pH-dependent assembly of supramolecular architectures from 0D to 2D networks

Five Cu(II)ibenzoate/4,4'-bipy complexes, namely, [Cu(H2O)(benzoate)2(4,4'-bipy)2](benzoic acid)2 center dot(4,4'-bipy) (1), [Cu-2(H2O)(2)(benzoate)(4)(4,4'-bipy)(3)]center dot(H2O)(9) (2), [Cu-2(benzoate)(4)(4,4'-bipy)(3)] (3), [Cu-3(H2O)(4)(benzoate)(6)(4,4'-bipy)(4.5)]center dot(4,4'-bipy) (H2O)(5) (4), and [Cu-3(OH)(2)(H2O)(2)(benzoate)(4)(4,4'-bipy)(2)] (5) (4,4'-bipy = 4,4'-bipyridine), have been synthesized through hydrothermal reaction of copper(II) nitrate, benzoic acid, and 4,4'-bipyridine under different pH conditions. The diverse product structures show the marked sensitivity of the structural chemistry of the aromatic carboxylate ligand to synthesis conditions. Complex 1, which exhibits a zero-dimensional (0D) structure of mononuclear copper(II), is formed at pH = 5.5. At pH = 6.0, dimeric copper(II) complexes of 2 and 3 are formed. Reaction at pH = 7 leads to a one-dimensional (11)) structure of 4. A further increase of the pH to 8.0 results in a two-dimensional (2D) structure of 5. Crystal data are monoclinic, space group P2/n, a = 13.992(4) angstrom, b = 5.7153(14) angstrom, c = 31.126(8) angstrom, beta = 100.513(5)degrees, Z = 2 for 1, monoclinic, space group C2/c, a = 30.283(5) angstrom, b = 15.139(2) angstrom = 14.457(2) angstrom, beta = 112.776(3)degrees, Z = 4 for 2, monoclinic, space group P2(1)/c, a = 5.8317(12) angstrom, b = 21.157(4) angstrom, c = 20.679(4) angstrom , beta = 94.343(3)degrees, Z = 2 for 3, triclinic, space group P (1) over bar, a = 14.016(3) angstrom, b = 18.492(4) angstrom, c = 19.353(4) angstrom, alpha = 66.220(3)degrees, beta = 79.948(4)degrees, gamma = 88.390(3)degrees, Z = 2 for 4, and monoclinic, space group P2(1)/c, a = 5.6880(16) angstrom, b = 17.917(5) angstrom, c 20.904(6) angstrom, beta = 92.959(5)degrees, Z = 2 for 5.