Competitive interaction of polyanions and anionic dye with bovine serum albumin

The binding of anionic dye, p-(2-amino-6-sulfonyl-8-naphthylazo)benzene sulfonic acid disodium salt (ASANA) to bovine serum albumin (BSA) at pH 7.5 has been studied by spectrophotometric techniques. The values of the dissociation constants were obtained with the use of the Benesi-Hildebrand equation for ASANA. Competitive binding of polyanions, sodium poly(styrene sulfonate) (PSSNa), potassium poly(vinyl sulfonate) (PVSK), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA) and anionic dye to BSA was evaluated through the variations in the different spectra of BSA-dye-polymer systems.     

New polymer syntheses: 59. Homo-and copolyesters of 4-(4′-hydrophenoxy)benzoic acid

The homopolyester of 4-(4′-hydroxyphenoxy)benzoic acid (poly(4-HPBA)), was prepared under two different reaction conditions and compared with a sample provided by another research group. Depending on the synthetic route, different melting points, d.s.c. traces and crystal lattices were found. However, after repeated heating and cooling, one thermodynamically stable modification with a melting point of 370–375°C can be obtained. Copolyesters of 4-hydroxybenzoic acid and 4-(4′-hydroxyphenoxy)benzoic acid were prepared with various molar ratios either in the melt (condensation in bulk) or in solution. These copolyesters were characterized by elemental analyses, ¹H n.m.r. spectroscopy, d.s.c. measurements, wide-angle X-ray scattering measurements at various temperatures, and optical microscopy. Whereas copolyesters prepared in solution do not melt below 500°C, those prepared by polycondensation in bulk show melting points down to approximately 260°C and form a nematic melt.     

Estimation of interaction between polyanions and bovine serum albumin by means of affinity chromatography

The ligand binding of some polyanions to bovine serum albumin immobilized on Sepharose 4B has been studied by column affinity chromatography. Frontal chromatography using a polyanion of low concentration on an affinity adsorbent gave the dissociation constant K_d of the polyanion-immobilized ligand complex. K_d values determined under various concentrations enabled us to discuss in detail the interactions of bovine serum albumin and polyanions.     

Ermüdungsprodukte des photochromen 2-(2′,4′-Dinitrobenzyl)-pyridins

Fatigue Products of Photochromic 2-(2′,4′-Dinitrobenzyl)-pyridine Under prolonged irradiation or frequent repetitions of its photochromic cycle, 2-(2′,4′-dinitrobenzyl)-pyridine 1 shows fatigue phenomena both in solid state and in solution. These phenomens — yellow discoloration, depression of the melting point, decrease of band intensity of the coloured form, shorter lifetime of the coloured form — are caused by irreversible redox processes and subsequent reactions at the methylene and ortho-nitro groups which are essential for photochromism. Azomethine 2 , ketone 3 and amine 4 are isolated as the major fatigue products.     

苯甲酸与牛血清白蛋白相互作用的荧光光谱研究

采用荧光光谱、三维荧光光谱、同步荧光光谱研究了苯甲酸与牛血清白蛋白(BSA)分子之间的相互作用机制、特征及苯甲酸对牛血清白蛋白构象的影响。根据不同温度下苯甲酸对牛血清白蛋白的荧光猝灭作用,利用Stem-Volmer和Lineweaver-Burk方程和热力学方程分别处理实验数据,求得它们之间的结合常数K为1.096×103L/mol、结合位点数n为1.12(20℃),ΔH=-31.8 kJ/mol,ΔG=-17.1 kJ/mol,ΔS=-50.2 J.mol-1.K-1。研究发现苯甲酸对BSA内源性荧光的猝灭作用属于静态猝灭,苯甲酸与BSA分子之间的相互作用是一个吉布斯自由能降低的自发过程,两者之间的主要作用力类型为氢键力或范德华力。     

Reactions of 4-[4′-(1′,3′-Diphenylpyrazolyl)methylene]-2-phenyl-5-oxo-2-oxazoline with grignard reagents and diazoalkanes

The title compound reacts with two moles of Grignard reagents with 1,2-addition to give the alcohol 4 , and/or the oxazoline 5 , or with 1,4-addition to give the amino ketone 6 . A reaction mechanism is proposed. Diazomethane is always added to the exocyclic double bond in 1 , but diphenyldiazomethane, in addition, replaces the carbonyl-oxygen by a benzhydrylidene group to give compound 9 .     

6-甲基-4-(4-甲氧酰基苯基)-5-甲氧羰基-3,4-二氢嘧啶-2-酮的合成及与牛血清白蛋白的相互作用

合成并表征了6-甲基-4-(4-甲氧酰基苯基)-5-甲氧羰基-3,4-二氢嘧啶-2-酮,利用荧光光谱法和紫外光谱法研究了该化合物与牛血清白蛋白(BSA)的相互作用。结果表明,化合物对BSA内源荧光的猝灭为静态猝灭;化合物与BSA的结合常数(Ka)和结合位点数(n)在298 K时分别是7.043 7×102L/mol和0.970 3,化合物与BSA以接近1∶1(物质的量比)的比例生成基态复合物;热力学数据表明化合物与BSA主要以疏水作用力相结合(ΔH0,ΔS0,ΔG0);结合距离(r)为3.49 nm,表明化合物与BSA分子之间发生了非辐射能量转移。     

