A Three-Dimensional A-D-A Structured, [2.2]Paracyclophane Linked Organoboron Complex Displays Masked Dual Fluorescence and Solvatofluorochromism

We synthesized and studied an organoboron complex which has a three-dimensional A–D–A structure, 2BF2, and is composed of two dihydrodioxaborinine ring moieties linked by [2.2]paracyclophane. In solution, 2BF2 exhibits dual fluorescence, with one band displaying solvatofluorochromism and the other not. Theoretical calculations revealed that the dual fluorescence of 2BF2 derives from coexsistence of centrosymmetric and non-centrosymmetric conformers in the excited singlet state, which exhibit contrastingly emission behaviors owing to their different symmetry characteristics and dipole moments.