共查询到20条相似文献,搜索用时 15 毫秒
1.
Raffaella Puliti Carlo Andrea Mattia 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):496-499
Ammonium N‐acetyl‐l ‐threoninate, NH4+·C6H10NO4?, and methylammonium N‐acetyl‐l ‐threoninate, CH6N+·C6H10NO4?, crystallize in the orthorhombic P212121 and monoclinic P21 space groups, respectively. The two crystals present the same packing features consisting of infinite ribbons of screw‐related N‐acetyl‐l ‐threoninate anions linked together through pairs of hydrogen bonds. The cations interconnect neighbouring ribbons of anions involving all the nitrogen‐H atoms in three‐dimensional networks of hydrogen bonds. The hydrogen‐bond patterns include asymmetric `three‐centred' systems. In both structures, the Thr side chain is in the favoured (g?g+) conformation. 相似文献
2.
Abdallah Khaoulana Idrissi Mohamed Saadi Mohamed Rafiq Elizabeth M. Holt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o604-o605
The solid‐state structure of the title compound, alternatively called 2‐aminoanilinium hydrogen phosphonate, C6H9N2+·H2PO3?, shows the monoprotonated diamine molecule to be multiply hydrogen bonded to HPO3H? anions. There is no inter‐phosphite hydrogen bonding, contrary to previous solid‐state observations of the species. 相似文献
3.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(1):120-127
When the amide‐containing receptor 1 + is in a solution of dimethyl sulfoxide (DMSO) in the presence of basic anions (CH3COO?, F?, H2PO4?), it undergoes deprotonation of the ‐NH fragment to give the corresponding zwitterion, which can be isolated as a crystalline solid. In the presence of less basic anions (Cl?, Br?, NO3?), 1 + establishes true hydrogen‐bond interactions of decreasing intensity. The less acidic receptor 2 + undergoes neat proton transfer with only the more basic anions CH3COO? and F?, and establishes hydrogen‐bond interactions with H2PO4?. An empirical criterion for discerning neutralisation and hydrogen bonding, based on UV/Vis and 1H NMR spectra, is proposed. 相似文献
4.
Jari T. Kovalainen Elina Wegelius Johannes A. M. Christiaans Juhani Huuskonen Jukka Gynther 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e216-e217
(Cyclohexylmethyloxymethyl)(1H‐imidazol‐4‐iomethyl)‐(S)‐ammonium dichloride, C13H25N3O+·2Cl?, and (4‐bromobenzyl)(1H‐imidazol‐4‐iomethyl)‐(S)‐ammonium dichloride, C13H18BrN3O+·2Cl?, are model compounds with different biological activities for evaluation of the histamine H3‐receptor activation mechanism. Both title compounds occur in almost similar extended conformations. 相似文献
5.
Hiroyuki Ishida Setsuo Kashino 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e202-e204
In the crystals of two title salts of chloranilic acid (2,5‐dichloro‐3,6‐dihydroxy‐p‐benzoquinone), namely ethylammonium chloranilate, C2H8N+·C6HCl2O4?, (I), and diethylammonium chloranilate, C4H12N+·C6HCl2O4?, (II), the chloranilate ions are present as a hydrogen‐bonded dimer which has an inversion center. The ethylammonium and diethylammonium ions link the dimers through N—H?O hydrogen bonds, forming a three‐dimensional hydrogen‐bond network in (I) and a one‐dimensional chain in (II). 相似文献
6.
