Natural photosynthetic systems precisely position molecular light-harvesting and catalytic modules into complex, hierarchical protein host frameworks which create directional electron transfer pathways and stabilize long-lived charge separated states, and present a structural model for abiotic solar energy conversion.  In this paper, we will describe our recent efforts to implement biological design principles to develop and discover new photocatalysts towards the goal of artificial photosynthesis.  Cobaloximes are among the most promising molecular compounds for H2 electrocatalysis known, and also in photocatalytic schemes when coupled with an appropriate light-harvesting component.   Here we describe a new approach to linked cobaloxime-based photocatalysts through metal-templated macrocycle formation decorated with Ru(II)polypyridyl photosensitizers.  Ultrafast and nanosecond transient optical spectroscopy were used to probe the species formed following photoexcitation.  We find that subtle differences in the linkage between photosensitizer and catalyst sites in these new supramolecular assemblies have dramatic implications for their overall photocatalytic efficiency.  The fundamental structure-function studies will be discussed in the context of actual measures of H2 catalysis efficiency.

Metal-templated self-assembly of cobaloxime-based photocatalysts

244th National Meeting (2012)

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