An unprecedented 2D copper(i)-cyanide complex with 20-membered metal rings: the effect of the co-ligand 4,5-diazafluoren-9-one.

A hydrothermal reaction of CuCl2·2H2O, 4,5-diazafluoren-9-one (L) and K3[Fe(CN)6], which is used as an environment friendly cyanide source, produces a two-dimensional copper cyanide complex Cu10(CN)10L4 (1). In the complex, the L ligands act as corner and bridge ligands simultaneously. With the help of the corner ligands, infinite Cu(CN)∞ chains are formed. The chains are further bridged by another type of L ligand forming a 2D layer with a Cu20(CN)18L2 macrocycle, which shows blue photoluminescence related to centered π-π* transitions of the L ligand.