Photochemistry using a host–guest charge transfer paradigm: DMABN as a dynamical probe of ground and excited states

Abstract

Photoexciting charge transfer (CT) transitions arising from host–guest interactions in a confined environment can efficiently yield kinetically trapped radicals. In order to predispose these photogenerated radicals for diffusion limited reactions it becomes imperative to understand the nature of the host–guest CT interactions in the ground and excited states. Here we probe the heterogeneity of guest orientations and the ensuing excited state charge transfer dynamics of an electron-rich molecular probe N,N-dimethylaminobenzonitrile (DMABN) incarcerated inside an electron deficient water-soluble cationic Pd₆L₄¹²⁺ nanohost. Using a combination of ¹H-NMR, resonance Raman spectrosocopy, and pump–probe spectroscopy we highlight the necessary challenges that need to be addressed in order to use molecular cages as photocatalytic reaction vessels.