Theoretical Investigations on the Electronic and Optical Properties of Luminescent Poly（alkylthiophene-co-pyridine）

Quantum-chemical techniques were applied to investigate a series of conjugated polymers： poly（3-octylthien-2,5-ylene-co-pyrid-2,6-ylene） （pl）, poly[pyrid-2,6-ylenebis（3-octylthien-2,5-ylene）] （p2） and poly[pyrid-2,5-ylenebis（3-octylthien-2,5-ylene）] （p3） comprising alternating n-excessive 3-alkylthiophene and n-deficient meta- or para-linked pyridine moieties. Their ground state and excited state structures were optimized with density functional theory B3LYP method, and the optical properties were calculated by the time-dependent density functional theory （TD-DFT） and ZINDO/S methods. Their HOMO-LUMO gaps （An-L）, the lowest excitation energies （Eex）, ionization potentials （IP） and electron affinities （EA） were obtained by extrapolating those of the polymers to the inverse chain length equal to zero （1/n=0）. The calculated results showed that the decrease of pyridylene content increased the HOMO level and decreased the LUMO level while the para-linkage further contributed to it. The IP are in the order： p1〉p2〉p3 but EA are： p1〈p2〈p3. In addition, the decrease of the pyridylene content and the para-linked pyridylene in the backbone of the polythiophene resulted in a narrowed energy gap and bathochromic absorption and emission peaks.     

系列噻吩和吡啶共聚物的电子结构和光谱性质的理论研究

采用量子化学方法研究了一系列含π-富电子烷基噻吩和间位或对位连接的π-缺电子吡啶共聚物，p1,p2,p3。运用密度泛函B3LYP方法对其基态和激发态进行几何构型优化，并采用含时密度泛函TD-DFT 方法和ZINDO/S方法分别计算了其相应化合物的光谱性质。通过外推低聚物的能隙（△H-L），最低激发能（Eex），电离势（IP），电子亲和势（EA）至链长倒数为零（1/n = 0）得到相应高聚物的对应性质的相关数据。计算结果表明，拉电子的吡啶基团使EA提高，即相应提高了电子的传输和注入能力。此外，含较少的吡啶成分和其在主链中以对位连接使其能隙变得更小，并导致吸收峰和发射峰红移。     

“华光礁Ⅰ号”沉船出水青白瓷表面沉积物的分析

为探讨"华光礁Ⅰ号"沉船出水陶瓷器表面沉积物的成分及物相,以青白瓷为例,利用扫描电镜(SEM)和能谱仪(EDS)联用、X射线荧光(XRF)、X射线衍射分析(XRD)三种分析方法,对青白瓷表面不同颜色的沉积物进行了结构和化学组成的测试.结果表明,沉积物主要以碳酸盐类的文石、方解石以及含铁类的磁铁矿、针铁矿为主.本研究可为南海海域出水陶瓷器的保护提供参考和借鉴.     

Theoretical Study on the Optical Properties for 2,7- and 3,6-Linked Carbazole Trimers by Time-dependent Density Functional Theory

Electronic properties, such as HOMO and LUMO energies, band gaps, ionization potential (IP) and electron affinity (EA) of 2,7- and 3,6-linked carbazole trimers, two conjugated oligomers with different linkages of carbazole, were studied by the density functional theory with Becke-Lee-Young-Parr composite exchange correlation functional (B3LYP). The absorption spectra of these compounds were also investigated by time-dependent density functional theory (TD-DFT) with 6-31G* basis set. The calculated results indicated that the HOMO and LUMO of the 2,7- and 3,6-linked carbazole trimers are both slightly destabilized on going from methyl substitution to sec-butyl substitution. Both IP and EA exhibit their good hole-transporting but poor electron- accepting ability. The presence of alkyl groups on the nitrogen atoms does not affect the intra-chain electronic delocalization along the molecular frame. Thus no significant effect on the band gap and absorption spectra of compounds has been found.