Self-assemblies of the semirigid dipolar ligand 1,4-bis(benzimidazol-1-ylmethyl)benzene (L) with zinc and cobalt salts have led to six new complexes, namely, 5), and {[Co(L) 2 (DMF) 2 ](ClO 4 ) 2 } n (6), respectively. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. Compounds 1 and 2 are isomorphous and present one-dimensional chain-like structures. It is interesting that three-dimensional (3D) organic-inorganic hybrid frameworks containing meso-helical chains (P + M) have been observed in the solid-state of 1 and 2, in which meso-helical chains are alternately trapped by the cooperative association of coordination interactions as well as hydrogen bonds. With the replacement of Zn II /Co II nitrate salts with ZnCl 2 or CoCl 2 in the above reactions, the resulting complexes 3 and 4 contain P-helical and M-helical chains with 2 1 screw axis but crystallize as a racemate. Through π • • • π stacking interactions between two well-overlapping benzimidazoleyl rings from two adjacent chains, the 3D racemic supramolecular network is further assembled. However, reaction of M(ClO 4 ) 2 (M ) Zn( 5), Co( 6)) and L yields two high dimensional compounds 5 and 6 with helical character, in which compound 5 has a two-dimensional (2D) (4,4) wave-like layer constructed by vertical crossing of the left-(M) and right-(P)-handed helical chains with the central Zn II ions as the hinge nodes, and similarly, the final 3D supramolecular structure is assembled via weak π • • • π interactions between two central benzene rings from two adjacent ligands L of two neighboring 2D layers. Compound 6 presents a four-connected 3-fold interpenetrated 3D diamondoid network containing meso-helical chains along two mutually perpendicular directions, respectively. Furthermore, the photoluminescent properties of compounds 1, 3, and 5 were studied.

Self-assembly of the symmetrical tetradentate N2O2 donor Schiff base ligand, that is, bis(salicylidene)trimethylenediamine (sy-H2L3), with different zinc salts has led to six anion-dependent complexes, namely, [Zn3(sy-L3)2(μ2-Cl)Cl(C2H5OH)]·C2H5OH (1), Zn[Zn(sy-L3)(μ2-NO2)(C2H5OH)]2·2H2O (2), Zn[Zn(sy-L3)(μ2-CH3COO)]2 (3), Zn(DMF)2[Zn(sy-L3)(H2O)(SCN)]2 (4), Zn[Zn(sy-L3)(μ2-HCOO)(DMF)]2·H2O (5) and Zn[Zn(sy-L3)(μ2-HCOO)]2 (6), respectively. Six compounds were characterized by elemental analyses, IR spectra, mass spectrometry and thermogravimetric analyses, of which five structures 1, 2, 4, 5, and 6 were further determined by single-crystal X-ray diffraction analyses, and compound 3 was previously reported in the literature. It was observed that μ2-bridges in these trinuclear complexes were formed through the phenolic oxygens of the ligand or the anions in the medium. In the presence of nitrite (for 2), acetate (for 3), thiocyanate (for 4), or formate (for 5−6), μ2-bridges formed between a pair of adjacent zinc atoms resulting in linear trinuclear complexes with one symmetrical center. However, μ2-bridges involving chloride and the phenolic oxygens of ligand sy-H2L3 led to the formation of a V-shaped trinuclear complex 1. It is noteworthy that in the assembling process of complexes 4−6, when the appropriate amount of DMF was added to the reaction mixture, thiocyanate anion coordinated to the terminal Zn2+ ion in a η1-N coordination manner and gave compound 4 with a coordination of water molecules and DMF molecules to the terminal and the middle zinc ions in a range from room temperature to 70 °C. Above ∼70 °C, C−N bond cleavage of part of the solvent DMF molecules induced the formation of compound 5 with coordination of formate and DMF to Zn2+. Upon increasing the temperature higher than 110 °C, because of the decomposition of a large number of DMF molecules, the same reaction produced trinuclear complex 6, in which only formate coordinated to a pair of the adjacent zinc atoms in a μ2-bridging coordination fashion. In addition, photoluminescent properties and biological activities of ligand sy-H2L3 and six corresponding compounds were also studied.

A family of lanthanide-zinc coordination polymers with two different types of three-dimensional (3-D) frameworks based on 4,5-imidazoledicarboxylic acid and oxalic acid, namely,2), Sm (3), Eu (4), and H 3 ImDC = 4,5-imidazoledicarboxylic acid, H 2 ox = oxalic acid) and 5), Dy (6), Ho (7), Er (8), Yb (9), and Lu (10)), were successfully constructed under certain conditions and characterized by elemental analysis, IR, thermogravimetric (TG), and single-crystal X-ray diffraction. The results reveal that compounds 1À4 (I structure) are isomorphous 3-D coordination frameworks containing two-dimensional (2-D) [Zn 2 (ImDC) 2 ] layers and one-dimensional (1-D) Ln 2 (μ 2 -O) 2 (ox) sine wave-like chains with 1-D square channels, while 4 0 À10 coordination polymers (II structure) are also isomorphous and feature 3-D pillar-layered coordination frameworks constructed from 2-D Zn-carboxylate [Zn 2 (ImDC) 2 ] layers and Ln 2 (ox) pillars with 1-D flat channels. The structural variation from I to II with the europium ion as a critical point, in which two types of europium complexes 4 and 4 0 can reversibly transform into each other, may be attributed to the lanthanide contraction effect. Meanwhile, the adsorption and photoluminescent properties of the partial compounds are also investigated.

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