Experimental and theoretical charge density study of the neurotransmitter taurine

The experimental electron density distribution in taurine, 2-aminoethane sulfonic acid, 1, has been determined from high-resolution X-ray diffraction data collected at a temperature of 100 K. Taurine crystallizes as a zwitterion in the monoclinic space group P2(1)/c. Topological analysis of the experimental electron density and a comparison with high-level theoretical gas-phase calculations show that the crystal environment has a significant influence on the electronic configuration of the sulfonate moiety in 1, which in the crystal is more delocalized than in the gas phase. This crystal effect is mainly due to hydrogen bonding.     

一维链状配位聚合物[Cu3(TFSSB)2·(H2O)4·4H2O]n的合成和晶体结构

The title complex [Cu₃(TFSSB)₂·(H₂O)₄·4H₂O]_n (TFSSB=taurine 3-formylsalicylic schiff base) was synthesized by TFSSB and copper(Ⅱ) acetate monohydrate in ethanol solution and the crystal structure was determined by X-ray diffraction method. The crystal belongs to monoclinic system, space group P2₁ / n，with cell parameters: a=0.927 9(6) nm, b=1.173 0(2) nm, c=1.471(2) nm, β=106.96(2)°, and V=1.531(2) nm³, Z=2, D_c=1.890 g·cm^-3, μ=2.291 mm^-1, F(000)=882, R₁=0.025 9, wR₂=0.065 9. The Cu1 is five-coordinate, the Cu2 is four-coordinate. CCDC: 253298.     

Synthesis, Crystal Structure, Properties and Thermoanalysis of Complexes of Cu（Ⅱ） and Ni（Ⅱ） with Taurine-5-chlorosalicylaldelyde Schiff Base

The reactions of transition metal salts with taurine 5‐chlorosalicylaldelyde Schiff base gave two complexes [Ni(TCSSB)(H₂O)₃].H₂O (1) and [Cu(TCSSB)(H₂O)₂]₂[Cu(TCSSB)₂].6H₂O (2) (TCSSB=taurine‐5‐chlorosalicylaldelyde Schiff base), which were characterized by elemental analysis and X‐ray diffraction analysis. The complex 1 crystallized in monoclinic system with space group P2 ₁/c, and a=1.4816(2) nm, b=1.3953(2) nm, c= 0.7466(1) nm, β= 100.499(3)°, V=1.5176(4) nm³, Z=4, and an infinite 3‐D network structure was formed by hydrogen bonds among sulfo group, crystal water and coordinated water. Complex 2 crystallized in triclinic system with space group P1 , with the cell parameters: a = 0.6413(2) nm, b= 1.4596(3) nm, c= 1.6188(4) nm, a= 102.473(5)°, β= 98.979(4)°, γ=101.739°, V=1.4165(6) nm³, Z=1. The coordination environment between Cu(1) and Cu(2) is different. Cu(1) is slightly distorted square pyramidal while Cu(2) is distorted square‐plane. The complex 1 is mononuclear while the complex 2 is made up of two coordinated subunits, namely [Cu(TCSSB)₂] and [CU(TCSSB)(H₂O)₂]₂. Besides that the TG‐DTG of the complex 1 was analyzed, the thermal decomposition reaction of the complex was studied under a non‐isothermal condition by TG‐DTG. The TG and DTG curves indicate that the complex was decomposed in three stages: .     

从文蛤提取牛磺酸的工艺

采用正交试验法 ,探讨热水提取文蛤中牛磺酸的最佳工艺条件 ,并用傅立叶红外光谱仪鉴定产品质量 .结果表明 ,在料剂比为 1 0 0 g·L-1和 1 0 0℃水浴 1 .0 h时 ,提取率最高 .用 H 型阳离子交换树脂 ,能得到高纯度的牛磺酸 ,但回收率受树脂用量和处理液浓度的影响 .红外光谱测定结果表明 ,产品的 FTIR谱图与 BR级的标准牛磺酸的 FTIR谱图吻合 .     

