Synthesis and Crystal Structure of Glycin·3,5-Dihydroxybenzoic Acid

The title compound glycin·3,5-dihydroxybenzoic acid (GDB) has been synthesized and characterized by single-crystal X-ray analysis. It crystallizes in orthorhombic, space group Pca21 with a = 25.513(10), b = 4.668(2), c = 9.150(4)(A), Z = 4, V = 1089.8(8)(A)3, C9H13NO7, Mr = 247.20, Dc = 1.507 g/m3, μ(MoKα) = 0.132 mm-1, F(000) = 520, R1 = 0.0322 and wR2 = 0.0611 for 885 observed reflections (I > 2σ(I)). The title compound is a 1:1 molecular complex of glycin and 3,5-dihydroxybenzoic acid, which is linked by O-H…O and N-H…O hydrogen bonds to form a three-dimensional framework. Test of SHG (second harmonic generation) indicates that NLO generation of the crystal is higher than that of KDP.     

A two-dimensional infrared correlation spectroscopic study on the thermal degradation of poly(2-hydroxyethyl acrylate)-co-methyl methacrylate/SiO2 nanohybrids

Two-dimensional infrared (2D IR) correlation spectroscopy was applied to study the structural changes occurring in the decomposition of PHEA-co-MMA/SiO₂. Complicated absorption spectral changes were observed in the heating process. 2D IR analysis indicates that during heating, covalent bonds, (Si-O-C), between the polymer and the inorganic moiety were formed, which was the main factor in the improvement in thermal properties of the hybrids such as the decomposition temperatures (T_d). The thermal stability of the hybrids was also studied by solid-state ²⁹Si MAS NMR spectroscopy and TGA tests. Their results complemented each other well.     

增容剂对聚丙烯/粘土纳米复合材料热分解动力学的影响

采用三单体固相接枝聚丙烯作为增容剂制备了聚丙烯粘土纳米复合材料.通过XRD和TEM表征了其纳米结构.利用动态TGA方法研究了聚丙烯和纳米复合材料的热稳定性.分别采用Flynn Wall Ozawa和Kissinger法研究了聚丙烯及其纳米复合材料的热分解动力学.结果都表明,蒙脱土的加入明显提高了聚丙烯的起始热分解温度,纳米复合材料热失重10%时的温度比聚丙烯提高40K左右;纳米复合材料的热分解温度区间明显比聚丙烯的窄;纳米复合材料热分解表观活化能明显增大,与聚丙烯相比提高50%以上.     

Recent progress in two-photon small molecule fluorescent probes for enzymes

This review aims to provide a summary of the progress in TP small molecule fluorescent probes for enzymes in recent years and displays the main fluorescent mechanisms that have been applied to design probes.     

碳糊电极阳极吸附伏安法测定大黄酸

在pH4.2的HAc-NaAc底液中,大黄酸在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为1.14V(vs.SCE)。该氧化峰的二阶导数峰电流与大黄酸的浓度在8.0×10-9~8.0×10-7mol/L(富集120s)范围内呈良好的线性关系(r=0.998),检出限为2×10-9mol/L(S/N=3,富集180s)。探讨了大黄酸在CPE上的伏安性质和电极反应机理,并将本法应用于中药大黄中的大黄酸的测定,结果良好。     

A new Fluorimetric Reagent for Highly Selective and Sensitive Determination of Terbium Ion

 In this work, a new ligand, 2,9-bis[N,N-bis(carboxymethyl)-aminomethyl]-1,10-phenanthroline (BBCAP), was synthesized and used to establish a novel fluorimetric method for the determination of trace amounts of terbium in a binary system. Its luminescence mechanism was studied. The excitation and emission wavelengths are 284 nm and 547 nm, respectively. Other rare-earth metal ions in 100-fold excess caused no interference. The fluorescence intensity was a linear function of the concentration of terbium in the range of 5.0 × 10⁻¹⁰–1.0 × 10⁻⁶ mol/L. The detection limit was 2.0 × 10⁻¹¹ mol/L (n = 12). The standard addition method was used to determine the terbium in a synthetic rare-earth sample with satisfactory results. This method represents a direct, rapid, selective and sensitive analytical procedure with a widely linear range. Received November 29, 2001 Revision February 9, 2002     

固液相变的分子动力学研究Ⅰ─—(KI)_(108)离子簇的熔化和凝固(英)

通过分子动力学模拟，考查并分析了（KI）108离子簇的结构、能量和相变的动力学行为．在加热和冷却过程中，离子簇再现了熔化和凝固现象，而且熔化起始于立方体的其一顶点，熔化的离子簇不是球形的，说明了离子簇的非湿特征．根据结晶的成核速率，讨论了电子衍射实验中观察KI凝固的可能性     

铝镓取代的钨硅杂多配合物位置异构体的合成表征及催化性能

合成了通式为Ｋ５－ｎＨｎ［α－，βｉ－ＳｉＷ１１Ｍ（Ｈ２Ｏ）Ｏ３９］·ｘＨ２Ｏ（Ｍ＝Ａｌ，Ｇａ，βｉ＝β１，β２，β３）的八种异构体。通过元素分析、红外光谱和紫外光谱、极谱和循环伏安、２７Ａｌ和１８３Ｗ核磁共振、Ｘ光电子能谱等方法进行了表征。所合成的各异构体在催化以Ｈ２Ｏ２为氧化剂的顺丁烯二酸环氧化反应中，β３异构体具有最高的催化活性     

不可逆电活性药物米托蒽醌与脱氧核糖核酸的相互作用

研究了抗癌新药米托蒽醌(MXT)的电化学行为及与脱氧核糖核酸(DNA)的相互作用，推导了适用于研究不可逆电活性分子与DNA相互作用的电化学公式，运用该公式可以简便、快速地测定靶向分子与DNA的结合常数和结合位点数。实验发现，MXT与小牛胸腺DNA的结合以蒽醌母核的嵌插作用为主，同时，烃氨基侧链与骨架磷酸基团之间的静电吸引对母核起稳定作用，使化合物易于嵌入DNA的平面结构。MXT与DNA相互作用引起的峰电流的变化可以用于分析测定DNA。     

一种新的判断高分子相容性的粘度判据

依据最近提出的高分子稀溶液粘度的浓度 依赖性的团簇理论 ,对高分子‘理想混合物’的定义进行了更新的理论分析 .在此基础上提出了一个新的判定高分子相容性的粘度判据 .从现有的大量实验数据看 ,该判据是和事实相符合的