Luminescence that lasts from Pt(trpy)Cl+ derivatives (trpy=2,2′;6′,2"-terpyridine)

This report outlines progress to date in preparing Pt(trpy)Cl+ derivatives that exhibit long-lived photoluminescence in solution (trpy = 2,2';6',2"-terpyridine). The trpy complex itself is a versatile binding agent/reporter probe for biological macromolecules but is non-emissive, except in solids or low-temperature glasses. Derivatives investigated are of the type Pt(4'-R-T)Y+, where 4'-R-T denotes a 4'-substituted form of the trpy ligand and Y is a pseudohalide co-ligand. Simple halide replacement yields the Pt(trpy)OH+ derivative which has facilitated luminescence-based DNA-binding studies. Other complexes with long-lived excited states in fluid solution include Pt(4'-NMe2-T)Cl+ and Pt(4'-Pyre1-T)Cl+, where Pyre1 designates a 1-pyrenyl substituent. Due to intra-ligand charge-transfer character, Pt(4'-NMe2-T)Cl+ and Pt(4'-Pyre1-T)Cl+ each exhibit relatively low energy absorption maxima. Open coordination sites support quenching by Lewis bases, however, the effect is less evident with increased intra-ligand orbital parentage in the excited state. (C) 2002 Elsevier Science B.V. All rights reserved.