5-氟尿嘧啶卟啉化合物的合成和光谱性质

首次合成并用元素分析、红外光谱、核磁和质谱等表征了6种新的5 氟尿嘧啶卟啉化合物. 对其紫外吸收、荧光性质和荧光寿命进行了研究,并与未修饰卟啉化合物光谱性质进行了比较. 5 氟尿嘧啶卟啉化合物荧光寿命为7 ns,受环境取代基和溶剂的影响较小.     

铂电极上醋酸-醋酐溶液中Mn(III)/Mn(II)电对研究

平衡电极电势实验确定了25 ℃, 1.5 mol•L－1醋酸钾＋醋酸-醋酐(3:1体积比)溶液中Mn(III)/Mn(II)的条件电极电势为0.719 V（vs SCE）;采用电势扫描和旋转圆盘电极技术研究了醋酸-醋酐溶液中铂电极上Mn(III)/Mn(II)电对的阳极氧化动力学. 结果表明:Mn(II)阳极氧化成Mn(III)的电极反应控制步骤属电荷传递过程, 阳极传递系数β=0.347,交换电流密度i0=5.84×10－6 A•cm－2,阳极标准反应速率常数ka=1.35×10－8 m•s－1, Mn(II)和OAc－的反应级数均为一级.     

无模板电化学沉积法制备多孔WO3·2H2O薄膜及其电致变色性能

二水合氧化钨(WO₃·2H₂O)因其独特的层状结构且富含层间结构水,与无水WO₃相比显示出更加优异的电致变色性能。我们采用简单、无模板的阴极电化学沉积方法,成功在氧化铟锡(ITO)导电玻璃基底上制备了WO₃·2H₂O薄膜。通过改变电沉积液中过氧化氢(H₂O₂)的加入量优化沉积液的成分,获得了具有纳米多孔结构的薄膜。由此制备的WO₃·2H₂O薄膜显示出大的光学对比度(633nm处的光学对比度大于90%)、快速的响应速度(着色、褪色时间均小于10s),以及良好的循环稳定性(经10000次循环后,光学对比度仍保持在90%左右)。     

取代基对醌的结构及电子转移能力的影响

用半经验的AM1,abinitio(HF/3-21G,HF/6-31G^*),及密度泛函[B3LYP/6-31G^*,B3LYP/6-311G(d,p)]方法对1,4-苯酯及其阴离子的结构与性质进行了研究。在此基础上用AM1及BLYP/6-31G(d,p)方法对泛醌Q~0,用AM1方法对泛醌Q~1,泛醌Q~2及其阴离子的结构与性质进行了研究。研究结果表明,由于取代基的影响,泛醌的环平面发生了扭曲,环上原子不再位于同一平面上。结构的变化导致了电子分布发生了变化,并由此导致了偶极矩随6位上取代基的增大而增大。随着6位支链的增长,泛醌的电离势逐渐减小而电子亲和势逐渐增大,泛醌传递电子的能力增强。在上述研究的基础上,对1,4-苯醌及泛醌的自交换电子转移反应过程进行了过程,计算了反应的内重组能,溶剂重组能及电子转移速率常数。结果表明内重组能的大小与取代基的长短无直接关系,而与得电子前后醌的结构变化程度密切相关。除高频振动的变化外,低频振动的变化对内重组能也有显著的贡献。计算所得1,4-苯醌自交换电子转移反应速率常数与实验值相符得很好。     

超临界二氧化碳中卟啉与钴(II)、镍(II)、锌(II)配合物反应动力学

用紫外-可见光谱研究了钴(II)、镍(II)、锌(II)的1,1,1,5,5,5-六氟-2,4-戊二酮-二水配合物[M(hfac)2(H2O)2,M=Co、Ni、Zn]与5,10,15,20-四(五氟苯基)卟啉[H2tpfpp]在超临界二氧化碳中反应生成金属卟啉[M(tpfpp)]的反应动力学.在金属配合物大大过量时,反应对卟啉为一级.其表观一级速率常数随钴(II)、镍(II)配合物的浓度增加先增加、而后趋于稳定,而表观一级速率常数随锌(II)配合物的浓度增加线形增加.根据实验事实,讨论了反应的机理,得到了相应的热力学和动力学参数.     

