Hydrothermal syntheses and X-ray crystal structures of three inorganic-organic hybrid materials in a copper vanadium phosphate family: CuL(VO₂)(PO₄) (L = 4,4'-bipy, 1,10-phen, 2,2'-bipy)

Three inorganic-organic hybrid compounds with the formula CuL(VO₂)(PO₄), L = 4,4'-bipy, 1,10-phen, and 2,2'-bipy, were hydrothermally synthesized at 160 °C for 120 h and characterized by single-crystal X-ray diffraction. The use of different bidentate organodiamine ligands in initial reaction systems gave rise to the variety in the structures of the products: Cu(4,4'-bipy)(VO₂)(PO₄) (1) and Cu(1,10-phen)(VO₂)(PO₄) (2) crystallize in a monoclinic system with space group C2/c, a = 21.952(4) Å, b = 8.0805(13) Å, c = 15.918(2) Å, β = 110.689(4)°, and V = 2641.5(7) ų, and a = 20.4557(12) Å, b = 11.6231(7) Å, c = 14.6422(8) Å, β = 127.5520(10)°, and V = 2760.0(3) ų, respectively. Cu(2,2'- bipy)(VO₂)-(PO₄) (3) crystallizes in a triclinic system with space group P1, a = 5.561(5) Å, b = 10.271(9) Å, c = 11.780(9) Å, α = 74.31(3)°, β = 79.98(3)°, γ = 85.74(3)°, and V = 637.6(9) ų. The structures of I and 2 possess the same {(VO₂)(PO₄)}2 four-membered rings, whereas the structure of 3 contains {(VO₂)(PO₄)}∞ infinite chains. In terms of the organic parts, the {Cu(4,4'-bipy)}∞ linear chains connect the ((VO₂)(PO₄)}₂ four-membered rings to build up a 3D framework in 1, whereas the Cu(1,10-phen)²⁺ and Cu(2,2'-bipy)²⁺ fragments link with the {(VO₂)(PO₄)}₂ four-membered rings and {(VO₂)(PO₄)}∞ infinite chains to give two 1D structures of 2 and 3, respectively. Their thermal stabilities were investigated.