苯并噻唑衍物的合成及结构-双光子吸收光物理特性关系

报道了三个具有典型A-π-A'型共轭结构的苯并噻唑衍生物的合成及结构-双光 子吸收光物理特性关系。通过对三个化合物的共轭结构增长和拉电子基强度变化对 化合物单光子荧光光谱、双光子诱导荧光光谱和双光子吸收截面等特性的影响研究 ，我们发现，苯并噻唑杂环中的杂原子硫在化合物共轭链链短时对其光物理特性影 响很强，在共轭链较长时影响减弱甚至消失。通常情况下，共轭链长度和拉电子基 强度共同对双光子吸收截面作贡献，我们的研究表明，当共轭链较长时，共轭链的 增长对增强分子双光子吸收截面的贡献远大于拉电子基强度变化的贡献。其中，新 化合物2（2-{4-2-（4-硝基苯基）-乙烯基]苯基}-乙烯基）苯并噻唑具有双光子 吸收截面大(181*10~(-50)cm~4s/photon)和荧光量子产率高(13.8%)的特点，是双 光子荧光显微与成像应用的一个良好的候选材料。

Synthesis of Novel Benzothiazolyl-derivatives and Relations between Their Structures and Two-photon Absorption Properties

Tine synthesis of three novel benzothiazolyl-derivatives with typical A-π-A' conjugation structures is reported. The influences of the structural modifications on the photophysical properties are studied. Experimental results show that, when the k-conjugation length of organic molecule is short, heteroatom in the π- conjugation structure (sulfur atom in our experiments) gives significant effects on the emission characteristics of the molecules; however, with the extension of the %-conjugation structure, such effects will be decreased and finally disappear. Experimental results also show that, although two-photon absorption cross-section is generally dependent on both the length of π-conjugation structure and the strength of acceptor (or donor), when the π-conjugation structure is long enough, the effect from π-conjugation length will play a dominant role. The results above will be beneficial to the design and synthesis of effective two-photon induced fluorescence molecules. Additionally, a new organic'molecule, named 2-(2-{4-2-(4-nitro-phenyl )-vinyl]-phenyl}-vinyl )-benzothiazole (NSSBT), has a large two-photon absorption cross-section (181 GM) and a high two-photon induced fluorescent efficiency (the quantum yield is 13.8%) , which implies that this molecule is a promising candidate for an application such as two-photon microscopy and imaging.