Exploiting coumarin-6 as ancillary ligands in 1,10-phenanthroline Ir(iii) complexes: generating triplet photosensitisers with high upconversion capabilities

Abstract

A series of new Ir(III) complexes incorporating 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (coumarin 6) and ethynylpyrene (EP) functionalised 1,10-phenanthroline (phen) were developed. [Ir(III)(coumarin 6)₂(3-EP-phen)](PF₆) (Ir-3) proved to be the most promising material in triplet photosensitising applications. Highly absorbing at λ = 485 nm (ε = 1.31 × 10⁵ M⁻¹ cm⁻¹), it exhibits high upconversion and singlet oxygen quantum yields (Φ_UC = 27.5%, Φ_Δ = 81.5%) and an exemplary upconversion capability (η = 3.60 × 10⁶ M⁻¹ cm⁻¹).