Three interpenetrated frameworks constructed by long flexible N,N′-bipyridyl and dicarboxylate ligands

Article abstract of DOI:10.1016/j.poly.2005.06.026

Three interpenetrated polymeric networks, {[Co(bpp)(OH-BDC)]·H ₂O}_n (1) [Ni(bpp)_1.5(H₂O)(OH-BDC)] _n (2) and {[Cd(bpp)(H₂O)(OH-BDC)]·2H ₂O}_n (3), have been prepared by hydrothermal reactions of 1,3-bis(4-pyridyl)propane (bpp), 5-hydroxyisophthalic acid (OH-H ₂BDC), with Co(NO₃)₂·6H₂O, Ni(NO₃)₂·6H₂O and Cd(NO ₃)₂·4H₂O, respectively. Single-crystal X-ray diffraction analyses reveal that the three compounds all exhibit interpenetrated but entirely different structures. Compound 1 is a fourfold interpenetrated adamantanoid structure with water molecules as space fillers, in which bpp adopts a TG conformation (T = trans, G = gauche). Compound 2 is an interdigitated structure from the interpenetrated long arms of one-dimensional molecular ladders, while bpp in 2 adopts both TT and TG conformations. Compound 3 is a twofold interpenetrated three-dimensional network from a one-dimensional metal-carboxylate chain bridged by TG conformational bpp. The hydrogen bonding interactions in 1-3 further stabilize the whole structural frameworks and play critical roles in their constructions.