pH-Dependent Assembly of Supramolecular Architectures from 0D to 2D Networks

Five Cu(II)/benzoate/4,4‘-bipy complexes, namely, [Cu(H 2 O)(benzoate) 2 (4,4‘-bipy) 2 ](benzoic acid) 2 ·(4,4‘-bipy) ( 1 ), [Cu 2 (H 2 O) 2 (benzoate) 4 (4,4‘-bipy) 3 ]·(H 2 O) 9 ( 2 ), [Cu 2 (benzoate) 4 (4,4‘-bipy) 3 ] ( 3 ), [Cu 3 (H 2 O) 4 (benzoate) 6 (4,4‘-bipy) 4.5 ]·(4,4‘-bipy)·(H 2 O) 5 ( 4 ), and [Cu 3 (OH) 2 (H 2 O) 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 (1D) 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 P 2/ n, a = 13.992(4) Å, b = 5.7153(14) Å, c = 31.126(8) Å, β = 100.513(5)°, Z = 2 for 1, monoclinic, space group C 2/ c, a = 30.283(5) Å, b = 15.139(2) Å, c = 14.457(2) Å, β = 112.776(3)°, Z = 4 for 2, monoclinic, space group P 2 1 / c, a = 5.8317(12) Å, b = 21.157(4) Å, c = 20.679(4) Å, β = 94.343(3)°, Z = 2 for 3, triclinic, space group P 1̄, a = 14.016(3) Å, b = 18.492(4) Å, c = 19.353(4) Å, α = 66.220(3)°, β = 79.948(4)°, γ = 88.390(3)°, Z = 2 for 4, and monoclinic, space group P 2 1 / c, a = 5.6880(16) Å, b = 17.917(5) Å, c = 20.904(6) Å, β = 92.959(5)°, Z = 2 for 5 .