Aminobenzodione-based polymers with low bandgaps and solvatochromic behavior

Abstract

Pd-catalyzed amination polymerization of deep blue aminobenzodifuranone monomer 3-(4-bromo-phenyl)-7-(4-octylaminophenyl)-benzo[1,2-b:4,5-b′]-difuran-2,6-dione (M1) is described, as well as polymerization of symmetric dibromophenyl-benzodifuranone (M2), or the corresponding dibromophenylbenzodipyrrolidone (M3) with N,N′-dialkylated phenylenediamines (M4a,b). The resulting polymers P1–3 exhibit low bandgaps (1.08–1.47 eV), broad UV/vis absorption bands (400–900 nm), and a large solvatochromic shift up to 3140 cm⁻¹ from n-hexane to hexamethylphosphoramide. Multiple linear regression analyses of _max of the solvent-dependent solvatochromic UV/vis absorption bands of M1, P1 and P2a are presented, from which Kamlet–Taft and Catalán solvent parameters were determined. All monomers and polymers exhibit high extinction coefficients up to 8.6 × 10⁴ L mol⁻¹ cm⁻¹ and high photostability, and might be suitable for electronic applications.