Michael Pennington, Kyle C. Edwards, Fengrui Qu, David A. Dixon* and Paul A. Rupar*,
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引用次数: 0
摘要
具有硼氧和硼氮原生键的四配位芳基硼芴可以表现出非常大的荧光斯托克斯位移。据推测,这种大的斯托克斯位移是由于激发态中的硼-供体配位键通过一种叫做 "键裂解诱导分子内电荷转移(BICT)"的机制发生裂解而产生的。目前这项研究的主要目标是通过对光学稳定性更好的四配位硼芴进行瞬态吸收光谱分析(TAS),直接观察 BICT 状态。我们合成了一种新的四配位芳基硼芴,其芳基环上有一个二价 B-O 键和两个叔丁基。这种新型硼芴的 TAS 与 BICT 假说所预测的激发态中存在的单一三配位物种一致。荧光寿命测量和 DFT 计算也支持 TAS 数据。
Detection of the BICT State in a Borafluorene with High Stokes Shift Fluorescence
Four-coordinate aryl borafluorenes with boron–oxygen and boron–nitrogen dative bonds can exhibit very large fluorescence Stokes shifts. The large Stokes shifts are hypothesized to arise from cleavage of the boron-donor dative bond in the excited state, via a mechanism called bond-cleavage-induced intramolecular charge transfer (BICT). The primary goal of this current investigation is to directly observe the BICT state by performing transient absorption spectroscopy (TAS) on four-coordinate borafluorenes, which have improved optical stability. A novel four-coordinate aryl borafluorene was synthesized which features a dative B–O bond and two tert-butyl moieties on the aryl ring. TAS of the new borafluorene is consistent with the existence of a single, three-coordinate species in the excited state, as predicted by the BICT hypothesis. The TAS data is supported by fluorescence lifetime measurements and DFT calculations.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.