有机光化学-辉煌之路

丁奎岭, 肖文精, 吴骊珠. 有机光化学-辉煌之路[J]. 化学学报, 2017, 75(1): 5-6.     

Imaging source with Gaussian proper time distribution

Making use of the maximum entropy method, we study the most probable source function in heavy ion collisions. An anisotropic Gaussian source is deduced by simply assuming that the particles are emitted within a finite proper-time. The general relations between the most probable source function and the minimal assumptions are discussed, which are instructive in constructing a self-consistent source function from observed Hanbury-Brown/Twiss（HBT） correlations.     

Cucurbit[7]uril-included neutral intramolecular charge-transfer ferrocene derivatives

CB[7] can significantly modulate the intramolecular charge-transfer state of the designed ferrocene derivatives, resulting in remarkable changes in the absorption spectra, (1)H NMR spectra and electrochemical properties.     

La1－xSrxNi1－yFeyO3型钙钛矿双功能氧电极的电化学性能研究

采用溶胶-凝胶法制备了一系列La_1－xSr_xNi_1－yFe_yO₃ (x＝0, 0.1, 0.2, 0.5; y＝0～1.0)型的钙钛矿催化剂, 以活性碳为载体, PTFE乳液为粘接剂制备双功能氧电极. 对催化剂进行了XRD结构分析以及SEM分析和BET比表面积测量. 采用三电极体系测试了氧电极的稳态极化曲线和电化学交流阻抗谱并对其阴极极化和阳极极化的交流阻抗谱图进行分析. 通过等效电路的拟合研究了该系列双功能氧电极氧还原反应的工作机理. 实验表明对于LaNiO₃化合物, B位掺杂可显著提高催化剂的电催化性能; 电极氧还原反应的极化主要由电荷转移反应和Nernstian扩散过程造成. 通过各个电极对于催化分解H₂O₂的分解速率常数的测定得知, Ni离子对于催化H₂O₂分解反应的活性大于Fe离子, 继续在对于氧还原反应和氧析出反应都具有较高电催化活性的LaNi_0.8Fe_0.2O₃催化剂上进行A位掺杂Sr离子后显著提高了催化剂分解H₂O₂的催化活性, 主要是因为氧空位的增多和金属离子d电子含量的降低有利于催化分解H₂O₂的活性的提高, 但由于氧空位的增多导致催化剂电导率的降低, 所以其电催化活性降低了. 通过多圈循环伏安扫描的测试, 催化剂LaNi_0.8Fe_0.2O₃有很好的稳定性.     

Highly sensitive and selective detection of beryllium ions using a microcantilever modified with benzo-9-crown-3 doped hydrogel

A microcantilever sensor modified by chitosan/gelatin hydrogels that are doped with benzo-9-crown-3 has been developed for the sensitive and selective detection of beryllium ions in an aqueous solution. The microcantilever undergoes bending deflection upon exposure to Be(2+) due to selective absorption of Be(2+) in the hydrogel. The detection limit is 10(-11) M. Other metal ions, such as Li(+), Na(+), K(+), Mg(2+), and Ca(2+), have a marginal effect on the deflection of the microcantilever. The mechanism of the bending is discussed and the results showed that the microcantilever may be used for in situ detection of beryllium.     

Visible Light-Induced Synthesis of 3,4-Diarylthiophenes from 3,4-Diaryl-2,5-dihydrothiophenes

Using a catalytic amount of platinum(II) terpyridyl complex 3, 3,4-diarylthiophenes (2a-f) could be synthesized from 3,4-diaryl-2,5-dihydrothiophenes (1a-f) under visible light (λ > 450 nm) irradiation in degassed CH(3)CN. Spectroscopic study and product analysis reveal that the reaction is initiated by photoinduced electron transfer from 3,4-diaryl-2,5-dihydrothiophenes to platinum(II) complex 3, leading to the formation of 3,4-diarylthiophenes.     

