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RESEARCH PRODUCT

Linking PO43− and HAsO42− anions with a dinuclear [ZnII2] complex: Formation and stabilization of novel decanuclear metallomacrocyclic [ZnII10] and tetranuclear [ZnII4] clusters

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The linkage of PO43- and HAsO42--anions with a newly synthesized five-coordinate dinuclear zinc complex, Zn-2(cpdp)(H2O)(2)]Cl (1) H(3)cpdp =N,N'-bis2-carboxybenzomethyl]-N,N'-bis2-pyridylmethyl]-1,3diamino propan-2-ol], has been explored. In methanol-water, the reaction of 1 with Na2HPO4 center dot 2H(2)O and Na2HAsO4 center dot 7H(2)O/NaBr separately, at ambient temperature, yielded the novel phosphate-bridged decanuclear zinc cluster, (H3O)(4)Zn-10(cPdP)(4)(mu(5)-PO4)(2)(H2O)(6)](6 center dot Cl)center dot 53H(2)O (2) and hydrogen arsenate bridged tetranuclear zinc cluster, Na-2Zn-4(cpdp)(2)(mu(4)-HAsO4)]ClBr center dot 13H(2)O (3), respectively. Analysis of the single crystal X-ray structure discloses that the metallic core of cluster 2 entails eight distorted trigonal bipyramidal and two distorted octahedral zinc ions, displaying a mu(5):eta(2):eta(1):eta(1):eta 1 bridging mode of two POi-groups. The metallic core of cluster 3 holds four distorted trigonal bipyramidal zinc ions, showing a mu(4):eta(1):eta(1):eta(1):eta 1 bridging mode of the HAsO42- group. In solution, UV-Vis titration spectra of complex 1 upon increasing the concentration of the PO43- and HAsO(4)(2-)anions show a significant binding-induced increase in the absorption intensities of 1, accompanied by a substantial red shift. Additionally, the integrity of all three zinc assemblies has been confirmed by H-1 and C-13 NMR spectroscopic data in solution. The thermal behaviors of 1, 2 and 3 have been studied by thermogravimetric analysis (TGA). (C) 2016 Elsevier Ltd. All rights reserved.