Modulation of the Excited States of Ruthenium(II)-perylene Dyad to Access Near-IR Luminescence, Long-Lived Perylene Triplet State and Singlet Oxygen Photosensitization
Isabele S. Campos, Andrea Fermi, Barbara Ventura, Carlos André Ferreira Moraes, Gabriel H. Ribeiro, Tiago Venâncio, Paola Ceroni, Rose Maria Carlos
Abstract
Herein, we present a novel ruthenium(II)-perylene dyad (RuPDI-Py) that combines the photophysical properties of pyrrolidine-substituted perylene diimide (PDI-Py) and the ruthenium(II) polypyridine complex [Ru(phen) 3 ] 2+ . A comprehensive study of excited-state dynamics was carried out using time-resolved and steady-state methods in a dimethyl sulfoxide solution. The RuPDI-Py dyad demonstrated excitation wavelength-dependent photophysical behavior. Upon photoexcitation above 600 nm, the dyad exclusively exhibits the near-infrared (NIR) fluorescence of the 1 PDI-Py state at 785 nm (τ fl = 1.50 ns). In contrast, upon photoexcitation between 350 and 450 nm, the dyad also exhibits a photoinduced electron transfer from the {[Ru(phen) 3 ] 2+ } moiety to PDI-Py, generating the charge-separated intermediate state {Ru(III)-(PDI-Py) •– } (4 μs). This state subsequently decays to the long-lived triplet excited state 3 PDI-Py (36 μs), which is able to sensitize singlet oxygen ( 1 O 2 ). Overall, tuning 1 O 2 photoactivation or NIR fluorescence makes RuPDI-Py a promising candidate for using absorbed light energy to perform the desired functions in theranostic applications.