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1.
The crystal structure of the title melaminium salt, bis(2,4,6‐tri­amino‐1,3,5‐triazin‐1‐ium) dl ‐malate tetrahydrate, 2C3H7N6+·C4H4O52−·4H2O, consists of singly protonated melaminium residues, dl ‐malate dianions and water mol­ecules. The melaminium residues are connected into chains by four N—H⃛N hydrogen bonds, and these chains form a stacking structure along the c axis. The dl ‐malate dianions form hydrogen‐bonded chains and, together with hydrogen‐bonded water mol­ecules, form a layer parallel to the (100) plane. The conformation of the malate ion is compared with an ab initio molecular‐orbital calculation. The oppositely charged moieties, i.e. the stacks of melaminium chains and hydrogen‐bonded dl ‐malate anions and water mol­ecules, form a three‐dimensional polymeric structure, in which N—H⃛O hydrogen bonds stabilize the stacking.  相似文献   

2.
In the title compound, [Cu(C4H6N2O3)(C8H8N2)]·3H2O, the CuII atom is coordinated in a square‐planar manner by one O atom and three N atoms from glycylglycinate and 2‐methyl­benzimidazole ligands. The ternary complexes assemble into one‐dimensional chains through C—H⋯π inter­actions and direct N—H⋯O hydrogen bonding, as well as into hydrogen‐bonded water helices with branches which also link the complex chains into a three‐dimensional supra­molecular structure.  相似文献   

3.
Neutron diffraction analysis studies reported an isolated hydronium ion (H3O+) in the interior of d ‐xylose isomerase (XI) and phycocyanobilin‐ferredoxin oxidoreductase (PcyA). H3O+ forms hydrogen bonds (H‐bonds) with two histidine side‐chains and a backbone carbonyl group in PcyA, whereas H3O+ forms H‐bonds with three acidic residues in XI. Using a quantum mechanical/molecular mechanical (QM/MM) approach, we analyzed stabilization of H3O+ by the protein environment. QM/MM calculations indicated that H3O+ was unstable in the PcyA crystal structure, releasing a proton to an H‐bond partner His88, producing H2O and protonated His88. On the other hand, H3O+ was stable in the XI crystal structure. H‐bond partners of isolated H3O+ would be practically limited to acidic residues such as aspartic and glutamic acids in the protein environment.  相似文献   

4.
In the title compound, 2,4,6‐tri­amino‐1,3,5‐triazin‐1‐ium maleate monohydrate, C3H7N6+·C4H3O4·H2O, containing singly protonated melaminium residues, maleate(1−) anions and water mol­ecules, the components are linked by hydrogen bonds into a three‐dimensional framework structure. The melaminium residues are connected by two pairs of N—H⋯N hydrogen bonds into chains in the form of stacks, with a distance of 3.26 (1) Å between the triazine rings, clearly indicating π–π interactions. The maleate anion contains an intramolecular O—H⋯O hydrogen bond and the anions interact with the water mol­ecules via O—H⋯O hydrogen bonds, forming zigzag chains, also in the form of stacks, in which the almost‐planar maleate anions are separated by 3.26 (1) Å. The experimental geometries of the ions are compared with molecular‐orbital calculations of their gas‐phase geometries.  相似文献   

5.
New liquid crystals having a non‐conventional structure have been synthesised from a six‐armed cyclotriphosphazene core, [N3P3(OC6H4OH‐4)6], which was condensed with polycatenar acids. Reactions were monitored by 31P{1H} and 1H NMR spectroscopy and the chemical structure of the resulting materials was confirmed by different spectroscopic techniques and mass spectrometry (MALDI‐TOF). Results were in accordance with monodisperse, fully functionalised cyclotriphosphazenes. Thermal and mesomorphic properties were studied by optical microscopy, differential scanning calorimetry and X‐ray diffraction. All of the synthesised phosphazenes, substituted with benzyl ether chains, show a high thermal stability and exhibit mesomorphic properties, which depend on the number and type of alkyl terminal chains located at the periphery of the mesogens. Mesomorphic properties range from Colh for cph‐A1 and cph‐A2 to a cubic phase detected for cph‐A3 , which has the larger number of alkyl chains. Furthermore, helical order was detected on X‐ray data of cph‐A2 , which has chiral branched chains. Circular dichroism spectra of annealed films at mesophase temperature show a signal attributed to the chiral helical arrangement of the mesogenic chromophores.  相似文献   

