Butadiene dyes based on 3-(dicyanomethylidene)indan-1-one and 1,3-bis(dicyanomethylidene)indane: synthesis, characterization and solvatochromic behaviour†
Novel donor–acceptor butadiene chromophores were synthesized by Knoevenagel condensation of different diaryl-substituted enals with 3-(dicyanomethylidene)indan-1-one and 1,3-bis(dicyanomethylidene)indane. The structures of two of these compounds were unambiguously confirmed by means of single-crystal X-ray diffraction. The absorption spectra of these dyes, as well as their solvatochromic behaviour, were studied in detail. In addition, DFT and TD-DFT quantum chemical calculations were performed to assess information regarding the topologies and absolute energies of their frontier molecular orbitals, as well as their absorption spectra.