Synthesis And Properties Of Extended Structures Based On Waugh-type {MnMo₉} Modified Rare Earth Organic Unit

In recent years,the development of material chemistry has made revolutionary progress from the structure composition to the application of materials.Inorganic nonmetallic materials,as an important branch of material chemistry,have made excellent achievements in the exploitation of new materials and research of properties.Polyoxometalates(POMs),acting as a class of inorganic materials,representing a series of metallic oxygen cluster compounds.Not only polyoxometalates have abundant constituent elements,diverse structural types,abundant surface oxygen atoms,and molecular size at the nanometer level,etc.with superior physical and chemical properties but also have shown important application prospects in the fields of adsorption,sensing and catalysis,etc.,and have become one of the key research directions of inorganic chemistry,materials science and other disciplines.Waugh-type POMs as one of the six kinds of typical structures has been reported rarely compared with other basic structures,in this work,eight novel MnMo9 building block based metal-organic frameworks have been successfully synthesized by introducing suitable amount of rare earth ions and organic ligands via hydrothermal synthesis method,not only these compounds has been characterized by IR,UV,XRD and P-XRD,the catalytic oxidation,photoelectron catalysis,cyanosilylation and oxidation properties of them has also been studied.The paper is mainly divided into the following two parts1.During the experiments,(NH4)6[MnMo9O32]·9H2O was used as precursor,2,6-pyridine dicarboxylic acid ligands and rare earth metals were introduced into the system.A series of three-dimensional rare earth-organic frameworks 1-3 based on the rare earth saturated Waugh type {MnMo9} building units were successfully synthesized according to the self-assembly hydrothermal synthesis methods H[Pr3(H2O)5(2,6-pydc)2(MnMo9O32)]·7H2O(1)H[Nd3(H2O)5(2,6-pydc)2(MnMo9O32)]·7H2O(2)H[La3(H2O)5(2,6-pydc)2(MnMo9032)]·7H2O(3)Which is the first{MnMo9} alkyd metal organic framework modified with 2,6-pyridine dicarboxylic acid and rare earth ions.Compounds 1-3 had optical bandgap widths of 3.9,3.9 and 3.3 eV,respectively and showed good photodegradation activity for organic dyes RhB and MB,besides,these compounds had good catalytic effect on the silonitrile alkylation of aldehydes and the oxidation of thioether.2.We took NH4[MnMo9O32]·9H2O as starting materials,and three kinds of double betaine ligands,1,1'-bis(4-carboxylatobenzyl)-4,4-bipyridinium dichloride(L1),1,1'-bis(4-carboxylatobenzyl)-3,3-bipyridinium dichloride(L2),and 1.1'-(1,4-phenylene-bis(methylene))-bis(pyridine-4-carboxylic acid)(L3)were introduced,respectively,which can coordinate with different rare earth metal via self-assembly method,fortunately,a series of Waugh-type {MnMo9} building unit based one dimensional extended structures 4-8 were obtained.H6[Pr2(H2O)5(L1)2(MnMo9O32)2]·14H2O(4)H5[Pr(H2O)5(L2)(MnMo9O32)]·6H2O(5)H5[La(H2O)5(L2)(MnMo9O32)]·6H2O(6)H6[Pr2(H2O)4(L3)2(MnMo9O32)2]·8H2O(7)H6[La2(H2O)4(L3)2(MnMo9O32)2]·8H2O(8)Compounds 4-8 constructed from L1,L2 and L3 can be seen as the first extended structures based on{MnMo9} units modified by dibetaine ligands and rare earth ions.The optical bandgap widths of compounds 4-8 were 3.6,3.1,3.1,2.1 and 2.1 eV,respectively.Compounds 5-8 showed good photodegradation activity to organic dyes MB,and these 5 compounds could catalyze the oxidation of sulfide to some extent.