串联催化剂在二甲醚与合成气制备乙醇反应中的性能研究

通过水热合成法和共沉淀法分别制备了分子筛催化剂和Cu/ZnO催化剂,将分子筛与Cu/ZnO调控成双层串联催化剂,并用于二甲醚与合成气通过两段反应制备乙醇。研究了反应温度和反应气组成等因素对反应的影响,比较了分子筛类型、助剂种类和含量等对催化剂活性的影响。结果表明,随反应温度增加,DME转化率和乙醇选择性呈现先增加后减小趋势,随着DME含量减少和CO含量增加,DME转化率和乙醇选择性增加。H-MOR分子筛与Cu/ZnO串联催化剂显示了最佳的催化活性;金属助剂能提高催化剂活性,尤其是含5%Cu的Cu/H-MOR与Cu/ZnO串联催化剂显示了最佳的催化反应活性,于最佳反应温度493 K下以Ar/DME/CO/H_2(1.6/1.0/47.4/50.0)为原料进行反应,DME转化率达到33.6%,乙醇选择性达到了44.5%。     

Radical Copolymerization of 2-(3′-Acryloxy)propoxythioxanthone and 1-Methyl-4-(3′-acryloxy)propoxythioxanthone with Methyl Methacrylate

Two new monomers based on thioxanthone, 2-(3′-acryloxy)propoxythioxanthone (M-2) and 1-methyl-4-(3′-acryloxy)propoxythioxanthone (M-4), were prepared and their radical copolymerization at 70°C with methyl methacrylate (MMA) was studied. By varying the conversion reached for a fixed feed composition, f_MMA=0·983, and using Jaacks method, the reactivity ratios were determined. Identical values of reactivity ratios were found for both systems, with values of r_MMA=2·46 and r_M-2=r_M-4=0·4. The homopolymerization of MMA in the presence of a model compound, 1-methyl-4-propoxythioxanthone, was also examined and confirmed that the thioxanthone chromophore does not have any influence on the free radical polymerization of MMA. © of SCI.     

The STOBBE condensation. X. The cyclisation of (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid,and (E)−3-methoxycarbonyl-4-(2′-furyl)-pent-3-enoic acid,to Benzofuran Derivatives

The condensation of 5-methyl-furan-2-aldehyde and 2-furyl-methyl ketone with dimethyl succinate using either potassium t-butoxide or sodium hydride as condensing agents, gives predominantly (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid 1a and (E)-3-methoxy-carbonyl-4-(2′furyl)-pent-3-enoic acid 5 respectively. Their configurations are inferred by cyclisation with sodium acetate in acetic anhydride to the corresponding benzofuran derivatives 2,6 . Alcoholysis of (E)-3-carboxy-4-(5′-methyl-2′-furyl)-but-3-enoic anhydride 3 gives the half-ester 1c which is isomeric with the half-ester 1a . A competing side reaction also gives the self-condensation product of the succinic ester 4 .     

4-(4-苯基丁氧基)苯甲酸的合成研究

以4-氯-1-丁醇为原料,三氯化铝为催化剂,三氯甲烷为溶剂,经四步反应生成4-(4-苯基丁氧基)苯甲酸,确定了关键反应步骤的反应条件、反应温度和反应时间,产品总收率达到54%,产品含量达到99.5%。     

Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

6-甲基-4-(4-氨基苯基)-5-乙氧基羰基-3,4-二氢嘧啶酮的晶体结构及与牛血清白蛋白的相互作用

本文合成了6-甲基-4-(4-氨基苯基)-5-乙氧基羰基-3,4-二氢嘧啶酮(AEMD),通过X射线单晶衍射对结构进行了确认。该晶体属于单斜晶系,P2(1) / c空间群,晶胞参数a=11.237(4)nm,b=5.799(2)nm,c=22.394(7)nm,α=90o,β=91.048(5)o,γ= 90o,Z=4。用荧光光谱法研究了AEMD与牛血清白蛋白(BSA)的相互作用,结果表明：AEMD对BSA有荧光猝灭作用;热力学参数(ΔH?0 and ΔS?0)表明：AEMD与BSA之间的主要作用力为氢键和范德华力;根据F?rster’s非辐射能量转移理论,AEMD与BSA的结合距离为2.19nm;同步荧光结果表明：AEMD使BSA分子构象发生了改变。     

4-(5-氨基-6-羟基-2-苯并噁唑基)苯甲酸的合成

系统地研究了AB型新单体：4-(5-氨基-6-羟基-2-苯并口恶唑基)苯甲酸（ABA）的合成方法以及产品析出时pH值条件对其分子形态及红外吸收的影响。以4-(5-氨基-6-羟基-2-苯并口恶 唑基)苯甲酸甲酯（MAB）为原料,60～100 ℃于碳酸钾水溶液中水解反应至溶液澄清,用还原性弱酸性盐的水液在pH值6.0析出结晶、制得纯度99.5%以上高质量的新单体、经FT-IR归属剖析确认为游离的酸式单体ABA,收率达85%;具有过程工艺简便,单体稳定性优异、且无残留DMF阻聚杂质以及聚合操作安全等特点,在制备聚合级AB型PBO单体中取得新进展。