Shaping D-pi-A Dyes for Dye-Sensitized Photocatalysis

Dye-sensitized photocatalysis (DSP) is a relatively new approach to convert sunlight into a fuel such as H2. The required optical and electrochemical properties of the dyes employed in DSP are very similar to those necessary for dye-sensitized solar cells (DSC). As a result, the classes of compounds most commonly employed in DSP belong to those classes that have shown the highest efficiencies in DSC. Nevertheless, it's still not clear how the dye structure affects the efficiency of catalysis in H2 production experiments. Thus, the aim of this work is to find reliable guidelines for the synthesis of D-?-A dyes with optimized structures for hydrogen production using different Sacrificial Electron Donors (SED). To date, there are only a few reports concerning the use in DSP of compounds containing the 2,1,3-benzothiadiazole moiety, a scaffold that has already shown impressive power conversion efficiencies in DSC, but no systematic study on their structural optimization. Here, the preparation and application in photocatalytic H2 production of several D-?-A benzothiadiazole-based dyes will be reported. Their photophysical and chemical properties were tuned by a proper choice of terminal groups, ?-spacers and side chains, leading to s in terms of H2 production rate and TON.