Shape of the proton potential in an intramolecular hydrogen-bonded system. Part II

The crystals of 5,5′-dibromo-3-diethylaminomethyl-2,2′-biphenol N-oxide were studied by X-ray and FT-IR spectroscopy. Within this molecule two short OHO intramolecular hydrogen bonds are formed. The NO?H⁺?O⁻ bond between the OH and the N-oxide groups is very strong, of 2.419(7) Å between the oxygen atoms. The proton potential of this hydrogen bond is flat, broad and has probably no barrier—consequently it could not be located from X-ray diffraction data. The other hydrogen bond formed between two hydroxyl groups appears asymmetrical from FT-IR spectra, and shows also relatively limited proton polarizability. The molecular conformation is non-planar, due to strong overcrowding effect between the oxygen atoms involved in the hydrogen bonds.     

Tröger's base scaffold in racemic and chiral fashion as a spacer for bisdistamycin formation. Synthesis and DNA binding study

‘Head-to-head’ oligo-N-methylpyrrole peptide dimers linked by a methano[1,5]diazocin scaffold are presented in racemic as well as chiral fashion. Their DNA binding activities were assayed on calf thymus DNA, poly(dA-dT)₂, and poly(dC-dG)₂ by NMR and ECD spectroscopies, and fluorescence probe displacement assay. The presented dimers prefer AT sequences, but show higher affinity to poly(dC-dG)₂ than distamycin A. The (4R,9R) configuration of methanodiazocin bridge was found to be better suited for interaction with ct-DNA and poly(dA-dT)₂ than (4S,9S) configuration.     

N,N′-双-(2-羟基苯亚甲基)-烷基(芳基)甲二胺类化合物质谱研究

本文对双Schiff碱类化合物的质谱进行了研究,由于其结构的特殊性,质谱的裂解过程中出现一些特殊的碎片离子,它包括羟基氢的迁移、双键的转换以及分子结构重排等,为研究这类化合物的结构和性质提供了重要的信息。     

H3PW12O40 and its cesium salts as pentane isomerization catalysts at ambient temperature

The activity of Mg−Al basic heterogeneous catalysts in the reactions of alcohols with ethylene oxide was studied. The kinetics of alcohol oxyethylation was examined. The kinetic equation of the reaction was determined and the structure of products was studied. The distribution coefficients of the oxyethylation reaction products were calculated. A comparison of the catalytic activity of Mg−Al hydroxides and products of their thermal treatment was made.     

Synthesis of Tetra—Schiff Base Macrocyclic Compound Containing Benzo—12—crown—4

Tetra-Schiff base macrocyclic compound containing benzo-12-crown-4 was synthesized via condensation of 2,6-diformyl-4-methyl-phenol with 4′，5′-diaminobenzo-12-C-4 promoted by proton. The compound was characterized by MS,IR ^1HNMR spectroscopy and elemental analysis.     

Synthesis and Antibacterial Activities of 4-Amino-3-(1-aryl-5-methyl-1,2,3-triazol-4-yl)-5-mercapto-1,2,4-triazoles/2-Amino-5-(1-aryl-5-methyl-1,2,3-triazol-4-yl)-1,3,4-thiadiazoles and Their Derivatives

ＩｎｔｒｏｄｕｃｔｉｏｎＳｃｈｉｆｆｂａｓｅｓ ,ａｍｉｄｅｓ ,ｉｍｉｄａｚｏｌｏ[2 ,1 ｂ] 1,3,4 ｔｈｉａｄｉａｚｏｌｅｓ,ａｎｄ 7Ｈ ｓ ｔｒｉａｚｏｌｏ[3,4 ｂ] 1,3,4 ｔｈｉａｄｉ ａｚｉｎｅｓｃｏｎｔａｉｎｉｎｇｈｅｔｅｒｏｃｙｃｌｅｓｈａｖｅｂｅｅｎａｔｔｒａｃｔｉｎｇｍｕｃｈａｔｔｅｎｔｉｏｎａｓｐｏｔｅｎｔｉａｌａｎｔｉｆｕｎｇａｌａｇｅｎｔｓ .1 51,2 ,3 ｔｒｉａ ｚｏｌｅ ,6 7ｍｅｒｃａｐｔｏ 1,2 ,4 ｔｒｉａｚｏｌｅ ,81,3,4 ｔｈｉａｄｉａｚｏｌｅ9 10ａｎｄｔｈｅｉｒｒｅｌａｔｅｄｃｏ…     

