Molecular Rotors Based on the Boron Dipyrromethene Fluorophore
Molecular Rotors Based on the Boron Dipyrromethene Fluorophore
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DOI：
10.1002/ejoc.200901135
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发表时间：
2010
影响因子：
2.8
通讯作者：
A. Benniston;A. Harriman;Victoria L. Whittle;M. Zelzer
中科院分区：
文献类型：
--
作者：
A. Benniston;A. Harriman;Victoria L. Whittle;M. Zelzer
为了研究旋转基团的大小的变化如何影响用于监测局部粘度变化的分子探针的功效，合成了具有中位菲单元的硼二吡咯亚甲基染料并进行了充分表征。19 F NMR光谱和分子模型表明，庞大的菲基单元不能完全围绕连接的C-C键旋转，但可以在合理的大二面角上振荡。这种情况与具有内消旋亚苯基环的相应染料形成对比。后一种染料用作周围溶剂粘度变化的分子探针，但基本上对溶剂极性的变化不敏感。对于菲基衍生物，发现相反的情况，其中电荷转移态位于比发射π，π * 激发态更高的能量处，但可以热接近。结果被认为是在考虑到旋转自由的能级图。光物理性质的报告，这两种染料在一系列的溶剂，和温度依赖性的研究进行了说明。
In order to examine how changes in the size of the rotary group affect the efficacy of molecular probes for monitoring changes in local viscosity, a boron dipyrromethene dye bearing a meso-phenanthrene unit has been synthesized and fully characterized. 19 F NMR spectroscopy, together with molecular modelling, indicates that the bulky phenanthryl unit cannot rotate completely around the connecting C―C linkage but can oscillate over a reasonably large dihedral angle. This situation is to be contrasted with the corresponding dye having a meso-phenylene ring. The latter dye functions as a molecular probe for changes in viscosity of the surrounding solvent but remains essentially insensitive to changes in the polarity of the solvent. The opposite situation is found for the phenanthryl derivative, where a charge-transfer state lies at higher energy than the emissive π,π * excited state but can be accessed thermally. The results are considered in terms of energy-level diagrams taking into account rotational freedom. Photophysical properties are reported for both dyes in a range of solvents, and temperature-dependent studies are described.