银胶和银岛膜上胸腺嘧啶的表面增强拉曼光谱对比研究

利用表面增强拉曼光谱对胸腺嘧啶在银胶和银岛膜上的吸附状态进行了对比研究.光谱分析表明,胸腺嘧啶吸附在银胶和银岛膜表面后其分子结构发生了互变异构,由原来的酮式结构变成了烯醇式结构.在银胶和银岛膜表面胸腺嘧啶主要以N(3)去质子化异构体的形式存在.胸腺嘧啶通过O(7)和N(3)倾斜地吸附在银胶颗粒表面,通过O(8)和N(3...     

6,8-二甲基-1,2,4-三唑并嘧啶-3-丁二酮基硫醚酮-烯醇互变异构平衡的1H NMR研究

用¹H NMR方法研究了不同溶剂和温度对6,8-二甲基-1,2,4-三唑并嘧啶-3-丁二酮基硫醚酮-烯醇互变异构平衡的影响,发现温度升高有利于平衡向酮式转变,而溶剂极性的改变对平衡的影响并不规律,获得了四种溶剂中的ΔH和ΔS.     

六元杂环分子电学特性的理论研究

在第一性原理基础上，利用弹性散射格林函数方法，研究了六元杂环分子结2,5-哒嗪二硫酚 、2,5-吡嗪二硫酚和2,5-嘧啶二硫酚的电子输运特性，分析了终端原子的选取对杂环分子吡 啶电学特性的影响. 利用分子前线轨道理论和微扰方法定量地确定了分子与金属的相互作用 能参数. 计算结果表明，2,5-哒嗪二硫酚具有较好的电学特性，而2,5-嘧啶二硫酚在外加电 压较低时电导值比较小. 对于吡啶分子，选取硒原子作为终端原子时，其导电特性优于分别 以氧原子和硫原子作为终端原子的情况. 关键词： 六元杂环分子 伏安特性 电子输运 分子电子学     

胞嘧啶-胸腺嘧啶二核苷SP光损伤反应的理论研究

在DNA光损伤产物中,有一种特殊的UV诱导生成的嘧啶二聚体(SP)．尽管胞嘧啶C和胸腺嘧啶T在分子结构上非常相似,在实验中还没有发现DNA相邻的C和T之间形成类似的SP产物．用密度泛函理论,以DNA中的片段CpT为模型分子,在B3LYP/6-311++G(d,p)//B3LYP/6-31G(d,p)计算水平上从理论的角度揭示 了阻碍CpT生成SP类似物的关键因素． 与生成类似SP产物相比较,CpT更倾向于通过光物理失活途径回到基态反应物     

4,6-二甲氧基-2-嘧啶氨基甲酸甲酯分子结构与光谱

运用密度泛函理论B3LYP方法,6-311G*和6-311 G*基函数对4,6-二甲氧基-2-嘧啶氨基甲酸甲酯分子结构与光谱性质进行理论研究,得到分子的平衡结构参数和最大吸收波长.4,6-二甲氧基-2-嘧啶氨基甲酸甲酯分子具有Cs对称性和较大的前线轨道能隙值.基函数对计算结果无影响.     

隐式溶剂环境中丙氨酸二肽酰胺-Ⅰ带光谱的神经网络预测

借助神经网络学习方法开展多肽振动光谱预测与解析,构建不同极性溶剂环境下丙氨酸二肽(ALAD)的酰胺-Ⅰ带振动频率预测的神经网络模型,探究ALAD各个构象异构体的骨架二面角、 CO键长及酰胺-Ⅰ带振动频率处于不同化学环境中的相关性。     

不同溶剂中硝基苯胺分子非线性光学性质的研究

在含时密度泛函理论水平上研究了溶剂对硝基苯胺分子非线性光学性质的影响 .溶剂效应通过极化连续模型来研究 .首先采用极化连续模型在密度泛函理论水平上优化了硝基苯胺分子在溶剂中的几何结构 ,从而研究了溶剂引起硝基苯胺分子几何结构的变化 .然后采用极化连续模型在含时密度泛函理论水平上计算了不同溶剂中硝基苯胺分子的激发态能量和电偶极矩 ,并利用两态模型首次给出了不同溶剂中二次谐波振荡过程的一阶非线性超极化率的色散关系 .计算结果表明 ,极性溶剂对硝基苯胺分子的非线性光学性质有较大的影响 .在低的辐射场频率下 ,理论给出的一阶非线性超极化率的色散关系和实验结果符合得较好 .最后对所得结果从理论上给出了可能的解释并讨论了两态模型的可靠性 .     

三种磺酰脲类除草剂水解反应机理的理论研究

采用量子化学从头算方法在HF/6-31G(d)水平上对氯磺隆、甲嘧磺隆和氟嘧磺隆三种典型的磺酰脲类除草剂在酸性和中性条件下水解反应的机理进行理论研究,分别优化了各反应途径中反应物、过渡态、中间体以及产物的几何构型,并通过振动分析确定反应的过渡态和中间体的真实性。同时,在B3LYP/6-31G(d)水平上计算各驻点的单点能,以及溶剂效应对水解反应的影响。从能量上看,酸性条件更有利于水解反应的进行,与实验结果较为吻合.     

带-NH2的嘧啶环对钌配合物与DNA相互作用的瞬态发光特性的影响

采用时间分辨的发光光谱技术,分别测量了两种新合成的钌配合物[Ru(bpy)2 (dpbpd(NH2)2)]2 和[Ru(phen)2(dpbpd(NH2)2)]2 与小牛胸腺脱氧核糖核酸(ctDNA)相互作用时的瞬态发光动力学过程,并与以往对[Ru(phen)2dppz]2 等的研究结果进行对比,从而研究带-NH2的嘧啶环对配合物与DNA作用动力学过程的影响.结果表明:这两种含有带-NH2的嘧啶环的钌配合物与DNA相互作用时的发光按双指数规律衰减,发光寿命为几十纳秒,比dppz类钌配合物与DNA作用时的发光衰变寿命(几百纳秒)小一个数量级.归因于嘧啶环上的N和-NH2可能与水分子、DNA的碱基对或磷酸骨架形成氢键,从而加快激发态的无辐射弛豫,削弱发射光强,缩短发光寿命.该结论为进一步研究配合物分子与DNA的相互作用的机理提供了一定的依据.     

四氯苯醌与嘧啶类核酸碱基的光化学氢抽取和电子转移反应

采用纳秒时间分辨的激光闪光光解实验技术,研究了四氯苯醌(TCBQ)分子与两种嘧啶核酸碱基(胸腺嘧啶和尿嘧啶)分子在355nm激发下的光化学反应动力学. 355 nm将TCBQ分子布居到激发三重态³TCBQ^*,高反应活性的³TCBQ^*与碱基分子发生两个平行的反应,氢抽取反应和电子转移反应,分别对应生成瞬态光谱上观测到的两个光反应产物TCBQH·和TCBQ·^-. 这两个反应同时生成的碱基自由基和碱基阳     

Molecular Simulations of Physical and Chemical Properties of Poly(Imino Ketone)s

Six kinds of poly(imino ketone)s (PIKs) with different structures were designed, involving different ratios of carbonyl and imino groups, and the insertion of two types of bulky groups in the main chain. Under 3D periodic boundary conditions, simulations of physical and chemical properties for PIKs with six different structures on the molecular level, including fractional free volume (FFV) and melt density, solubility, and glass transition temperature, were carried out.     

