarene G4C crystalline network through a combination of non‐covalent interactions. UV irradiation of the crystals transforms the entrapped Me21 into a 4,6‐dimethyl‐Dewar‐β‐lactone intermediate, Me22 , and rectangular‐bent 1,3‐dimethylcyclobutadiene, Me2CBDR , which are sufficiently stable under the confined conditions at 175 K to allow a conventional structure determination by X‐ray diffraction. Further irradiation drives the reaction towards Me23&Me2CBDS /CO2 (63.7 %) and Me2CBDR (37.3 %) superposed crystalline architectures and the amplification of Me2CBDR . The crystallographic models are supported by additional FTIR and Raman experiments in the solid state and by 1H NMR spectroscopy and ESI mass spectrometry experiments in aqueous solution. Amazingly, the 4,6‐dimethyl‐Dewar‐β‐lactone, Me22 , the cyclobutadiene‐carboxyl zwitterion, Me23 , and 1,3‐dimethylcyclobutadiene, Me2CBD , were obtained by ultraviolet irradiation of an aqueous solution of G4C{Me21} . 1,3‐Dimethylcyclobutadiene is stable in water at room temperature for several weeks and even up to 50 °C as demonstrated by 1H NMR spectroscopy. 相似文献
3.
Vasanthi Palanisamy Palash Sanphui Muthuramalingam Prakash Vladimir Chernyshev 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(8):1102-1117
Lesinurad (systematic name: 2‐{[5‐bromo‐4‐(4‐cyclopropylnaphthalen‐1‐yl)‐4H‐1,2,4‐triazol‐3‐yl]sulfanyl}acetic acid, C17H14BrN3O2S) is a selective uric acid reabsorption inhibitor related to gout, which exhibits poor aqueous solubility. High‐throughput solid‐form screening was performed to screen for new solid forms with improved pharmaceutically relevant properties. During polymorph screening, we obtained two solvates with methanol (CH3OH) and ethanol (C2H5OH). Binary systems with caffeine (systematic name: 3,7‐dihydro‐1,3,7‐trimethyl‐1H‐purine‐2,6‐dione, C8H10N4O2) and nicotinamide (C6H6N2O), polymorphs with urea (CH4N2O) and eutectics with similar drugs, like allopurinol and febuxostat, were prepared using the crystal engineering approach. All these novel solid forms were confirmed by XRD, DSC and FT–IR. The crystal structures were solved by single‐crystal and powder X‐ray diffraction. The crystal structures indicate that the lesinurad molecule is highly flexible and the triazole moiety, along with the rotatable thioacetic acid (side chain) and cyclopropane ring, is almost perpendicular to the planar naphthalene moiety. The carboxylic acid–triazole heterosynthon in the drug is interrupted by the presence of methanol and ethanol molecules in their crystal structures and forms intermolecular macrocyclic rings. The caffeine cocrystal maintains the consistency of the acid–triazole heterosynthons as in the drug and, in addition, they are bound by several auxiliary interactions. In the binary system of nicotinamide and urea, the acid–triazole heterosynthon is replaced by an acid–amide synthon. Among the urea cocrystal polymorphs, Form I (P, 1:1) consists of an acid–amide (urea) heterodimer, whereas in Form II (P21/c, 2:2), both acid–amide heterosynthons and urea–urea dimers co‐exist. Density functional theory (DFT) calculations further support the experimentally observed synthon hierarchies in the cocrystals. Aqueous solubility experiments of lesinurad and its binary solids in pH 5 acetate buffer medium indicate the apparent solubility order lesinurad–urea Form I (43‐fold) > lesinurad–caffeine (20‐fold) > lesinurad–allopurinol (12‐fold) ? lesinurad–nicotinamide (11‐fold) > lesinurad, and this order is correlated with the crystal structures. 相似文献
4.
