阴离子对水的羟基伸缩振动拉曼光谱的影响

通过比较纯水、NaX(X=F, Cl, Br, I)、Na2S、NaOH、NaNO3、Na2CO3、Na2SO4溶液的羟基伸缩振动拉曼光谱, 发现所研究的阴离子对水的结构都有破坏作用. 通过比较阴离子对水的羟基伸缩振动拉曼光谱的影响, 可将所研究的阴离子分为两类, 一类阴离子有F−、OH−、S2−、CO32−, 另一类阴离子有Cl−、Br−、I−、NO3−和SO42−. 它们的主要区别在于对羟基伸缩振动拉曼光谱3600 cm−1、2900−3100 cm−1处影响不同, 产生这些区别的原因在于阴离子与水分子之间氢键的强弱. 阴离子对水的羟基伸缩振动拉曼光谱的影响因素有离子半径、离子电荷和离子结构, 它们的影响程度为离子结构>离子电荷>离子半径.     

Some features of RuCl3-catalyzed periodate oxidation of 3-N-substituted 5-allenyl-2,5-dichloro-4,4-dimethoxycyclopent-2-en-1-ones

3-N-Substituted 5-(1Z-carboxymethylene)-2-chloro-4,4-dimethoxycyclopent-2-en-1-ones have been prepared from the corresponding 3-N-substituted 5-allenyl-2,5-dichloro-4,4-dimethoxycyclopent-2-en-1-ones using selective oxidative cleavage of their allene bond by the RuCl₃−NaIO₄ system. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1646–1648, September, 1997.     

Development of aryl-containing dipyrrolyldiketone difluoroboron complexes (BONEPYs): Tune the hydrogen bond o–CH···F for fluoride recognition

Dipyrrolyldiketone difluoroboron complexes (BONEPYs) were synthesized by condensation of the corresponding pyrroles and malonyl chloride followed by treatment with BF₃·OEt₂. The aryl-substituted pyrrole is introduced to form a cyclic system in order to investigate anion binding studies. In BONEPYs 1–3 the o-H of the aryl group forms hydrogen bonding with F⁻ to give a more table complex. In contrast, the intramolecular hydrogen-bonded BONEPY endo-4 is more stable than its exo isomer. While adding F⁻, the hydrogen bonds must be broken first to give 4·(3)F⁻. Owing to the electron-rich group (-OMe), the o-H of the phenyl group can hardly interact with F⁻ via hydrogen bonding to give the less stable complex 4·(5)F⁻. The energy differences between the different conformations were calculated using DFT methods, which is consistent to the experimental observations.     

键连接性指数的建构及其在有机体系中的应用研究

以化学键为基础建构了键连接性指数及分子键连接性指数，该指数同时考虑顶 点原子的化学特征及键的性质．对于任意化学键，键连接性指数Si＝1+△I/R·[（ Z1-h1)m2/n1+(Z2-h2)m1/n2]，分子键连接性指数S为∑i=1^m√Si或∑i=1^m1/√ Si，其中，Z1，Z2为化学键键连原子的价电子数；n1，n2成键原子的价层最高主量 子数；m1，m2为成键原子的氧化数；h1，h2为与成键原子相连的氢原子个数；△I 为成键原子的电负性差(△I≥0)；R为化学键的相对键长．与以顶点为基础的价连 接性指数不同，该指数不仅能方便而有效地应用于饱和碳氢体系亦能有效地应用于 含多重键的不饱和体系及含杂原子的有机体系．研究了饱和碳氢体系标准生成焓， 不饱和碳氢体系和酮、醚、酯体系在水中的溶解度和辛醇/水分配系数，卤代甲烷 体系的标准生成焓，卤代苯体系辛醇/水分配系数，均取得比较满意的结果。     

N,N,N′-Trialkyl-1,8-diaminonaphthalenes: convenient method of preparation from protonated proton sponges and the first X-ray information

A simple procedure for the synthesis of N,N,N′-trialkyl-1,8-diaminonaphthalenes is described. It consists in partial demethylation (dealkylation) of commercially available proton sponge [1,8-bis(dimethylamino)naphthalene] and some of its derivatives at heating with HBr-KI-DMF system. Limitation, scope and a possible mechanistic pathway for the reaction are discussed. For isomeric 8-dimethylamino-1-methylamino- and 1-dimethylamino-8-methylamino-4-nitronaphthalenes, X-ray measurements have been conducted. The first examples of complete realkylation reactions in the naphthalene proton sponges are reported.     

