Visible-Light-Induced Direct Photoamination of BODIPY Dyes with Aqueous Ammonia.

By taking advantage of their strong absorption ability, visible-light-induced direct photoamination of BODIPY dyes with aqueous ammonia was developed to give structurally diverse α-amino BODIPYs. The excited state of BODIPYs possessed higher electron affinity than the ground state and thus showed largely enhanced reactivity toward weak nucleophile of ammonia. Those α-amino BODIPYs are valuable synthetic intermediates and have been successfully demonstrated in several post-transformation reactions. The work indicates that photoreaction is an excellent alternative to conventional functionalization of this popular fluorophore.

A Photochemical Dehydrogenative Strategy for Direct and Regioselective Dimerization of BODIPY Dyes.

By taking advantage of their intense visible-light absorptions, a photoinduced, AgI promoted oxidative dimerization of BODIPY dyes was developed to give structurally unprecedented α,α- and α,γ-linked dimers. In contrast to classical oxidative aromatic coupling, this methodology does not need a strong oxidant and relies on the singlet electron transfer process between excited-state BODIPYs and an electron acceptor to generate BODIPY based radical species.

Visible Light Excitation of BODIPYs Enables Dehydrogenative Enamination at Their α-Positions with Aliphatic Amines.

A photoredox-mediated route to enamination of boron dipyrromethene (BODIPY) dyes with aliphatic amines is reported by activating both the ß-C(sp3)-H bond of amines and the α-C(sp2)-H bond of BODIPYs under visible light illumination. Dehydrogenation of amines by excited-state BODIPYs and/or photoredox catalyst gave enamine intermediates, which were further trapped by BODIPYs to give a series of α-enamineBODIPYs. These resultant α-enamineBODIPYs showed red-shifted absorption and emission maxima with ratiometric pH-dependent fluorescence.