Theoretical analysis of the experimental UV-Vis absorption spectra of some phenolic Schiff bases

The time-dependent density functional theory (TDDFT) was applied in conjunction with the natural bond orbital analysis to examine the UV-Vis properties of 10 phenolic Schiff bases. The calculations were performed with different functionals, but main discussion refers to results obtained at the B3LYP/6-311+G(d,p) level of theory. The approach based on the natural localised molecular orbital clusters indicates similar behaviour for majority of examined compounds. The HOMO (“highest occupied molecular orbital”) cluster is delocalised over the ring which is electron richer, the HOMO-1 cluster is spread over the other ring, whereas the LUMO (“lowest unoccupied molecular orbital”) cluster is situated on the imino group. The two bands at long wavelengths correspond to the HOMO → LUMO and HOMO-1 → LUMO transitions, i.e. from both A and B rings to the imino group. The next band originates from a transition from the imino group to the imino group. The band at the smallest wavelengths originates from a transition from the A ring to the A ring, or from the B ring to the B ring. Our findings are in very good agreement with the existing literature data.     

New laser dyes based on 3-imidazopyridylcoumarin derivatives

A comparative analysis of the spectral-luminescent characteristics and generation parameters of a number of 3-imidazopyridylcoumarin derivatives has been carried out under nano- and microsecond excitation by coherent and incoherent light. New coumarin dyes are offered that feature the ability to lase under different types of pumping in the spectral range 525–580 nm; high lasing efficiency reaching 20% and 1% under laser and lamp pumping, respectively; and high photochemical stability (3–5 times higher than that of rhodamine 6 G) under conditions of powerful nonmonochromatic pumping.     

An efficient and selective way to new highly functionalized coronands or spiro derivatives using ultrasonic irradiation

A new, selective, straightforward and general method for preparation of highly functionalized coronands or spiro derivatives bearing 1,2-dihydroxyacetophenone unit, under conventional conditions and ultrasonic irradiation, is reported. The reaction setup involves only one step, acylation of an α-chloro-3,4-dihydroxyacetophenone with phthaloyl dichloride derivatives. 1,3- and 1,4-Phthaloyl dichloride derivatives leads to coronands only, while 1,2-phthaloyl dichlorides lead either to coronands or to spiro derivatives. A feasible explanation for the different behavior between conventional and ultrasound methods could be the different reaction mechanism involved in the two procedures: tetrahedral nucleophilic substitution under conventional conditions and radical substitution under ultrasound. Ultrasound induces a remarkable acceleration of the reactions (from days to minutes) and, most significantly, the yields are twice as high. A feasible explanation for the efficiency of the reactions under ultrasonic irradiation is presented.     

香草酸酰胺衍生物的制备及其止血活性的动力学法研究

以香草酸为母体,分别与6-氨基己酸(EACA)、止血芳酸(AMBA)和止血环酸(AMCA)反应,合成3种未见文献报道的香草酸酰胺衍生物,并采用IR、ESI-MS、1H NMR和13C NMR进行结构鉴定。以传统方法、荧光动力学法和紫外动力学法测定其对血浆复钙时间(PRT)的影响。为了研究衍生物在血液中的稳定性,在模拟生理条件下,运用荧光光谱、紫外光谱及分子对接技术研究了它分别与人血清白蛋白(HSA)的结合。结果表明,3种衍生物在一定浓度范围内都可以有效缩短PRT,具有显著的止血活性。新的动力学测定方法,不仅有效避免了传统方法引入的人为误差,重现性良好,而且判断标准更加科学,并可以获得更多血浆凝结过程中的信息。3种衍生物均主要通过氢键和范德华力与HSA结合形成稳定的复合物,表明它可通过HSA在血液中传递并运输到相应部位而发生药理作用。     

Theoretical study of the optical,electronic, and charge-transfer properties of 1,2,4,5-tetrakis(phenylethynyl)benzene derivatives for solar cell applications

A series of 1,2,4,5-tetrakis(phenylethynyl)benzene derivatives has been investigated at the CAM-B3LYP/6-31G(d) and TD-CAM-B3LYP/6-31?+?G(d,p) levels to design materials with high performance with respect to suitable frontier molecular orbitals (FMOs), broad absorption spectra, and better and balanced charge-transfer properties. The calculated results reveal that the molecule possessing benzene has the largest torsion angle of these derivatives. Different branches have a slight influence on the distributions of the FMOs of the molecules. 2-vinyl-thieno[3,2-b]thiophene branches display a small HOMO–LUMO gap corresponding to red shifts of the absorption spectra. These molecules are potential ambipolar charge-transport materials under the appropriate operating conditions.     

