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Zenkina OV Keske EC Wang R Crudden CM 《Angewandte Chemie (International ed. in English)》2011,50(35):8100-8104
Three gases, one crystal: rhodium NHC complexes undergo back-to-back single-crystal-to-single-crystal transformations by selective nonreversible ligand exchange reactions. Slow diffusion of O(2) converts a dinitrogen complex into a dioxygen complex, and CO subsequently replaces O(2). 相似文献
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Michael T. Kirchner Dr. Dieter Bläser Roland Boese Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2131-2146
Acetylene is an amazingly versatile component for the formation of co‐crystals. It requires careful handling and special techniques for crystallisation, but the efforts seem to be rewarding when attaining co‐crystals with small molecules as partners. Many basic questions such as the dominance of specific heterogeneous intermolecular interactions, their driving force for the formation of multicomponent crystals instead of neat ones are expected to be easily analysed. The underlying packing patterns and resulting stoichiometries based on the known supramolecular synthons seem to be straightforward for such small molecules and crystal engineering, considered as the prototype of supramolecular synthesis, should be a simple task. Nineteen co‐crystals with acetylene are presented in this paper, some of which have been previously reported individually. An attempt has been made to find features shared by the groups of co‐crystals, including those that could not be co‐crystallised. But in spite of clear ideas and experiences from previous experiments, surprisingly almost none of systems reached our expectations. Our intuitive approach was not fulfilled, which demonstrates that multicomponent crystals even of small molecules will remain a great challenge for theoretical methods and the crystal structures shown herein represent good candidates for future testing. On the other hand, we wish to encourage other groups to present their views on the crystal structures with an unbiased approach that may offer a better explanation than we are able to outline in this article. 相似文献
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Two isomorphous 3D metal-organic frameworks, {[Cu2(BPnDC)2(bpy)].8 DMF.6 H2O}n (1) and {[Zn2(BPnDC)2(dabco)].13 DMF.3 H2O}n (2), have been prepared by the solvothermal reactions of benzophenone 4,4'-dicarboxylic acid (H2BPnDC) with Cu(NO3)(2).2.5 H2O and 4,4'-bipyridine (bpy), and with Zn(NO3)(2).6 H2O and 4-diazabicyclo[2.2.2]octane (dabco), respectively. Compounds 1 and 2 are composed of paddle-wheel {M2(O2CR)4} cluster units, and they generate 2D channels with two different large pores (effective size of larger pore: 18.2 A for 1, 11.4 A for 2). The framework structure of desolvated solid, [Cu2(BPnDC)2(bpy)]n (SNU-6; SNU=Seoul National University), is the same as that of 1, as evidenced by powder X-ray diffraction patterns. SNU-6 exhibits high permanent porosity (1.05 cm3 g(-1)) with high Langmuir surface area (2910 m2 g(-1)). It shows high H2 gas storage capacity (1.68 wt % at 77 K and 1 atm; 4.87 wt % (excess) and 10.0 wt % (total) at 77 K and 70 bar) with high isosteric heat (7.74 kJ mol(-1)) of H2 adsorption as well as high CO2 adsorption capability (113.8 wt % at 195 K and 1 atm). Compound 2 undergoes a single-crystal-to-single-crystal transformation on guest exchange with n-hexane to provide {[Zn2(BPnDC)2(dabco)].6 (n-hexane).3 H2O}n (2hexane). The transformation involves dynamic motion of the molecular components in the crystal, mainly a bending motion of the square planes of the paddle-wheel units resulting from rotational rearrangement of phenyl rings and carboxylate planes of BPnDC2-. 相似文献
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Shinobu Tanimura Takaaki Matsuoka Mitsuru Nakano Arimitsu Usuki 《Journal of Polymer Science.Polymer Physics》2001,39(9):973-978
