Synthesis, crystal structure and optical properties of a naphthylbisimide-Ni complex: a framework on TiO2 for visible light H2 production.

A novel ligand N,N'-di-(3-(pyridin-2-yl)-1H-pyrazole-5-carbohydrazide) naphthalene 1,4,5,8-tetracarboxylic acid bisimide (PPNB) and its nickel (ii) complex (Ni-PPNB) were synthesized and systematically characterized. Both the molecules show higher sensitization activity on the TiO2 semiconducting system. These composites have interesting photophysical properties as they enable photocatalytic hydrogen production from water with a sacrificial electron donor (SED) using visible light, while neither component alone is able to do so. The photocatalysts have shown long term stability and a maximum turnover number (TON) of 7866 based on Ni-PPNB was obtained after 6 h of irradiation at a catalyst concentration of 2.5 × 10(-5) mol g(-1).