6.
Hydrothermal reactions generated a cobalt–hypoxanthine framework [Co3(OH)4(Hpxt)2]?2 H2O (H2pxt=6‐hydroxypurine, 1 ?2 H2O), which became a microporous framework [Co3(OH)4(Hpxt)2] ( 1 ) through a single‐crystal‐to‐single‐crystal transformation. Compound 1 ?2 H2O shows a three‐dimensional umr topological structure with two types of spiral channels constructed by rod‐shaped {Co3(μ‐OH)4(N‐C‐N)2(N‐C‐C‐O)2} second building units (SBUs). The larger channel is filled by fourfold spiral water chains. An unprecedented μ5‐O6,N3,N7,N9 coordination mode of the Hpxt anion was observed. Both complexes 1 ?2 H2O and 1 qualitatively show similar metamagnetism from anti‐parallel to parallel ferromagnetic cobalt‐hydroxide chains. Compared with 1 ?2 H2O, a smaller Curie constant and more negative Weiss constant in 1 indicate that the helical water chains tend to suppress antiferromagnetic coupling between Co3(OH)4 ferromagnetic chains. Detailed magnetic studies of 1 ?2 H2O revealed that the competitive interactions between interchain antiferromagnetic exchange coupling and single‐ion anisotropy of CoII resulted in a partly canted antiferromagnetic sate in low fields. Anti‐parallel arrangement of adjacent ferromagnetic chains in middle fields gives 3D antiferromagnetic ordering, and magnetic ground states in high fields are a parallel arrangement of ferromagnetic chains.  相似文献   

7.
Three coordination polymers (CPs) based on the 5‐[4‐(1H‐imidazol‐1‐yl)phenyl]‐1H‐tetrazole ( HL ) ligand, namely, [Cu(μ2‐ L )(μ4‐pbda)(H2O)] ( 1 ), [Cu2(μ‐Hbtc)(H2btc)(μ3‐OH)(μ4‐ HL )] ( 2 ) and [Cu53‐ L )(μ4‐ L )(μ3‐ip)(μ3‐OH)(H2O)2] · 2H2O ( 3 ) (H2pbda = 1,4‐benzenedicarboxylic acid, H3btc = 1,3,5‐benzenetricarboxylic acid, H2ip = isophthalic acid) were hydrothermally synthesized and structurally characterized. Complex 1 represents “weave”‐type 2D layers consisting of wave‐like 1D chains and 1D straight chains, which are further connected by hydrogen bonds to form a 3D supramolecular structure. Complex 2 exhibits a uninodal (4)‐connected 2D layer with a point symbol of {44 · 62}, in which the L ligand can be described as μ5‐bridging and the H2btc ions display multiple kinds of coordination modes to connect CuII ions into 1D “H”‐type Cu‐H2btc chains. In complex 3 , 2D Cu‐ L layers with two kinds of grids and 1D “stair”‐type Cu‐ip chains link each other to construct a 3D {412 · 63} framework, which contains the pentanuclear subunits. Deprotonated degree and coordination modes of carboxylate ligands may consequentially influence the coordination patterns of main ligands and the final structures of complexes 1 – 3 . Furthermore, electrochemical behaviors and electrocatalytic activities of the title complexes were analyzed at room temperature, suggesting practical applications in areas of electrocatalytic reduction toward nitrite and hydrogen dioxide in aqueous solutions, respectively.  相似文献   

8.
The title compound, C25H35N3O2, is a novel urea derivative. Pairs of intermolecular N—H...O hydrogen bonds join the molecules into centrosymmetric R22(12) and R22(18) dimeric rings, which are alternately linked into one‐dimensional polymeric chains along the [010] direction. The parallel chains are connected via C—H...O hydrogen bonds to generate a two‐dimensional framework structure parallel to the (001) plane. The title compound was also modelled by solid‐state density functional theory (DFT) calculations. A comparison of the molecular conformation and hydrogen‐bond geometry obtained from the X‐ray structure analysis and the theoretical study clearly indicates that the DFT calculation agrees closely with the X‐ray structure.  相似文献   

