Syntheses, Structures And Properties Of Heteropolyoxomolybdates Constructed By Multicarboxylic Acids

Carboxylic acids, as an important subclass of organic ligands, have wide varieties and various structures as well as rich coordination modes. In this paper, in the light of molecular design and assembly, making use of ammonium heptamolybdate and multicarboxylic acids as the reactants, three different series of heteropolyoxomolybdates constructed by multicarboxylic acids have been successfully synthesized under conventional aqueous method by changing the central atoms and multicarboxylic acid ligands. The seventeen compounds were further charactered by single-crystal X-ray diffraction, spectroscopic properties (IR, XRPD, UV), thermogravimetric analyses (TG). Further, the photochromism and thermochromism of some compounds were studied systematically.This dissertation contains:1. Eight heteropolyoxomolybdates constructed by benzene-1,3,5-triacetic acid Cs5[(HPMo6O21){C9H9(COO)3}]·7H2O (1), [(CH3)4N]2H3[(HPMo6O2]){C9H9(COO)3}]·3H2O (2), Cs5 [(SeMo6O21){C9H9(COO)3}]·6H2O (3), [(CH3)4N]2H3[(SeMo6O2]){C9H9(COO)3}]·2H2O (4), (NH4)6 [(AsMo6O21){C9H9(COO)3}]·7H20 (5), (NH4)6[(SbMo6O21){C9H9(COO)3}]·3H2O (6), Cs5[(TeMo6 O21){C9H9(COO)3}]·7H2O (7) and [(CH3)4N]2H3[(TeMo6O21){C9H9(COO)3}]·4H2O (8) have been successfully obtained for the first time. They are all monomers with the similar bowl shaped structures, which are consist of{XMo6} (X= P, Se, As, Sb, Te) unit and benzene-1,3,5-triacetic acid ligand. This series of compounds show interesting photochromism and some of them also represent thermochromism.2. Four heteropolyoxomolybdates constructed by 1,3,5-benzenetricarboxylic acid (CN3H4)6H14[(HPMo6O21)4{C6H3(COO)3}4]·16H2O (9), (CN3H4)16H4[(SeMo6021)4{C6H3(CO O)3}4]-34.5H2O (10), (NH4)24[(SbMo6O21)4{C6H3(COO)3}4]-8H2O (11) and (CN3H4)16H4 [(TeMo6O21)4{C6H3(COO)3}4]16H2O (12) have been successfully obtained. They are tetramers with the same structures, which are consist of four{XMo6} (X= P, Se, Sb, Te) units and four 1,3,5-benzenetricarboxylic acid ligands alternately connecting to form a cage with large inner volume. Several of this series of compounds represent attractive photochromism and thermochrom i sm.3. Five heteropolyoxomolybdates constructed by aliphatic dicarboxylic acids (C3N2H5)6(CH3)4N]H3[(WMo6O2,)2{OOC(CH2)6COO}3]·3H2O (13),(NH4)8(C3N2H5)2H2[(SbMo6O21)2 {OOC(CH2)6COO}3]·8H2O (14), (C3N2H5)8H2[(TeMo6O21)2{O2C(CH2)6CO2}3]·3.5H2O (15),(NH4)4(C3N2 H5)4H4[(SbMo6O21)2{OOC(CH2)4COO}3]·7H2O (16) and (C3N2H5)4H6[(TeMo6O21)2 {O2C(CH2)2CO2}3]·9.5H2O (17) have been successfully obtained. They are dimers with the same pillar shaped structures, which are consist of two{XMo6} (X= P, Sb, Te) units and three aliphatic dicarboxylic acid ligands. These compounds also show intriguing photochromism and thermochromism.