Cyclometalated Trinuclear Ir(III)/Pt(II) Complex as a Luminescent probe for Histidine-rich Proteins
Organometallic complexes have important applications in the field of protein staining, with the potential for use in proteomic analysis. The rational synthesis of a trinuclear luminescent organometallic complex with two platinum(II) centres appended to the cyclometalated ligand of the iridium(III) centre is reported here. Two di-2-picolylamine groups bonded to the cyclometalated phenyl pyridine moiety provide three coordinating sites to each platinum centre. The replacement of chloride from the fourth coordination site of two square planar platinum metal centres with imidazole nitrogen or sulphur atom of histidine/cysteine is evident from the change in luminescence intensity upon binding these amino acids. The increase in luminescent emission intensity on binding of histidine to the organometallic complexallowed it to be used as a protein staining agent. Reversibility of the staining upon washing with imidazole enhances the possibility of its application in mass spectrometric analysis.