Synthesis and photophysical properties of multimetallic gold/zinc complexes of (P,N,N,N,P) and (P,N,N) ligands

Novel ligands carrying bipyridine and terpyridine analogue motifs were synthesized. These N-donor sites were linked to phosphine moieties with alkyl chains of defined lengths allowing heterobi- and -trimetallic complexes to be obtained. The orthogonal coordination behavior of the donor centers is proved by their selectivity in coordinating zinc( ii ) as a hard and gold( i ) as a soft Lewis acid. The ligands and complexes obtained in this manner were characterized by means of spectroscopic methods and X-ray structure analysis. Their photophysical properties were explored by measuring electronic absorption and fluorescence spectra as well as fluorescence lifetimes and were compared with the results of DFT calculations, all analyzed taking into account the issue of cooperativity. Orthogonal coordination of gold and zinc yields mono- and bimetallic complexes, which are investigated concerning their photophysics.