Blue rhenium tricarbonyl DPPZ complexes – low energy charge-transfer absorption at tissue-penetrating wavelengths

Abstract

fac-[Re(CO)₃(dppz)] complexes of amido ligands generated in situ under basic conditions display an intense (ε = 16460 L mol⁻¹ cm⁻¹) absorption band between 500–700 nm which are assigned to an n(amido,RNH–) → π* (dppz) inter-ligand charge transfer band offering an extraordinarily low energy charge separating absorption with potential for imaging and energy application.