Isaac Odiase Catherine E. Nicholson Ruksanna Ahmad Jerry Cooper Dmitry S. Yufit Sharon J. Cooper 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(4):276-283
Four new cocrystals of pyrimidin‐2‐amine and propane‐1,3‐dicarboxylic (glutaric) acid were crystallized from three different solvents (acetonitrile, methanol and a 50:50 wt% mixture of methanol and chloroform) and their crystal structures determined. Two of the cocrystals, namely pyrimidin‐2‐amine–glutaric acid (1/1), C4H5N3·C6H8O4, (I) and (II), are polymorphs. The glutaric acid molecule in (I) has a linear conformation, whereas it is twisted in (II). The pyrimidin‐2‐amine–glutaric acid (2/1) cocrystal, 2C4H5N3·C6H8O4, (III), contains glutaric acid in its linear form. Cocrystal–salt bis(2‐aminopyrimidinium) glutarate–glutaric acid (1/2), 2C4H6N3+·C6H6O42−·2C6H8O4, (IV), was crystallized from the same solvent as cocrystal (II), supporting the idea of a cocrystal–salt continuum when both the neutral and ionic forms are present in appreciable concentrations in solution. The diversity of the packing motifs in (I)–(IV) is mainly caused by the conformational flexibility of glutaric acid, while the hydrogen‐bond patterns show certain similarities in all four structures. 相似文献
5.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(2):177-185
We report a novel 1:1 cocrystal of β‐alanine with dl ‐tartaric acid, C3H7NO2·C4H6O6, (II), and three new molecular salts of dl ‐tartaric acid with β‐alanine {3‐azaniumylpropanoic acid–3‐azaniumylpropanoate dl ‐tartaric acid–dl ‐tartrate, [H(C3H7NO2)2]+·[H(C4H5O6)2]−, (III)}, γ‐aminobutyric acid [3‐carboxypropanaminium dl ‐tartrate, C4H10NO2+·C4H5O6−, (IV)] and dl ‐α‐aminobutyric acid {dl ‐2‐azaniumylbutanoic acid–dl ‐2‐azaniumylbutanoate dl ‐tartaric acid–dl ‐tartrate, [H(C4H9NO2)2]+·[H(C4H5O6)2]−, (V)}. The crystal structures of binary crystals of dl ‐tartaric acid with glycine, (I), β‐alanine, (II) and (III), GABA, (IV), and dl ‐AABA, (V), have similar molecular packing and crystallographic motifs. The shortest amino acid (i.e. glycine) forms a cocrystal, (I), with dl ‐tartaric acid, whereas the larger amino acids form molecular salts, viz. (IV) and (V). β‐Alanine is the only amino acid capable of forming both a cocrystal [i.e. (II)] and a molecular salt [i.e. (III)] with dl ‐tartaric acid. The cocrystals of glycine and β‐alanine with dl ‐tartaric acid, i.e. (I) and (II), respectively, contain chains of amino acid zwitterions, similar to the structure of pure glycine. In the structures of the molecular salts of amino acids, the amino acid cations form isolated dimers [of β‐alanine in (III), GABA in (IV) and dl ‐AABA in (V)], which are linked by strong O—H…O hydrogen bonds. Moreover, the three crystal structures comprise different types of dimeric cations, i.e. (A…A)+ in (III) and (V), and A+…A+ in (IV). Molecular salts (IV) and (V) are the first examples of molecular salts of GABA and dl ‐AABA that contain dimers of amino acid cations. The geometry of each investigated amino acid (except dl ‐AABA) correlates with the melting point of its mixed crystal. 相似文献
6.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(9):743-748
In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4‐diamino‐5‐(3,4,5‐trimethoxybenzyl)pyrimidin‐1‐ium ferrocene‐1‐carboxylate], (C14H19N4O3)[Fe(C5H5)(C6H4O2)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N—H…O hydrogen bonds, generating a robust R 22(8) ring motif (heterosynthon). However, in the cocrystal 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–ferrocene‐1‐carboxylic acid (1/1), [Fe(C5H5)(C6H5O2)]·C6H8ClN3, (II), the carboxyl–aminopyrimidine interaction [R 22(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O—H…N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N—H…N hydrogen bonds, generating an R 22(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site‐occupation ratio of 0.573 (10):0.427 (10). In this study, the two five‐membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C…Cg …Cg …C pseudo‐torsion angles, which are in the range 36.13–37.53° for (I) and 22.58–23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C…Cg …Cg …C pseudo‐torsion angles, which are in the range 79.26–80.94°. Both crystal structures are further stabilized by weak π–π interactions. 相似文献
7.
