Tunable Luminescence of Bithiophene-Based Flexible Lewis Pairs

Bithiophene-based
flexible Lewis pairs with P­(O)­R2 (R
= phenyl, isopropyl) and BMes2 (Mes = 2,4,6-trimethylphenyl)
functionalities are able to toggle between closed, Lewis adduct and
open, unbound Lewis pair structures. The open structure is favored
in strong hydrogen bond donating solvents or at higher temperatures
giving rise to an intense charge-transfer (CT) luminescence, while
the closed structure without this emission dominates in non-hydrogen
bond donating solvents or at lower temperatures. Intermediate solvents
result in an equilibrium mixture of both structures, which shows unusual
mixed emission that is dependent on excitation wavelength.