Chemical Substitutions in Tl 2 Mn 2 O 7 Pyrochlore,Synthesized Under High Pressure: Effects on the Colossal Magnetoresistance

Tl 2 Mn 2 O 7 pyrochlore has recently been described as a half-metallic ferromagnet showing colossal magnetoresistance (CMR) properties. New series of Tl 2 Mn 2 O 7 derivatives have been prepared under high pressure conditions. We have replaced Tl 3+ cations by Bi 3+ and Cd 2+ , leading to different modifications of the physical properties, with dramatic improvements of CMR. The Mn 4+ cations have also been partially replaced by Sb 5+ and Te 6+ . In particular, moderate Sb substitution leads to significant increments of T C . In this work we discuss on the effects of the different chemical substitutions on the structural, magnetic and transport properties.     

近红外反射光谱法(NIRS)测定棉仁粉中蛋白质和棉酚含量的研究

选用49份不同蛋白质和棉酚含量的陆地棉种质资源和188份陆地棉重组近交系为材料,以多年份、多地点种植收获的种子材料组成原始样品集,分别对棉仁粉中蛋白质含量和棉酚含量进行化学测定,采用改进的偏最小二乘法(Modified PLS)和(2,4,4,1)的数学转换方法建立近红外反射光谱(NIRS)定标模型,以寻找棉籽蛋白质含量和棉酚含量的快速测定方法。结果表明,蛋白质含量的定标决定系数(RSQ=0.933)和交叉检验决定系数(1-VR=0.929)较高,定标标准误差(SEC=0.623)和交互校验标准误差(SECV=0.638)较小,预测模型的建模效果较好,可替代化学分析。棉酚含量预测模型的RSQ,1-VR,SEC和SECV分别为0.836,0.811,0.074和0.079,模型预测效果略差于蛋白质模型,但仍可用于棉仁粉中棉酚含量的测定。     

Study of plasma membrane heterogeneity using a phosphatidylcholine derivative of 1,6-diphenyl-1,3,5-hexatriene [2-(3-(diphenylhexatriene)propanoyl)-3-palmitoyl-l-α-phosphatidylcholine]

The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) and DPH derivatives have been used to characterize structural and physicochemical properties of specific membrane domains. Steady-state and fluorescence decay measurements of three probes, DPH (1,6-diphenyl-1,3,5-hexatriene), TMA-DPH [1-(4-trimethyl-ammonium-phenyl)-6-phenyl-1,3,5-hexatriene], and a phosphatidylcholine derivative of DPH, DPH-pPC [2-(3-(diphenylhexatriene)propanoyl)-3-pamitoyl-L--phosphatidyl choline], have been performed in erythrocyte membranes and in lymphocyte plasma membranes. The steady-state fluorescence polarization of the three probes showed a similar trend in both membranes. In fact either in erythrocyte or in lymphocyte plasma membranes the fluorescence polarization values of DPH-pPC and TMA-DPH were similar, but significantly higher with respect to DPH. A better characterization of erythrocyte and lymphocyte plasma membranes was possible by using fluorescence decay measurements. The data suggest the possible use of different DPH derivatives to characterize specific domains in biological membranes.     

水溶性白杨素磺化衍生物制备及Ag(Ⅰ)配合物的合成

以白杨素为原料,控制磺化温度制得白杨素-6-磺酸钠、白杨素-8-磺酸钠和白杨素-4’-磺酸钠。白杨素-6-磺酸钠与Ag(Ⅰ)作用合成配合物。采用薄层色谱法、红外光谱法、紫外分光光度法及核磁共振谱对白杨素-6-磺酸钠、白杨素-8-磺酸钠、白杨素-4’-磺酸钠和白杨素-6-磺酸银配合物进行分析鉴别及结构表征,并讨论白杨素的磺化机理。