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Abstract: A series of lanthanide-organic complexes based on polyoxometalates (POMs) [Ln2(DNBA)4(DMF)8][W6O19] (Ln=La(1), Ce(2), Sm(3), Eu(4), Gd(5); DNBA=3,5-dinitrobenzoate; DMF=N,N-dimethylformamide) has been synthesized. These complexes consist of [W6O19]2− and dimeric [Ln2(DNBA)4(DMF)8]2+ cations. The luminescence properties of 4 are measured in solid state and different solutions, respectively. Notably, the emission intensity increases gradually with the increase of solvent permittivity, and this solvent effect can be directly observed by electrospray mass spectrometry (ESI-MS). The analyses of ESI-MS show that the eight coordinated solvent DMF units of dimeric cation are active. They can move away from dimeric cations and exchange with solvent molecules. Although the POM anions escape from 3D supramolecular network, the dimeric state structure of [Ln2(DNBA)4]2+ remains unchanged in solution. The conservation of red luminescence is attributed to the maintenance of the aggregated state structures of dimeric cations. [Copyright &y& Elsevier]

Abstract: Reactions of different metal salts with 3-pyridin-4-yl-benzoic acid (3,4-Hpybz) under ambient condition afford a series of 3-D metal-organic frameworks with two new types of (3,6)-connected net topologies. In the isomorphic complexes [M 2(μ-H2O)(3,4-pybz)4] n (M II=MnII for 1, ZnII for 2, or CdII for 3), the octahedral metal nodes are extended by the 3-connected pybz tectons to constitute 3-D arrays with the Schläfli symbol of (3.4.5)(32.44.55.62.72), whereas [Pb(3,4-pybz)2] n (4) shows a completely different 3-D (42.6)2(44.62.89) framework, which represents a subnet of the (4,8)-connected fluorite lattice. [Copyright &y& Elsevier]