Gutmann's Donor Numbers Correctly Assess the Effect of the Solvent on the Kinetics of SNAr Reactions in Ionic Liquids
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jazmín Alarcón‐Espósito Prof. Dr. Renato Contreras Prof. Dr. Ricardo A. Tapia Dr. Paola R. Campodónico 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13347-13351
We report an experimental study on the effect of solvents on the model SNAr reaction between 1‐chloro‐2,4‐dinitrobenzene and morpholine in a series of pure ionic liquids (IL). A significant catalytic effect is observed with reference to the same reaction run in water, acetonitrile, and other conventional solvents. The series of IL considered include the anions, NTf2?, DCN?, SCN?, CF3SO3?, PF6?, and FAP? with the series of cations 1‐butyl‐3‐methyl‐imidazolium ([BMIM]+), 1‐ethyl‐3‐methyl‐imidazolium ([EMIM]+), 1‐butyl‐2,3‐dimethyl‐imidazolium ([BM2IM]+), and 1‐butyl‐1‐methyl‐pyrrolidinium ([BMPyr]+). The observed solvent effects can be attributed to an “anion effect”. The anion effect appears related to the anion size (polarizability) and their hydrogen‐bonding (HB) abilities to the substrate. These results have been confirmed by performing a comparison of the rate constants with Gutmann's donicity numbers (DNs). The good correlation between rate constants and DN emphasizes the major role of charge transfer from the anion to the substrate. 相似文献
7.
Sh. Sh. Nabiev 《Russian Chemical Bulletin》1999,48(4):711-717
IR and Raman spectra of X+ AuF6 ? (X=CIF2, CIO2, CIOF2, CIF4, CIF6) were studied. The vibration frequencies of these compounds in the solid phase and in solutions in anhydrous HF were assigned. Peculiar features of the vibrational spectra of solid X+ AuF6 ?, associated both with structural transformations of cations and anions in the crystal lattice field and cation—anion interactions and also with the Jahn—Teller effect, Fermi resonance, non-rigid intramoleciular rearrangements.,etc., were discussed. 相似文献
8.
B.G. Oliveira R.C.M.U. Araújo A.B. Carvalho M.N. Ramos 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):563-566
B3LYP/6-311++G(d,p) calculations were used to predict some molecular properties of the C2H6N+?BeH2, C2H6N+?MgH2, C3H8N+?BeH2 and C3H8N+?MgH2 dihydrogen-bonded complexes. In these systems, it was demonstrated that the C2H6N+ and C3H8N+ protonated rings are potential candidates to bind with protonic hydrogens derived from alkaline earth metal compounds, BeH2 and MgH2. In terms of structural parameters and quantification of the dihydrogen bond energies, we should mention that the C2H6N+ three-membered ring provides the formation of stronger bound systems, which are 4.0 kJ mol?1 more stables than C3H8N+ four-membered ones. As complement, the analysis of the infrared spectrum indicated that red-shifts and blue-shifts are occurring in the N–H bonds of both C2H6N+ and C3H8N+ cationic rings. However, these two vibrational shifts were also verified on BeH2 and MgH2, what lead us to affirm that cationic compounds derived from small nitrogen rings and earth alkaline molecules are able to form unusual dihydrogen-bonded complexes by means of distinct spectroscopic phenomena, the red-shits and blue-shifts. 相似文献
9.
Anwar Usman Suchada Chantrapromma Hoong‐Kun Fun Bo‐Long Poh Chatchanok Karalai 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):o46-o47
In the title complex, the 1:1 ionic adduct of hexamethylenetetraminium and 2,4,6‐trinitrophenolate, C6H13N4+·C6H2N3O7?, the cation acts as a donor for bifurcated hydrogen bonds to the O atoms of the phenolate and one of the nitro groups of the 2,4,6‐trinitrophenolate anion. The crystal structure is built from sheets of cations and anions, and is stabilized by intermolecular C—H?O and C—H?π interactions. 相似文献
10.
