Multibranched calix[4]arene based sensitizers for efficient photocatalytic hydrogen production

In the field of direct production of hydrogen from solar energy and water, photocatalytic methods hold great potential especially when metal-free molecular components are preferred. In this work, we have developed a new class of calix[4]arene-based molecular photosensitizers to be used as antenna systems in the photocatalytic production of hydrogen. The structure of the dyes has a typical donor-π-acceptor molecular architecture where a calix[4]arene scaffold is used as an embedded donor. The new materials have been fully characterized in their optical, electrochemical, and photocatalytic properties. The properties conferred by the calix[4]arene donor afforded twice larger performances compared to the corresponding linear system though showing similar quantitative optical properties. The new molecular design paves the way to a new strategy for photocatalytic hydrogen production where the calix[4]arene scaffold can afford more efficient systems and can offer the potential for host-guest supramolecular effects.