Anticancer and antibacterial properties of trinuclear Cu(I), Ag(I) and Au(I) macrocyclic NHC/urea complexes

Synthesis and characterisation of the first macrocyclic Cu(I), Ag(I) and Au(I) tricarbene/urea N-heterocyclic carbene (NHC) complexes is described and their fluorescence properties are compared to related tetracarbene complexes. The newly described silver and gold complexes show luminescence with emission maxima at λem,max = 481 nm and λem,max = 334 nm, respectively. Moreover, their ability to inhibit the growth of bacteria (S. aureus and E. coli) and cancer cells (HeLa and MCF7) is investigated. A strong influence of the metal is observed. While the copper and gold complexes are inactive against bacteria, the silver complex depicts a moderate activity (MIC ≈ 30 µM). The copper and silver complexes exhibit antiproliferative activity in both cell lines, ranging from 25.1 µM to 3.03 µM.