Benny Luijsterburg Peter Jobse Daniel Hermida Merino Ton Peijs Han Goossens 《Journal of Polymer Science.Polymer Physics》2014,52(16):1071-1082
Isotactic polypropylene (i‐PP) can crystallize in different crystal modifications. In this article, the effect of sepiolite (one‐dimensional) and carbon black (three‐dimensional) fillers on the solid‐state drawability of i‐PP is discussed. The cross‐hatched structure of thermodynamically most stable α‐crystal phase in i‐PP does not allow for perfect chain alignment during solid‐state drawing. The β‐phase i‐PP, obtained by addition of specific nucleating agents, crystallizes in a non‐cross‐hatched spherulitic structure and allows more easy drawing. Depending on the filler type, β–α transformation takes place at different draw ratios, as was observed by in situ wide‐angle X‐ray diffraction measurements. It was observed that β‐nucleated i‐PP has a lower yield stress and can be drawn further than i‐PP crystallized in the α‐crystal phase. If added in the right amount, both carbon black and sepiolite have a reinforcing effect on PP tapes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1071–1082 相似文献
8.
Christian Albrecht Christoph Wagner Kurt Merzweiler Tadeusz Lis Dirk Steinborn 《应用有机金属化学》2005,19(11):1155-1163
The platina‐β‐diketone [Pt2{(COMe)2H}2(µ‐Cl)2] ( 1 ) was found to react with monodentate phosphines to yield acetyl(chloro)platinum(II) complexes trans‐[Pt(COMe)Cl(PR3)2] (PR3 = PPh3, 2a ; P(4‐FC6H4)3, 2b ; PMePh2, 2c ; PMe2Ph, 2d ; P(n‐Bu)3, 2e ; P(o‐tol)3, 2f ; P(m‐tol)3, 2g ; P(p‐tol)3, 2h ). In the reaction with P(o‐tol)3 the methyl(carbonyl)platinum(II) complex [Pt(Me)Cl(CO){P(o‐tol)3}] ( 3a ) was found to be an intermediate. On the other hand, treating 1 with P(C6F5)3 led to the formation of [Pt(Me)Cl(CO){P(C6F5)3}] ( 3b ), even in excess of the phosphine. Phosphine ligands with a lower donor capability in complexes 2 and the arsine ligand in trans‐[Pt(COMe)Cl(AsPh3)2] ( 2i ) proved to be subject to substitution by stronger donating phosphine ligands, thus forming complexes trans‐[Pt(COMe)Cl(L)L′] (L/L′ = AsPh3/PPh3, 4a ; PPh3/P(n‐Bu)3, 4b ) and cis‐[Pt(COMe)Cl(dppe)] ( 4c ). Furthermore, in boiling benzene, complexes 2a – 2c and 2i underwent decarbonylation yielding quantitatively methyl(chloro)platinum(II) complexes trans‐[Pt(Me)Cl(L)2] (L = PPh3, 5a ; P(4‐FC6H4)3, 5b ; PMePh2, 5c ; AsPh3, 5d ). The identities of all complexes were confirmed by 1H, 13C and 31P NMR spectroscopy. Single‐crystal X‐ray diffraction analyses of 2a ·2CHCl3, 2f and 5b showed that the platinum atom is square‐planar coordinated by two phosphine ligands (PPh3, 2a ; P(o‐tol)3, 2f ; P(4F‐C6H4)3, 5b ) in mutual trans position as well as by an acetyl ligand ( 2a, 2f ) and a methyl ligand ( 5b ), respectively, trans to a chloro ligand. Single‐crystal X‐ray diffraction analysis of 3b exhibited a square‐planar platinum complex with the two π‐acceptor ligands CO and P(C6F5)3 in mutual cis position (configuration index: SP‐4‐3). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
9.
