The influence of crystal packing on the solid state fluorescence behavior of alkyloxy substituted phenyleneethynylenes
作者:Reji Thomas、Shinto Varghese、G. U. Kulkarni
DOI:10.1039/b902937k
日期:——
The study reports the solid state photophysical properties of a series of alkyloxy-substituted oligo(phenyleneethynylene)s, methoxy to hexyloxy, supported by a detailed analysis of molecular packing obtained from single crystal X-ray diffraction data. While the emission peaks are highly red shifted (by as much as 114 nm) in the solid state, all molecules exhibit similar absorption and emission in dilute solutions. The red shift is maximum in ethoxy and minimum in methoxy, while other crystalline films exhibit intermediate values. In the crystal structures, the spacing between the molecular pairs forming the J-aggregates is varied between 3.48 to 4.65 Å, with no systematic dependence on the chain length. The red shifted emission maximum is found to vary linearly with the spacing between the interacting molecules in the J-aggregate. Thus, the emission in the solid state is determined by the extent of dipolar coupling between the molecules, the alkyl chain length influencing the properties only indirectly.
研究报告了一系列烷氧基取代的低聚(苯乙炔)在固态下的光物理特性,这些取代基的范围从甲氧基到己氧基,研究得到了来自单晶X射线衍射数据的详细分子堆积分析。虽然在固态下发射峰大幅红移(红移幅度可达114纳米),但所有分子在稀溶液中的吸收和发射特性相似。红移在乙氧基中最大,在甲氧基中最小,而其他结晶薄膜则表现出中间值。在晶体结构中,形成J-聚集体的分子对之间的间距介于3.48到4.65 Å之间,且与链长没有系统的依赖关系。红移的发射最大值被发现与J-聚集体中相互作用分子之间的间距呈线性变化。因此,固态下的发射特性由分子之间的偶极耦合程度决定,烷基链的长度仅间接影响这些特性。