Rational design and structural diversity of copper(II) complexes assembled from 3-sulfobenzoate and 2,2'-bipyridine

Three new Cu-II/3-sb/2,2'-bipy complexes, [Cu(2,2'-bipy)(2)(3-sb)]center dot 4 H2O (1), ([Cu(2,2'-bipy)(3-sb)(H2O)(2)]center dot 2. 5H(2)O}(n) (2), and {[Cu(2,2'-bipy)(3-sb)(H2O)]center dot 2H(2)O}(n) (3), in addition to the our previously reported {[Cu(2,2'-bipy)(3-sb)(H2O)](H2O)}(n) (4) and [Cu(2,2'-bipy)(2)Cl](3-Hsb)center dot 3H(2)O (5) [3-sb = 3-sulfobenzoate dianion; 2,2'-bipy = 2,2'-bipyridine], have been synthesized by hydrothermal reactions or the combination of hydrothermal reactions and solution evaporation. The molecular structure of complex I is a monomer in which the 3-sb monodentately coordinates to the Cut, ion. Complexes 2-4 exhibit one-dimensional infinite chain structures in which the 3-sb ligands serve as bridges. Complex 5 is a cation-anion species in which the 3-Hsb is non-coordinating. Five complexes exhibit four coordination geometries, irregular geometry between square pyramid and trigonal bipyramid in 1, distorted octahedron in 2, square pyramid in 3-4, and trigonal bipyramid in 5. These complexes contain lattice and/or coordinated water molecules, therefore extensive hydrogen bonds occur. The extended hydrogen-bonding architectures are 1-D chains for 4 and 5, 2-D layers for 1 and 3, and 3-D network for 2. Complexes 3 and 4 have same crystal system and space group, and afford similar 1-D frameworks but have different lattice water molecules, therefore the addition lattice water molecule in complex 3 leads to more compact packing, longer metal-lattice water distance, and shorter Cu center dot center dot center dot Cu separation by 3-sb compared to those in complex 4. The fluorescent emissions of complexes 1-3 are stronger than those of ligands, indicating the coordination of 3-sb and 2,2'-bipyridine can enhance the emissions. (C) 2007 Elsevier B.V. All rights reserved.