Three rare-earth-containing heteropolyoxometalates with different sizes, Na9[Eu(W5 O18)2], K13[Eu(SiW11O39)2], and K17[Eu(P2W17O61)2], have been incorporated by self-assembly into the interlayer of synthetic multibila...Three rare-earth-containing heteropolyoxometalates with different sizes, Na9[Eu(W5 O18)2], K13[Eu(SiW11O39)2], and K17[Eu(P2W17O61)2], have been incorporated by self-assembly into the interlayer of synthetic multibilayer films of dimethyldioctadecylammonium chloride and exhibited different orientations.展开更多
Some new heteropolyoxometalates of large organic cations with molybdotungstosilicic acids （general formula： （CTMA）4SiMoxW12-xO40·mH2O·nDMF, x=0,2,4,6,8,10,12） were prepared by the reaction of cetyltrime...Some new heteropolyoxometalates of large organic cations with molybdotungstosilicic acids （general formula： （CTMA）4SiMoxW12-xO40·mH2O·nDMF, x=0,2,4,6,8,10,12） were prepared by the reaction of cetyltrimethylammonium bromide （CTMAB,C16H33N（CH3）3Br） with H4SiMoxW12-xO40（x=0,2,4,6,8,10,12） in aqueous solution and recrystallization in DMF, and characterized by elemental analysis, IR spectra,TG- DTA and XRD techniques. The IR spectrum confirms the presence of Keggin structure and organic cations in these compounds, and it is indicated that the stretching vibration of the M-Od, M-Ob-M and Si-Oa becomes more red-shifted when molybdenum is gradually substituted for the tungsten atom. In particular, the thermal decomposition of the heteropolyoxometalates was studied in nitrogen atmosphere. The TG-DTA curves show that their thermal behaviors not only contain the release of water molecule, DMF molecule, CTMA and its fragments but also contains simultaneous collapse of Keggin anion. Their end products of the thermal decomposition are the mixture of WO3, MoO3 and SiO2. And from the final decomposition temperature of view, it is found that the thermal stability of these compounds gradually is decreased when the number of molybdenum atoms is increased.展开更多
A series of photochromic hybrid films were prepared through entrapping Dawson type tungsten heteropolyoxomet-allates (P2W18C626-) and molybdenum heteropolyoxometallate (P2Mo18O626-) into polyacrylamide matrix. FTIR re...A series of photochromic hybrid films were prepared through entrapping Dawson type tungsten heteropolyoxomet-allates (P2W18C626-) and molybdenum heteropolyoxometallate (P2Mo18O626-) into polyacrylamide matrix. FTIR results showed that the Dawson geometry of heteropolyoxometallates is still preserved inside the composites and strong coulombic interaction is built between heteropolyoxometallates and polyacrylamide via hydrogen bonding. Irradiated with ultraviolet light, the transparent films change from colorless to blue and show reversible photochromism. The bleaching process occurs when the films are in contact with air or O2 in the dark. The molybdenum heteropolyoxometallate hybrid film has higher photochromic efficiency and slower bleaching reaction than tungsten heteropolyoxometallate hybrid film. ESR results indicated that polyacrylamide is a hydrogen donor and the photoreduced process is in accordance with the radical mechanism.展开更多
Layered double hydrotalcites pillared by het erop olyoxometates, ZnAl- GeW11Z (Z=Ni2+, Cu2+) and ZnAl-GeW11 have been synhesized by ion exchange. A procedure for intercalating layered double hydroxides is described in...Layered double hydrotalcites pillared by het erop olyoxometates, ZnAl- GeW11Z (Z=Ni2+, Cu2+) and ZnAl-GeW11 have been synhesized by ion exchange. A procedure for intercalating layered double hydroxides is described in this paper, powder X-ray diffraction and IR spectra measuremnts confirm that for GeW11O39Z (H2O)6- and GeW11O8-39intercalation takes place and the gallery heights are of 9.9A. The new compounds are found to be calalytically efficient for the esterification of acetic acid with n-butanol in liquld-phase.展开更多
The novel class of inorganic nanoclusters, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[SiW\-\{11\}O\-\{39\}CoCl\]\}\511H\-2O, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[P\-2W\-\{18\}O\-\{62\}\]\...The novel class of inorganic nanoclusters, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[SiW\-\{11\}O\-\{39\}CoCl\]\}\511H\-2O, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[P\-2W\-\{18\}O\-\{62\}\]\}Cl\533H\-2O and \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\-2\[NaP\-5W\-\{30\}O\-\{110\}\]\524H\-2O, consisting of Keggin cations and heteropolyoxometalates, has been synthesized and characterized by ICP, IR and NMR. It is proved that the intrinsic identities of Keggin cation and heteropolyanions of the clusters are preserved within the gels.展开更多