Aqueous Self‐Assembly and Cation Selectivity of Cobaltabisdicarbollide Dianionic Dumbbells
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Màrius Tarrés Prof. Clara Viñas Patricia González‐Cardoso Dr. Mikko M. Hänninen Prof. Reijo Sillanpää Vladimír Ďorďovič Dr. Mariusz Uchman Prof. Francesc Teixidor Dr. Pavel Matějíček 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6786-6794
The anion [3,3′‐Co(C2B9H11)2]? ([COSAN]?) produces aggregates in water. These aggregates are interpreted to be the result of C?H???H?B interactions. It is possible to generate aggregates even after the incorporation of additional functional groups into the [COSAN]? units. The approach is to join two [COSAN]? anions by a linker that can adapt itself to act as a crown ether. The linker has been chosen to have six oxygen atoms, which is the ideal number for K+ selectivity in crown ethers. The linker binds the alkaline metal ions with different affinities; thus showing a distinct degree of selectivity. The highest affinity is shown towards K+ from a mixture containing Li+, Na+, K+, Rb+ and Cs+; this can be indicative of pseudo‐crown ether performance of the dumbbell. One interesting possibility is that the [COSAN]? anions at the two ends of the linker can act as a hook‐and‐loop fastener to close the ring. This facet is intriguing and deserves further consideration for possible applications. The distinct affinity towards alkaline metal ions is corroborated by solubility studies and isothermal calorimetry thermograms. Furthermore, cryoTEM micrographs, along with light scattering results, reveal the existence of small self‐assemblies and compact nanostructures ranging from spheres to single‐/multi‐layer vesicles in aqueous solutions. The studies reported herein show that these dumbbells can have different appearances, either as molecules or aggregates, in water or lipophilic phases; this offers a distinct model as drug carriers. 相似文献
11.
Richard Goddard Stephan Hütte Manfred T. Reetz 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):878-880
The title compound, C16H36N+·C6H7O3?, crystallizes with two independent anions and two independent cations in the asymmetric unit. Each anion adopts an s‐trans conformation and forms O?H—C hydrogen bonds to the α‐methylene groups of four neighbouring tetrabutylammonium cations, to create a three‐dimensional hydrogen‐bonded network. 相似文献
12.
Cecilia Rodríguez de Barbarín Sylvain Berns Blanca Njera Perla Elizondo 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o597-o599
Two salts of acyclic Schiff base cationic ligands, namely N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride monohydrate, C17H22N4O42+·2Cl−·H2O, (I), and 2‐hydroxy‐N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride, C17H22N4O52+·2Cl−, (II), were synthesized as precursors in order to obtain new acyclic and macrocyclic multidentate ligands and complexes. The cation conformations in compounds (I) and (II) are different in the solid state, although the cations are closely related chemically. Similarly, the hydrogen‐bonding networks involving ammonium cations, hydroxyl groups and chloride anions are also different. In the cation of compound (II), the hydroxyl group is disordered over two sets of sites, with occupancies of 0.785 (8) and 0.215 (8). 相似文献
13.
By mixing acidic solutions of 1,4,8,11-tetraazacyclotetradecane (Cy) with CuX2 (X = Cl?, Br?), either the hexahalocuprates of the tetraprotonated form of the macrocycle ([CyH4] [CuX6]) or the tetrahalocuprates of its Cu2+ complex ([CuCy] [CuX4]) are obtained. The structures of the chloro derivatives are established by X-ray diffraction analysis. In [CyH4] [CuCl6], the Cu2+ is in a tetragonally distorted octahedral geometry with four short and two long Cu? Cl bonds. The tetraprotonated macrocycle is centrosymmetric, and its conformation is exodentate, so that the four ammonium groups are as far as possible from each other to minimize the electrostatic repulsion. In [CuCy] [CuCl4], the Cu2+ ion complexed by the macrocycle is surrounded by four N-atoms in a square-planar arrangement. In addition, the axial positions are occupied by two Cl? ions of two CuCl units, which act as bridges. The macrocycle is in the trans-III-configuration. The other Cu2+ ion is coordinated by four Cl? ions in a distorted tetrahedral geometry. IR and VIS spectra of the chloro and bromo derivatives are used to discuss the structure of the bromo species. 相似文献
14.
Introduction Interest in the selective recognition and sensing of anionic species continues to attract the attention of su-pramolecular chemistry community.1 The importance of anions in chemical and biological process can not be underestimated. It is well known that in nature neutral proteins bind anions only via hydrogen bonding interac-tions.2 Several anion receptors have been constructed from five-membered heterocycle,3 amide,4 (thio) urea,5 since these groups form relatively strong NHanio… 相似文献
15.
