2015 |
Diaz, C; Barrera, G; Segovia, M; Valenzuela, M L; Osiak, M; O'dwyer, C Crystallizing Vanadium Pentoxide Nanostructures in the Solid-State Using Modified Block Copolymer and Chitosan Complexes Artículo de revista Journal of Nanomaterials, 10.1155/2015/105157 , 2015, ISSN: 1687-4110. Resumen | Enlaces | BibTeX | Etiquetas: electrochemical gold growth, intercalation, mechanisms, nanocomposites, nanoparticles, optical-properties, photoluminescence, precursors, properties, ruthenium @article{RN255, title = {Crystallizing Vanadium Pentoxide Nanostructures in the Solid-State Using Modified Block Copolymer and Chitosan Complexes}, author = { C. Diaz and G. Barrera and M. Segovia and M.L. Valenzuela and M. Osiak and C. O'dwyer}, url = {/brokenurl#<Go to ISI>://WOS:000354681800001}, doi = {10.1155/2015/105157}, issn = {1687-4110}, year = {2015}, date = {2015-01-01}, journal = {Journal of Nanomaterials}, volume = {10.1155/2015/105157}, abstract = {A systematic study of the synthesis of V2O5 nanostructured materials using macromolecular PS-co-4-PVP center dot(VCl3)(y) and chitosan center dot(VCl3)(y) complexes is presented. It is demonstrated that various coordination degrees of the metal into the polymeric chain specifically influence the product formation after pyrolysis. PS-co-4-PVP center dot(VCl3)(y) and chitosan center dot(VCl3)(y) complexes were prepared by simple coordination reaction of VCl3 with the respective polymer inmolar ratios 1 : 1, 1 : 5, and 1 : 10 metal/polymer and characterized by elemental analysis, IR spectroscopy, and TGA/DSC analysis. Solid-state thermolysis of these precursors at several temperatures under air results in nanostructured V2O5 using all precursors. The size and shape of the nanostructured V2O5 depend on the nature of the polymer. For the chitosan center dot(VCl3)(y) precursors sub-10nm nanocrystals are formed. The calcination process, involved in the preparation method, produces V2O5 with photoluminescence in the visible light region, suggesting the possible application in oxygen sensing devices.}, keywords = {electrochemical gold growth, intercalation, mechanisms, nanocomposites, nanoparticles, optical-properties, photoluminescence, precursors, properties, ruthenium}, pubstate = {published}, tppubtype = {article} } A systematic study of the synthesis of V2O5 nanostructured materials using macromolecular PS-co-4-PVP center dot(VCl3)(y) and chitosan center dot(VCl3)(y) complexes is presented. It is demonstrated that various coordination degrees of the metal into the polymeric chain specifically influence the product formation after pyrolysis. PS-co-4-PVP center dot(VCl3)(y) and chitosan center dot(VCl3)(y) complexes were prepared by simple coordination reaction of VCl3 with the respective polymer inmolar ratios 1 : 1, 1 : 5, and 1 : 10 metal/polymer and characterized by elemental analysis, IR spectroscopy, and TGA/DSC analysis. Solid-state thermolysis of these precursors at several temperatures under air results in nanostructured V2O5 using all precursors. The size and shape of the nanostructured V2O5 depend on the nature of the polymer. For the chitosan center dot(VCl3)(y) precursors sub-10nm nanocrystals are formed. The calcination process, involved in the preparation method, produces V2O5 with photoluminescence in the visible light region, suggesting the possible application in oxygen sensing devices. |