Enhancement of diastereoselectivity in photodimerization of alkyl 2-naphthoates with chiral auxiliaries via inclusion within γ-cyclodextrin cavities

Irradiations of alkyl 2-naphthoates are known to result in four isomeric "cubane-like" photodimers: anti(HH)-2, syn(HH)-2, anti(HT)-2, and syn(HT)-2 where the anti(HH)-2, anti(HT)-2, and syn(HT)-2 consist of pairs of diastereomers. Here, chiral auxiliary and chiral microreactor strategies have been combined to achieve high diastereoselectivity in photodimerizations of an enantiomeric pair of 2-naphthoates with (R)- and (S)-1-methoxycarbonylethyl esters as chiral auxiliaries (1R and 1S). Thus, irradiations of their γ-cyclodextrin (γ-CD) complexes have been conducted. Fluorescence, IR, and NMR spectra of both enantiomers of 1 demonstrate that their γ-CD complexes are mainly 2:2 with the molecules of 1 in head-to-head orientations. Irradiation of the complexes in the solid state mainly resulted in anti(HH)-2. The absolute configuration of each diastereomer of anti(HH)-2 has been established for the first time here. The diastereomeric excesses (de's) of anti(HH)-2 from 1R and 1S were 94% and 86%, respectively. These de's are much higher than those found from irradiations in solution (55% for 1R and 1S), where the opposite diastereomeric form is in excess! Calculations of the energies of various conformations of the head-to-head 2:2 inclusion complexes were performed using the PM3 approach. The predicted major diastereomers based on the calculation are consistent with those found experimentally.     

Electron transfer and hydrogen generation from a molecular dyad: platinum(II) alkynyl complex anchored to [FeFe] hydrogenase subsite mimic

A PS-Fe(2)S(2) molecular dyad 1a directly anchoring a platinum(II) alkynyl complex to a Fe(2)S(2) active site of a [FeFe] H(2)ase mimic, and an intermolecular system of its reference complexes 1b and 2, have been successfully constructed. Time-dependence of H(2) evolution shows that PS-Fe(2)S(2)1a as well as complex 2 with 1b can produce H(2) in the presence of a proton source and sacrificial donor under visible light irradiation. Spectroscopic and electrochemical studies on the electron transfer event reveal that the reduced Fe(I)Fe(0) species generated by the first electron transfer from the excited platinum(II) complex to the Fe(2)S(2) active site in PS-Fe(2)S(2)1a and complex 2 with 1b is essential for photochemical H(2) evolution, while the second electron transfer from the excited platinum(II) complex to the protonated Fe(I)Fe(0) species is thermodynamically unfeasible, which might be an obstacle for the relatively small amount of H(2) obtained by PS-Fe(2)S(2) molecular dyads reported so far.     

离子液体-水双相体系悬浮聚合法制备对苯二酚分子印迹聚合物微球

通过在[Bmim]PF6离子液体-水双相体系中,以对苯二酚为模板分子,甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇脂为交联剂,采用悬浮聚合法制备得到对苯二酚印迹聚合物微球(MIMs-IL),并通过FTIR等测试技术对MIMs-IL进行了表征。对不同离子液体进行了选择,[Bmim]PF6介质中制备的MIMs-IL的识别性能最好。与从氯仿介质中制备的印迹聚合物微球(MIMs-Or)相比较,MIMs-IL的产率为70.8%,明显高于MIMs-Or的48.7%。采用静态吸附法考察其印迹识别能力的结果表明,MIMs-IL对水中的对苯二酚的识别能力大大强于MIMs-Or。对MIMs-IL识别吸附的热力学和动力学研究结果表明,12h时MIMs-IL及其非印迹聚合物微球(nMIMs-IL)均达到各自饱和吸附量,对于0.50g/L对苯二酚水溶液,MIMs-IL的饱和吸附量是nMIMs-IL的2.67倍。     

Photochemical preparation of pyrimidin-2(1H)-ones by rhenium(I) complexes with visible light

With visible light irradiation (λ > 400 nm) of rhenium(I) complexes (P1-P4), a photochemical conversion from 3,4-dihydropyrimidin-2(1H)-ones to pyrimidin-2(1H)-ones at room temperature has been achieved with good to excellent yields in CH(3)CN-H(2)O solution containing CCl(4) and K(2)CO(3). Luminescence quenching study and product analysis reveal that photoinduced electron transfer between rhenium(I) complex P and 3,4-dihydropyrimidin-2(1H)-ones plays an important role in the initial event.