Raatikainen K Beyeh NK Rissanen K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(48):14554-14564
A series of symmetrical tri‐ and tetrameric N‐ethyl‐ and N‐phenylurea‐functionalized cyclophanes have been prepared in nearly quantitative yields (86–99 %) from the corresponding tri‐ and tetraamino‐functionalized piperazine cyclophanes and ethyl or phenyl isocyanates. Their conformational and complexation properties have been studied by single‐crystal X‐ray diffraction, variable‐temperature NMR spectroscopy, and ESI‐MS analysis. The rigid 27‐membered trimeric cyclophane skeleton assisted by a seam of intramolecular hydrogen bonds results in a preorganized ditopic recognition site with an all‐syn conformation of the urea moieties that, complemented by a lipophilic cavity of the cyclophane, binds molecular and ionic guests as well as ion pairs. The all‐syn conformation persists in acidic conditions and the triprotonated triurea cyclophane binds an unprecedented anion pair, H2PO4????HPO42?, in the solid state. The tetra‐N‐ethylurea cyclophane is less rigid and demonstrates an induced‐fit recognition of diisopropyl ether in the solid state. The guest was encapsulated within the lipophilic interior of a quasicapsule, formed by intramolecular hydrogen‐bond‐driven folding of the 36‐membered cyclophane skeleton. In the gas phase, the essential role of the urea moieties in the binding was demonstrated by the formation of monomeric 1:1 complexes with K+, TMA+, and TMP+ as well as the ion‐pair complexes [KI+K]+, [TMABr+TMA]+ and [TMPBr+TMP]+. In the positive‐mode ESI‐MS analysis, ion‐pair binding was found to be more pronounced with the larger tetraurea cyclophanes. In the negative mode, owing to the large size of the binding site, a general binding preference towards larger anions, such as the iodide, over smaller anions, such as the fluoride, was observed. 相似文献
16.
K. Anitha S. Athimoolam S. Natarajan 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o567-o570
In the structure of l ‐prolinium picrate, C5H10NO2+·C6H2N3O7−, the Cγ atom of the pyrrolidine ring has conformational disorder. Both the major and minor conformers of the pyrrolidine ring adopt conformations intermediate between a half‐chair and an envelope. Both the cation and anion are packed through chelated three‐centred N—H⋯O hydrogen bonds. The prolinium cation connects two different picrate anions, leading to an infinite chain running along the b axis. In 2‐methylpyridinium picrate, C6H8N+·C6H2N3O7−, the cations and anions are packed separately along the a axis and are interconnected by N—H⋯O hydrogen bonds. Intramolecular contacts between phenolate O atoms and adjacent nitro groups are identified in both structures. A graph‐set motif of R12(6) is observed in both structures. 相似文献
17.
Magorzata Katarzyna Cabaj Roman Gajda Anna Hoser Anna Makal Paulina Maria Dominiak 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(8):1036-1044
Crystals of hypoxanthinium (6‐oxo‐1H,7H‐purin‐9‐ium) nitrate hydrates were investigated by means of X‐ray diffraction at different temperatures. The data for hypoxanthinium nitrate monohydrate (C5H5N4O+·NO3?·H2O, Hx1 ) were collected at 20, 105 and 285 K. The room‐temperature phase was reported previously [Schmalle et al. (1990). Acta Cryst. C 46 , 340–342] and the low‐temperature phase has not been investigated yet. The structure underwent a phase transition, which resulted in a change of space group from Pmnb to P21/n at lower temperature and subsequently in nonmerohedral twinning. The structure of hypoxanthinium dinitrate trihydrate (H3O+·C5H5N4O+·2NO3?·2H2O, Hx2 ) was determined at 20 and 100 K, and also has not been reported previously. The Hx2 structure consists of two types of layers: the `hypoxanthinium nitrate monohydrate' layers (HX) observed in Hx1 and layers of Zundel complex H3O+·H2O interacting with nitrate anions (OX). The crystal can be considered as a solid solution of two salts, i.e. hypoxanthinium nitrate monohydrate, C5H5N4O+·NO3?·H2O, and oxonium nitrate monohydrate, H3O+(H2O)·NO3?. 相似文献
18.
