Synthesis and electrochemistry of undeca-substituted metallo-benzoylbiliverdins

The high-yield preparation of metallo-benzoylbiliverdins 9, 10, and 11 from either oxidation of dodeca-substituted porphyrin 6 in the presence of NaNO2/TFA and air followed by metalation or by reaction of the Ni(II) or Cu(II) complexes of 6 with m-chloroperoxybenzoic acid in pyridine under air is reported. The X-ray structures of complexes 9 and 10 and the electrochemistry and spectroelectrochemistry of metallo-benzoylbiliverdins 9-11 are presented and discussed.     

Formation and properties of cyclo[6]pyrrole and cyclo[7]pyrrole

Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]pyrroles, as well as the known cyclo[8]pyrrole. This "matched set" of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.     

Porphyrazines with annulated diazepine rings. 2. Alternative synthetic route to tetrakis-2,3-(5,7-diphenyl-1,4-diazepino)porphyrazines: new metal complexes, general physicochemical data, ultraviolet-visible linear and optical limiting behavior, and electrochemical and spectroelectrochemical properties

Following a previous report on the synthesis and physicochemical characterization of a novel class of porphyrazines carrying peripherally annulated seven-membered rings, i.e., tetrakis-2,3-(5,7-diphenyl-1,4-diazepino)porphyrazine [Ph(8)DzPzH(2)].4H(2)O and its metal derivatives [Ph(8)DzPzM].xH(2)O (x = 2-7, M = Mg(II)(H(2)O), Cu(II), and Zn(II)), a new more convenient procedure is reported here, allowing the preparation in high yields of the Li(I) and Na(I) derivatives of formulas [Ph(8)DzPzLi(2)].5H(2)O and [Ph(8)DzPzNa(2)].6H(2)O, which can be directly converted into other metal derivatives under mild conditions (room temperature) and in good yields. The series studied has been extended to include the Mn(II) and Co(II) complexes also reported here for the first time. Physicochemical characterization of the new "diazepinoporphyrazines" was based on fast atom bombardment (FAB) mass spectrometry and X-ray powder patterns, infrared (IR), electron paramagnetic resonance (EPR), and room-temperature magnetic susceptibility measurements. A detailed discussion of the UV-vis spectra emphasizes the role played by the external diazepine rings in electron delocalization through their tautomeric or protonated forms present in neutral, basic, and acidic media. The nonlinear optical effect of optical limiting for the different species [M = 2H, Mg(II)(H(2)O), Mn(II), Co(II), Cu(II), and Zn(II)] has also been measured. It has been observed that the extent of the optical limiting depends on the specific M center. The observed nonlinear optical features are analyzed and discussed in terms of the electronic and magnetic properties exhibited by some of the metal ions and taking into account the model of the excited-state absorption in which the nature of M determines the kinetics of formation of the highly absorbing state of the specific complex examined. As evidenced by the detailed electrochemical and spectroelectrochemical study carried out on this new class of macrocycles, one of the most important aspects is the facilitated electron delocalization for the oxidized and reduced species allowed by a 1H-6Htautomerism taking place on the peripheral diazepine rings.     

Substituent effects on the site of electron transfer during the first reduction for gold(III) porphyrins

Gold(III) porphyrins of the type (P-R)AuPF(6), where P = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin and R is equal to H (1), NO(2) (2), or NH(2) (3) which is substituted at one of the eight beta-pyrrolic positions of the macrocycle, were investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous media. Each compound undergoes three reductions, the first of which involves the central metal ion to give a Au(II) porphyrin or a Au(III) porphyrin pi-anion radical depending upon the nature of the porphyrin ring substituent. A similar metal-centered reduction also occurs for compounds 1, 3, and Au(III) quinoxalinoporphyrin, (PQ)AuPF(6) (4), where PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b]porphyrin, and these results on the three Au(III) porphyrins overturn the long held assumption that reductions of such complexes only occur at the macrocycle. In contrast, when a NO(2) group is introduced on the porphyrin ring to give (P-NO(2))AuPF(6) (2), the site of electron transfer is changed from the gold metal to the macrocycle to give a porphyrin pi-anion radical in the first reduction step. This change in the site of electron transfer was examined by electrochemistry combined with thin-layer UV-vis spectroelectrochemistry and ESR spectroscopy of the singly reduced compound produced by chemical reduction. The reorganization energy (lambda) of the metal-centered electron transfer reduction for (P-H)AuPF(6) (1) in benzonitrile was determined as lambda = 1.23 eV by analyzing the rates of photoinduced electron transfer from the triplet excited states of an organic electron donor to 1 in light of the Marcus theory of electron transfer. The lambda value of the metal-centered electron transfer of gold porphyrin (1) is significantly larger than lambda values of ligand-centered electron transfer reactions of metalloporphyrins.     

