Synthesis and CO2 photocatalytic reduction of heterometallic one-dimensional titanium-based coordination polymers

Four new transition metal doped one-dimensional titanium-based coordination polymers, [Ti₂L₂M(phen)] (M = Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, L = Embonic acid, phen = 1,10-phenanthroline), have been synthesized under solvothermal conditions utilizing the Ti₄L₆ precursors. In the structure of [Ti₂L₂M(phen)], a dinuclear titanium cluster is formed by coordinating two Ti atoms with two L ligands. The oxygen atoms from the carboxylate groups of the L ligands, which possess vacant coordination sites, further interact with the M(phen) unit, resulting in a Z-shaped one-dimensional chain-like structure. All compounds are determined by single crystal X-ray diffraction analysis, thermogravimetric analysis, PXRD, UV–vis and IR spectra. Notably, all frameworks exhibit excellent stability and can be used as heterogeneous catalysts to reduce CO₂ to syngas (CO+H₂) under light conditions. Specifically, the total yield of syngas for Ti₂L₂Co is up to 20.3 mmol g^–1 h^–1