Teresa Santos | University of Aveiro (original) (raw)
Papers by Teresa Santos
Chem. Mater, Jan 1, 2005
A layered double hydroxide pillared by 2, 2&#... more A layered double hydroxide pillared by 2, 2'-bipyridine-5, 5'-dicarboxylate anions was used as a porous matrix to intercalate LnCl3 (Ln= Eu, Gd) at a loading of 0.6-0.7 mmol g-1. The hybrid materials were characterized by powder X-ray diffraction, IR and Raman ...
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](New Journal of …, Jan 1, 1999
Inorg. Chem, Jan 1, 2004
A Zn,Al layered double hydroxide (LDH) with Zn/Al = 1.45 and containing nitrate anions was prepar... more A Zn,Al layered double hydroxide (LDH) with Zn/Al = 1.45 and containing nitrate anions was prepared by coprecipitation and characterized by powder X-ray diffraction, Zn K-edge extended X-ray absorption fine structure spectroscopy (EXAFS), thermogravimetric analysis, FTIR and FT Raman spectroscopy, and (27)Al MAS NMR spectroscopy. Three Zn...O and four Zn...M (M = Zn, Al) shells could be fitted to the low-temperature (40 K) EXAFS spectrum, in accordance with a model for an ordered cationic sheet. The nitrate anions were easily exchanged by 2,2'-bipyridine-5,5'-dicarboxylate anions, resulting in an increase in the basal spacing from 9 to 18 A. The basal spacing of the pillared derivative indicates that the anions are arranged with their longest dimension nearly perpendicular to the host layers. This material exhibits a high encapsulating ability, as evidenced by its interaction with a dichloromethane solution of the dioxomolybdenum(VI) complex MoO(2)Cl(2)(THF)(2). A material with a metal loading of 11.2 wt % was obtained. Molybdenum K-edge EXAFS analysis could not substantiate the formation of a supported complex of the type MoO(2)Cl(2)(N-N) but instead indicated the formation of unidentate-bridged entities of the type [O(2)Mo-O-MoO(2)] with a metal-metal separation of 3.29 A. The molybdenum-containing LDH was active as a catalyst for the liquid-phase epoxidation of cis-cyclooctene, 1-octene, and trans-2-octene using tert-butyl hydroperoxide as the oxygen source, yielding the corresponding epoxides as the only products. For reactions carried out with no additional solvent (other than n-decane) or in the presence of 1,2-dichloroethane, the solid catalyst could be recycled with no major loss of activity. Other tests confirmed that the systems functioned as true heterogeneous catalysts.
Chem. Mater, Jan 1, 2005
A layered double hydroxide pillared by 2, 2&#... more A layered double hydroxide pillared by 2, 2'-bipyridine-5, 5'-dicarboxylate anions was used as a porous matrix to intercalate LnCl3 (Ln= Eu, Gd) at a loading of 0.6-0.7 mmol g-1. The hybrid materials were characterized by powder X-ray diffraction, IR and Raman ...
New Journal of …, Jan 1, 1999
Inorg. Chem, Jan 1, 2004
A Zn,Al layered double hydroxide (LDH) with Zn/Al = 1.45 and containing nitrate anions was prepar... more A Zn,Al layered double hydroxide (LDH) with Zn/Al = 1.45 and containing nitrate anions was prepared by coprecipitation and characterized by powder X-ray diffraction, Zn K-edge extended X-ray absorption fine structure spectroscopy (EXAFS), thermogravimetric analysis, FTIR and FT Raman spectroscopy, and (27)Al MAS NMR spectroscopy. Three Zn...O and four Zn...M (M = Zn, Al) shells could be fitted to the low-temperature (40 K) EXAFS spectrum, in accordance with a model for an ordered cationic sheet. The nitrate anions were easily exchanged by 2,2'-bipyridine-5,5'-dicarboxylate anions, resulting in an increase in the basal spacing from 9 to 18 A. The basal spacing of the pillared derivative indicates that the anions are arranged with their longest dimension nearly perpendicular to the host layers. This material exhibits a high encapsulating ability, as evidenced by its interaction with a dichloromethane solution of the dioxomolybdenum(VI) complex MoO(2)Cl(2)(THF)(2). A material with a metal loading of 11.2 wt % was obtained. Molybdenum K-edge EXAFS analysis could not substantiate the formation of a supported complex of the type MoO(2)Cl(2)(N-N) but instead indicated the formation of unidentate-bridged entities of the type [O(2)Mo-O-MoO(2)] with a metal-metal separation of 3.29 A. The molybdenum-containing LDH was active as a catalyst for the liquid-phase epoxidation of cis-cyclooctene, 1-octene, and trans-2-octene using tert-butyl hydroperoxide as the oxygen source, yielding the corresponding epoxides as the only products. For reactions carried out with no additional solvent (other than n-decane) or in the presence of 1,2-dichloroethane, the solid catalyst could be recycled with no major loss of activity. Other tests confirmed that the systems functioned as true heterogeneous catalysts.