| In this dissertation, twenty transition-metal-lanthanide heterometallic polyoxotungstates have been hydrothermally synthesized by reaction of K8Na2[A-a-GeW9O34]·25H2O or Na9[B-a-SbW9O33]·19.5H2O precursors with transition metal(TM) cations and lanthanide (Ln) cations in the presence of organic carboxylic acid ligands by adjusting the pH, reaction time, reaction temperature and the molar ratio of reactants, and further characterized by elemental analyses, single crystal X-ray diffraction, infrared spectroscopy and thermogravimetric analyses.By introducing different organic carboxylic acid ligands (from monocarboxylic to multicarboxylic ligands) into the TM-Ln-tungstogermanate/ tungstoantimonate systems, TM-Ln heterometallic polyoxotungstates with different structural characteristics were obtained, indicating that the inherent nature of carboxylic acid ligands plays a directing and controlling role in the construction of the final architectures, synchronously highlighting the structure-direcing role of carboxylate linkages in the assembly process of the multidimensional frameworks. Furthermore, photoluminescence behaviors of some compounds have been investigated.This dissertation will be divided into three parts to expand my work:In the first section, the main developments of TM-Ln heterometallic polyoxotungstates have been summarized.In the second section, six acetate-bridged mono-Ln-substituted dimeric 3d-4f heterometallic Keggin-type tungstogermanates [Cu(en)2(H2O)]6[Nd(H2O)(CH3COO)(?-GeW11O39)]2·8H2O(1),[Cu(en)2(H2O)]6[Sm(H2O)(CH3COO)(?-GeW11O39)]2·8H2O(2), [Cu(en)2(H2O)]6[Eu(H2O)(CH3COO)(a-GeW11O39)]2·8H2O(3),[Cu(en)2(H2O)]6[Gd(H2O) (CH3COO)(?-GeW11O39)]2·8H2O(4), [Cu(en)2(H2O)]6[Dy(H2O)(CH3COO)(?-GeW11O39)]2·8 H2O (5) and [Cu(en)2(H2O)]6[Ho(H2O)(CH3COO)(?-GeW11O39)]2·8H2O (6) have been successfully prepared under hydrothermal conditions.1-6 are obtained by reacting the K8Na2[A-?-GeW9O34]·25H2O precursor with Cu2+ and Ln3+ ions in the existence of organic ligands. The isomorphic 1-6 are isolated structures, featuring that two mono-Ln-substituted monolacunary Keggin-type [a-GeW11O39]8- units are linked by two acetate ligands into a sandwich-type dimer with six appended [Cu(en)2]2+ cations. The solid-state photoluminescence measurements of 3 and the KgNa2[A-a- GeW9O34]·25H2O precursor have been performed. The photoluminescence properties of 3 mainly originate from the characteristic emission of the Eu3+ ions. Moreover, tungstogermanate cluster also makes some contribution to the photoluminescence behavior of 3.In the third section, six 3-D Fe?-Ln? heterometallic tungstoantimonates Na4[La (H2O)5]2[Fe4(H2O)2(pic)4(SbW9O33)2]·40H2O(7),Na4[Pr(H2O)5]2[Fe4(H2O)2(pic)4(SbW3O33)2]·40 H2O(8), Na4[Nd(H2O)5]2[Fe4(H2O)2(pic)4(SbW9O33)2]·40H2O(9),Na4[Sm(H2O)5][Fe4(H2O)2 (pic)4(SbW9O33)2]·40H2O(10) and Na4[Eu(H2O)5]2[Fe4(H2O)2(pic)4(SbW93O33)2]·40H2O(11) have been successfully made under hydrothermal conditions by introducing TM, Ln cations and organic carboxylate ligands into the Na9[B-?-SbW9O33]·19.5H2O system.7-11 are isostructural and represent the first carboxylate ligands functionalized 3-D Fe?-Ln? heterometallic tungstoantimonates. The main skeleton is composed of an organic-inorganic hybrid [Fe4(H2O)2(pic)4(SbW9O33)2]10-polyanion with two [Ln(H2O)5]3+ cations on both sides.The [Fe4(H2O)2(pic)4(SbW9O33)2]10- polyanion consists of two [SbW9O33]9- units bridged by the central belt{Fe4(H2O)2(pic)4}, which is further connected by the pic and Ln linkers from neighboring structural units into a novel 3-D extended framework. From the viewpoint of topology,7-11 exhibit the 3,6-connected (4·62)2(42·610·83) topology. The solid-state photoluminescence properties of 10,11 and Na9[B-?-SbW9O33]·19.5H2O precursor have been investigated at room temperature. In comparison with the decay lifetimes of 10 and 11 with Na9[B-?-SbW9O33]·19.5H2O, it can be found that their photoluminescence behaviors are accomplished by the combined action of Na9[B-?-SbW9O33]·19.5H2O and Ln cations.In the fourth section, two types of 3-D tungstoantimonate frameworks [Pr(H2O)4(pdc)2[Pr(H2O)7]2[Fe4(H2O)2(pdc)2(SbW9O33)2]·18H2O(12),[Nd(H2O)4(pdc)]2[Nd (H2O)7]2[Fe4(H2O)2(pdc)2(SbW9O33)2]·18H2O(13),[Sm(H2O)6]2[Fe4(H2pdc)4(SbW9O33)2]·49 H2O(14), [Eu(H2O)6]2[Fe4(H2pdc)4(SbW9O33)2]·49H2O(15), [Gd(H2O)6]2[Fe4(H2pdc)4(Sb W9O33)2]·49.33H2O(16), [Tb(H2O)6]2[Fe4(H2pdc)4(SbW9O33)2]·49.33H2O(17), [Dy(H2O)6]2 [Fe4(H2pdc)4(SbW9O33)2]·49.33H2O(18), [Ho(H2O)6]2[Fe4(H2pdc)4(SbW9O33)2]·49.33H2O (19) and [Er(H2O)6]2[Fe4(H2pdc)4(SbW9O33)2]·49.33H2O (20) have been hydrothermally prepared by introducing pyridine-2,5-dicarboxylic acid ligand into the TM-Ln-tungstoantimonate system.12-13 exhibit the novel 3-D extended structure constructed from the carboxylic acid substituted tetra-Fe? sandwiched Krebs-type dimers connected by the carboxylic acid and Ln linkages. In 12-13, two pdc ligands substitutes for eight water ligands located on the sandwich belt of the Krebs-type dimers and link with two [Ln(H2O)7]3+ actions, this phenomenon is for the first time observed in the Krebs-type derivatives.Whereas in 14-20, this situation that ten water ligands located on the central belt are totally replaced by four pdc ligands is also first observed in the Krebs-type species, which further demonstrating that the coordinate water molecules are really active. It's worth mentioning that in 14-20, there exit two channels of A and B with different radius and each A channel is surrounded by six B channels, which is rare in 3d-4f heterometallic tungstoantimonates. Topologically,12-13 4display the 3-D network with the (53)2(54·62)2(56·64·72·93) topology and 14-20 exhibit the (36·412·58·62)topology structures.12-13 and 14-20 have different structures though they are obtained in the same synthetic conditions, indicating that the radius of Ln3+cations play a vital role on the construction of the final products. Moreover, the solid-state photoluminescence properties of 14?15?17?18 have been conducted at ambient temperature and they all exhibit the characteristic emission of the Ln3+ cations. The magnetic properties of 18 are also investigated. |
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