Zeolite membrane-based artificial photosynthetic assembly for long-lived charge separation

Abstract

Photochemically generated long-lived charge separation is the key step in processes that aim for conversion of solar energy into chemical energy. In this study, we focus on a Ru polypyridyl complex [(bpy)₂Ru(II)L, bpy = bipyridine, L = 1,2-bis[4-(4'-2,2'-bipyridyl) ethene] encapsulated on the surface of a pinhole-free zeolite membrane by quaternization of L and surrounded with intrazeolitic bipyridinium ions (N,N'-trimethyl-2,2'-bipyridinium ion, 3DQ²⁺). Visible-light irradiation of the Ru complex side of the membrane in the presence of a sacrificial electron donor led to formation of PVS^-. on the other side. Pore-blocking disilazane-based chemistry allows for Na⁺ to migrate through the membrane to maintain charge balance, while keeping the 3DQ²⁺ entrapped in the zeolite. These results provide encouragement that the zeolite membrane based architecture has the necessary features for not only incorporating molecular assemblies with long-lived charge separation but also for ready exploitation of the spatially separated charges to store visible light energy in chemical species.