Preparation and Physicochemical Properties of Mesoscopic-stractural polyoxometallolanthanoates as a Nanotechnology Material

1.Structure and photoluminescence of square-antiprisrnatic ewopium(III)octahydrate ion+in[Eu(H_2O)_2L_2[V_&lt；10&gt；O_&lt；28&gt；]·8H_2O were studied.The data provided information about a behavior of Eu^&lt；3+&gt；in aqueous solutions.2。Photoluminescence and Tb^&lt；3+&gt；→Eu^&lt；3+&gt；energy transfer in[Tb_&lt；1.4&gt；Eu_&lt；1.6&gt；(H_2O)_3(SbW_9O_&lt；33&gt；)(W_5O_&lt；18&gt；)_3]^&lt；18-&gt；and[Tb_&lt；4.3&gt；Eu_&lt；1.7&gt；)O_2(H_2O)_6Al_2(Nb_6O_&lt；19&gt；)_5]^&lt；26-&gt；with various Tb-Eu distances(3.8-6.0A)were investigated.The results showed that the energy transfer occurs with dipole-dipole interaction of the Forster-Dexter type.3 Five new rare earth(RE)polyoxotunstates，[(RE)_2(H_2O)_2(SbW_9O_&lt；33&gt；)(W_5O_&lt；18&gt；)_2]^&lt；15-&gt；，[(RE)_3(H_2O)_4(SbW_9O_&lt；33&gt；)_2(W_5O_&lt；18&gt；)_2]^&lt；21-&gt；，[(RE)_2O(H_2O)(AsW_9O_&lt；33&gt；)_2]^&lt；14-&gt；，[{(RE)(H_2O)_2(AsW_9O_&lt；33&gt；)}_4]^&lt；24-&gt；，[{(RE)(H_2O)_2(AsW_9O_&lt；33&gt；)}_6]^&lt；36-&gt；，were prepared and structurally characterized.All the complexes^consist of polyoxotungstate groups of the lacunary Keggin([XW_9O_&lt；33&gt；]^&lt；9-&gt；)and lacunary Lindqvist([W_5O_&lt；18&gt；]^&lt；6-&gt；)type，and RE^&lt；3+&gt；cations which act as linkers of the polyoxotungstate groups.4。Population of RE^&lt；3+&gt；cations in[(RE)_2(H_2O)_2(SbW_9O_&lt；33&gt；)(W_5O_&lt；18&gt；)_2]^&lt；15-&gt；was studied for Y/Eu-and Eu/Lumixed systems with a help of photoluminescence spectroscopy and X-ray crystallography.The results revealed that one of the two RE sites is preferentially occupied by small RE^&lt；3+&gt；cation.5。Structures were determined for new rare earth molybdates，(RE)_2Mo_5O_&lt；18&gt；，(RE)_6Mo_&lt；12&gt；O_&lt；45&gt；，(RE)_4Mo_7O_&lt；27&gt；，(RE)_6Mo_&lt；10&gt；O_&lt；39&gt；，which were formed by pyrolysis of[(RE)_2Mo_8O_&lt；27&gt；]·18H_2O(RE=Eu，Gd，Tb)at 750-800℃for 2h.We found that Eu_xGd__&lt；2-x&gt；Mo_5O_&lt；18&gt；(x=1.2)is a phosphor exhibiting significantly intense red photoluminescence.

1. Structure and photoluminescence of square-antiprisrnatic ewopium(III) octahydrate ion+ in [Eu(H_2O)_2l_2[V_<10>O_<28>]・8H_2O were studied. The data provided information about a behavior of Eu^<3+> in aqueous solutions.2. Photoluminescence and Tb^<3+>→Eu^<3+> energy transfer in [Tb_<1.4>Eu_<1.6>(H_2O)_3(SbW_9O_<33>)(W_5O_<18>)_3]^<18-> and [Tb_<4.3>Eu_<1.7>O_2(H_2O)_6Al_2(Nb_6O_<19>)_5]^<26-> with various Tb-Eu distances (3.8-6.0 A) were investigated. The results showed that the energy transfer occurs with dipole-dipole interaction of the Forster-Dexter type.3 Five new rare earth (RE) polyoxotunstates, [(RE)_2(H_2O)_2(SbW_9O_<33>)(W_5O_<18>)_2]^<15->, [(RE)_3(H_2O)_4(SbW_9O_<33>)_2(W_5O_<18>)_2]^<21-> , [(RE)_2O(H_2O)(AsW_9O_<33>)_2]^<14->, [{(RE)(H_2O)_2(AsW_9O_<33>)}_4]^<24-> , [{(RE)(H_2O)_2(AsW_9O_<33>)}_6]^<36->, were prepared and structurally characterized. All the complexes ^consist of polyoxotungstate groups of the lacunary Keggin ([XW_9O_<33>]^<9->) and lacunary Lindqvist ([W_5O_<18>]^<6-> ) type, and RE^<3+> cations which act as linkers of the polyoxotungstate groups.4. Population of RE^<3+> cations in [(RE)_2(H_2O)_2(SbW_9O_<33>)(W_5O_<18>)_2]^<15-> was studied for Y/Eu- and Eu/Lumixed systems with a help of photoluminescence spectroscopy and X-ray crystallography. The results revealed that one of the two RE sites is preferentially occupied by small RE^<3+> cation.5. Structures were determined for new rare earth molybdates, (RE)_2Mo_5O_<18>, (RE)_6Mo_<12>O_<45>, (RE)_4Mo_7O_<27>, (RE)_6Mo_<10>O_<39>, which were formed by pyrolysis of [(RE)_2Mo_8O_<27>]・ 18H_2O (RE= Eu, Gd, Tb) at 750-800℃ for 2 h. We found that Eu_xGd__<2-x>Mo_5O_<18> (x=1.2) is a phosphor exhibiting significantly intense red photoluminescence.