H-bonding assisted intramolecular charge transfer in 1-aminopyrene derivatives

The electronic spectroscopy and photochemical properties of new derivatives of pyrene-1-aminovinylene containing strong electron withdrawing groups are reported. 2-((Pyren-8-ylamino)methylene) malononitrile (I) ethyl 2-cyano-3-(pyren-8-ylamino) acrylate (II), and diethyl 2-((pyren-8-ylamino)methylene) malonate (III) were prepared. These molecules show excited-state intramolecular charge transfer (ESICT). The carbonyl in II and III gives rise to a solvent dependent intramolecular H-bond interaction which not only enhances the mixing between π–π∗ and n–π∗ states but also influences the ESICT dynamics.