Toro, R; Seguel, R J; Morales, R G E; Leiva, M A Ozone, Nitrogen Oxides, and Volatile Organic Compounds in a Central Zone of Chile Artículo de revista Air Quality Atmosphere and Health, 8 (6), pp. 545-557, 2015, ISSN: 1873-9318. Resumen | Enlaces | BibTeX | Etiquetas: air central chile, compound, environmental chemistry, izmir, organic ozone ozone, precursors, santiago, surface voc, volatile zone @article{RN221, title = {Ozone, Nitrogen Oxides, and Volatile Organic Compounds in a Central Zone of Chile}, author = { R. Toro and R.J. Seguel and R.G.E. Morales and M.A. Leiva}, url = {/brokenurl#<Go to ISI>://WOS:000362881100003}, doi = {10.1007/s11869-014-0306-3}, issn = {1873-9318}, year = {2015}, date = {2015-01-01}, journal = {Air Quality Atmosphere and Health}, volume = {8}, number = {6}, pages = {545-557}, abstract = {The relationships between ozone (O-3) and its precursors, nitrogen oxides (NO (x) ) and volatile organic compounds (VOCs), were investigated in the VIR region (34A degrees 10' S, 71A degrees 36' W), referred to as Libertador General Bernardo O'Higgins of Chile. Observations were obtained from a field study performed at four monitoring sites, which represented different environmental conditions, i.e., rural-coastal (Marchihue, MA), urban (Rancagua, RA, and Rengo, RE), and semi-urban (Codegua, CO) during the summer (between Feb 1 and Mar 12, 2010). Overall, greater O-3 concentrations were identified at the urban sites compared with the semi-urban and rural sites. In addition, the O-3 precursor concentrations were high in the early morning hours as a consequence of fresh vehicular emissions (from 11 to 40 ppbv for NO (x) and from 15 to 36 ppbC for VOC). The total VOC/NO (x) ratios at the study sites indicated that the formation of O-3 was limited by VOCs. Most O-3 was formed from ethene, isoprene, propene, 2-methylpropene, m- and p-xylenes, and toluene. These VOCs accounted for more than 50 % of the O-3 formation. The m- and p-xylene/ethylbenzene ratio confirmed the reception of aged air masses at the CO site. In contrast, at the RA site, the impact of pollution was primarily local. Control measures should be implemented to prevent O-3 exceedances of the National Ambient Air Quality Standard (NAAQS), despite the fact that the current O-3 concentrations do not exceed the current 8-h standard of 61 ppbv. These measures should include the control of VOC emissions and their chemical reactivity.}, keywords = {air central chile, compound, environmental chemistry, izmir, organic ozone ozone, precursors, santiago, surface voc, volatile zone}, pubstate = {published}, tppubtype = {article} } The relationships between ozone (O-3) and its precursors, nitrogen oxides (NO (x) ) and volatile organic compounds (VOCs), were investigated in the VIR region (34A degrees 10' S, 71A degrees 36' W), referred to as Libertador General Bernardo O'Higgins of Chile. Observations were obtained from a field study performed at four monitoring sites, which represented different environmental conditions, i.e., rural-coastal (Marchihue, MA), urban (Rancagua, RA, and Rengo, RE), and semi-urban (Codegua, CO) during the summer (between Feb 1 and Mar 12, 2010). Overall, greater O-3 concentrations were identified at the urban sites compared with the semi-urban and rural sites. In addition, the O-3 precursor concentrations were high in the early morning hours as a consequence of fresh vehicular emissions (from 11 to 40 ppbv for NO (x) and from 15 to 36 ppbC for VOC). The total VOC/NO (x) ratios at the study sites indicated that the formation of O-3 was limited by VOCs. Most O-3 was formed from ethene, isoprene, propene, 2-methylpropene, m- and p-xylenes, and toluene. These VOCs accounted for more than 50 % of the O-3 formation. The m- and p-xylene/ethylbenzene ratio confirmed the reception of aged air masses at the CO site. In contrast, at the RA site, the impact of pollution was primarily local. Control measures should be implemented to prevent O-3 exceedances of the National Ambient Air Quality Standard (NAAQS), despite the fact that the current O-3 concentrations do not exceed the current 8-h standard of 61 ppbv. These measures should include the control of VOC emissions and their chemical reactivity. |
2013 |
