Synthesis and photophysical properties of Au(III)-Ag(I) aggregates

Cyclometallated gold (III) complexes of the type (C^N^C)AuX [HC^N^CH = 2,6-bis(4-ButC6H4)pyrazine; 2,6-bis(4-ButC6H4)pyridine, or 2,6-bis(4-ButC6H4)4-Butpyridine; X = CN, CH(COMe)2 or CH(CN)2] have been used as building blocks for the construction of the first family of AuIII/AgI aggregates. The crystal structures of these aggregates reveal the formation of complex architectures in which the Ag+ cations are stabilized by the basic centers present on each of the Au precursors. The photophysical properties of these aggregates are reported. Compared to mononuclear pincer complexes, a general red-shift and an increase in the emission intensity are observed. In agreement with DFT calculations the lowest energy absorption and the emission are assigned to 1IL(C^N^C) and 3IL(C^N^C) transitions dominated by the HOMO and the LUMO orbitals.