9.
The crystal structure of the title new melaminium salt, 2,4,6‐tri­amino‐1,3,5‐triazin‐1‐ium glutarate monohydrate, C3H7N6+·C5H7­O4?·H2O, is built up from singly protonated melaminium residues, mono‐dissociated glutarate ions and water mol­ecules. The melaminium residues are interconnected by four N—H?N hydrogen bonds to form chains. These chains of melaminium residues form a stacking structure. The glutarate anions form a hydrogen‐bonded zigzag polymer of the form [?HOOC(CH2)3COO?HOOC(CH2)3COO?]n. The oppositely charged moieties, i.e. the melaminium and glutarate chains, form two‐dimensional polymeric sheets. These sheets are interconnected by O—H?O hydrogen bonds between the COO? moieties and the water mol­ecules, and these hydrogen bonds stabilize the stacking structure.  相似文献   

10.
Meyer–Schuster rearrangements of 2‐phenyl‐3‐butyn‐2‐ol with H3O+ and (H2O)6 model in high‐temperature water (HTW) have been investigated by the use of density functional theory calculations. In the substrate 2‐phenyl‐3‐butyn‐2‐ol catalyzed by H3O+ and (H2O)6, the Meyer–Schuster rearrangements were predicted by the frontier molecular orbital theory. The results show that the rearrangement does not involve the carbonium ion intermediates, but the first transition state is carboniumion like. Dehydration and hydration may occur via the intermolecular proton relay along the hydrogen‐bond chains and the second step of reaction path is a total acid–base catalytic process. Based on the results, a model considered both HTW ambient and water molecules are proposed to represent mechanisms of other reactions in HTW. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011  相似文献   

11.
The title compound (H2L), C27H28N4O2, is an asymmetric binucleating ligand with well defined soft (N3O‐donor) and hard (NO2‐donor) sides. H2L was designed as a ligand for the preparation of heterodinuclear mixed‐valence MIII/MII complexes which are models for heterobimetallic active sites of enzymes, principally calcineurin. The mol­ecular structure of H2L shows a spatial pre‐organization of the donor groups for coordination. This conformation is stabilized by bifurcated intra‐ and inter­molecular O—H⋯N hydrogen bonds involving both phenol groups. The inter­molecular hydrogen bonds link mol­ecules of H2L into chains running parallel to the crystallographic c axis.  相似文献   

12.
The title salt, C13H12N3+·H2PO4, contains a nonplanar 2‐(2‐aminophenyl)‐1H‐benzimidazol‐3‐ium cation and two different dihydrogen phosphate anions, both situated on twofold rotation axes in the space group C2. The anions are linked by O—H...O hydrogen bonds into chains of R22(8) rings. The anion chains are linked by the cations, via hydrogen‐bonding complementarities and electrostatic interactions, giving rise to a sheet structure with alternating rows of organic cations and inorganic anions. Comparison of this structure with that of the pure amine reveals that the two compounds generate characteristically different sheet structures. The anion–anion chain serves as a template for the assembly of the cations, suggesting a possible application in the design of solid‐state materials.  相似文献   

13.
A new copper(II) phosphonatobenzenesulfonate incorporating 4,4′‐bipyridine (4,4′‐bipy) as auxiliary ligand has been discovered through systematic high‐throughput (HT) screening of the system Cu(NO3)2·3H2O/H2O3PC6H4SO3H/4,4′‐bipy using different solvents. The hydrothermal synthesis of [Cu(HO3PC6H4SO3)(C10H8N2)]·H2O ( 1 ) was further optimized by screening various copper(II) salts. The crystal structure of 1 was determined by single‐crystal X‐ray diffraction and unveiled the presence of isolated sixfold coordinated Jahn–Teller‐distorted Cu2+ ions. The isolated CuN2O4 octahedra are interconnected by phosphonate and sulfonate groups to form chains along the c‐axis. The organic groups, namely phenyl rings and 4,4′‐bipy molecules cross‐link the chains into a three‐dimensional framework. Water molecules are found in the narrow voids in the structure which are held by weak hydrogen bonds. Upon dehydration, the structure of 1 undergoes a phase transition, which was confirmed by TG measurements and temperature dependent X‐ray powder diffraction. The new structure of 1‐h was refined with Rietveld methods. Detailed inspection of the structure revealed the directional switching of the Jahn–Teller distortion upon de/rehydration. Weak ferro‐/ferrimagnetic interactions were observed by magnetic investigations of 1 , which switch to antiferromagnetic below 3.5 K. Compounds 1 and 1‐h are further characterized by thermogravimetric and elemental analysis as well as IR spectroscopy.  相似文献   

