Supramolecular activation of a molecular photocatalyst

Abstract

The effects of the planar aromatic organic molecules anthracene and pyrene on the catalytic performance of the intramolecular hydrogen evolving photocatalyst [Ru(tbbpy)₂(tpphz)PdCl₂](PF₆)₂ functioning as a photocatalytic dyad have been studied. ¹H-NMR studies on [Ru(tbbpy)₂(tpphz)PdCl₂](PF₆)₂ and [Ru(tbbpy)₂(tpphz)](PF₆)₂ show a pronounced interaction of pyrene with the ruthenium complexes due to π–π-interactions. The solid state structure of [Ru(tbbpy)₂(tpphz)PdCl₂]₂[Mo₈O₂₄] shows a pronounced π–π-stacking of the polyaromatic ligands. In addition, dimerization constants for the complexes and association constants between the complexes and pyrene were determined. Studies on the photocatalytic hydrogen production show a decreased induction phase and increased turn over frequencies during the initial phase of the catalysis in the presence of anthracene and pyrene utilising the catalyst [Ru(tbbpy)₂(tpphz)PdCl₂](PF₆)₂ irrespective of the nature of the polycyclic aromatic hydrocarbon.