Carriedo GA García Alonso FJ García Alvarez JL Lombardo GM Pappalardo GC Punzo F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(15):3775-3782
The intrachain conformation, molecular structure and interchain assembly of isotactic (R)-poly(2,2'-dioxy-1,1'-binaphthyl)phosphazene (P-DBNP) both in the bulk state (I) and in the cast film (II) were studied by molecular dynamics (MD) simulations of models, as implemented by a bias potential for the analysis of the radial distribution function (RDF) obtained from large-angle X-ray scattering (LAXS) data. The microscopic structure and order extension of the polymer changed from I to II, as qualitatively shown in the shapes of their experimentally measured RDF curves. With the use of a bias potential, the MD simulations provided a much more accurate analysis of the models, as seen in the reproduction of the RDFs. The chiral P-DBNP chain was found to be consistent with helix conformations in both the I and the II samples. The predominant interchain clustering motif was best reproduced with a seven-chain model. In the case of I, the maximum chain length was 18 monomeric -R(2)NP- units, while in the case of the cast film II the chain was more elongated, up to distances of approximately 100 A, equivalent to over 48 monomeric -R(2)NP- units. The seven-chain assembly was accounted for in terms of nonbonded interactions favouring the minimum voids area between the seven tubular structures of the material. The results validate our earlier finding that MD analysis with implementation of a biasing potential for the RDFs can provide quantitative information on the structural and conformational features of amorphous solids. The combined theoretical and experimental approach was found to be a useful tool to detect, locate and evaluate the intra- and intermolecular modifications of materials subsequent to their phase transformation and, as in the present case, changes in their microscopic structures or preparation methods. 相似文献
10.
Uttam Kumar Das Dr. Parthasarathi Dastidar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13079-13090
A series of bis‐amides derived from L ‐(+)‐tartaric acid was synthesized as potential low‐molecular‐weight gelators. Out of 14 bis‐amides synthesized, 13 displayed organo‐, hydro‐, and ambidextrous gelation behavior. The gels were characterized by methods including circular dichroism, differential scanning calorimetry, optical and electron microscopy, and rheology. One of the gels derived from di‐3‐pyridyltartaramide ( D‐3‐PyTA ) displayed intriguing nanotubular morphology of the gel network, which was exploited as a template to generate highly aligned 1D silica fibers. The gelator D‐3‐PyTA was also exploited to generate metallogels by treatment with various CuII/ZnII salts under suitable conditions. A structure–property correlation on the basis of single‐crystal and powder X‐ray diffraction data was attempted to gain insight into the structures of the gel networks in both organo‐ and metallogels. Such study led to the determination of the gel‐network structure of the CuII coordination‐polymer‐based metallogel, which displayed a 2D sheet architecture made of a chloride‐bridged double helix that resembled a 5‐c net SnS topology. 相似文献
11.
Novel Lanthanide(III) Ternary Complexes with Naphthoyltrifluoroacetone: A Synthetic and Spectroscopic Study
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Thi‐Nguyet Trieu Thi‐Hien Dinh Hung‐Huy Nguyen Ulrich Abram Minh‐Hai Nguyen 《无机化学与普通化学杂志》2015,641(11):1934-1940
A series of lanthanide complexes with general formula [Ln(NTA)3X] were prapared [Ln = Y ( a ), Er ( b ), Eu ( c ), NTA = naphthoyltrifluoroacetone, X = H2O ( 1 ), phen = phenanthroline ( 2 ), bpyO1 = 2, 2′‐bipyridine N‐oxide ( 3 ), and bpyO2 = 2, 2′‐bipyridine‐N,N′‐dioxide ( 4 )]. The crystal structures of [Eu(NTA)3bpyO2] ( 4b ), [Er(NTA)3bpyO1] ( 3c ), and [Er(NTA)3phen] ( 2c ) were determined. X‐ray crystallographic analysis reveals that the complexes are of mononuclear structure with three NTA and one ancillary ligand. The photoluminescence spectra of 3c and 4b exhibit strong characteristic emissions arising from Eu3+ central ion due to the efficient sensitization of bpyO1 and bpyO2, respectively. 相似文献
12.