Diaz, C; Valenzuela, M L; Caceres, S; O'dwyer, C Solution and Surfactant-Free Growth of Supported High Index Facet Sers Active Nanoparticles of Rhenium by Phase Demixing Artículo de revista Journal of Materials Chemistry A, 1 (5), pp. 1566-1572, 2013, ISSN: 2050-7488. Resumen | Enlaces | BibTeX | Etiquetas: excitation gold graphene, morphology, nanocatalysts, nanocrystals, nanoparticles, precursors @article{RN144, title = {Solution and Surfactant-Free Growth of Supported High Index Facet Sers Active Nanoparticles of Rhenium by Phase Demixing}, author = { C. Diaz and M.L. Valenzuela and S. Caceres and C. O'dwyer}, url = {/brokenurl#<Go to ISI>://WOS:000314640100008}, doi = {10.1039/c2ta00262k}, issn = {2050-7488}, year = {2013}, date = {2013-01-01}, journal = {Journal of Materials Chemistry A}, volume = {1}, number = {5}, pages = {1566-1572}, abstract = {Stable, high-index facet Re nanoparticles have been grown by a solid state synthetic method, negating the need for solutions or surfactants to control seeding, supracrystallization and NP shape. By using mixtures of K[ReO4] and the cyclic triphosphazene [NP(O2C12H8)](3), high-index facet nanoparticles and nanocrystals similar to 3 nm in size can be seeded and grown from drop-cast films and powders due to phase demixing of the metallopolymer. NP dispersions are formed directly within a carbon support that liquefies, allowing NP coarsening and ripening, and the eventual formation of a solidified graphitic support filled with crystals. Successful growth of mesoscale supracrystals of Re also occurs from ripening of nucleated NP seeds, incubated within a solidified and partially dewetted solid support that patterns the surface. The supported Re NP dispersions also exhibit surface enhanced Raman scattering within a graphitic matrix.}, keywords = {excitation gold graphene, morphology, nanocatalysts, nanocrystals, nanoparticles, precursors}, pubstate = {published}, tppubtype = {article} } Stable, high-index facet Re nanoparticles have been grown by a solid state synthetic method, negating the need for solutions or surfactants to control seeding, supracrystallization and NP shape. By using mixtures of K[ReO4] and the cyclic triphosphazene [NP(O2C12H8)](3), high-index facet nanoparticles and nanocrystals similar to 3 nm in size can be seeded and grown from drop-cast films and powders due to phase demixing of the metallopolymer. NP dispersions are formed directly within a carbon support that liquefies, allowing NP coarsening and ripening, and the eventual formation of a solidified graphitic support filled with crystals. Successful growth of mesoscale supracrystals of Re also occurs from ripening of nucleated NP seeds, incubated within a solidified and partially dewetted solid support that patterns the surface. The supported Re NP dispersions also exhibit surface enhanced Raman scattering within a graphitic matrix. |
Diaz, C; Valenzuela, M L; Caceres, S; Diaz, R; O'dwyer, C Solvent and Stabilizer Free Growth of Ag and Pd Nanoparticles Using Metallic Salts/Cyclotriphosphazenes Mixtures Artículo de revista Materials Chemistry and Physics, 143 (1), pp. 124-132, 2013, ISSN: 0254-0584. Resumen | Enlaces | BibTeX | Etiquetas: annealing, derivatives, electron gold, mechanical-behavior, metals, microscopy, nanoparticles, nanorods organometallic palladium polyphosphazenes, precursors, properties, pyrolysis, shape-controlled solid-state surface synthesis, thermolytic transformation @article{RN146, title = {Solvent and Stabilizer Free Growth of Ag and Pd Nanoparticles Using Metallic Salts/Cyclotriphosphazenes Mixtures}, author = { C. Diaz and M.L. Valenzuela and S. Caceres and R. Diaz and C. O'dwyer}, url = {/brokenurl#<Go to ISI>://WOS:000327684100017}, doi = {10.1016/j.matchemphys.2013.08.034}, issn = {0254-0584}, year = {2013}, date = {2013-01-01}, journal = {Materials Chemistry and Physics}, volume = {143}, number = {1}, pages = {124-132}, publisher = {2013 Elsevier B.V.