Ionothermal synthesis of novel Pb–OH–Cu–X (X = Cl, Br and I) quaternary heterometallic frameworks with tunable optical properties

Abstract

Reported herein is the new application of ionothermal synthesis for inorganic optical materials. Under ionothermal conditions with different imidazolium ionic liquids, novel quaternary heterometallic frameworks based on [Pb₄(OH)₄] cubane and [CuCl₄] or [CuBr₄] chains and [Cu₂I₆] binuclear clusters have been successfully produced. Simple chlorine, bromine and iodine replacement leads to not only the space group change (tetragonal I41/acd for 1 and 2, and orthorhombic Fddd for 3) but also the topological net transformation (8,12-net for 1 and 2, and 6,6-net for 3). Notably, compounds 1, 2 and 3 all show tunable solid-state semiconducting and luminescence properties.