Computational Assessment of Novel Ruthenium Phenoxazine‐Based Complexes as Photosensitizers in Photodynamic Therapy

Abstract A computational examination of two new polypyridyl ruthenium complexes, containing meldola blue (MDB) and nile blue (NB) chromophores, is here reported in order to assess the applicability of phenoxazine‐containing complexes in photodynamic therapy (PDT). The designed complexes, named Ru‐3ENB and Ru‐3EMDB , are based on a recently synthesized Ru(II)‐based complex bearing a bipyridyl‐ethynyl‐Nile Red (NR) ligand and proposed for PDT applications. DFT outcomes elucidated how the replacement of NR with MDB induces a red shift of the maximum absorption wavelength within the therapeutic window, up to 638 nm. A change in the molecular orbitals involved in the population of excited states was observed upon chromophore substitution that results in ISC kinetic significantly faster than that computed for the synthesized complex Ru‐3ENR .