Synthesis of alkoxymethyl derivatives of resorcinarene via the Mannich reaction catalysed with iminodiacetic acid

The conditions of a simple synthesis of tetra(alkoxymethyl) derivatives of resorcinarene via the Mannich reaction catalysed with iminodiacetic acid are described. A possibility of high yield synthesis of such derivatives for the selected straight-chain alcohols is shown. A possible mechanism of this reaction is suggested.     

用于直接合成碳酸二甲酯的新型高活性催化剂 A Novel Highly Active Catalyst for the Direct Synthesis of Dimethyl Carbonate

 将CO2直接合成法和酯交换法相结合,通过超强碱的引入和催化剂的微粉化,制备了一种新型的负载于MgO表面的碱-金属盐路易斯酸双组分催化剂,实现了以CO2,甲醇和环氧丙烷为原料的碳酸二甲酯一步直接合成.     

Physicochemical and structural properties of bacteriostatic sulfonamides: Theoretical study

A theoretical study at the Hartree–Fock and density functional theory levels is performed on sulfonamide‐type bacteriostatic compounds with the aim to provide an insight into their structure–activity relationship. The basicity of the p‐amino group is analyzed by means of the proton affinities and the protonation energies, showing that molecules presenting bacteriostatic activity are less basic, i.e., they are characterized by larger protonation energies and smaller proton affinities. The acidity of the amide group is analyzed through the deprotonation energy. The results reveal that the more acidic molecules present a larger bacteriostatic activity. This result is also confirmed from a study of bond orders. A bond order analysis of the amide group suggests that the electron attracting group in these molecules is responsible for the increase in acidity. The charge of the SO₂ group is also shown to be affected by the presence of the electron attracting group and consequently related to the acidity of the molecules. A geometric analysis shows that structures in which the amino group is more coplanar with respect to the benzenic ring possess larger bacteriostatic activity. A conformational analysis of these molecules illustrates that active molecules have relatively larger torsion energy barriers. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 165–172, 2003     

错配核酸的研究进展

本文通过介绍多种错配核酸的结构及其热力学性质，详细地描述了非Watson-Crick配对核酸的最新进展。这方面的研究有利于阐明生物体内错配核酸的识别修复机理及核酸二级结构的预测，并为合理设计新的人工核酸修复酶提供了理论基础。     

Molecular Recognition of Nucleic Acid Bases in Water by Hydrogen Bonding of Poly(vinyldiaminotriazine)

Poly(2-vinyl-4,6-diamino-1,3,5-triazine) efficiently binds nucleic acid bases and nucleosides in water by using complementary hydrogen bonding. The binding activity decreases in the order: U, T > A C, G. The corresponding monomer shows virtually no activity, indicating a predominant role of polymer effect for the molecular recognition in water.     

A novel indicator series for measuring pKa values in acetonitrile

A series of substituted azobenzene dyes was found to span a range of 8 pK_a units in acetonitrile. The UV absorption spectra of the dyes are responsive to protonation, changing in both absorption maximum and intensity. These characteristics make the dyes useful as indicators for the measurement of pK_a values of neutral organic bases that absorb in the visible region of the spectrum.     

万古霉素手性固定相分离曼尼希碱类化合物对映体

采用大环抗生素类万古霉素手性固定相高效液相色谱法研究了一系列曼尼希碱类化合物的手性分离情况,并讨论了流动相中有机相的种类和比例、缓冲盐的种类和浓度、pH和柱温对该类化合物手性分离的影响。最佳实验条件为:乙腈:硝酸铵(35mmol/L,pH3.8)=15∶85(V/V),柱温15℃,流速0.6mL/min,检测波长300nm;四氢呋喃:硝酸铵(20mmol/L,pH4)=15∶85(V/V),柱温15℃,流速0.6mL/min,检测波长350nm。通过对比研究8种曼尼希碱类化合物的色谱行为,从结构上讨论了化合物中各种官能团对手性分离的影响,并探讨了手性分离的内在机制。     

Carbon dendron nano-chains with π-extended conjugation based on end-capped N,N-dimethylamino in linear 1,4-phenylethynyl or in 1,5-naphthylethynyl subunits: fluorescence analysis

The synthesis of dendrons with the end-capped 5-(N,N-dimethylamino)naphthyl-1-ethynyl unit connected to conjugated naphthylethynyl or p-phenylethynyl chains, as the branches of the 1,3,5-substituted benzene core, have been undertaken by heterocoupling reaction between 1,3,5-triiodobenzene and the convenient end-capped 5-(N,N-dimethylamino)naphthylacetylene or 5-(N,N-dimethylamino)naphthylethynylphenylacetylene in the presence of the palladium-copper catalyst system, in excellent yields. The influence of the alternating naphthylethynyl-phenylethynyl chains on the fluorescence emission radiation, in the dendron structures, has been analyzed.     

Modified Coumarins. 11. Synthesis and Biological Activity of Mannich Bases of Substituted 1,3-Dihydrocyclopenta[c]chromen-4-ones

Mannich bases containing the dialkylaminomethyl group in the 6- and 8-positions of 2,3-di-hydrocyclopenta[c]chromen-4-ones were prepared by condensation of 7- and 9-hydroxy-2,3-dihydrocyclopenta[c]chromen-4-ones with substituted 1,1-diaminomethanes. The effects of 8-chloro-7-hydroxy-6-(1-pyrrolidinylmethyl)-2,3-dihydrocyclopenta[c]chromen-4-one and 8-chloro-7-hydroxy-6-(morpholinomethyl)-2,3-dihydrocyclopenta[c]chromen-4-one on the central and peripheral nervous systemwere defined and enable the presence of tranquilizing and neuroleptic properties to be predicted.     

Schiff碱双核Mn配合物的合成、结构和性能研究

Five manganese complexes of Schiff base were synthesized： [Mn^Ⅳ，Ⅳ(μ-O)(Salen)]₂·DMF·H₂O (1)， [Mn^Ⅳ，Ⅳ(μ-O)(5-BrSalen)]₂·DMF·0.5H₂O (2)， {Mn^Ⅳ，Ⅳ(μ-O)[Sal(1，2-pn)]}₂·H₂O (3)， {Mn^Ⅳ，Ⅳ(μ-O)[5-Br-Sal(1，2-pn)]}₂·H₂O (4)， {Mn^Ⅳ，Ⅳ(μ-O)[5-CH₃-Sal(1，2-pn)]}₂·2H₂O (5)， and were characterized by element analysis， IR and UV-Vis spectra. The results of cyclic voltammogram show that Schiff base ligands can drop the potential of manganese and steady high oxide state of manganese. The magnetic properties of 1 and 3 have also been studied. The results show that there is a weak ferromagnetically coupling of Mn^Ⅳ₂ pair at room and low temperature， and the interactions of complex 3 are weaker than complex 1.