聚天冬酰胺衍生物水凝胶的合成和溶胀性能

以L-天冬氨酸为单体，通过缩合反应合成聚丁二酰亚胺，用不同比例的牛磺酸和赖氨酸进行开环和交联，获得可生物降解聚天冬酰胺衍生物水凝胶．研究了反应条件对水凝胶溶胀性能的影响．实验结果表明，赖氨酸的用量、牛磺酸的用量对水凝胶吸水性能影响较大，引入磺酸基后，水凝胶的吸水倍率由47增大到174．水凝胶在不同溶液中的溶胀测试表明水凝胶具有较强的溶剂敏感性．溶胀倍率随着溶液pH值增大而升高，水凝胶在pH=7．4的溶液中收缩．水凝胶的溶胀倍率随着溶液离子强度的增大而降低．     

柱前衍生高效液相色谱法测定红牛维生素功能饮料中牛磺酸含量

用邻苯二甲醛(OPA)柱前衍生高效液相色谱法,运用C18色谱柱为固定相,甲醇 0.05mol/L NaAc溶液(45 55)为流动相,检测波长330nm,测定红牛维生素功能饮料的牛磺酸.结果衍生化反应迅速,分离效果好,在10～50μg/ml的浓度范围内,牛磺酸色谱峰面积与浓度之间的线性相关系数为0.9999,加标回收率为97.48%～101.0%,RSD为2.5%.     

5-氯,N(2-磺酸基乙基)水杨醛亚胺 Schiff碱的合成及表征

用5-氯水杨醛设计合成了5-氯，N(2-磺酸基乙基)水杨醛亚胺Sehiff碱，其组成和结构用元素分析和红外光谱等进行表征．对该化合物进行抑菌试验，结果表明，该化合物对大肠杆菌和绿脓杆菌有一定的抑制作用，抑菌环直径分别达12mm和9mm．     

离子强度对牛磺酸离子交换平衡的影响

采用静态吸附法研究离子强度对牛磺酸/OH-体系在阴离子树脂D290上离子交换平衡的影响,测定了不同离子强度下牛磺酸在碱式阴离子交换树脂上的交换平衡等温线.研究结果表明:(1)随着溶液离子强度的升高,阴离子树脂对牛磺酸的平衡交换吸附容量逐渐降低,牛磺酸在树脂上的分配系数λTau逐渐下降;(2)随着溶液离子强度增大,达到平衡时液相的pH值升高,溶液中牛磺酸阴离子Tau±含量迅速增加,而牛磺酸两性离子Tau±含量迅速降低;(3)在一定的牛磺酸浓度范围内,溶液离子强度增大,有利于提高离子交换树脂对牛磺酸的选择性.     

Synthesis of Polyanionic Cellulose Carbamates by Homogeneous Aminolysis in an Ionic Liquid/DMF Medium

Polyanionic cellulose carbamates were synthesized by rapid and efficient homogeneous aminolysis of cellulose carbonate half-esters in an ionic liquid/DMF medium. Cellulose bis-2,3-O-(3,5-dimethylphenyl carbamate), as a model compound, reacted with different chloroformates to cellulose carbonates. These intermediates were subjected to aminolysis, for which both the reactivity of different chloroformates towards C6-OH and the reactivity/suitability of the respective carbonate half-ester in the aminolysis were comprehensively studied. Phenyl chloroformate and 4-chlorophenyl chloroformate readily reacted with C6-OH of the model cellulose derivative, while 4-nitrophenyl chloroformate did not. The intermediate 4-chlorophenyl carbonate derivative with the highest DS (1.05) was then used to evaluate different aminolysis pathways, applying three different amines (propargyl amine, β-alanine, and taurine) as reactants. The latter two zwitterionic compounds are only sparingly soluble in pure DMF as the typical reaction medium for aminolysis; therefore, several alternative procedures were suggested, carefully evaluated, and critically compared. Solubility problems with β-alanine and taurine were overcome by the binary solvent system DMF/[EMIM]OAc (1:1, v/v), which was shown to be a promising medium for rapid and efficient homogeneous aminolysis and for the preparation of the corresponding cellulose carbamate derivatives or other compounds that are not accessible by conventional isocyanate chemistry. The zwitterionic cellulose carbamate derivatives presented in this work could be promising chiral cation exchangers for HPLC enantiomer separations.     

Novel properties from experimental charge densities: an application to the zwitterionic neurotransmitter taurine

The charge distribution of taurine (2-aminoethane-sulfonic acid) is revisited by using an orbital-based method that describes the density in a fixed molecular orbital basis with variable orbital occupation numbers. A new neutron data set is also employed to explore whether this improves the deconvolution of thermal motion and charge density. A range of molecular properties that are novel for experimentally determined charge densities are computed, including Weinhold population analysis, Mayer bond orders, and local kinetic energy densities, in addition to charge topological analysis and quantum theory of atoms-in-molecules (QTAIM) integrated properties. The ease with which a distributed multipole analysis can be performed on the fitted density matrix makes it straightforward to compute molecular moments, the lattice energy, and the electrostatic interaction energies of molecules removed from the crystal. Results are compared with high-level (QCISD) gas-phase calculations and band structure calculations employing density functional theory. Finally, the avenues available for extending the range of molecular properties that can be calculated from experimental charge densities still further using this approach are discussed.