Structural Variations in Coordination Polymers of Sodium and Cesium Dicarboxylates

The coordination polymer {[Na₂L(μ-H₂O)(H₂O)₃]·H₂O} _n (1) derived from 2,2′-(phenylmethylidene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H₂ L) has repeat units comprising of hexa-coordinate diaqua-bridged dinuclear sodium complex ions. These units are connected through intervening mononuclear complex parts having penta-coordinated sodium ions. The sodium ions adopt repeated hexameric chair-like arrangement in the polymer. The cesium salt of H₂ L namely [Cs(HL)(μ-H₂O)(H₂O)] _n (2) is a coordination polymer. In this case one acid group of the ligand is deprotonated and 2 form self-assembly by intermolecular hydrogen bonds between the free carboxylic acid groups. The fluoro-substituted ligand 2,2′-(2-fluorophenylmethyledene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H ₂ L _f ) forms disodium salt with a composition [{Na₂L_f(μ-H₂O)(H₂O)₃}·H₂O] _n (3); which is a two dimensional coordination polymer. On the other hand the corresponding cesium salt of H ₂ L _f has a composition [{(H₂O)Cs(μ-H₂O)(μ-L_f)Cs(H₂O)₂}] (4); which is also a 2-D coordination polymer. The cesium ions are six or nine coordinate in the polymer and the coordination polymer possesses unusual Cs···F–C coordination bond.     

二元羧酸稀土热稳定剂的合成和应用研究

通过双滴加法制备了一系列二元羧酸稀土盐，采用稀土离子滴定测定产物的产率，用红外光谱检测其结构，并通过刚果红法和热烘法两种热稳定试验方法研究了二元羧酸稀土盐对聚氯乙烯（PVC）的热稳定作用，并与硬脂酸稀土、二聚酸钙等热稳定剂作了比较。结果表明，二元羧酸稀土盐能有效延长PVC的热稳定时间，减缓PVC的变色速度，尤其是二聚酸镧碱式盐（Ⅱ）可使PVC刚果红变色时间长达74min，180℃热烘90min基本不变色；不同稳定剂对PVC热稳定效果的对比发现相同酸根的镧盐热稳定效果比铈盐好，己二酸的稀土盐热稳定效果差于二聚酸的铈盐，二聚酸碱式盐热稳定效果好于二聚酸正盐。     

Syntheses and Characterization of Three Coordination Polymers of Zinc(II) and Cadmium(II) with Dicarboxylates and Bis(thiabendazole) Ligands

Three d ¹⁰ coordination polymers formulated as [Zn(L1)₂(mip)] _n (1), [Zn(L1)(2,6-ndc)] _n (2) and [Cd(L2)_0.5(bpdc)] _n (3) (L1 = 1,1′-(1,3-propanediyl)bis(thiabendazole), L2 = 1,1′-(1,6-hexanediyl)bis(thiabendazole), H₂mip = 5-methylisophthalic acid, 2,6-H₂ndc = 2,6-naphthalenedicarboxylic acid, H₂bpdc = 4,4′-biphenyldicarboxylic acid) were hydrothermally synthesized. Complexes 1–3 were characterized by elemental analysis, IR spectroscopy, X-ray powder diffraction analysis, and single crystal X-ray diffraction. Complexes 1 and 2 present different chain structures, both of them are extended into 2D supramolecular architectures via C–H···O hydrogen bonds, while 3 is a three-fold interpenetrating three-dimensional framework with binodal 4,4-connected mog topology. The thermal stability, UV–visible spectroscopy and luminescence properties of complexes 1–3 were also examined. Furthermore, complex 3 exhibits relatively positive catalytic activity towards the degradation of methyl orange in a Fenton-like process.