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1.
The crystalline inclusion compounds of cholic acid (CA) and deoxycholic acid (DCA) with several nitrosobenzenes were prepared. The IR spectra and crystal structures of these compounds confirmed inclusion of the monomeric form of the C-nitroso compounds. The DCA compounds have 2 : 1 host:guest stoichiometry and P21 symmetry. Guest molecules are enclosed in channels and disordered. In the CA-nitrobenzene inclusion compound (1·CA) the host:guest stoichiometry is 1 : 1. The host molecules form typical CA bilayer aggregates and guest molecules are accommodated in helicoidal channels. The guest nitroso group is not coplanar with the phenyl ring; the torsion angle on the C–N bond is 8.6(8)°. The solid-state circular dichroism spectrum of 1·CA shows the negative Cotton effect at 780 nm corresponding to the n–* electronic transition that can be associated with the P helicity of the guest molecule. The extremely weak magnitude of the Cotton effects exhibited by the DCA complexes points to a nearly planar arrangement of the NO group and the phenyl ring in the guest molecules.  相似文献   

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Abstract

Alkyliminotrialkylphosphoranes form stable complexes with BF3 which structures have not been studied earlier. It is possible that these complexes are formed at the first stage of imide-amide rearrangement under action of the BF3 etherate. As the adducts cannot be isolated, we decided to study the stable BF3 adducts with phenyliminotriphenylphosphorane (la), p-fluorophenyliminotriphenyl-phosphorane (lb) and benzyliminotriphenylphosphorane (Ic), all being crystalline compounds.  相似文献   

3.
The correlation between the spectral characteristics of molecular complexes of iodine with various benzene derivatives and the ionization potentials of the donor molecules is discussed. The isomerism of these complexes, determined by the structure of the electronic level with which the orbital of the acceptor interacts and by the steric structure of the donor molecules, is revealed.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 438–444.Original Russian Text Copyright © 2005 by Pryalkin.  相似文献   

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Abstract

Under conditions of interphase catalysis complexiDg agenta L1, L2 and L3 have been synthesizedl. Using spectral and X-ray methods complex fomation of thises ligands with AgNO3 has been studied  相似文献   

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卤代有机物是环境领域的主要污染物类型之一.氢解脱卤是实现卤代有机物降解的有效途径,而探索不同催化氢解脱卤方法已成为该领域持续的研究热点.其中,金属配位化合物因其特殊的电子效应及空间效应可有效进行氢解脱卤,从而成为近年来报道的新型催化脱卤方法.基于此,本文总结了各种类型金属配合物进行氟、氯及溴代有机物催化脱卤过程的反应类型及过程机理,指出了配合物与卤代有机物之间电子转移状况、空间结构及配体亲卤性对脱卤反应起决定作用.另外,还探讨了中心离子、配体、卤代有机物类型和还原剂等影响因素对配位催化脱卤反应的作用机制,提出了当前配位催化脱卤研究存在的问题,并对今后该领域的实用性研究进行了展望.  相似文献   

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A thorough thermodynamic analysis by isothermal titration calorimetry of allosteric and chelate cooperativity effects in divalent crown ether/ammonium complexes is combined with DFT calculations including implicit solvent on the one hand and large‐scale molecular dynamics simulations with explicit solvent molecules on the other. The complexes studied exhibit binding constants up to 2×106 m ?1 with large multivalent binding enhancements and thus strong chelate cooperativity effects. Slight structural changes in the spacers, that is, the exchange of two ether oxygen atoms by two isoelectronic methylene groups, cause significantly stronger binding and substantially increased chelate cooperativity. The analysis is complemented by the examination of solvent effects and allosteric cooperativity. Such a detailed understanding of the binding processes will help to efficiently design and construct larger supramolecular architectures with multiple multivalent building blocks.  相似文献   

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The energy minimum of H complexes of methanol with carbonyl compounds corresponds to the nonlinear structure in which the bridging hydrogen atom deviates from the axis of the C=O bond. The stretching vibration bands of the OH bonds in these H complexes, observed in the IR spectra of solutions (CCl4), have a complex shape or are asymmetrical, which is due to the existence of two configuration isomers differing in the direction of the H bond. Difference in the orientation of the subunits of the complex may cause significant differences in the OH stretching frequencies.  相似文献   

14.
This article reviews recent discovery and progress of copolymerization of CO with cyclic monomers such as methylenecyclopropanes and propylene oxide promoted by transition metal complexes. 2-Aryl-1-methylenecyclopropanes react with CO in the presence of the Pd catalyst under mild conditions (1 atm, room temperature) to afford the polyketones. The reaction involves alternating insertion of the two monomers and opening of the three-membered ring of the cyclic monomers. Mechanistic study of the polymer growth revealed that 2-aryl-1-methylenecyclopropane undergoes 1,2-insertion into the Pd–acyl bond and subsequent -alkyl elimination of the cyclopropylmethylpalladium group. A bicyclic methylenecyclopropane, 7-methylenebicyclo[4.1.0]heptane, also reacts with CO in the presence of the Pd complexes with diimine ligands to afford the polyketone with six-membered rings in the repeating unit. The NMR spectra of the polyketone indicate the regulated tacticity of the monomer units. Co complexes and a mixture of Co and Ru complexes with carbonyl ligands promote the copolymerization of CO with propylene oxide in the presence of amine additives under CO pressure at 50 atm. Structures of the produced polyesters vary depending on the reaction conditions.  相似文献   

