Helicity in Photocatalysis – Advantage or Obstacle? Studies on Silver Complexes – Synthesis, Structure, and Photocatalytic Activity

Abstract

Much attention has been focused recently on the improvement of the photocatalytic efficiencies of known degradation catalysts and the design of new ones. As silver(I) compounds are of high interest in the field of photodegradation owing to their good optical and electron properties concerning their HOMO–LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) band gaps, we have synthesized two new complexes with a Schiff base type ligand (L) of formulas [AgL(OTf)] (OTf = triflate) and [Ag2L2][PF6]2 (monomeric and helical, respectively). In this study, we have shown that the mono- and dinuclear species are both capable of consuming the organic waste in water; however, the monomeric complex [AgL(OTf)] is more active towards the degradation of the model compounds methylene blue (MB) and quinoline yellow (QY) owing to the lability of one of its coordination site. At the same time, the AgI ions in the helical complex [Ag2L2][PF6]2 are hindered in a cavity formed by the two ligands wrapped around them, and this slightly inactivates the complex. However, the helical complex is recyclable, whereas [AgL(OTf)] decomposes after one cycle of irradiation.