Temperature‐constant and pressure‐constant molecular dynamics simulations of crystalline 1,4‐linked poly(cyclohexa‐1,3‐diene) (CHD) were performed using the COMPASS force field. Powder X‐ray diffraction spectra calculated from the simulated atomic coordinates were compared with the measured spectrum of the crystal of 1,4‐linked poly(CHD), obtained using a bis(allylnickel bromide) (ANiBr)/methylaluminoxane (MAO) catalyst. As a result of the comparison, the geometrical isomerism of the 1,4‐linked poly(CHD) obtained with the ANiBr/MAO catalyst was found to be cis syndiotactic. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 973–978, 2001 相似文献
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Tuning the Guest‐Binding Ability of a Helically Folded Capsule by In Situ Modification of the Aromatic Oligoamide Backbone 下载免费PDF全文
Dr. Guillaume Lautrette Dr. Christophe Aube Dr. Yann Ferrand Dr. Muriel Pipelier Dr. Virginie Blot Dr. Christine Thobie Dr. Brice Kauffmann Prof. Didier Dubreuil Dr. Ivan Huc 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1547-1553
Starting from a previously described aromatic oligoamide helically folded capsule that binds tartaric acid with high affinity and diastereoselectivity, we demonstrate the feasibility of the direct in situ modification of the helix backbone, which results in a conformational change that reduces its affinity for guests by two orders of magnitude. Specifically, ring contraction of the central pyridazine unit into a pyrrole in the full helical sequence was investigated by using electrochemical and chemical processes. The sequence containing the pyrrole was synthesized independently in a convergent manner to ascertain its structure. The conformation of the pyrrolic folded capsule was elucidated in the solid state by X‐ray crystallography and in solution by using 1H and 13C NMR spectroscopy. Solution studies revealed an unanticipated solvent‐dependent equilibrium between the anti–anti and syn–syn conformations of the pyrrole ring with respect to its two adjacent pyridine units. Titrations of the pyrrole‐containing sequence monitored by 1H NMR spectroscopy confirmed the expected drop in affinity for tartaric acid and malic acid that arises from the conformation change in the backbone that follows the replacement of the pyridazine by a pyrrole. The reduction of the pyridazine to a pyrrole was characterized by cyclic voltammetry both on the entire sequence and on a shorter precursor. The lower cathodic potential of the precursor made its preparative‐scale electroreduction possible. Direct in situ modification of the pyridazine within the entire capsule sequence was achieved chemically by using zinc in acetic acid. 相似文献
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Pathik Sahoo Ravish Sankolli Dr. Hee‐Young Lee Prof. Dr. Srinivasa R. Raghavan Dr. Parthasarathi Dastidar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(26):8057-8063
An easy access to a library of simple organic salts derived from tert‐butoxycarbonyl (Boc)‐protected L ‐amino acids and two secondary amines (dicyclohexyl‐ and dibenzyl amine) are synthesized following a supramolecular synthon rationale to generate a new series of low molecular weight gelators (LMWGs). Out of the 12 salts that we prepared, the nitrobenzene gel of dicyclohexylammonium Boc‐glycinate ( GLY.1 ) displayed remarkable load‐bearing, moldable and self‐healing properties. These remarkable properties displayed by GLY.1 and the inability to display such properties by its dibenzylammonium counterpart ( GLY.2 ) were explained using microscopic and rheological data. Single crystal structures of eight salts displayed the presence of a 1D hydrogen‐bonded network (HBN) that is believed to be important in gelation. Powder X‐ray diffraction in combination with the single crystal X‐ray structure of GLY.1 clearly established the presence of a 1D hydrogen‐bonded network in the xerogel of the nitrobenzene gel of GLY.1 . The fact that such remarkable properties arising from an easily accessible (salt formation) small molecule are due to supramolecular (non‐covalent) interactions is quite intriguing and such easily synthesizable materials may be useful in stress‐bearing and other applications. 相似文献
