Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pune 411008, Maharashtra, India.
ACS Appl Mater Interfaces. 2013 Jun 26;5(12):5578-91. doi: 10.1021/am400868e. Epub 2013 Jun 7.
New classes of luminescent linear, bent-core, and star-shaped oligophenylenevinylenes (OPVs) having 1,4-para and 1,3-meta rigid aromatic cores were designed and developed. 3-Pentadecylphenol, a renewable resource molecule, was chosen as the flexible unit at the longitudinal or middle position of the OPV aromatic core for solid state ordering. Depending upon the nature of the π-core, the OPVs exhibited either mosaic-type liquid crystalline textures or spherulitic crystalline solids. The enthalpies of melting transitions revealed that the bent-core OPV structure showed enhanced solid state packing compared to linear or star-shaped OPVs. Small and wide-angle X-ray diffraction analysis confirmed layered-like assemblies in OPV molecules. Photophysical experiments such as excitation, emission, and time-resolved fluorescence decay dynamics were carried out to trace the molecular self-organization of OPV chromophores. Time correlated single photon counting technique (TCSPC) luminescent decay profiles and decay lifetimes (τ1 and τ2 values) revealed that the OPV chromophores showed faster exciton decay in the tightly packed bent-core structure. The weakly packed star-shaped OPV showed enhanced excited state luminescence stability up to 10 ns. A direct correlation between the OPV chemical structure, solid state ordering, and photophysical characteristics was established.
新型的发光线性、弯曲核和星形寡苯乙烯基乙烯（OPV）具有 1,4-para 和 1,3-meta 刚性芳香核，已被设计和开发出来。3-十五烷基苯酚，一种可再生资源分子，被选为 OPV 芳香核的纵向或中间位置的柔性单元，用于固态有序化。根据π-核的性质，OPV 表现出马赛克型液晶织构或球晶状晶体固体。熔融转变的焓表明，与线性或星形 OPV 相比，弯曲核 OPV 结构表现出增强的固态堆积。小角和广角 X 射线衍射分析证实了 OPV 分子中的层状组装。进行了光物理实验，如激发、发射和时间分辨荧光衰减动力学，以追踪 OPV 发色团的分子自组织。时间相关单光子计数技术（TCSPC）发光衰减曲线和衰减寿命（τ1 和 τ2 值）表明，OPV 发色团在紧密堆积的弯曲核结构中显示出更快的激子衰减。松散堆积的星形 OPV 显示出增强的激发态发光稳定性，可达 10 ns。已经建立了 OPV 化学结构、固态有序化和光物理特性之间的直接相关性。
