Tuning strategies for ruthenium-bipyridine phototriggers

Abstract

Abstract Caged compounds, also called phototriggers are formed by a photo-removable protecting group attached to a molecule of interest, hindering its potential interactions or reaction partners. A particular chemical bond is broken when the phototrigger absorbs light of a given wavelength, yielding a non-interacting “cage” and a free interacting molecule. Numerous organic based caged compounds have been devised, and many of them have broad applications, usually in physiology research. The tunability of these phototriggers is scarce, and the common strategy consists in changing the photoremovable group. Conversely, ruthenium-polypyridine caged compounds are built around a Ru center that can accommodate six coordinated molecules or groups including the photo-releasable molecule. The design of the coordination sphere yields many ways to achieve a desired property, or modulate a property, such as hydrophilicity, redox potential, absorption, 2P capabilities, action cross section, etc. In this work we will show how the tuning of quantum yield of photorelease, absorption wavelength and thermal stability is feasible, and discuss the rationale and the limits of the ligand-tuning technique.