iClick-Mediated Au(I) Functionalization of Polystyrene: Lighting Up Polystyrene with Phosphorescence

A series of polystyrene-based polymers that are randomly functionalized with Au(I) chromophores that exhibit phosphorescence and electrophosphorescence are reported. The polymers feature side-chain conjugated moieties that are based on R3P–Au(I)–CC–Ar (where Ar = phenyl or 1-naphthyl and R = ethyl or phenyl) and a novel digold triazole functionality that is derived from an iClick reaction between R3P–Au(I)–N3 and the R3P–Au(I)–CC–Ar units. The R3P–Au(I)-CC–Ar substituted polymers are prepared by the reaction of R3P–AuCl with the ethynyl-functionalized polystyrenes (10 mol % ethynyl groups). Subsequently, an iClick reaction is carried out on the R3P–Au(I)–CC–Ar functionalized polymers to afford the digold triazole functionalized polymers. The iClick reactions are monitored by in situ 1H and 31P NMR spectroscopy. Molecular dynamics (MD) simulations of the monogold R3P–Au(I)–CC–Ar polymers reveal that there are significant attractive interactions between the metalated repeat units, especially in the polymers featuring triethylphosphine ligands at the Au(I) centers (e.g., Et3P–Au(I)–CC–Ar). The photophysical study of the polymers reveals that the emission is dominated by phosphorescence from 3π,π* excited states localized on the metalated units. The phenyl-based polymers exhibit phosphorescence in the blue region (λmax ∼ 435 nm), whereas the naphthyl-based polymers exhibit yellow-red phosphorescence (λmax ∼ 600 nm). Preliminary studies demonstrate the application of side-chain functionalized polymers in electroluminescent devices.