Synthesis, Crystal Structure, and Photophysical Properties of Bromothiophene-Functionalized BF 2 -Curcuminoid as a Versatile Building Block.

A novel bromothiophene-functionalized BF 2 -curcuminoid (BTC-BF 2 ) is synthesized by Knoevenagel condensation reaction. The structure of BTC-BF 2 is determined by 1 H-nuclear magnetic resonance ( 1 H NMR), 13 C-nuclear magnetic resonance ( 13 C NMR), and high-resolution mass spectrometry (HRMS). Moreover, a nearly coplanar single crystal structure is successfully obtained and form a mesh structure through intermolecular multiple C─H···F hydrogen bond interactions. As expected, as-prepared BTC-BF 2 exhibits solvent-dependent photophysical properties in solvents with different polarity and an intense red solid-state fluorescence. Density functional theory calculations further verify the relationships between its intrinsic electronic features and the photophysical properties. For its potential application aspect, BTC-BF 2 shows a certain ability to generate singlet oxygen under irradiation with 530 nm green light. Moreover, BTC-BF 2 can be utilized as versatile building block to construct novel far-red or NIR BF 2 -curcuminoid complexes for widely biological applications.