14.
The crystal structure of the title compound {(C5H14N2)2[Cd2Cl8]}n, (I), consists of hydrogen‐bonded 2‐methylpiperazinediium (H2MPPA2+) cations in the presence of one‐dimensional polymeric {[CdCl33‐Cl)]2−}n anions. The CdII centres are hexacoordinated by three terminal chlorides and three bridging chlorides and have a slightly distorted octahedral CdCl33‐Cl)3 arrangement. The alternating CdCl6 octahedra form four‐membered Cd2Cl2 rings by the sharing of neighbouring Cd–Cl edges to give rise to extended one‐dimensional ladder‐like chains parallel to the b axis, with a Cd...Cd distance of 4.094 (2) Å and a Cd...Cd...Cd angle of 91.264 (8)°. The H2MPPA2+ cations crosslink the [CdCl33‐Cl)]n chains by the formation of two N—H...Cl hydrogen bonds to each chain, giving rise to one‐dimensional ladder‐like H2MPPA2+–Cl2 hydrogen‐bonded chains [graph set R42(14)]. The [CdCl33‐Cl)]n chains are interwoven with the H2MPPA2+–Cl2 hydrogen‐bonded chains, giving rise to a three‐dimensional supramolecular network.  相似文献   

15.
The title compound, {(C6H14N2O2)[Cu2Cl6(H2O)]}n, consists of 1,4‐dihydroxy‐1,4‐diazoniabicyclo[2.2.2]octane dications and one‐dimensional inorganic anionic {[Cu2Cl6(H2O)]2−}n chains in which both five‐coordinate [CuCl3(H2O)] and five‐coordinate [CuCl3] units exist. These two distinct type of unit are linked together by one chloride ion and are bridged across centres of inversion to further units of their own type through two chloride ions, giving rise to novel polymeric zigzag chains parallel to the c axis. The chains are connected by O—H...Cl hydrogen bonds to produce R24(16) ring motifs, resulting in two‐dimensional layers parallel to the ac plane. These layers are linked into a three‐dimensional framework with the organic cations via O—H...Cl hydrogen bonds. Hydrogen bonding between the chains, and between the chains and the organic cations, provides stability to the crystal structure.  相似文献   

16.
Two new 3D heterometallic frameworks, [Me2NH2][CaCd2(BTC)(HBTC)2] · 4H2O ( 1 ) and [Ba11Co2(BTC)83‐OH)22‐H2O)6(H2O)16] ( 2 ) (H3BTC = 1,3,5‐benzenetricarboxylic acid, Me2NH2 = protonated dimethylamine), were synthesized using solvothermal and hydrothermal techniques, respectively. Complex 1 features a 3D microporous framework; it contains hourglass‐like trinuclear [CaCd2(COO)6] clusters that are bridged by –COO groups and form zigzag chains. These chains are further interlinked by the –COO groups of BTC3– ligands into 2D layers with interesting flower‐like configuration, which, in turn, are connected by HBTC2– ligands to afford the 3D structure. Me2NH2+ cations not only balance the negative charges of the host framework but also play template roles to fill in the channels, further consolidating the whole framework. The complicated 3D network of complex 2 is constructed by the interconnection of 2D layers, which, in turn, are made of the infinite inorganic chains based on hexanuclear [Ba6] clusters, and these 1D chains are decorated by {CoO6} octahedrons. Interestingly, the 2D layer can be viewed as a unique structure composed of two different kinds of heart‐shaped rings, which partially overlapped in apical positions to produce a ten‐membered ring window. Moreover, the luminescence properties of 1 – 2 and the gas adsorption property of 1 have also been studied.  相似文献   

17.
The crystal structures of almotriptan {systematic name: N,N‐dimethyl‐2‐[5‐(pyrrolidin‐1‐ylsulfonylmethyl)‐1H‐indol‐3‐yl]ethanamine}, C17H25N3O2S, and almotriptan malate {systematic name: N,N‐dimethyl‐2‐[5‐(pyrrolidin‐1‐ylsulfonylmethyl)‐1H‐indol‐3‐yl]ethanaminium malate, C17H26N3O2S+·C4H5O5, a novel selective serotonin 1B/D agonist, have been determined in order to gain further insight into the structure–activity relationships of triptans. The two structures differ in the orientation of their sulfonylpyrrolidine side chains. A comparison with other triptans reveals that molecules of almotriptan, sumatriptan, zolmitriptan and rizatriptan can adopt two principal conformations. N—H...N, N—H...O and O—H...O hydrogen bonds are responsible for the molecular packing.  相似文献   

