Influence of the Nature of the Amino Group in Highly Fluorescent Difluoroborates Exhibiting Intramolecular Charge Transfer.

A series of difluoroborates were synthesized from CH acids. All compounds were substituted with dialkylamino groups (NR2). The lone electron pair of the nitrogen atom of this donor moiety is variably delocalized toward the difluoroborate core that acts as the electron acceptor. This was rationalized in light of the various geometries of the amino group. The degree of charge transfer was quantified on the basis of the results of time-dependent density functional theory calculations.