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981.
982.
983.
Single crystals of a new organic material, 4-hydroxy-l-proline-l-tartaric acid (HPTA) adduct, were grown by slow evaporation of an aqueous solution containing equimolar concentrations of 4-hydroxy-l-proline and l-tartaric acid at room temperature. Formation of new crystal has been confirmed by single crystal X-ray diffraction and NMR spectroscopic techniques. The single crystal XRD analysis shows that a molecule of 4-hydroxy-l-proline and a molecule of free l-tartaric acid both of which are interlinked to each other by two types of H-bonding interactions, namely O(6)–H(6)⋯O(2) and N(1)–H(1B)⋯O(10). The title compound (HPTA) crystallizes in monoclinic crystal system with non-centrosymmetric space group P21. The suitability of the crystal for optical applications was studied by UV–Vis–NIR spectroscopy. Fourier transform infrared (FT-IR) spectral analysis was used to confirm the presence of various functional groups in the grown crystals. The thermal stability of the compound was investigated by thermogravimetric and differential thermal analyses. The dielectric constant and dielectric loss of the crystal were studied as a function of frequency and temperature. The fluorescence spectral analysis of the title crystal shows an indigo emission. The second order nonlinear optical (NLO) property of the crystal was confirmed by the modified Kurtz–Perry powder second harmonic generation (SHG) test. 相似文献
984.
Dr. Alexander G. Shtukenberg Prof. Yurii O. Punin Ankit Gujral Prof. Bart Kahr 《Angewandte Chemie (International ed. in English)》2014,53(3):672-699
Crystals of a variety of substances including elements, minerals, simple salts, organic molecular crystals, and high polymers forgo long‐range translational order by twisting and bending as they grow. These deviations have been observed in crystals ranging in size from nanometers to centimeters. How and why so many materials choose dramatic non‐crystallographic distortions is analyzed, with an emphasis on crystal chemistries that give rise to stresses operating either on surfaces of crystallites or within the bulk. 相似文献
985.
Dr. Liping Cao Dr. Marina Šekutor Dr. Peter Y. Zavalij Prof. Dr. Kata Mlinarić‐Majerski Prof. Dr. Robert Glaser Prof. Dr. Lyle Isaacs 《Angewandte Chemie (International ed. in English)》2014,53(4):988-993
Host?guest complexes between cucurbit[7] (CB[7]) or CB[8] and diamantane diammonium ion guests 3 or 6 were studied by 1H NMR spectroscopy and X‐ray crystallography. 1H NMR competition experiments revealed that CB[7]? 6 is among the tightest monovalent non‐covalent complexes ever reported in water with Ka=7.2×1017 M ?1 in pure D2O and 1.9×1015 M ?1 in D2O buffered with NaO2CCD3 (50 mM ). The crystal structure of CB[7]? 6 allowed us to identify some of the structural features responsible for the ultratight binding, including the distance between the NMe3+ groups of 6 (7.78 Å), which allows it to establish 14 optimal ion‐dipole interactions with CB[7], the complementarity of the convex van der Waals surface contours of 6 with the corresponding concave surfaces of CB[7], desolvation of the C?O portals within the CB[7]? 6 complex, and the co‐linearity of the C7 axis of CB[7] with the N+???N+ line in 6 . This work further blurs the lines of distinction between natural and synthetic receptors. 相似文献
986.
Structure‐Based Design of Inhibitors of the Aspartic Protease Endothiapepsin by Exploiting Dynamic Combinatorial Chemistry
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Milon Mondal Nedyalka Radeva Dr. Helene Köster Dr. Ahyoung Park Dr. Constantinos Potamitis Dr. Maria Zervou Prof. Dr. Gerhard Klebe Dr. Anna K. H. Hirsch 《Angewandte Chemie (International ed. in English)》2014,53(12):3259-3263
Structure‐based design (SBD) can be used for the design and/or optimization of new inhibitors for a biological target. Whereas de novo SBD is rarely used, most reports on SBD are dealing with the optimization of an initial hit. Dynamic combinatorial chemistry (DCC) has emerged as a powerful strategy to identify bioactive ligands given that it enables the target to direct the synthesis of its strongest binder. We have designed a library of potential inhibitors (acylhydrazones) generated from five aldehydes and five hydrazides and used DCC to identify the best binder(s). After addition of the aspartic protease endothiapepsin, we characterized the protein‐bound library member(s) by saturation‐transfer difference NMR spectroscopy. Cocrystallization experiments validated the predicted binding mode of the two most potent inhibitors, thus demonstrating that the combination of de novo SBD and DCC constitutes an efficient starting point for hit identification and optimization. 相似文献
987.
Stephanie M. Barbon Pauline A. Reinkeluers Dr. Jacquelyn T. Price Prof. Dr. Viktor N. Staroverov Prof. Dr. Joe B. Gilroy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11340-11344
The straightforward synthesis of a series of 3‐cyanoformazanate boron difluoride dyes is reported. Phenyl, 4‐methoxyphenyl and 4‐cyanophenyl N‐substituted derivatives were isolated and characterized by single‐crystal X‐ray crystallography, cyclic voltammetry, and UV/Vis spectroscopy. The compounds were demonstrated to possess tunable, substituent‐dependent absorption, emission, and electrochemical properties, which were rationalized through electronic structure calculations. 相似文献
988.
Dr. Jie Liang Dr. Jie Su Prof. Yingxia Wang Yanping Chen Prof. Xiaodong Zou Fuhui Liao Prof. Jianhua Lin Prof. Junliang Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16097-16101
A germanate zeolite, PKU‐14, with a three‐ dimensional large‐pore channel system was structurally characterized by a combination of high‐resolution powder X‐ray diffraction, rotation electron diffraction, NMR, and IR spectroscopy. Ordered Ge4O4 vacancies inside the [46.612] cages has been found in PKU‐14, in which a unique (H2O)2 dimer was located at the vacancies and played a structure‐directing role. It is the first time that water clusters are found to be templates for ordered framework vacancies. 相似文献
989.
Alkyl Ammonium Cation Stabilized Biocidal Polyiodides with Adaptable High Density and Low Pressure
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Dr. Chunlin He Dr. Damon A. Parrish Prof. Dr. Jean'ne M. Shreeve 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6699-6706
The effective application of biocidal species requires building the active moiety into a molecular back bone that can be delivered and decomposed on demand under conditions of low pressure and prolonged high‐temperature detonation. The goal is to destroy storage facilities and their contents while utilizing the biocidal products arising from the released energy to destroy any remaining harmful airborne agents. Decomposition of carefully selected iodine‐rich compounds can produce large amounts of the very active biocides, hydroiodic acid (HI) and iodine (I2). Polyiodide anions, namely, I3?, I5?, which are excellent sources of such biocides, can be stabilized through interactions with large, symmetric cations, such as alkyl ammonium salts. We have designed and synthesized suitable compounds of adaptable high density up to 3.33 g cm?3 that are low‐pressure polyiodides with various alkyl ammonium cations, deliverable iodine contents of which range between 58.0–90.9 %. 相似文献