Triazole-based osmium(ii) complexes displaying red/near-IR luminescence: antimicrobial activity and super-resolution imaging.

Cellular uptake, luminescence imaging and antimicrobial activity against clinically relevant methicillin-resistant (MRSA) bacteria are reported. The osmium(ii) complexes [Os(^)] (^ = 1-benzyl-4-(pyrid-2-yl)-1,2,3-triazole ( ); 1-benzyl-4-(pyrimidin-2-yl)-1,2,3-triazole ( ); 1-benzyl-4-(pyrazin-2-yl)-1,2,3-triazole ( )) were prepared and isolated as the chloride salts of their meridional and facial isomers. The complexes display prominent spin-forbidden ground state to triplet metal-to-ligand charge transfer (MLCT) state absorption bands enabling excitation as low as 600 nm for /- and observation of emission in aqueous solution in the deep-red/near-IR regions of the spectrum.