Blue emissive amidinate-based tetra-coordinated boron compounds

Abstract

A series of novel amidinate ligated four-coordinated boron compounds, [(Ar)-C(^tBuN)₂BF₂] (1BF₂–6BF₂), were synthesised and structurally characterised (Ar = 1-phenyl, 2-naphthyl, 2-anthryl, 9-anthryl, 9-phenanthryl and 1-pyrene). The increased π-conjugation of Ar-substitution on the amidinate ligand results in dark blue-emission in compounds 3BF₂–6BF₂. All these compounds are emissive in the solution state. The 2-anthryl substituted compound 3BF₂ was found to exhibit a maximum quantum yield of 48% in dichloromethane. Theoretical studies were carried out which validate the hypothesis about the increased π-conjugation.