Search

Solvothermal reactions of Cu(NO3)2 and 4,4'-([3,4'-bipyridine]-2',6'-diyl)dibenzoic acid (H2L1), 3,3'-([4,4'-bipyridine]-2,6-diyl)dibenzoic acid (H2L2), or 4,4'-([4,4'-bipyridine]-2,6-diyl)dibenzoic acid (H2L3) yielded three new metal-carboxylate frameworks (MCF-28, MCF-29 and MCF-30) with a common formula [Cu2(L)2] (H2L = pyridyldicarboxylic acid). X-ray crystallography showed that MCF-28, MCF-29, and MCF-30 are three-dimensional (3,6)-connected rtl, eea and pyr networks, respectively, based on 3-connected tripodal ligands and 6-connected Cu2(RCOO)4(py)2 units (RCOO and py denote carboxylate and pyridyl groups, respectively). Thermogravimetry, powder X-ray diffraction, and gas adsorption measurements indicated that the three compounds became shrunk and amorphous structures after guest removal. Interestingly, single-crystal X-ray diffraction showed that MCF-28 exhibited drastic temperature-induced framework breathing. [ABSTRACT FROM AUTHOR]

The article discusses a research that investigated the induction of structural phase transition behavior by ligand motion in a polar coordination polymer and a distinct phase behavior in an isomorphic compound when ligand motion was restrained. Topics discussed include displacement of thiocyanate group passing through the copper thiocyanate chain, modulation in the size and geometry of the motional units and role of steric hindrance in the transition behavior of isomorphic compound.

Heterotrinuclear Zn2Ln (Ln = Nd 2, Eu 3, Tb 4, Er 5, Yb 6) clusters [(Znq2)2](μ-CH3COO){Ln(hfac)2} (q= 8-hydroxylquinolinate, hfac = hexafluoroacetylacetonate) have been synthesized. The Zn2Ln framework is ligated by two q ligands featuring μ-phenoxo and two q ligands featuring μ3-phenoxo coordination modes, and one μ-CH3COO−anions. Since the short intramolecular separations of ZnLn (ca.3.354–3.373 Å) allow energy transfer from Znq2-based sensitizers to the LnIIIcentres through two energy transfer pathways, the lanthanide luminescence is indeed “lighted up” by excitation of the Znq2-based chromopores. Photophysical measurements revealed that these Zn2Ln complexes exhibit the so-called “dual emission” originating from both Znq2-based luminophores and lanthanide emitters. By virtue of the dual luminescence with complementary colours, the Znq2-based cyan emission and EuIII-centred red luminescence are combined to generate a white-light emission in the Zn2Eu (3) complex. [ABSTRACT FROM AUTHOR]

A neutral pentadentate ligand, di(pyrazolecarbimido)amine (Hdcadpz), and its adduct with HCIO4, [H2dcadpz]+[ClO4]-, were for the first time isolated from our previously reported [Cu3(dcadpz)2(Hpz)2(CIO4)2](CIO4)2·H2O by the use of (NH4)2S to remove the CuII ions and characterized by IR, EA, UV, NMR, MS, and X-ray crystallography. Reactions of copper(ll) or nickel(ll) nitrate with Hdcadpz in a 1:2 molar ratio generated two mononuclear precursors of [Cu-(dcadpz)2] (1) and [Ni(dcadpz)2]·2/3DMF (2). Furthermore, three new linear homo- and heterotrinuclear complexes of the same motif [M{M′(dcadpz)2}M] (M = CoII, NiII, M′ = CuII, NiII), [{Co(pdm)}2{Cu(dcadpz)2}](NO3)4 (3), [{Ni(pdm)}2{Cu(dcadpz)2}](NO3)4 (4), and [{Ni(MeOH)(H2O)2}2{Ni(dcadpz)2}](NO3)4 (5), were synthesized from these two precursors (pdm = 2,6-pyridinedimethanol) and characterized by X-ray crystallography. Magnetic studies show that the central Cu(dcadpz)2 motif is antiferromagnetically coupled with both the terminal Co(ll) atoms via the dcadpz- ligand in 3 with a J value of -5.27 cm-1 and ferromagnetically coupled with both the terminal Ni(ll) atoms in 4 with a J value of 2.50 cm-1, while 5 behaves only as a Curie paramagnet between 2 and 300 K due to the diamagnetic character of the central square-planar Ni(lI) atom. [ABSTRACT FROM AUTHOR]

Self-assembly of Ni(ii)/Co(ii) with 4,4′-oxybis(benzoate) and 4,4′-bipyridyl under hydrothermal conditions yielded polyrotaxane ring-and-rod double chains and 6-fold interpenetrated (10,3)-a coordination networks. [ABSTRACT FROM AUTHOR]

Selective cleavage of both active and inert C-C bonds in substituted allylcyclopropanes was realized via a novel ligand-controlled approach using zirconocene(II)-1-butene or zirconocene(II)-benzyne complexes. [ABSTRACT FROM AUTHOR]

Synthesis and structural characterization of halfsandwich rare-earth metal tris ( trimethylsilylmethyl) anionic complexes bearing one 1 -phenyl- 2,3,4,5- tetrapropylcyclopentadienyl ligand are achieved. These soluble anionic compounds show good reactivity in the stoichiometric reaction with dibenzoylmethane (DBM) to give the salt-free half-sandwich complex bearing two chelate DBM ligands. More importandy, they can serve as excellent and general catalyst precursors for the addition of different types of amines including primary aromatic amines (ArNH2), acyclic (RR'NH, ArRNH, and ArAr'NH; R, R' = Alkyl group, Ar, Ar' = Aromatic group), or cyclic secondary aliphatic amines to carbodiimides yielding efficiently guanidines. Acyclic secondary amines of the general formula ArAr'NH and ArRNH cannot be achieved efficiently by the previous rare-earth catalysts because of their weak nucleophilicity and steric hindrance. Our results show clearly the reactivities of anionic trialkyl precursors are comparable with the corresponding neutral alkyl complex in the stoichimetric reaction but exhibit better catalytic activity than the known catalysts. [ABSTRACT FROM AUTHOR]