Interrogation of cobaloxime-based supramolecular photocatalyst architectures

This perspective provides a discussion of recent work focused on elucidating the fundamental interactions of artificial photosynthesis in newly developed supramolecular photocatalysts composed of linked chromophore and catalyst modules. Supramolecular photocatalyst architectures are of particular interest because of their potential to overcome many of the limitations of molecular or multimolecular systems and amenability to conventional and emerging physical characterization techniques. As such, changes to the oxidation state and/or physical structure of either chromophore or catalyst modules in response to light excitation is readily monitored with high spatial and temporal resolution. To illustrate this approach, the design evolution of photocatalysts based on Ru(II)poly(pyridyl) chromophores linked to cobaloxime-based H2 catalysts is discussed. In this work, new synthesis, transient optical spectroscopy, and X-ray scattering were combined to develop next generation photocatalysts capable of ultrafast charge transfer and identification of a key intermediate for hydrogen photocatalysis. Recent and upcoming advances in light source capabilities are ideally suited to monitor light-generated transient structures and well-poised to dramatically impact the drive toward technologically relevant systems for artificial photosynthesis.