Ainonic clays pillared by heteropolyoxometalate Zn2Al-PW11Z (Z= Cr3+ , Ti4+ and V5+) were synthesized via ion exchange reaction. The IR spectra and XRD patterns showed that the layered anions remained the integrity of...Ainonic clays pillared by heteropolyoxometalate Zn2Al-PW11Z (Z= Cr3+ , Ti4+ and V5+) were synthesized via ion exchange reaction. The IR spectra and XRD patterns showed that the layered anions remained the integrity of Keggin structure, and the gallery heights of the layered compounds were 1.01± 0.01 nm. The MAS NMR spectra of 27Al and 31P indicated the layered ahion had little effect on the Al of the octahedra center of the hydroalde, but the layer and octallydron VO6 had great effect on the P of the layered PW11V. The peak of 31P MAS NMR split to the two peaks of -11.867 ppm and -14.031 ppm whose corresponding area ratio is 2:1. All these results showed that the C2 axia of the heteropolyoxometalate in the layer was perpondicular to the brucite layer. Further experiments found that these compounds had high selectivity and activity for the esterification of acetic acid with n-butyl alcohol.展开更多
The half Dawson structure complex has been prepared by reaction of Na2WO4·2H2O, Na2MoO4·2H2O and NaH2PO4 in water. 4H3[PW6Mo4Cu2O38(H2O)2] have been synthesized by reaction of 9- and Cu2+ in water and recrys...The half Dawson structure complex has been prepared by reaction of Na2WO4·2H2O, Na2MoO4·2H2O and NaH2PO4 in water. 4H3[PW6Mo4Cu2O38(H2O)2] have been synthesized by reaction of 9- and Cu2+ in water and recrystallized in a mixed acetone/water solvent. They were characterized by elemental analyses, IR spectra and electronic spectra. The crystal structure of 4H3[PW6Mo4Cu2O38(H2O)2] has been determined by X ray structure analysis for the first time, which belongs to trigonal with space group R 3, a=b=c=1.53081 (18) nm, α=β=γ=109.458(17)°, Z=1, Dc=3.141Mg·m-3, R=0.0780, Rw=0.1480. The sites of the molybdenum, tungsten and copper atoms are disordered over 12 possible locations in the crystal, and the anion has a high symmetry due to the disorder of the molybdenum, tungsten and copper atoms. CCDC: 176656.展开更多
基金supported by the National Nature Science Foundation of China(20071007)the Foundation for University Key Teacher by the Ministry of Education of China
文摘Three rare-earth-containing heteropolyoxometalates with different sizes, Na9[Eu(W5 O18)2], K13[Eu(SiW11O39)2], and K17[Eu(P2W17O61)2], have been incorporated by self-assembly into the interlayer of synthetic multibilayer films of dimethyldioctadecylammonium chloride and exhibited different orientations.
基金the Natural Science Foundation of the Educational Commission of Hubei Province(No.J200522002 and Z200622001)
文摘Some new heteropolyoxometalates of large organic cations with molybdotungstosilicic acids （general formula： （CTMA）4SiMoxW12-xO40·mH2O·nDMF, x=0,2,4,6,8,10,12） were prepared by the reaction of cetyltrimethylammonium bromide （CTMAB,C16H33N（CH3）3Br） with H4SiMoxW12-xO40（x=0,2,4,6,8,10,12） in aqueous solution and recrystallization in DMF, and characterized by elemental analysis, IR spectra,TG- DTA and XRD techniques. The IR spectrum confirms the presence of Keggin structure and organic cations in these compounds, and it is indicated that the stretching vibration of the M-Od, M-Ob-M and Si-Oa becomes more red-shifted when molybdenum is gradually substituted for the tungsten atom. In particular, the thermal decomposition of the heteropolyoxometalates was studied in nitrogen atmosphere. The TG-DTA curves show that their thermal behaviors not only contain the release of water molecule, DMF molecule, CTMA and its fragments but also contains simultaneous collapse of Keggin anion. Their end products of the thermal decomposition are the mixture of WO3, MoO3 and SiO2. And from the final decomposition temperature of view, it is found that the thermal stability of these compounds gradually is decreased when the number of molybdenum atoms is increased.
