Stabilization of Excited State Using Through-Space Interaction between Independent π-Systems Mediated by a<i>peri</i>-Substituted Hydroxy Group in 1-Arylnaphthalenes: Unexpected Blue Emission of 1,3,5-Tris(<i>peri</i>-hydroxynaphthyl)benzene
作者:Hideto Nakajima、Makoto Yasuda、Kenji Shimizu、Naomi Toyoshima、Yasunori Tsukahara、Takao Kobayashi、Shinichiro Nakamura、Kouji Chiba、Akio Baba
DOI:10.1246/bcsj.20110139
日期:2011.10.15
The control of photoluminescence wavelength is important for the design of emitting materials, and compounds bearing aryl–aryl bonds are considered to be useful candidates for the synthesis of these materials. However, the biaryl system lacks an efficient linkage of independent conjugated moieties because of a structure that, rather than planar, is made up of almost perpendicular dihedral angles due to steric effect. In this paper, we report a novel method to link independent π-systems in biaryl compounds. The oxy-substituents at the peri-position in 1-arylnaphthalene systems, which are biaryl compounds, showed interesting and unexpected photophysical properties of a bathochromic shift of emission. In particular, peri-OH-substituted arylnaphthalenes showed a large bathochromic shift that was induced by polarization based on intramolecular OH–aryl interaction. Quantum chemical (TDDFT) calculations accurately reproduced the large bathochromic shifts of peri-OH-substituted arylnaphthalenes. The through-space interaction between the peri-substituted OH and aryl groups generated an unexpected extended conjugation system. The substituting position of OH in 1-arylnaphthalenes is quite critical, because the hydroxy group mediates the independent π-systems to expand conjugation. Based on this concept, 1,3,5-tris(peri-hydroxynaphthyl)benzene had characteristic photophysical properties, giving an unexpected blue emission.
光致发光波长的控制对于发光材料的设计非常重要,而带有芳基-芳基键的化合物被认为是合成这些材料的有用候选物。然而,由于空间位阻效应,双芳基体系缺乏独立共轭基团的有效连接,其结构不是平面结构,而是由几乎垂直的二面角组成。本文中,我们报告了一种在双芳基化合物中连接独立π体系的新方法。1-芳基萘体系(双芳基化合物)中外围位置的氧基取代基表现出有趣且出乎意料的光物理性质,即发射的色散移位。特别是,外围-OH取代的芳基萘表现出大的色散移位,这是由基于分子内OH-芳基相互作用的极化引起的。量子化学(TDDFT)计算准确地再现了外围-OH取代的芳基萘的大色散移位。外围取代的OH和芳基基团之间的空间相互作用产生了一个意想不到的扩展共轭体系。1-芳基萘中OH的取代位置非常关键,因为羟基介导独立π体系以扩展共轭。基于这一概念,1,3,5-三(外围羟基萘基)苯具有独特的光物理性质,产生意想不到的蓝色发射。