Cation effect on the inorganic–organic layered structure of pyrazole-4-sulfonate networks and inhibitory effects on copper corrosion
作者:Isurika R. Fernando、Nikos Daskalakis、Konstantinos D. Demadis、Gellert Mezei
DOI:10.1039/b9nj00361d
日期:——
The present study demonstrates that the pyrazole-4-sulfonate anion (4-SO3-pzH = Lâ) is a versatile ligand for the preparation of layered, 3-D solid state lattices. The ligand itself can coordinate to metals with both its sulfonate group and aromatic N-atom, as well as participate in hydrogen bonding both as donor and acceptor, and form various extended ÏâÏ networks. Five new complexes with Rb+, Cs+, Mg2+, Sr2+ and Cu2+ have been prepared and characterized including single crystal X-ray diffraction: RbL, tetragonal I41/a, a = 9.7332(4) Ã
, b = 9.7332(4) Ã
, c = 29.941(1) Ã
, V = 2836.5(2) Ã
, Z = 16; CsL, monoclinic P21/c, a = 8.821(1) Ã
, b = 8.109(1) Ã
, c = 9.889(2) Ã
, β = 91.560(3)°, V = 707.1(2) Ã
, Z = 4; Mg(H2O)6L2, triclinic P, a = 7.0543(7) Ã
, b = 7.7307(8) Ã
, c = 8.6389(9) Ã
, α = 72.572(2)°, β = 74.370(2)°, γ = 76.045(2)°, V = 426.22(8) Ã
, Z = 1; SrL2, triclinic P, a = 6.027(2) Ã
, b = 7.243(3) Ã
, c = 14.186(5) Ã
, α = 92.491(8)°, β = 101.383(7)°, γ = 97.471(7)°, V = 426.22(8) Ã
, Z = 2; Cu(H2O)2L2·4H2O, monoclinic P21/c, a = 9.032(1) Ã
, b = 13.297(1) Ã
, c = 7.7103(9) Ã
, β = 109.747(2)°, V = 871.5(2) Ã
, Z = 2. The varying size and charge of the cations in these five complexes produce unique, alternating inorganicâorganic layered materials. We find a correlation between the size and charge of cations and the coordination mode of the ligand as well as hydration of the metal, but no correlation between the nature of the cation and the thickness of the inorganic/organic layers. We conclude that the overall 3-D structure of these layered materials is determined by a subtle balance between the coordination preferences of the metal ion and an intricate lattice of hydrogen bonds and aromatic interactions. Ligand HL and its complexes with Na, K, Rb, Cs, Mg, Ca, Sr and Ba were tested as potential corrosion inhibitors of copper metal surfaces at three different pH values (2, 3, and 4). All the above mentioned compounds show significant corrosion inhibition at pH 4 and 3, while no activity is observed at pH 2. The correlation of inhibition activity with pH of ligand HL and its different metal complexes is discussed.
本研究表明,吡唑-4-磺酸阴离子(4-SO3-pzH = Lâ)是一种多功能配体,可用于制备层状三维固态晶格。配体本身可以通过其磺酸盐基团和芳香 N 原子与金属配位,也可以作为供体和受体参与氢键作用,并形成各种扩展的 ÏâÏ 网络。我们制备了五种与 Rb+、Cs+、Mg2+、Sr2+ 和 Cu2+ 的新配合物,并对其进行了单晶 X 射线衍射表征:RbL, tetragonal I41/a, a = 9.7332(4) à , b = 9.7332(4) à , c = 29.941(1) à , V = 2836.5(2) à , Z = 16; CsL, monoclinic P21/c, a = 8.821(1) à , b = 8.109(1) à , c = 9.889(2) à , δ = 91.560(3)°, V = 707.1(2) à , Z = 4; Mg(H2O)6L2, 三斜 P, a = 7.0543(7) à , b = 7.7307(8) à , c = 8.6389(9) à , δ = 72.572(2)°, δ = 74.370(2)°, δ³ = 76.045(2)°, V = 426.22(8) à , Z = 1; SrL2, 三菱 P, a = 6.027(2) à , b = 7.243(3) à , c = 14.186(5) à , δ± = 92.491(8)°, δ² = 101.383(7)°, δ³ = 97.471(7)°, V = 426.22(8) à , Z = 2; Cu(H2O)2L2Â-4H2O, 单斜 P21/c, a = 9.032(1) à , b = 13.297(1) à , c = 7.7103(9) à , δ² = 109.747(2)°, V = 871.5(2) à , Z = 2.这五种络合物中阳离子的大小和电荷的变化产生了独特的、交替的无机有机层状材料。我们发现阳离子的大小和电荷与配体的配位模式以及金属的水合作用有关,但阳离子的性质与无机/有机层的厚度无关。我们的结论是,这些层状材料的整体三维结构是由金属离子的配位偏好与氢键和芳香族相互作用的复杂晶格之间的微妙平衡决定的。配体 HL 及其与 Na、K、Rb、Cs、Mg、Ca、Sr 和 Ba 的配合物作为铜金属表面的潜在缓蚀剂,在三个不同的 pH 值(2、3 和 4)下进行了测试。讨论了配体 HL 及其不同金属配合物的抑制活性与 pH 值的相关性。