Vertex Correction at Finite Temperature and Decoupling Transition in (2+1) Dimensional Chiral Gross-Neveu Model

With the aid of imaginary time temperature field theory and fermion mass spectrum derived from Ward-Takahashi identities with composite fields,the vertex correction among fermions and σ meson is calculated beyond the leading order in 1/N expansion,and the change of vertex function with temperature and decoupling transition are discussed in (2+1) dimensional chiral Gross-Neveu model.It turns out that the critical temperature of decoupling transitionarises with increasing fermion mass and π meson mass at zero temperature;the vertex correction resulting from thermal fluctuation will affect the fermion dynamical mass and cannot be ignored at finite temperature.     

Electroanalytical Behaviour of a Nanoarray Self-Assembled Thiocholesterol Gold Electrode

Thiocholesterol forms a self-assembled monolayer (SAM) on polycrystalline gold, offering a defect-rich hydrophobic surface. This SAM gold electrode has been exploited in batch and flow injection analysis (FIA) as it allows selective detection of hydrophobic analytes such as phenothiazines in presence of potentially interfering species such as ascorbic acid. Several phenothiazines have been investigated. Quantification has been achieved in FIA, in a broad linear concentration range: 0.5–100?μM. The stability of the modified electrode allows more than 500 sample injections in FIA.     

Synthesis,Characterization and Xerographic Performance of the Triazo Pigments from Tris(4-amino)triphenylamine

As the era for digital printer has come since the 1990s,the investigation into a highly photosensitive charge generator materials(CGM) suitable for IR photoreceptor is concerned.^1-2 This research focuses on the triphenylamine triazo pigments, which exhibit a broad spectral response(450-800mn) and an excellent photosensitivity, especially in the near red-infrared region where solid-state diode laser emit(450-800nm). They are particularly potential CGM for laser printer and digital printer.     

有理插值问题存在性的一个判别准则

１引言我们知道,多项式Ｌａｇｒａｎｇｅ插值是适定的［１,２］,但有理插值函数却未必存在［８,３］．并且到目前为止,也没有类似于多项式Ｌａｇｒａｎｇｅ插值的能够揭示插值结构的显式插值公式．不过有理插值已有许多算法,比如Ｓｔｏｅｒ算法,Ｔｈｉｅｌｅ倒差商算法,Ｓａｌｚｅｒ算法以及Ｗｕｙｔａｃｋ算法等等,见［８,４,５,６］．本文为寻求尽可能接近显式的插值公式,进而揭示有理插值问题的内在结构,得到了有理插值函数存在的一个充要条件,同时也给出了有理插值函数的一种表现形式,参见［１１］．本文约定,所有矩阵…     

四组分纳米结构复合电极的制备及电化学性能

在5 mmol/L H2 PtCl6的稀硫酸溶液中,采用循环伏安法(CV),扫描电位为～0.2～0.6V和0.0～0.6v,分别扫描30和15循环,在碳纳米管/纳米TiO2-聚苯胺复合膜上实现了Pt纳米粒子的高度有效分散,得到多壁碳纳米管/纳米TiO2-聚苯胺载铂四组分纳米结构复合电极,通过CV法和计时电位法并结合扫描电镜对复合电极的电化学性质和结构进行表征,研究了复合电极对葡萄糖的电催化氧化性能.结果表明,该复合电极对葡萄糖的电氧化有高催化活性,具有性能稳定、重现性好、抗毒化作用强、能耐高温、易保存且使用寿命较长的优点.     

求解具有确定性线性不等式约束的有补偿随机规划问题的近似ε——容许方向法

1引言形如线性不等式确定性约束的有补偿随机规划问题