13.
Dr. Yves‐Marie Legrand Dan Dumitrescu Dr. Arnaud Gilles Eddy Petit Dr. Arie van der Lee Dr. Mihail Barboiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4946-4950
Shatruk and Alabugin propose an alternative structural model for the observed electron density that we have attributed to the photochemical formation of 1,3‐dimethylcyclobutadiene in a protective solid crystalline matrix. The main criticism from Shatruk and Alabugin concerns the modeling of the disorder in the calixarene cavity and in particular the neglect of a residual electron density close to the O1 atom. We published (Chem. Eur. J. 2011 , 17, 10021) our opinion concerning this “ignored peak” in the Supporting Information of the paper. The current response to the Correspondence demonstrates that Shatruk and Alabugin have over‐modeled our data by assigning a small electron density peak, which is hardly more than the density corresponding to a hydrogen atom, to an under‐occupied oxygen site, using inappropriate refinement contraints. 相似文献
14.
Yaogang Hu Peng Teng Wenyang Gao Xiaobing Zuo Lukasz Wojtas Randy W. Larsen Shengqian Ma Jianfeng Cai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2501-2507
Foldamers offer an attractive opportunity for the design of novel molecules that mimic the structures and functions of proteins and enzymes including biocatalysis and biomolecular recognition. Herein we report a new class of nonnatural helical sulfono‐γ‐AApeptide foldamers of varying lengths. The crystal structure of the sulfono‐γ‐AApeptide monomer S6 illustrates the intrinsic folding propensity of sulfono‐γ‐AApeptides, which likely originates from the bulkiness of tertiary sulfonamide moiety. The two‐dimensional solution NMR spectroscopy data for the longest sequence S1 demonstrates a 10/16 right‐handed helical structure. Optical analysis using circular dichroism further supports well‐ defined helical conformation of sulfono‐γ‐AApeptides in solution containing as few as five building blocks. Future development of sulfono‐γ‐AApeptides may lead to new foldamers with discrete functions, enabling expanded application in chemical biology and biomedical sciences. 相似文献
15.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(1):100-107
The crystal structure of the cocrystal salt form of the antimalarial drug pyrimethamine with 2,4‐dihydroxybenzoic acid in methanol [systematic name: 2,4‐diamino‐5‐(4‐chlorophenyl)‐6‐ethylpyrimidin‐1‐ium 2,4‐dihydroxybenzoate methanol monosolvate, C12H14ClN4+·C7H5O4−·CH3OH] has been studied using X‐ray diffraction data collected at room temperature. The crystal structure was refined using the classical Independent Atom Model (IAM) and the Multipolar Atom Model by transferring electron‐density parameters from the ELMAM2 database. The Cl atom was refined anharmonically. The results of both refinement methods have been compared. The intermolecular interactions have been characterized on the basis of Hirshfeld surface analysis and topological analysis using Bader's theory of Atoms in Molecules. The results show that the molecular assembly is built primarily on the basis of charge transfer between 2,4‐dihydroxybenzoic acid and pyrimethamine, which results in strong intermolecular hydrogen bonds. This fact is further validated by the calculation of the electrostatic potential based on transferred electron‐density parameters. 相似文献
16.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(1):13-19
Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid–maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers. The present paper reports the crystal structures of two new salts of the dl ‐norvaline–maleic acid system with 1:1 and 2:1 stoichiometries, namely dl ‐norvalinium hydrogen maleate, C5H12NO2+·C4H3O4−, (I), and dl ‐norvalinium hydrogen maleate–dl ‐norvaline, C5H12NO2+·C4H3O4−·C5H11NO2, (II). These are the first examples of molecular salts of dl ‐norvaline with an organic anion. The crystal structure of (I) has the same C 22(12) structure‐forming motif which is common for hydrogen maleates of amino acids. The structure of (II) has dimeric cations. Of special interest is that the single crystals of (I) which are originally formed on crystallization from aqueous solution transform into single crystals of (II) if stored in the mother liquor for several hours. 相似文献
17.
