Crystal engineering of a versatile building block toward the design of novel inorganic–organic coordination architectures

Abstract

Six novel inorganic–organic coordination supramolecular networks based on a versatile linking unit 4-pyridylthioacetate (pyta) and inorganic Co^II, Cu^II, Ag^I, Zn^II, Mn^II and Pb^II salts have been prepared in water medium and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of CoCl₂·6H₂O with Hpyta afforded a neutral mononuclear complex [Co(pyta)₂(H₂O)₄] (1), which exhibits a two-dimensional (2-D) layered architecture through intermolecular O–H⋯O interactions. Reaction of CuCl₂·2H₂O with Hpyta yielded a neutral one-dimensional (1-D) coordination polymer {[Cu(pyta)₂(H₂O)]·0.5H₂O}_n (2) consisting of rectangle molecular square units, which show a three-dimensional (3-D) supramolecular network through S⋯S and O–H⋯O weak interactions. However, when AgNO₃, Zn(OAc)₂·2H₂O or MnCl₂·4H₂O salts were used in the above self-assembled processes, the neutral 2-D coordination polymers [Ag(pyta)]_n (3), {[Zn(pyta)₂]·4H₂O}_n (4) or {[Mn(pyta)₂(H₂O)]}_n (5) with different topologies were obtained, respectively. While substituting the transition metal ions used in 1–5 with Pb(OAc)₂·3H₂O, a one-dimensional coordination polymer [Pb(pyta)₂]_n (6), which shows a novel 2-fold interpenetrating 2-D supramolecular architecture through weak S⋯S interactions, was isolated. It is interesting to note that the building block pyta anion exhibits different configurations and coordination modes in the solid structures of complexes 1–6. These results indicate that the versatile nature of this flexible ligand, together with the coordination preferences of the metal centers, play a critical role in construction of these novel coordination polymers or supramolecules. The spectral and thermal properties of these new materials have also been investigated.