}, abstract = {Cyclotriphosphazene is used as a sacrificial solid-state template to synthesize a range of Ag and Pd nanoparticles with diverse geometries by thermal treatment using MLn/N3P3(O2C12H8)(3) mixtures. The Pd and Ag nanoparticles are synthesized by solid-state pyrolysis of AgPPh3[CF3SO3]/N3P3(O2C12H8)(3) and PdCl2/N3P3(O2C12H8)(3) mixtures with molar relationships of 1:1, 1:5 and 1:10 respectively, in air and at 800 degrees C. The morphology of the as-prepared nanoparticles is found to depend on the molar ratio of the precursor mixture, the preparation method and of the nature of the metal. Ag and Pd, microcrystals were thermally grown on Si from the respective 1:1 precursors while that metal foams were grown from 1:5 ratios precursors on SiO2 wafers. High resolution transmission electron microscopy investigations reveal in most cases small crystals of Pd. HRSTEM measurements indicate that the formation of the Pd and Ag nanoparticles occurs through a phase demixing and dewetting mechanism. This approach has potential to be a useful and facile method to prepare metallic nanoparticles without requiring solutions or surfactants for application in electronic, catalytic and sensor materials and devices.}, keywords = {annealing, derivatives, electron gold, mechanical-behavior, metals, microscopy, nanoparticles, nanorods organometallic palladium polyphosphazenes, precursors, properties, pyrolysis, shape-controlled solid-state surface synthesis, thermolytic transformation}, pubstate = {published}, tppubtype = {article} } Cyclotriphosphazene is used as a sacrificial solid-state template to synthesize a range of Ag and Pd nanoparticles with diverse geometries by thermal treatment using MLn/N3P3(O2C12H8)(3) mixtures. The Pd and Ag nanoparticles are synthesized by solid-state pyrolysis of AgPPh3[CF3SO3]/N3P3(O2C12H8)(3) and PdCl2/N3P3(O2C12H8)(3) mixtures with molar relationships of 1:1, 1:5 and 1:10 respectively, in air and at 800 degrees C. The morphology of the as-prepared nanoparticles is found to depend on the molar ratio of the precursor mixture, the preparation method and of the nature of the metal. Ag and Pd, microcrystals were thermally grown on Si from the respective 1:1 precursors while that metal foams were grown from 1:5 ratios precursors on SiO2 wafers. High resolution transmission electron microscopy investigations reveal in most cases small crystals of Pd. HRSTEM measurements indicate that the formation of the Pd and Ag nanoparticles occurs through a phase demixing and dewetting mechanism. This approach has potential to be a useful and facile method to prepare metallic nanoparticles without requiring solutions or surfactants for application in electronic, catalytic and sensor materials and devices. |
Diaz, C; Valenzuela, M L; Bobadilla, D Bimetallic Au/Ag Metal Superstructures from Macromolecular Metal Complexes in Solid-State Artículo de revista Journal of the Chilean Chemical Society, 58 (4), pp. 1994-1997, 2013, ISSN: 0717-9707. Resumen | Enlaces | BibTeX | Etiquetas: and au complexes, derivatives, fabrication, gold, macromolecular metallic morphology, nanocrystals, nanoparticles, organometallic polyphosphazenes, precursors, pyrolysis pyrolysis, superstructures, thermolytic transformation @article{RN143, title = {Bimetallic Au/Ag Metal Superstructures from Macromolecular Metal Complexes in Solid-State}, author = { C. Diaz and M.L. Valenzuela and D. Bobadilla}, url = {/brokenurl#<Go to ISI>://WOS:000331238800015}, doi = {10.4067/S0717-97072013000400019}, issn = {0717-9707}, year = {2013}, date = {2013-01-01}, journal = {Journal of the Chilean Chemical Society}, volume = {58}, number = {4}, pages = {1994-1997}, abstract = {Novel bimetallic Au/Ag superstructures have been prepared from solid-state pyrolysis of the macromolecular complexes Chitosan( MLn/M'Ln)(n) y PSP-4-PVPx(MLn/M'Ln)(n) with MLn = AuCl3 and M'Ln = Ag(CF3SO3). The characterization was made from XRD (X-ray diffraction of powder), SEM and EDS analysis. Morphologies are influenced by both the nature of the polymer and the metal/polymer, molar ratio of the polymer precursor. EDS analysis suggests a core/shell Au/Ag structure for the materials. A probable mechanism of the formation of these superstructures is discussed. Although separated reports of metallic superstructures of Au or Ag have been recently described, the here reported are the first bimetallic Au/Ag.