Taking advantage of the pH and pO2 sensitivity of a luminescent macrocyclic terbium phenanthridyl complex

Abstract

Strong metal-based emission with [TbL¹] in aqueous media occurs in the absence of protons and oxygen; dissolved molecular oxygen quenches the phenanthridyl triplet (1/K_SV = 58 Torr O₂) but back-energy transfer to the organic triplet occurs efficiently only with the excited protonated complex (pK_a″ = 5.7).