Reduced band gap in [Pb2I4(datone)2]n: Synthesis, properties and calculations

Phenanthroline derivative, 4,5-diazafluoren-9-one(dafone), was introduced into lead iodine hybrid to synthesize a new hybrid [Pb2I4(dafone)2]n (1), in which each lead atom adopts a distorted octahedral coordination and presents a one-dimensional polymer by edge-sharing mode. Due to the presence of O acceptor in dafone, C–H⋯O hydrogen bonds can be observed and contribute to the formation of 2-D layer. Experimental and theoretical optical property investigation indicate that 1 possesses semiconductor property. Specially, DFT calculation suggests that 1 displays a reduced band gap (1.36 eV), which is assigned to a more dispersed LUMO band compared with [Pb2I4(phen)2]n and [Pb2I4(bipy)2]n.