Excited-State Dynamics of a Two-Photon-Activatable Ruthenium Prodrug.

Simon E Greenough,Nichola A Smith,Peter J Sadler,Martin J Paterson,Michael D Horbury,Vasilios G Stavros

doi:10.1002/cphc.201501075

Abstract

We present a new approach to investigate how the photodynamics of an octahedral ruthenium(II) complex activated through two‐photon absorption (TPA) differ from the equivalent complex activated through one‐photon absorption (OPA). We photoactivated a RuII polypyridyl complex containing bioactive monodentate ligands in the photodynamic therapy window (620–1000 nm) by using TPA and used transient UV/Vis absorption spectroscopy to elucidate its reaction pathways. Density functional calculations allowed us to identify the nature of the initially populated states and kinetic analysis recovers a photoactivation lifetime of approximately 100 ps. The dynamics displayed following TPA or OPA are identical, showing that TPA prodrug design may use knowledge gathered from the more numerous and easily conducted OPA studies.

Highlights

We present a new approach to investigate how the photodynamics of an octahedral ruthenium(II) complex activated through two-photon absorption (TPA) differ from the equivalent complex activated through one-photon absorption (OPA)
Ruthenium pyridyl complexes have been deployed in a myriad of technological and medical applications, such as light harvesting,[1] light-emitting devices,[2] fluorescence imaging,[3] cytotoxic action,[3b,4] and, of particular relevance to the present study, photodynamic therapy (PDT).[5,6]
PDT is used to treat a number of skin conditions,[9] a major hindrance to its more widespread usage is the low transmittance of UV and visible light through biological tissue, with a transmission, or PDT window, existing between 620 and 1000 nm.[10]

Summary

Introduction

We present a new approach to investigate how the photodynamics of an octahedral ruthenium(II) complex activated through two-photon absorption (TPA) differ from the equivalent complex activated through one-photon absorption (OPA). We photoactivated a RuII polypyridyl complex containing bioactive monodentate ligands in the photodynamic therapy window (620–1000 nm) by using TPA and used transient UV/Vis absorption spectroscopy to elucidate its reaction pathways.

Results

Conclusion