Structural diversity and magnetic properties of six metal-organic polymers based on semirigid tricarboxylate ligand of 3,5-bi(4-carboxyphenoxy)-benzoic acid

Solvothermal reactions of the semirigid 3,5-bi(4-carboxyphenoxy)benzoic acid (H3BCP) and transitional metal cations with the help of three ancillary bridging imidazole linkers afforded six coordination polymers, namely, [Co(HBCP)(1,4-bib)(0.5)](n) (1), {[Mn-1.5(BCP)(1,4-bib)(0.5)(mu(2)-H2O)(H2O)(2)]center dot(1,4-bib)(0.5)}(n) (2), {[Mn-0.5(1,4-bib)(H2O)]center dot(H2BCP)}(n) (3), {[Fe(BCP)(0.5)(HCOO)(0.5)(4,4'-bibp)(0.5)]center dot 2H(2)O}(n) (4), [Ni-2.5(HBCP)(BCP) (4,4'-bibp)(2)(mu(2)-H2O)(H2O)(2)](n) (5), and [Ni(HBCP)(1,4-bidb)(1.5)(H2O)(2)](n) (6), (1,4-bib = 1,4-bis(1H-imidazol-4-yl)benzene, 1,4-bidb = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene, 4,4'-bibp = 4,4'-bis(imidazol-1-yl)-biphenyl). Their structures and properties were determined by single-crystal and powder X-ray diffraction analyses, IR spectra, elemental analyses, thermogravimetric analyses (TGA), and X-ray photoelectron spectroscopy (XPS). Complex 1 displays unusual 2D + 2D -> 2D parallel entangled networks consisting of (3,4)-connected 3,4L83 sheets. Complex 2 exhibits an interesting 2-fold interpenetrated framework with a trinodal (4,4,6)-connected (3.4.5.6(2).7)(2)(3.6.7(4))(2)(3(2).4(2).5(2).6(2).7(6).9) topology. The host network of complex 3 is a 2D 4-connected (4(4).6(2))-sql sheet. Complex 4 affords unprecedented 3D (4,6,6)-coordinated framework with point symbol of (4(5).6)(4(8).6(7))(4(9).6(3).8(3))(2), in which the 1D helix water chains occupy the void channels. Complex 5 can be regarded as a novel self-penetrating (4,4,4,5)-coordinated framework with point symbol of (4.5(4).6)(2)(4.6(5).7.8(3))(2)(5.6.7.8(3))(2)(5(2).8(3).9(2)), which contains two interpenetrated (3,4,4,5)-coordinated (4.5(4).6)(2)(4.6(5).7.8(3))(2)(5.6.7)(2)(5(2).8(3).9(2)) subnets linked by mu(2)-H2O. Complex 6 shows a 1D ladder chain, which are further assembled into a 3D supramolecular structure via O-H center dot center dot center dot O and pi center dot center dot center dot pi interactions. Moreover, magnetic studies indicate that both complex 2 and 4 show antiferromagnetic properties.