Rhenium(I)-tetrazolato functional luminescent polymers: Organic-inorganic hybrids via RAFT and post-polymerization modification

Abstract

A series of well-defined tetrazole-functionalized (co)polymers based on the styrenic structural motif that are able to serve as macromolecular ligands for the coordination of a luminescent rhenium(I) complex are presented. Copolymers of styrene with 4-cyanostyrene containing different ratios of cyano appended groups have been synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Post-polymerization modification of the cyano groups via reaction with NaN3 yielded the corresponding tetrazole functionalized copolymers. These tetrazole functional materials are able to serve as macromolecular ligands for the coordination of metal complexes: a rhenium(I) species has been incorporated into the polymeric structure by coordination to the tetrazole groups on the copolymers. The parent (co)polymers have been characterised by size exclusion chromatography (SEC), while inverse-gated proton decoupled 13C NMR spectroscopy and infrared spectroscopy confirmed the formation of the tetrazole functional group and subsequent metal coordination. The photophysical properties of the copolymer-rhenium(I) hybrid luminescent materials have been fully investigated. Absorption and emission profiles confirmed coordination between the tetrazole functionality appended to the polymer material and the rhenium(I) precursor complex. Lifetime measurements and quantum yields confirmed that the presence of the polymeric scaffold does not interfere with the luminescent properties of the rhenium(I) complex.