Study on the Anion Recognition Properties of Synthesized Receptors （Ⅲ）： Convenient Synthesis and Anion Recognition Property of Bisthiosemicarbazone Derivative

A new series of bisthiosemicarbazone derivative receptors(1,2 and 3)have been synthesized by simple steps ingood yields.Their anion recognition properties were studied by UV-Vis and ~1H NMR spectroscopy.The resultshowed that the receptors 1,2 and 3 all had a better selectivity to F~-,CH_3COO~- and H_2PO_4~-,but no evidentbinding with Cl~-,Br~-,I~-,NO_3~- and HSO_4~-.Upon addition of the three anions to the receptors in DMSO,thesolution acquired a color change from colorless to dark yellow that can be observed by the naked-eyes,thus the re-ceptors can act as fluoride ion sensors even in the presence of other halide ions.The data showed that it was regularthat the three receptors had different binding ability with the three anions.For the same anion,the association con-stants followed the trend:receptor 1>3>2.The UV-Vis data indicates that a 1:1 stoichiometry complex isformed through hydrogen bonding interactions between compound 1,2 or 3 and anions.     

Ab initio SCF investigation of the intramolecular hydrogen bonding in δ-aminopentanoic acid

The potential energy surface of the neutral form of-aminopentanoic acid was investigated by means of ab initio 4-31G SCF calculations. Four symmetry unique local minima are stabilized by an intramolecular O-H NH₂ hydrogen bond. The geometries, energies, and wave numbers of these conformers are reported. The hydrogen bond is discussed with respect to all reactions of these conformers and in comparison with the homologues glycine,-alanine, and-aminobutyric acid and also with the bimolecular adducts between formic acid, acetic acid, and propionic acid, on the one hand, and ammonia, methylamine, and ethylamine, on the other hand.     

Anion recognition by bisimidazolium and bisbenzimidazolium cholapods

Bile acid-based acyclic receptors bearing two imidazole and benzimidazole moieties have been synthesized. Anion binding studies using ¹H NMR revealed that imidazolium receptor exhibits high selectivity for chloride ion while benzimidazolium receptor showed selectivity for Y-shaped acetate ion through hydrogen bond interactions involving imidazolium C-2 and acetyl methylene hydrogens.     

Structure and property of the hydrogen bonding complex between triazines and water

The study of the intermolecular interactions that drive the solvation of six-membered nitrogenated aromatic rings is of particular importance since they are known to constitute key building blocks of pro- teins and nucleotides[1―5]. The investigation of the 1:1 adduct of these molecules with water will be the first step in the understanding of such interactions. These molecules possess two different proton-acceptor sites: the ring π cloud and the lone pairs of electrons on the nitrogen atoms…     

Synthesis and Crystal Structure of [{Cd(hmbdc)(H_2O)_3}·2H_2O]_n

A novel coordination polymer [{Cd(hmbdc)(H2O)3}·2H2O]n (hmbdc = 5-hydroxy- isophthalic acid) has been synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c, with a = 9.599(3), b = 18.699(5), c = 7.557(2) , β = 108.198(4)°, V = 1288.6(6) 3, Z = 4, Mr = 382.60, Dc = 1.972 g/cm3, F(000) = 760, μ = 1.740, the final R = 0.0555 and wR = 0.0995 for 1732 observed reflections with I > 2σ(I). The structural analysis shows that the intermolecular hydrogen bonds and π-π interactions result in a three-dimensional supramolecular framework.