It Takes Three to Tango - the length of the oligothiophene determines the nature of the long-lived excited state and the resulting photocytotoxicity of a Ru(II) photodrug.

ABSTRACT: TLD1433 is the first Ru(II) complex to be tested as a photodynamic therapy agent in a clinical trial. In this contribution we study TLD1433 in the context of structurally-related Ru(II)-imidozo[4,5-f][1,10]phenanthroline (ip) complexes appended with thiophene rings to decipher the unique photophysical properties which are associated with increasing oligothiophene chain length. Substitution of the ip ligand with ter- or quaterthiophene changes the nature of the long-lived triplet state from metal-to-ligand charge-transfer to ³ππ* character. The addition of the third thiophene thus presents a critical juncture which not only determines the photophysics of the complex but most importantly its capacity for ¹O₂ generation and hence the potential of the complex to be used as a photocytotoxic agent.

Entry for the table of contents

A low-lying triplet intraligand state (³IL) determines the properties of the long-lived excited states in a series of Ru(II) complexes. The ³IL state can be accessed by increasing the length of an oligothiophene chain. The ³IL state is extremely efficient at generating ¹O₂ and thus enhances the potency of the complexes as PDT agents.

SUBMITTER: Chettri A 

PROVIDER: S-EPMC8323708 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature