Effect of ancillary ligand substitution on photocatalytic hydrogen production

Abstract

Three novel bis(quinolinyl)isothiocyanate-Pt(II) complexes 2, 3 and 4 were synthesized by treating their respective chloride analogues (R1, 1 and R2) with excess KSCN. The confirmation of the synthesis of the complexes was given by a set of analytical techniques. All the –NCS (isothiocyanate) adducts were optoelectronically compared with their respective chloride analogues. Based on their appealing photophysical and electrochemical properties, these were applied for photodriven hydrogen production. Although the turnover number (TON) and the turnover frequency (TOF) of the chloride analogues (R1, 1 and R2) were found to be superior to those of the isothiocyanate analogues (2, 3 and 4), the latter were found to be more operationally sustainable. In addition to this, all the complexes when used as catalysts were found to be molecular in nature as confirmed by XPS, PXRD and SEM analysis, indicating the fact that Pt(II) in the complex was the actual site of proton reduction.