15.
Inclusion compounds of transition metal complexes of cycloocta-1,5-diene (cod) and norbornadiene (nbd) with cyclodextrins were prepared. Two-to-one (cyclodextrin:guest) inclusion compounds were obtained in high yields by the treatment of β-cyclodextrin (β-CD) with [(L)RhCl]2 (L = nbd or cod) and 1:1 inclusion compounds were obtained by the reaction of β-CD with (cod)PtX2 (X = Cl, Br, or I) in high yields, while γ-CD formed 1:1 inclusion compounds with (cod)PtX2 (X = Br or I). The formation of inclusion compounds is selective. α-CD did not form inclusion compounds with any transition-metal complexes with cycloocta-1,5-diene. Thermogravimetric measurements show that the complexes are stabilized by inclusion in cyclodextrin cavities. The inclusion compounds were characterized by 1 H-NMR, IR, UV, and circular dichroism spectra.  相似文献   

16.
Understanding the interactions of organic donor and acceptor molecules in binary associates is crucial for design and control of their functions. Herein, we carried out a theoretical study on the properties of charge transfer complexes of 1,3,6-trinitro-9,10-phenanthrenequinone (PQ) with 23 aromatic π-electron donors. Density functional theory (DFT) was employed to obtain geometries, frontier orbital energy levels and amounts of charge transfer in the ground and first excited states. For the most effective donors, namely, dibenzotetrathiafulvalene, pentacene, tetrathiafulvalene, 5,10-dimethylphenazine, and tetramethyl-p-phenylenediamine, the amount of charge transfer in the ground state was shown to be 0.134−0.240 e. Further, a novel charge transfer complex of PQ with anthracene was isolated in crystalline form and its molecular and crystal structure elucidated by single-crystal synchrotron X-ray diffraction.  相似文献   

17.
Symmetrical marcoheterocyclic compounds derived from substituted 1,2,4-triazoles were reacted with tin(IV) and titanium(IV) chlorides to prepare the corresponding metal complexes. Macroheterocyclic compounds insoluble in organic solvents give mixtures of products on complex formation.  相似文献   

18.
Supramolecular complexes of calix[4]resorcinolarene tetramethylsulfonate with certain organophosphorus compounds, such as dimethyl (1,1-dimethyl-3-oxobutyl)phosphonate, 1-O-[bis(N,N-diethylamino)thiophosphinoyl]-3,5-O-[(N,N-diethylamino)thiophosphonoyl)-2,4-O-methylenexylitol, and 2-O-[bis(N,N-diethylamino)thiophosphinoyl]-3,5-O-[(N,N-diethylamino)thiophosphonoyl)-1,4-anhydroxylitol, were prepared in aqueous and organic media. The complexes were isolated and characterized by elemental analysis and 1H and 13C NMR spectroscopy.  相似文献   

19.
Consumers are becoming more mindful of their well-being. Increasing awareness of the many beneficial properties of peppermint essential oil (EO) has significantly increased product sales in recent years. Hydrodistillation (HD), a proven conventional method, and a possible alternative in the form of microwave-assisted hydrodistillation (MWHD) have been used to isolate peppermint EO. Standard Soxhlet and alternatively supercritical fluid (SFE), microwave-assisted, and ultrasound-assisted extraction separated the lipid extracts. The distillations employed various power settings, and the EO yield varied from 0.15 to 0.80%. The estimated environmental impact in terms of electricity consumption and CO2 emissions suggested that MWHD is an energy efficient way to reduce CO2 emissions. Different extraction methods and solvent properties affected the lipid extract yield, which ranged from 2.55 to 5.36%. According to the corresponding values of statistical parameters, empiric mathematical models were successfully applied to model the kinetics of MWHD and SFE processes.  相似文献   

20.
芳香氮化物-CHCl3系列复合物密度泛函法研究   总被引:1,自引:0,他引:1  
报道对芳香氮化物吡咯(C4H5N)、苯胺(C6H5NH2)、对位氯代吡啶(C5H4NCl)、吡啶(C5H5N)及吡咯负离子(C4H4N-)与三氯甲烷(CHCl3)形成的系列弱作用复合物的理论计算结果.把复合物看作是一个超分子,在密度泛函B3LYP/6-311G(d,p)的水平上进行计算,探讨该系列复合物的稳定性规律、电荷转移及主要几何参数变化等规律.计算结果表明:此类芳香氮化物与三氯甲烷(CHCl3)可形成一系列弱化学作用复合物,特别是带负电荷的芳香氮化物可与CHCl3形成较稳定的复合物.形成复合物的过程包含着电荷转移,该系列复合物的稳定性与广义H键距离的变化规律相一致,与电荷转移量的变化规律大体一致.  相似文献   

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