Measurements of the thermal expansion coefficients (TECs) of chitin crystals in the lateral direction are reported. We investigated highly crystalline α chitin from the Paralithodes tendon and an anhydrous form of β chitin from a Lamellibrachia tube from room temperature to 250 °C, using X‐ray diffraction at selected temperatures in the heating process. For α chitin, the TECs of the a and b axes were αa = 6.0 × 10−5 °C−1 and αb = 5.7 × 10−5 °C−1, indicating an isotropic thermal expansion in the lateral direction. However, the anhydrous β chitin exhibited an anisotropic thermal expansion in the lateral direction. The TEC of the a axis was constant at αa = 4.0 × 10−5 °C−1, but the TEC of the b axis increased linearly from room temperature to 250 °C, with αb = 3.0–14.6 × 10−5 °C−1. These differences in the lateral thermal expansion behaviors of the α chitin and the anhydrous β chitin are due to their different intermolecular hydrogen bonding systems. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 168–174, 2001 相似文献
18.
Maria Lalia‐Kantouri Prof. Dr. Antonios G. Hatzidimitriou David Williams 《无机化学与普通化学杂志》2009,635(15):2495-2502
The reaction of bis(3‐cyano‐2,4‐pentanedionato)copper(II), [Cu(NC‐acac)2] with the nitrogenous base N,N‐dimethyl, N′‐ethyl‐1,2‐ethylenediamine (dmeen) in the presence of Cu(ClO4)2 · 6H2O, afforded a new cationic mixed‐ligand chelate [Cu(CN‐acac)(dmeen)]+. Its structure was characterized spectroscopically (IR, UV/Vis, EPR) and verified by X‐ray diffraction studies as [Cu(CN‐acac)(dmeen)(H2O)]ClO4. The coordination of CN‐acac– as bridging ligand leads to a polymeric helical chain, which extends in the crystallographic c axis. Density functional theory (DFT) calculations suggest that in the solid state the anion CN‐acac– binding is envisaged through the nitrogen atom of the cyanido group, establishing an octahedral arrangement around copper, whereas in solution, the square‐planar arrangement is prevailed, in accordance with the EPR findings. 相似文献
19.
Muhammad Umer Faroque Sajida Noureen Shafaat Hussain Mirza Muhammad Nawaz Tahir Maqsood Ahmed 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(1):46-53
Pyrimethamine is an antimalarial drug. The cocrystal salt form of pyrimethamine with 3,5‐dihydroxybenzoic acid in water solvent has been synthesized, namely 2,4‐diamino‐5‐(4‐chlorophenyl)‐6‐ethylpyrimidin‐1‐ium 3,5‐dihydroxybenzoate hemihydrate, C12H14ClN4+·C7H5O4?·0.5H2O. X‐ray diffraction data were collected at room temperature. Refinement of the crystal structure was carried out using the classical Independent Atom Model (IAM), while the electrostatic properties were studied by transferring electron‐density parameters from an electron‐density database. The Cl atom was refined anharmonically. The results of both refinement methods were compared. Topological analyses were carried out using Bader's theory of Atoms in Molecules (AIM). The three‐dimensional Hirshfeld surface analysis and the two‐dimensional fingerprint maps of individual molecules revealed that the crystal structures are dominated by H…O/O…H and H…H contacts. Other close contacts are also present, including weak C…H/H…C contacts. Charge transfer between the pyrimethamine and 3,5‐dihydroxybenzoic acid molecules results in a molecular assembly based on strong intermolecular hydrogen bonds. This is further validated by the calculation of the electrostatic potential based on transferred electron‐density parameters. The current work proves the significance of the transferability principle in studying the electron‐density‐derived properties of molecules in cases where high‐resolution diffraction data at low temperature are not available. 相似文献
20.
Polyaniline‐sulfate salt acts as a simple and powerful polymer‐supported acid catalyst in the condensation of phenolic compounds and β‐keto esters into coumarin derivatives by a thermal heating process. This process is being reported for the first time. The catalytic use of polyaniline salt is quite feasible because of its easy preparation, activity, recovery, recyclability, stability and eco‐friendliness of the catalyst. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献