18.
The asymmetric unit of the title compound, 3C10H12N22+·2C10H11N2+·8C6H5NO5P, contains one and a half naphthalene‐1,5‐diaminium cations, in which the half‐molecule has inversion symmetry, one 5‐aminonaphthalen‐1‐aminium cation and four hydrogen (5‐carboxypyridin‐3‐yl)phosphonate anions. The crystal structure is layered and consists of hydrogen‐bonded anionic monolayers between which the cations are arranged. The acid monoanions are organized into one‐dimensional chains along the [101] direction via hydrogen bonds established between the phosphonate sites. (C)O—H...Npy hydrogen bonds (py is pyridine) crosslink the chains to form an undulating (010) monolayer. The cations serve both to balance the charge of the anionic network and to connect neighbouring layers via multiple hydrogen bonds to form a three‐dimensional supramolecular architecture.  相似文献   

19.
The structure of 1‐benzofuran‐2,3‐dicarboxylic acid (BFDC), C10H6O5, (I), exhibits an intramolecular hydrogen bond between one –COOH group and the other, while the second carboxyl function is involved in intermolecular hydrogen bonding to neighbouring species. The latter results in the formation of flat one‐dimensional hydrogen‐bonded chains in the crystal structure, which are π–π stacked along the normal to the plane of the molecular framework, forming a layered structure. 1:1 Cocrystallization of BFDC with pyridine, phenazine and 1,4‐phenylenediamine is associated with H‐atom transfer from BFDC to the base and charge‐assisted hydrogen bonding between the BFDC monoanion and the corresponding ammonium species, while preserving, in all cases, the intramolecular hydrogen bond between the carboxyl and carboxylate functions. The pyridinium 2‐carboxylato‐1‐benzofuran‐3‐carboxylic acid, C5H6N+·C10H5O5, (II), and phenazinium 3‐carboxylato‐1‐benzofuran‐2‐carboxylic acid, C12H9N2+·C10H5O5, (III), adducts form discrete hydrogen‐bonded ion‐pair entities. In the corresponding crystal structures, the two components are arranged in either segregated or mixed π–π stacks, respectively. On the other hand, the structure of 4‐aminoanilinium 2‐carboxylato‐1‐benzofuran‐3‐carboxylic acid, C6H9N2+·C10H5O5, (IV), exhibits an intermolecular hydrogen‐bonding network with three‐dimensional connectivity. Moreover, this fourth structure exhibits induction of supramolecular chirality by the extended hydrogen bonding, leading to a helical arrangement of the interacting moieties around 21 screw axes. The significance of this study is that it presents the first crystallographic characterization of pure BFDC, and manifestation of its cocrystallization with a variety of weakly basic amine molecules. It confirms the tendency of BFDC to preserve its intramolecular hydrogen bond and to prefer a monoanionic form in supramolecular association with other components. The aromaticity of the flat benzofuran residue plays an important role in directing either homo‐ or heteromolecular π–π stacking in the first three structures, while the occurrence of a chiral architecture directed by multiple hydrogen bonding is the dominant feature in the fourth.  相似文献   

20.
The reaction of 2, 6‐diacetylpyridine bis(thiosemicarbazone) (H2DAPTSC) with dimethylthallium hydroxide yielded the complexes [(TlMe2)2(DAPTSC)] and [TlMe2(HDAPTSC)]. The structure of [TlMe2(HDAPTSC)], determined by X‐ray diffractometry, exhibits a hitherto unknown coordination mode of the HDAPTSC anion in which its deprotonated thiosemicarbazone chain coordinates one metal atom through its sulphur and hydrazinic N atoms while a second metal atom is weakly coordinated through the S atom of the undeprotonated thiosemicarbazone chain. Each thallium atom is coordinated in both ways, with the result that the [TlMe2(HDAPTSC)] units are linked in infinite helical chains in the direction of the b axis. When reacting with diphenylthallium(III) hydroxide, H2DAPTSC induced a dephenylation process which led to the monophenylthallium(III) complex [TlPh(DAPTSC)]. Recrystallization from acetone yielded crystals of [TlPh(DAPTSC)]·C3H6O in which X‐ray diffractometry showed DAPTSC2— to be pentadentate, coordinating through its sulphur, azomethine N and pyridine N atoms. The 1H, 13C and 205Tl NMR data of [TlPh(DAPTSC)] indicate that its solid state molecular structure persists in DMSO solution, while those of [TlMe2(HDAPTSC)] indicate rapid alternation between coordination of the metal atom to one of the HDAPTSC thiosemicarbazone chains and its coordination to the other.  相似文献   

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