若干锰(Ⅲ)希夫碱配合物的合成和表征

合成了六种锰(Ⅲ)希夫碱配合物:Mn(bzacem)X(X~-=Cl~-,Br~-,I~-,NCS~-,NO_2~-)和Mn(bzacen)ClO_4·2H_2O,其中bzacen~(2-)为N,N′-二(苯甲酰丙酮缩)-乙二胺阴离子.用NMR法测定配合物在DMSO溶液中的有效磁矩值为4.46—4.63,表明为高自旋配合物,将电子光谱中的吸收带分别按配位场带、荷移带和配体带进行了归属,在配合物的红外光谱中,原配体H_2bzacen中的ν_(N-H)带消失,ν_(C-O)带移向低频,并对Mn-O、Mn-N和Mn-X的伸缩带进行了归属。     

An open chain product in the reaction of benzil with thiocarbohydrazide

An open chain compound was obtained by reaction of benzil with thiocarbohy-drazide in acidic condition. Its derivative, namely, benzil bis-(5-isopropylidene-3-thiocarbohydrazone) has been structurally characterized by X-ray single crystal diffraction method. Crystallographic data: C22H26N8S2, Mr=466.62, monoclinic, space group C2/c, a=12.215(3), b=11.473(2), c=17.032 (3)A, B=98.96(2)0, V=2357.7(9)A3, Z=4, Dc=1.32 g/cm3, F(000)=1040, u(Mo Ka)=2.43 cm-1. Final R=0.050, Rw=0.061 for 1103 unique and observed reflections with I> 3o(I). The effect of the structures on the formation of the open-chain intermediates during the cyclization of (2:2) Schiff base macrocyclic compound has been discussed and a possible mechanism for the ring closure has been suggested.     

碱金属沸石上乙醇双分子缩合反应及其机理

首次发现在碱金属Ｘ沸石上乙醇能够发生以正丁醇为主产物的双分子缩合反应，在所研究的催化剂中，含Ｒｂ的ＬｉＸ沸石表现出较高的反应活性和选择性。反应机理的研究表明，反应不经过ａｌｄｏｌ缩合步骤。在此基础上，对反应机理提出了新建议：在碱性沸石作用下，乙醇的β－位Ｃ－Ｈ键被活化，双分子脱水导致缩合。碳链的增长按此模式进行。     

Enantioselective catalytic epoxidation of nonfunctionalized prochiral olefins by dissymmetric chiral Schiff base complexes of Mn(III) and Ru(III) metal ions II

A series of new dissymmetric chiral Schiff base complexes has been obtained by a systematic condensation of (1S,2S)(+)-diaminocyclohexane and 3-acetyl-4-hydroxy-6-methyl-2-pyrone with salicylaldehyde, 5-chloro-, 5-methoxy-and 5-nitrosalicylaldehyde and by subsequent metallation with manganese and ruthenium. The characterization of the complexes 1–8 was accomplished by physico chemical studies viz. microanalysis, IR-, UV/VIS-, and CD spectral studies, optical rotation, molar conductance measurements and cyclic voltammetry. Enantioselective epoxidation of non functionalised olefins, viz. cis-stilbene, trans-3-nonene and trans-4-octene with iodosyl benzene as oxidant was demonstrated in the presence of catalytic amounts of chiral Mn(III) and Ru(III) dissymmetric Schiff base complexes. Good optical yields of epoxides were obtained for the catalyst 4 with the substrates trans-3-nonene and cis-stilbene.