Synthesis, properties and reactivity of BCl₂ aza-BODIPY complexes and salts of the aza-dipyrrinato scaffold

Abstract

Conversion of F-aza-BODIPYs to Cl-aza-BODIPYs enables facile substitution at boron using aryl Grignard reagents as well as controlled deborylative deprotection to give the parent azadipyrrin.

Syntheses and Investigations of Conformationally Restricted, Linker-Free α-Amino Acid–BODIPYs via Boron Functionalization

“…Presumably, the reaction of BODIPY 1 in the presence of boron trichloride proceeds via either the formation of a boronium cation intermediate, 41 followed by the nucleophilic attack of the amino acid carboxylate group on boron to produce product A , or via the in situ formation of a Cl 2 -BODIPY intermediate 43 − 45 leading to products B and C .…”

Substitution at boron in BODIPYs

“…For example, formation of the Cl-aza-BODIPY 36 occurs through stepwise halogen exchange and a mixed halogen BODIPY intermediate featuring a -BClF unit. 86 Cl-aza-BODIPYs such as 36 were found to be unstable after a few days of exposure to air, decomposing to the aza-dipyrrin HCl salts. The utility of the Cl-aza-BODIPY scaffold, as contained within the subphthalocyanine motif, 87 extends to substitution at boron under mild conditions through treatment with aryl Grignard reagents, courtesy of the lability of the B-Cl bond.…”

Monophenylboryl aza-BODIPY with free rotation of the B-phenyl group for enhanced photothermal conversion

“…7 In 2020, Thompson et al reported a series of diaryl-substituted aza-BODIPYs on the boron atom generated by the reaction of BCl 2 -aza-BODIPY complexes with a Grignard reagent, and the maximum absorption wavelengths of diphenyl-substituted aza-BODIPYs with low quantum yield ( Φ f < 0.01) were also found to be hypochromatically shifted by 35 nm. 8 Until now, only the synthesis and simple optical properties of aryl-substituted aza-BODIPYs have been investigated, and it is therefore urgent that we explore the potential application of aryl-substituted aza-BODIPYs. We noticed weak fluorescence of diphenyl-substituted aza-BODIPY (DPh-azaBODIPY) on the boron centre, which provides favorable conditions for PTT, according to the Jablonski diagram.…”