Department of Chemistry, University of Alabama-Birmingham, 201 Chemistry Building, 901 14th Street South, Birmingham, Alabama 35294-1240, USA.
Dalton Trans. 2013 Oct 21;42(39):14281-97. doi: 10.1039/c3dt51499d.
Two new series of phosphonato-substituted bithiophenes, BpP(X)(C4H2S)2H and BpP(X)(C4H2S)2P(X)Bp (Bp = 2,2'-C12H8O2, X = O, S, Se), have been synthesized and characterized using linear absorption and emission spectra, and third-order nonlinear absorption measurements at 430 nm with 27 ps laser pulses. The compounds were synthesized in three steps: (1) reacting lithiated bithiophene with (Et2N)2PCl; (2) reacting the product from the first step with biphenol; and (3) reacting the product from the second step with the appropriate chalcogen. The X-ray crystal structures of two of the compounds, BpP(O)(C4H2S)2P(O)Bp and BpP(Se)(C4H2S)2P(Se)Bp, are reported and show a number of intermolecular π-π interactions. The linear absorption spectra, emission spectra, and emission quantum yields show distinct trends with respect to the chalcogen and the number of phosphorus substituents attached to the 2,2'-bithiophene ring. The compounds show emission maxima at wavelengths ranging from 380-400 nm and, BpP(S)(C4H2S)2H shows a 23-fold increase in fluorescence quantum yield relative to that of 2,2'-bithiophene. Fluorescence lifetimes and radiative and non-radiative decay rate constants for the first singlet excited state have been extracted from the quantum yields using time-dependent DFT calculations. Nonlinear transmission measurements indicate that all of the compounds show nonlinear absorption at 430 nm with 27 ps laser pulses in spite of their low solubilities. Notably, the nonlinear absorption threshold of a 0.16 mol L(-1) CH2Cl2 solution of BpP(Se)(C4H2S)2H is 0.9 J cm(-2). The excellent emission quantum yields and good nonlinear absorptions make these compounds promising candidates for optical power limiting applications and as host materials for violet-blue organic light emitting diodes.
我们合成了两个新系列的膦酸取代联二噻吩，BpP(X)(C4H2S)2H 和 BpP(X)(C4H2S)2P(X)Bp（Bp=2,2'-C12H8O2，X=O，S，Se），并通过线性吸收和发射光谱以及三阶非线性吸收测量对其进行了表征，测量使用的激光脉冲波长为 430nm，脉宽为 27ps。这些化合物通过三步法合成：（1）将锂化的联二噻吩与（Et2N）2PCl 反应；（2）将第一步的产物与联苯酚反应；（3）将第二步的产物与合适的硫属元素反应。报道了其中两个化合物的 X 射线晶体结构，BpP(O)(C4H2S)2P(O)Bp 和 BpP(Se)(C4H2S)2P(Se)Bp，它们显示了许多分子间的π-π相互作用。线性吸收光谱、发射光谱和发射量子产率与硫属元素和连接到 2,2'-联二噻吩环上的磷取代基的数量均表现出明显的趋势。这些化合物在 380-400nm 范围内显示出发射峰，BpP(S)(C4H2S)2H 的荧光量子产率相对于 2,2'-联二噻吩提高了 23 倍。通过时间相关的 DFT 计算，从量子产率中提取了第一单重激发态的荧光寿命、辐射和非辐射衰减速率常数。尽管这些化合物的溶解度较低，但所有化合物在 430nm 处均显示出 27ps 激光脉冲的非线性吸收。值得注意的是，0.16mol L(-1)的 BpP(Se)(C4H2S)2H 的二氯甲烷溶液的非线性吸收阈值为 0.9J cm(-2)。这些化合物具有优异的发射量子产率和良好的非线性吸收特性，有望成为光限幅应用和作为紫光-蓝光有机发光二极管的主体材料的候选化合物。