基金The authors acknowledge the National Natural Science Foundation of China (No. 59932040) for the provision of financial support.
文摘A series of photochromic hybrid films were prepared through entrapping Dawson type tungsten heteropolyoxomet-allates (P2W18C626-) and molybdenum heteropolyoxometallate (P2Mo18O626-) into polyacrylamide matrix. FTIR results showed that the Dawson geometry of heteropolyoxometallates is still preserved inside the composites and strong coulombic interaction is built between heteropolyoxometallates and polyacrylamide via hydrogen bonding. Irradiated with ultraviolet light, the transparent films change from colorless to blue and show reversible photochromism. The bleaching process occurs when the films are in contact with air or O2 in the dark. The molybdenum heteropolyoxometallate hybrid film has higher photochromic efficiency and slower bleaching reaction than tungsten heteropolyoxometallate hybrid film. ESR results indicated that polyacrylamide is a hydrogen donor and the photoreduced process is in accordance with the radical mechanism.
文摘Layered double hydrotalcites pillared by het erop olyoxometates, ZnAl- GeW11Z (Z=Ni2+, Cu2+) and ZnAl-GeW11 have been synhesized by ion exchange. A procedure for intercalating layered double hydroxides is described in this paper, powder X-ray diffraction and IR spectra measuremnts confirm that for GeW11O39Z (H2O)6- and GeW11O8-39intercalation takes place and the gallery heights are of 9.9A. The new compounds are found to be calalytically efficient for the esterification of acetic acid with n-butanol in liquld-phase.
文摘The novel class of inorganic nanoclusters, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[SiW\-\{11\}O\-\{39\}CoCl\]\}\511H\-2O, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[P\-2W\-\{18\}O\-\{62\}\]\}Cl\533H\-2O and \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\-2\[NaP\-5W\-\{30\}O\-\{110\}\]\524H\-2O, consisting of Keggin cations and heteropolyoxometalates, has been synthesized and characterized by ICP, IR and NMR. It is proved that the intrinsic identities of Keggin cation and heteropolyanions of the clusters are preserved within the gels.
文摘Ainonic clays pillared by heteropolyoxometalate Zn2Al-PW11Z (Z= Cr3+ , Ti4+ and V5+) were synthesized via ion exchange reaction. The IR spectra and XRD patterns showed that the layered anions remained the integrity of Keggin structure, and the gallery heights of the layered compounds were 1.01± 0.01 nm. The MAS NMR spectra of 27Al and 31P indicated the layered ahion had little effect on the Al of the octahedra center of the hydroalde, but the layer and octallydron VO6 had great effect on the P of the layered PW11V. The peak of 31P MAS NMR split to the two peaks of -11.867 ppm and -14.031 ppm whose corresponding area ratio is 2:1. All these results showed that the C2 axia of the heteropolyoxometalate in the layer was perpondicular to the brucite layer. Further experiments found that these compounds had high selectivity and activity for the esterification of acetic acid with n-butyl alcohol.
文摘The half Dawson structure complex has been prepared by reaction of Na2WO4·2H2O, Na2MoO4·2H2O and NaH2PO4 in water. 4H3[PW6Mo4Cu2O38(H2O)2] have been synthesized by reaction of 9- and Cu2+ in water and recrystallized in a mixed acetone/water solvent. They were characterized by elemental analyses, IR spectra and electronic spectra. The crystal structure of 4H3[PW6Mo4Cu2O38(H2O)2] has been determined by X ray structure analysis for the first time, which belongs to trigonal with space group R 3, a=b=c=1.53081 (18) nm, α=β=γ=109.458(17)°, Z=1, Dc=3.141Mg·m-3, R=0.0780, Rw=0.1480. The sites of the molybdenum, tungsten and copper atoms are disordered over 12 possible locations in the crystal, and the anion has a high symmetry due to the disorder of the molybdenum, tungsten and copper atoms. CCDC: 176656.
