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A series of hemicyanine dyes was synthesized starting from the vinyl chloride-based cyanine dye IR-780. The dyes absorbed and emitted in the near-infrared region, while heavy atom (bromo and iodo) substitution promoted the generation of both singlet oxygen (1O2) as well as a range of other reactive oxygen-based species (ROS) upon irradiation at wavelengths greater than 610 nm. One hemicyanine dye displayed an outstanding singlet oxygen quantum efficiency (φΔ = 0.8) and was successfully applied in in vitro studies to mimic photodynamic therapy application.

Taking inspiration from the assembly of so-called peptoids (N-alkylglycine oligomers) we present a new synthetic methodology whereby N-heterocyclic carbene (NHC) based Pd ligands were assembled using a sub-monomer approach and loaded with Pd via solid-phase synthesis. This allowed the rapid generation a library of NHC–palladium catalysts that were readily functionalised to allow bioconjugation. These catalysts were able to rapidly activate a caged fluorophore and ‘switch-on’ an anticancer prodrug in 3D cell culture.