The Synthesis, Structure And Properties Of Supramolecular Compounds Of Keggin-POMs And2-aminonicotinic Acid

The synthesis and properties of inorganic-organic supramolecular compoundshave aroused people’s wide attention. There is one important research subject ofpolyoxometalate chemistry that polyoxometalates are drawn into the synthesis systemof inorganic-organic supramolecular compounds.In this paper, two POMs-supramolecular compounds with hydrogen bonds as themain force have been synthesized by the Keggin-POMs H4SiW12O40·20H2O and itsderivatives Na9[PW9O34]·7H2O, transition metal copper and2-aminonicotinic acid, inconventional aqueous condition:(2-HANA)2(H2SiW12O40)·4H2O (1)(2-HANA)(H2PW12O40)·5H2O (2)2-ANA=2-aminonicotinic acidA series of characterization of compounds1and2, such as elemental analyses,IR spectra, TG analyses, and single-crystal X-ray diffraction analyses were carried out.The composition and structure of the two compounds are determined, and theelectrochemical and thermal stability properties of compounds1and2wereinvestigated. In the synthesis of compound1, the H4SiW12O40·20H2O was used asmaterials. The hydrogen bonds between the protonated [H2SiW12O40]2-anions andwater molecules, and between2-ANA and water molecules leads to a "ladder-like"double-deck2D supramolecular structure. In the synthesis of compound2, theNa9[PW9O34]·7H2O was used as materials,[PW9O34]9-anions have transformed to[PW12O40]3-anions under the condition of pH=1. The protonated [H2PW12O40]-anions and2-ANA, adjacent [H2PW12O40]-anions form1D chain supramolecularstructure by hydrogen bonds interaction. In a word, different kinds ofpolyoxometalates as starting materials have important influence in the structure ofcompounds1and2. The synthesis of compounds1and2provides the importantreference path in different dimension POMs-supramolecular compounds. Theelectrochemical tests of compounds1and2shows that there are two pairs ofreversible redox peaks.