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Deciphering the Non‐Equivalence of Serine and Threonine O‐Glycosylation Points: Implications for Molecular Recognition of the Tn Antigen by an anti‐MUC1 Antibody 下载免费PDF全文
Dr. Nuria Martínez‐Sáez Jorge Castro‐López Jessika Valero‐González Dr. David Madariaga Ismael Compañón Dr. Víctor J. Somovilla Míriam Salvadó Dr. Juan L. Asensio Dr. Jesús Jiménez‐Barbero Dr. Alberto Avenoza Dr. Jesús H. Busto Dr. Gonçalo J. L. Bernardes Dr. Jesús M. Peregrina Dr. Ramón Hurtado‐Guerrero Dr. Francisco Corzana 《Angewandte Chemie (International ed. in English)》2015,54(34):9830-9834
The structural features of MUC1‐like glycopeptides bearing the Tn antigen (α‐O‐GalNAc‐Ser/Thr) in complex with an anti MUC‐1 antibody are reported at atomic resolution. For the α‐O‐GalNAc‐Ser derivative, the glycosidic linkage adopts a high‐energy conformation, barely populated in the free state. This unusual structure (also observed in an α‐S‐GalNAc‐Cys mimic) is stabilized by hydrogen bonds between the peptidic fragment and the sugar. The selection of a particular peptide structure by the antibody is thus propagated to the carbohydrate through carbohydrate/peptide contacts, which force a change in the orientation of the sugar moiety. This seems to be unfeasible in the α‐O‐GalNAc‐Thr glycopeptide owing to the more limited flexibility of the side chain imposed by the methyl group. Our data demonstrate the non‐equivalence of Ser and Thr O‐glycosylation points in molecular recognition processes. These features provide insight into the occurrence in nature of the APDTRP epitope for anti‐MUC1 antibodies. 相似文献
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Pathik Sahoo Dr. D. Krishna Kumar Dr. Srinivasa R. Raghavan Dr. Parthasarathi Dastidar 《化学:亚洲杂志》2011,6(4):1038-1047
Easy access to a class of chiral gelators has been achieved by exploiting primary ammonium monocarboxylate ( PAM ), a supramolecular synthon. A combinatorial library comprising of 16 salts, derived from 5 l ‐amino acid methyl esters and 4 cinnamic acid derivatives, has been prepared and scanned for gelation. Remarkably, 14 out of 16 salts prepared (87.5 % of the salts) show moderate to good gelation abilities with various solvents, including commercial fuels, such as petrol. Anti‐solvent induced instant gelation at room temperature has been achieved in all the gelator salts, indicating that the gelation process is indeed an aborted crystallization phenomenon. Rheology, optical and scanning electron microscopy, small angle neutron scattering, and X‐ray powder diffraction have been used to characterize the gels. A structure‐property correlation has been attempted, based on these data, in addition to the single‐crystal structures of 5 gelator salts. Analysis of the FT‐IR and 1H NMR spectroscopy data reveals that some of these salts can be used as supramolecular containers for the slow release of certain pest sex pheromones. The present study clearly demonstrates the merit of crystal engineering and the supramolecular synthon approach in designing new materials with multiple properties. 相似文献
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Virgil Percec Prof. Mihai Peterca Dr. Yusuke Tsuda Prof. Brad M. Rosen Satoshi Uchida Prof. Mohammad R. Imam Dr. Goran Ungar Prof. Paul A. Heiney Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):8994-9004
