Cu(II)/Ni(II)-organic frameworks constructed from the homometallic clusters by 5-(2carboxyphenoxy) isophthalic acid and N-ligand: synthesis, structures and visible light-driven photocatalytic properties

Four new complexes, namely, Cu2(O-cpia)(btb) 0.5$(OH) (1), Cu3(O-cpia) 2(bpy) 2 (2), [ Ni2(O-cpia)(phen)$(OH)$ H2O]$ 2H2O (3) and [ Ni3(O-cpia) 2(bpy) 3$ 2H2O]$ 2H2O (4) (O-cpia 1/4 5-(2-carboxyphenoxy) isophthalic acid, btb 1/4 1,4-bis(1,2,4-triazol-1-yl) butane, bpy 1/4 4,4 0 -bipyridine) were successfully isolated under hydrothermal conditions. The four complexes exhibit different architectures constructed from different homometallic clusters varying from mononuclear, binuclear to tetranuclear metal(II) polyhedra as Second Building Blocks (SBUs). 1 features a 3D framework constructed from the tetranuclear clusters [ Cu4(m3-OH) 2] as SBUs, linked with Cu(1) O4N and Cu(2) O 5 polyhedra by O-cpia/btb mixed linkers. 2 also exhibits a 3D structure based on trinuclear clusters [ Cu3(COO) 4] SBUs, bridged with Cu(1) O3N2 and Cu(2) O4 polyhedra via O-cpia/bpy mixed ligands. 3 shows a 2D network consisting of tetranuclear clusters [ Ni4(m3-OH) 2] SBUs, which are bridged with Ni(1) O4N2 and Ni(2) O6 through O-cpia ligands. It is worth noting that 4, with a 3D structure, is generated from the binuclear clusters [ Ni2(COO) 4] (Ni(1) O 4 N) and mononuclear metal Ni(2) cores (Ni(2) O4N2) as SBUs, and bridged by O-cpia/bpy mixed ligands. Meanwhile, the degradation of dyes (RhB) by the complexes under visible light irradiation was studied. 1-4 are semiconducting in nature, with Eg of 1.30 eV (1), 1.78 eV (2), 2.85 eV (3) and 2.14 eV (4). Cu(II) complexes 1 and 2 are highly efficient photocatalysts for the degradation of RhB under visible light irradiation.