Luminescence behaviour of Au(i)–Cu(i) heterobimetallic coordination polymers based on alkynyl-tris(2-pyridyl)phosphine Au(i) complexes

Abstract

A set of alkynyl-tris(2-pyridyl)phosphine Au(I) complexes was synthesized and characterized. Free coordination functions on the ligand environment periphery, namely ‘scorpionate’ PPy₃ and the CC bond, allowed these ditopic metalloligands to be selectively linked to 1D coordination polymers by reaction with Cu(I), which used both Cu–(N-PPy₃) and Cu–(η²-CC) coordination modes. Single-crystal and powder XRD, NMR, and XPS techniques were used to characterize the coordination polymers obtained. Heterobimetallic Au(I)–Cu(I) coordination polymers demonstrate triplet photoluminescence which was studied by spectroscopic and computational methods to understand the pathway of energy transfer inside the chain of linked chromophore centres. The intriguing feature of the electronic structure of heterobimetallic supramolecular assemblies is the ‘long-distance’ electronic transition involving PhC₂ and PPy₃ ligands located at a distance of more than 1 nm from each other. Thus, the assembly of a heterobimetallic coordination polymer from relatively simple ‘building blocks’ retains the block-wise nature of the electronic structure, but the photophysical properties of the polymer are fundamentally different from the properties of discrete organometallic components.