Density functional investigation on electron-transfer catalysis of cycloreversion of cyclobutane: radical anion mechanism

The mechanism of cycloreversion of cyclobutane radical anion (c-C(4)H(8) (-)) has been investigated at the UB3LYP/6-31++G(d,p) level, and compared with those of neutral c-C(4)H(8) and c-C(4)H(8) (+) radical cation. Although both c-C(4)H(8) (-) and C(2)H(4) are shown to be Rydberg states unstable with respect to electron ejection, the activation barrier for the "rotating" cycloreversion of c-C(4)H(8) (-) (37.3 kcal/mol) is lower by about 25.2 kcal/mol than that of c-C(4)H(8), and even the intervention of tetramethylene radical anion intermediate may reduce the activation barrier for the cycloreversion of c-C(4)H(8) by about 8.4 kcal/mol, mainly due to stronger electron-deficiency of intermediate biradical species than close-shell cyclobutanes. For the cycloreversion for c-C(4)H(8) (-), side isomerization reaction may be efficiently prevented by the low kinetic stability of tetramethylene radical anion intermediate towards dissociation, just different from the radical cation case. Our theoretical results have suggested the possibility of electron-attachment catalysis of the cycloreversion of some electron-deficient substituted cyclobutanes.     

A new isopiestic apparatus for the determination of osmotic coefficients

A new isopiestic apparatus has been designed and constructed following several criteria. It consists mainly of several small sample cups for holding small quantities of reference standard solutions, and a big sample cup for a bigger quantity of a test solution. Using this apparatus, experiments on NaOH solutions have been performed. The experimental procedure, the consistency among the samples in equilibrium, the equilibration process, and the determined osmotic coefficients of NaOH solutions are discussed. The apparatus is found to ensure a consistent temperature among the samples in equilibrium, meeting the experimental requirements for samples of molalities less than 0.05 mol · kg⁻¹. Inside the apparatus, the temperature can reach the desired uniform temperature within less than 0.5 d. In the experiments, the equilibration process is essentially determined by changes in the reference standard solutions in the small cups. Thus the apparatus is not only reliable and stable, but is also suitable for experiments on solutions of viscous, complex and unstable solutes. The equilibration time of the experiments is fast, which is practical for samples of molalities less than 0.05 mol · kg⁻¹. Moreover, with the new apparatus it is easy to determine the end point of the equilibration.     

Quasinormal modes of a stationary axisymmetric EMDA black hole

The massless scalar quasinormal modes (QNMs) of a stationary axisymmetric Einstein--Maxwell dilaton--axion (EMDA) black hole are calculated numerically using the continued fraction method first proposed by Leaver. The fundamental quasinormal frequencies (slowly damped QNMs) are obtained and the peculiar behaviours of them are studied. It is shown that these frequencies depend on the dilaton parameter $D$, the rotational parameter $a$, the multiple moment $l$ and the azimuthal number $m$, and have the same values with other authors at the Schwarzschild and Kerr limit.     

Late-Time Evolution of the Phantom Scalar Perturbation in the Background of a Spherically Symmetric Static Black Hole

The late-time evolution of the phantom scalar perturbation is investigated in the spacetime of a four-dimensionai spherically symmetric static black hole. It is revealed that the asymptotic tail of the phantom scalar field is dominated by the growth behavior t-（l＋3/2）eμt, which depends on the multipole moment l and the field moss but is independent of the mass M and charge Q of the black hole. This growth behavior is in strong contrast to the decaying tall of the usual massive scalar perturbation and shows that the external phantom scalar perturbation is unstable in the spherically symmetric static black hole spacetime.     

A facile asymmetric synthesis of Δ-2-Hydroxybakuchiol,Bakuchiol and ent-Bakuchiol

A facile asymmetric synthesis of Δ³-2-Hydroxybakuchiol, Bakuchiol, and ent-Bakuchiol is described through one common intermediate bearing a chiral all-carbon quaternary carbon center, which involves stereoselectively unconjugated alkylation of the α,β-unsaturated imide bearing Evans' auxiliary, Takai–Utimoto reaction, Negishi reaction, and Heck reaction as key steps.