The design and synthesis of coordination polymers with a self-penetrating architecture has attracted much interest not only due to their interesting structures but also due to their potential applications. 5,5′-Bis(pyridin-4-yl)-2,2′-bithiophene (bpbp), as a conjugated bithiophene ligand, can exhibit trans and cis conformations and this can lead to the construction of a self-penetrating architecture. In addition, the semi-rigid ancillary ligand 4,4′-oxybis(benzoic acid) (H2oba) can adopt different coordination modes, resulting in coordination polymers with high-dimensional skeletons. A new CdII coordination polymer based on mixed ligands, namely poly[diaquapentakis[μ-5,5′-bis(pyridin-4-yl)-2,2′-bithiophene-κ2
N:N′]bis(nitrato-κ2
O,O′)tetrakis(μ3-4,4′-oxydibenzoato)-κ10
O:O,O′:O′′,O′′′;κ6
O:O′:O′′-pentacadmium(II)], [Cd5(C14H14O5)4(NO3)2(C18H12N2S2)5(H2O)2]
n
, (I), has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction indicates that there are three crystallographically independent CdII cations, three bpbp ligands, two deprotonated oba2− ligands, one nitrate ligand and one coordinated water molecule in the asymmetric unit. One CdII centre is seven-coordinated, exhibiting a distorted {CdN2O5} pentagonal bipyramidal geometry, while the other two Cd centres are both six-coordinated, showing slightly distorted {CdN2O4} octahedral geometries. The most interesting feature is the co-existence of trans and cis conformations in a single net, allowing structural interpenetration via self-threading and yet the expected self-penetrating structure was obtained. Topological analysis shows that the whole three-dimensional framework can be classified as a 3-nodal (4,6,6)-c net with Schläfli symbol {613.82}2{66}, which is a new topology. Furthermore, the luminescence properties of (I) were examined in the solid state at room temperature.
Spectral, Thermal, Crystal Structure, Hirshfeld Surface Analyses and Biological Activities of New Hydrazinium Dipicolinato Copper(II) Tetrahydrate