}, keywords = {and au complexes, derivatives, fabrication, gold, macromolecular metallic morphology, nanocrystals, nanoparticles, organometallic polyphosphazenes, precursors, pyrolysis pyrolysis, superstructures, thermolytic transformation}, pubstate = {published}, tppubtype = {article} } Novel bimetallic Au/Ag superstructures have been prepared from solid-state pyrolysis of the macromolecular complexes Chitosan( MLn/M'Ln)(n) y PSP-4-PVPx(MLn/M'Ln)(n) with MLn = AuCl3 and M'Ln = Ag(CF3SO3). The characterization was made from XRD (X-ray diffraction of powder), SEM and EDS analysis. Morphologies are influenced by both the nature of the polymer and the metal/polymer, molar ratio of the polymer precursor. EDS analysis suggests a core/shell Au/Ag structure for the materials. A probable mechanism of the formation of these superstructures is discussed. Although separated reports of metallic superstructures of Au or Ag have been recently described, the here reported are the first bimetallic Au/Ag. |
2012 |
Diaz, C; Valenzuela, M L; Garrido, D; Aguirre, P Sol-Gel Incorporation of Organometallic Compounds into Silica: Useful Precursors to Metallic Nanostructured Materials Artículo de revista Journal of the Chilean Chemical Society, 57 (2), pp. 1155-1162, 2012, ISSN: 0717-9707. Resumen | Enlaces | BibTeX | Etiquetas: bridged magnetic-properties, materials, matrix, mesoporous molecular nanoclusters nanocomposites, nanoparticles, nanostructured, nanowires, organic-inorganic polysilsesquioxanes, precursors, pyrophosphates, silica, sol-gel, source thermolytic transformation @article{RN87, title = {Sol-Gel Incorporation of Organometallic Compounds into Silica: Useful Precursors to Metallic Nanostructured Materials}, author = { C. Diaz and M.L. Valenzuela and D. Garrido and P. Aguirre}, url = {/brokenurl#<Go to ISI>://WOS:000305169800021}, issn = {0717-9707}, year = {2012}, date = {2012-01-01}, journal = {Journal of the Chilean Chemical Society}, volume = {57}, number = {2}, pages = {1155-1162}, abstract = {Inclusion of the organometallic MLn = [HOC5H4N center dot Cp2TiCl][PF6] (I), HOC5H4N center dot W(CO)(5) (2), HOC5H4N center dot Mo(CO)(5) (3), [HOC6H4CH2CN center dot Cp2TiCl][PF6] (4), HOC6H4CH2CN center dot W(CO)(5) (5) and HOC6H4CH2CN center dot Mo(CO)(5) (6) into amorphous silica using the gelator precursor TEOS and N3P3N-H[CH2](3)Si[OEt](3)(6) afford the gels (MLn)(SiO2)(n). The inorganic-organic hybrid nanocomposites were pyrolyzed under air at 800 degrees C to give nanostructured metal oxides and/or metal pyrophosphates (phosphates) included in the silica matrices. The morphology of the monolithic nanocomposites exhibited a strong dependence on the gel precursor used being mainly laminar for those prepared using N2P3NH[CH2](3)Si[OEt](3) as gelator. TEm images show different shape and size such as circular nanoparticles, nanocables and agglomerates in some cases with sizes of 20 nm for the circular nanostructures, and diameter about 25 nm for the nanocables.}, keywords = {bridged magnetic-properties, materials, matrix, mesoporous molecular nanoclusters nanocomposites, nanoparticles, nanostructured, nanowires, organic-inorganic polysilsesquioxanes, precursors, pyrophosphates, silica, sol-gel, source thermolytic transformation}, pubstate = {published}, tppubtype = {article} } Inclusion of the organometallic MLn = [HOC5H4N center dot Cp2TiCl][PF6] (I), HOC5H4N center dot W(CO)(5) (2), HOC5H4N center dot Mo(CO)(5) (3), [HOC6H4CH2CN center dot Cp2TiCl][PF6] (4), HOC6H4CH2CN center dot W(CO)(5) (5) and HOC6H4CH2CN center dot Mo(CO)(5) (6) into amorphous silica using the gelator precursor TEOS and N3P3N-H[CH2](3)Si[OEt](3)(6) afford the gels (MLn)(SiO2)(n). The inorganic-organic hybrid nanocomposites were pyrolyzed under air at 800 degrees C to give nanostructured metal oxides and/or metal pyrophosphates (phosphates) included in the silica matrices. The morphology of the monolithic nanocomposites exhibited a strong dependence on the gel precursor used being mainly laminar for those prepared using N2P3NH[CH2](3)Si[OEt](3) as gelator. TEm images show different shape and size such as circular nanoparticles, nanocables and agglomerates in some cases with sizes of 20 nm for the circular nanostructures, and diameter about 25 nm for the nanocables. |
