Via hydrothermal synthesis, the self-assembly of M(II) ions, H3BTC or H2NDC with three structure-related flexible bis(imidazole) ligands, L1, L2, and L3, generated six metal−organic polymers (M = Co, Ni, Zn; BTC = 1,3,5-benzenetricarboxylate, NDC = 1,2-benzenebicarboxylate, L1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L2 = 1,1′-(1,4-butanediyl)bis(imidazole), L3 = 1,1′-(1,4-hexanediyl)bis (imidazole)): {Co3(L1)3(BTC)2(μ-H2O)3·2H2O} n (1), {Zn2(L2)(HBTC)2·2H2O} n (2), {Co(L3)(HBTC)} n (3), {Co(L1) (NDC)} n (4), {Ni(L2)(NDC)} n (5), and {Co(L3) (NDC)} n (6). The structure of 1 is the rare 4-connected self-penetrating metal−organic framework (MOF) with the (63)2(64·82)2(62·84) topology notation; polymers 2 and 6 are two-dimensional (2D) (3,4)-connected and 4-connected nets, respectively. If the O−H…O/2.631 Å hydrogen bonds between HBTC2− dianions are not accounted for, then polymer 3 is a 2D (3,5)-connected net; contrarily, it is a pillar-layered three-dimensional supramolecular framework characterized by (4,5)-connected (42·62·82)(42·68) topology. 4 and 5 show 4-connected MOFs with 65·10 and 65·8 CdSO4-type topology, respectively. Furthermore, their thermal properties are studied by thermogravimetric analysis.

Three series of porous lanthanide metal-organic coordination polymers, namely [Cu(bpy)Ln(3)(ip)(5)(Hip)(H(2)O)] [Ln = Er (1a), Y (1b), Eu (1c); bpy = 2,2'-bipyridine, H(2)ip=isophthalic acid], [Cu(3)(bpy)(2)Ln(2)(ip)(6)(H(2)O)(5)] [Ln = Yb (2a), Gd (2b), Tb (2c)], and [Cu(3)Ln(2)(ip)(6)] [Ln = Eu (3a), Gd (3b)] have been synthesized hydrothermally by the reaction of the combination of 3d-4f metal centers and N-/O-donor ligands. X-ray diffraction analyses reveal that polymers 1a-c and 2a-c, as well as 3a, b are isomorphous in structure. Polymers 1a-c consist of 3D alpha-Po networks based on a inorganic rod-shaped secondary building units (SBUs) of {Er(6)Cu(2)(bipy)(2)(O(2)C)(11)} which are 27.03 A in length. Polymers 2a-c also contain 3D alpha-Po networks, constructed from shorter (14.79 A) but similarly rod-shaped SBUs of {Yb(2)Cu(3)(bpy)(2)(O(2)C)(12)}. The structure also contains hydrogen-bonded (H(2)O)(6) chains which can be reversibly dehydrated/rehydrated. Polymers 3a, b contain metal carboxylate substructures which have 2D (6,3) topologies; these layers are bridged by the ip(2-) ligands to give an overall 3D network which contains two sorts of cavities. This series of Ln-Cu coordination polymers are further characterized by antiferromagnetic behavior.

The first coordination chemistry of a multidentate ligand benzimidazole-5,6-dicarboxylic acid (H2L) was investigated, and six novel two-dimensional (2D) coordination polymers based on this ligand, namely, [MnL] n (1), {[Ni2L2(H2O)4]·3H2O} n (2), {[Tb(L)(HL)(H2O)]·H2O} n (3) and {[Ln2L2(HL)2(H2O)2]} n (Ln = Ho (4), Er (5), Lu (6)), were synthesized under hydrothermal conditions. Compund 1 shows a novel coordination network with 4462 topology and contains unusual five-coordinated one-dimensional {Mn−O} n chains along the b-axis. Compound 2 is a 2D layer structure of 4.82 topology in the ab plane and displays a three-dimensional (3D) supramolecular network via multiple intermolecular hydrogen bonds. Compound 3 also shows a 4462 topology, but its coordination network is completely different from compound 1. Compounds 4−6 were isostructural, and each Ln (Ln = Ho (4), Er (5), Lu (6)) center in the framework acts as a five-connected node to give rise to a unique network with a (3.4.6)(32.4.5.62.74) topology in the ab plane. Six complexes exhibit six types of bridging modes of the ligand. The numbers of L ligands around the metal centers increase from 3 (Ni) to 4 (Mn) and finally to 5 (Ln) as a result of an increase in metal ionic radii. The temperature-dependent magnetic susceptibility data have been explained with the Fisher model, with parameters g = 2.05, J = −3.06 cm−1 for 1, and g = 2.09, J = −0.35 cm−1 for 2, indicating antiferromagnetic coupling. The luminescent properties of 3 were studied.

One novel 3d-4f polymer, namely Gd 3 (IN) 10 (µ-OH 2 ) 6 Cu 5 (µ 2 -Cl) 4 (H 2 O) (1) (HIN ) isonicotinic acid), has been synthesized hydrothermally and characterized by X-ray diffraction analysis. The overall structure motif of polymer 1 is the pillared 3D 3d-4f framework made up of carboxylate-bridged 4f metal layers and diverse pillars, H-shaped pillars, and (double acalixarene)-related pillars. Varibletemperature magnetic susceptibility measurements reveal the occurrence of a significantly dominant ferromagnetic interaction at 70-300 K.

One-pot solvothermal self-assembly is employed to prepare a series of Co3 based porous coordination polymers, viz. 1, [H2N(CH3)2]2[Co3(ip)4]·H2O, 2, [H2N(CH3)2]2[Co3(bdc)4]·(DMF)2, 3, [H2N(CH3)2]2[Co3(bpdc)4]·(CH3OH)2(DMF)1.5, where ip, bdc, bpdc, and DMF are 1,3-benzenedicarboxylate, 1,4-benzenedicarboxylate, 4,4′-biphenyldicarboxylate, and N,N′-dimethylformamide, respectively. Via different organic connectors such as ip, bdc, and bpdc, such Co3 molecular building blocks (MBB), [Co3(CO2)8]2−, are associated together to give a tunable 8-connected topological framework, viz. 42464 for 1, 36414576 for 2, and 36418536 for 3. Upon the geometry and the length of organic connectors, their corresponding porosity occupied by c counterions plus solvent molecules also can be tunable, for example, with the consideration of [H2N(CH3)2]+ counterions, the solvent-accessible volume is 460.2 Å3 for 1, equal to 23.9% of the cell volume, 3320.4 Å3 for 2, equal to 56.3% of the cell volume, 4107.2 Å3 for 3, equal to 50% of the cell volume. Notably, besides these outstanding features of tunable 8-connected topology and porosity, their magnetic properties such as ferromagnetic behavior without magnetic ordering for 1, spin-canting and metamagnetic behavior with magnetic ordering for 2, as well as spin-canting, metamagnetic, and spin-glass behavior with magnetic ordering for 3 also can be tunable.