Wojciech Nitek Agnieszka Kania Henryk Marona Anna M. Waszkielewicz Ewa esawska 《Acta Crystallographica. Section C, Structural Chemistry》2022,78(1):14-22
The aroxyalkylaminoalcohol derivatives are a group of compounds known for their pharmacological action. The crystal structures of four new xylenoxyaminoalcohol derivatives having anticonvulsant activity are reported, namely, 2-{[2-(2,6-dimethylphenoxy)ethyl]amino}-1-phenylethan-1-ol, C18H23NO2, 1 , the salt N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxy-1-phenylethan-2-aminium 3-hydroxybenzoate, C18H24NO2+·C7H5O3?, 2 , and two polymorphs of the salt (R)-N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxy-1-phenylethan-2-aminium chloride, C18H24NO2+·Cl?, 3 and 3p . Both polymorphs crystallize in the space group P21212 and each has two cations and two anions in the asymmetric unit (Z′ = 2). The molecules in the polymorphs show differences in their molecular conformations and intermolecular interactions. The crystal packing of neutral 1 is dominated by intermolecular O—H…N hydrogen bonds, resulting in the formation of one-dimensional chains. In the crystal structures of the salt forms ( 2 , 3 and 3p ), each protonated N atom is engaged in a charge-assisted hydrogen bond with the corresponding anion. The protonation of the N atom also influences the conformation of the molecular linker between the two aromatic rings and changes the orientation of the rings. The crystal packing of the salt forms is dominated by intermolecular O—H…O hydrogen bonds, resulting in the creation of chains and rings. Structural studies have been enriched by the calculation of Hirshfeld surfaces and the corresponding fingerprint plots. 相似文献
19.
Peng Lian Weipeng Lai Haibo Chang Yanan Li Hui Li Wei Yang Youbing Wang Bozhou Wang Yongqiang Xue 《中国化学》2012,30(3):639-643
The structures and the stabilities of polynitrogen compounds N5+Y? [Y=B(CF3)4, BF4, PF6, and B(N3)4], as the potential high energy density compounds, have been investigated at the B3LYP/6‐31G(d,p) and B3LYP/6‐311+G(d,p) levels. On the basis of our geometry optimization calculations, the structural properties of the N5+Y? compounds are discussed, and it is found that the combination of the N5+ cation and the Y? anions leads to distortion of the structures of the Y? anions. Based on the TS calculations for the N2‐loss dissociations of the N5+Y? compounds, the stabilities of these compounds are discussed, and the following conclusion can be drawn that among the four compounds, N5+B(CF3)4? is the most stable one and N5+B(N3)4? is the most unstable, and the relative stability of these compounds is always consistent using different basis sets. From these discussions, it is revealed that there are close correlations between the stuctrual distortions of the Y? anions and the stabilities of the N5+Y? compounds, and between the nitrogen content in the compounds and the stabilities of the N5+Y? compounds. 相似文献
20.
Two different hydrogen-bonded inclusion compounds, [2,4,6-C5H2N(COO?)3]0.5·[C(NH2) 3 + ]0.5·[(C2H5)4N+]·2H2O (1) and [2,4,6-C5H2N(COO?)3]·[C(NH2) 3 + ]·[(C2H5)4N+]·[(C3H7)4N+]·6H2O (2) are reported in this paper, in which 2,4,6-pyridine-tricarboxylic anions, guanidiniums and water molecules jointly construct host lattices while tetraalkylammonium cations are accommodated as guest species. Both two compounds formed sandwich-like hydrogen-bond inclusion compounds. In compound 1, the dimers composed of 2,4,6-pyridine-tricarboxylic anions and guanidiniums form 2D hydrogen-bonded layers by connecting with water molecules. In compound 2, 2,4,6-pyridine-tricarboxylic anions, guanidiniums and water molecules contribute to generate an undulate rosette hydrogen-bonded architecture. Interestingly, in compound 2, there are two species of guest molecules, tetraethylammonium and tetrapropylammonium, which are alternately arranged between the neighboring layers. Mixed guest cations accommodated in hydrogen-bonded inclusion compounds are seldom seen. 相似文献