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.