The synthesis, and structural and retrostructural analysis of a library of second‐generation conical dendrons that self‐assemble into spherical supramolecular dendrimers is reported. This library consists of amphiphilic dendrons with n‐alkyl groups containing from 4 to 16 carbon atoms. The dendrons containing 6 to 16 carbon atoms in their n‐alkyl groups self‐assemble into spherical supramolecular dendrimers that self‐organize in a Pm n cubic lattice. The structural and retrostructural analysis of the Pm n lattices generated from the supramolecular dendrimers demonstrated that the volume of the aromatic core of the spherical dendrimers is not dependent on the number of carbon atoms from their alkyl groups. This result facilitated the calculation of the average values of the absolute electron density of the aliphatic and aromatic domains of the spherical supramolecular dendrimers. The relative intensity of the higher order diffraction peaks of the Pm n lattice increases as the volume of the aliphatic part of the sphere mediated by the number of carbon atoms in the n‐alkyl groups decreases. This study demonstrates the maximum increase of the relative intensity of the higher order diffraction peaks of the Pm n lattice generated from non‐hollow supramolecular dendrimers. 相似文献
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Domenico Acierno Luciano Di Maio Pio Iannelli 《Journal of Polymer Science.Polymer Physics》1999,37(14):1601-1607
The molecular structure of the phase—stable at room temperature—for the polymer with formula [ p C6H4 COO p C6H3(R) p C6H3(R) OOC p C6H4 O (CH2)10O ]x, with R = CH2 CHCH2, is reported. The cell is hexagonal (a = b = 13.43 Å, c = 33.3 Å, γ = 120°), space group P63, six chains per unit cell (dcalcd = 1.23 g cm−3). The six chains are packed together to give a bundle with the center of mass set at the origin of the unit cell. The allyl groups are placed inside the bundle, thus explaining the unexpected reactivity of the double bonds to give crosslinking when fiber samples are annealed in the solid state. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1601–1607, 1999 相似文献
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Xing Wang Na Liu Hui Cao Wei Liu Chunhai Chen Wanjin Zhang Yen Wei 《Macromolecular rapid communications》2005,26(7):554-557
Summary: The crystal structure of rigid, hollow, racemic binaphthyl poly(ether ketone) macrocycles has been elucidated by single crystal X‐ray analysis. Multitudinal interactions were identified within the chiral space group P212121. The structural analysis revealed that this macrocyclic compound contains an elliptic chiral cavity with a size of 9.80 × 5.18 Å, which is similar to that of cyclodextrins. The knowledge about the interaction sites and the structure of the binaphthyl‐based macrocycle provides a unique opportunity to understand its molecular or chiral recognition properties.
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Prof. Dr. Wen‐Kui Dong Yin‐Xia Sun Guo‐Hua Liu Li Li Xiu‐Yan Dong Xiong‐Hou Gao 《无机化学与普通化学杂志》2012,638(9):1370-1377
Two nickel(II) complexes, namely {[NiL(MeOH)(μ‐OAc)]2Ni} · 2CH2Cl2 · 2MeOH ( 1 ) and {[NiL(EtOH)(μ‐OAc)]2Ni} · 2EtOH ( 2 ) {H2L = 5, 5′‐dimethoxy‐2, 2′‐[(ethylene)dioxybis(nitrilomethylidyne)]diphenol}, were synthesized and structurally characterized. Two trinuclear NiII complexes are both hexacoordinate around the central NiII atoms, showing octahedral coordination arrangements, and each complex comprises three divalent NiII atoms, two deprotonated L2– ligands, in which four μ‐phenoxo oxygen atoms forming two [NiL(X)] (X = MeOH or EtOH) units, and coordinated and non‐coordinated solvent molecules. Complex 1 exhibits a 2D supramolecular network through intermolecular O–H ··· O, C–H ··· O and C–H ··· π interactions, whereas complex 2 forms an infinite 1D chain by intermolecular C–H ··· O hydrogen bonding interactions. 相似文献
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C Tyrsted KM Ornsbjerg Jensen ED Bøjesen N Lock M Christensen SJ Billinge B Brummerstedt Iversen 《Angewandte Chemie (International ed. in English)》2012,51(36):9030-9033
Supercritical growth: The formation and evolution of ceria nanoparticles during hydrothermal synthesis was investigated by in?situ total scattering and powder diffraction. The nucleation of pristine crystalline ceria nanoparticles originated from previously unknown cerium dimer complexes. The nanoparticle growth was highly accelerated under supercritical conditions. 相似文献
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