Diaz, C; Valenzuela, M L; Carrillo, D; Riquelme, J; Diaz, R The Inclusion of Organometallic Derivatives of Cyclotriphosphazenes inside Sio2 Matrix and Their Conversion to Nanostructured Metal-Oxides and Phosphates Artículo de revista Journal of Inorganic and Organometallic Polymers and Materials, 22 (5), pp. 1101-1112, 2012, ISSN: 1574-1443. Resumen | Enlaces | BibTeX | Etiquetas: bridged catalyst, copper cyclotriphospahzenes, mesoporous metallic nanoparticles, nanostructures, phosphoric-acid polysilsesquioxanes, precursors, silica, sol-gel sol-gel, synthesis, thermolytic thin-films, transformation, xerogel @article{RN88, title = {The Inclusion of Organometallic Derivatives of Cyclotriphosphazenes inside Sio2 Matrix and Their Conversion to Nanostructured Metal-Oxides and Phosphates}, author = { C. Diaz and M.L. Valenzuela and D. Carrillo and J. Riquelme and R. Diaz}, url = {/brokenurl#<Go to ISI>://WOS:000307754600022}, doi = {10.1007/s10904-012-9692-x}, issn = {1574-1443}, year = {2012}, date = {2012-01-01}, journal = {Journal of Inorganic and Organometallic Polymers and Materials}, volume = {22}, number = {5}, pages = {1101-1112}, abstract = {Organometallic derivatives of the cyclotriphosphazene N3P3[OC6H4CH2CN center dot TiClCp2](6) (1), N3P3(O6H5)(5)[OC6H4N center dot W(CO)(5)] (2), N3P3[OC6H4CH2CN center dot Mo(CO)(5)](6) (3), [N3P3(O6H5)(5)(OC5H4N center dot CpRu(PPh3)(2))][PF6] (4), [N3P3(O2C12H8)(2)OC5H4N center dot Ag(PPh3)][OSO2CF3] (5), N3P3[OC6H5](5) [OC5H4N center dot Cu][PF6] (6) and N3P3[OC6H4CH2CN center dot CuCl](6)[PF6](6) (7),were incorporated inside SiO2 through the sol-gel method. The metal-organic nanocomposites of the general formula N3P3[OC6H4CH2CN center dot TiClCp2](6)center dot nSiO(2) (G (1) ), N3P3[OC6H4N center dot W(CO)(5)]center dot nSiO(2) (G (2) ), N3P3[OC6H4CH2CN center dot Mo(CO)(5)](6)center dot nSiO(2) (G (3) ), N3P3(O6H5)(5)OC5H4N center dot CpRu(PPh3)(2)][PF6]center dot nSiO(2) (G (4) ), [N3P3(O2C12H8)(2)OC5H4N center dot Ag(PPh3)][OSO2CF3]center dot nSiO(2) (G (5) ), N3P3[OC6H5](5)[OC5H4N center dot Cu][PF6]center dot(SiO2) (n) (G (6) ), and N3P3[OC6H4CH2CN center dot CuCl](6)[PF6](6)center dot(SiO2) (n) (G (7) ), were characterized by IR spectroscopy; C-12, (31) P and Si-29 MAS NMR measurements as well as UV-Visible diffuse reflectance spectra, indicating the presence of the respective organometallic derivatives of the cyclotriphosphazene incorporated into SiO2. Pyrolysis of these nanocomposites under air at 800 A degrees C gives rise to nanostructured metal-oxides and metal phosphates incorporated into amorphous SiO2, with the presence in some cases of complexes phase mixtures. From some precursors, we obtained metal-oxides/phosphates nanoparticles separated from the SiO2 nanoparticles instead the oxides/phosphates nanoparticles inside the SiO2 matrix. Additionally and for comparison purposes, we used the compound N3P3[NH(CH2)(3)Si(OEt)(3)](6) as gelator. Nanocomposites (G' (1) ), (G' (2) ) and (G' (3) ) exhibited mainly morphological differences while in some cases composition differences when using TEOS as gelator., Some simple metal-containing compounds as (O3SCF3)Ag(PPh3)(HOC5H4N), [CuCl2 center dot NC5H4OH] and [CuCl2 center dot NCCH2C6H4OH]-which are useful models of the most complexes (G (5) ), (G (6) ) and (G (7) ) were also prepared and incorporated in amorphous silica. Their pyrolytic products were compared with those of more complex cyclotriphosphazene analogous. Interestingly, the pyrolysis of the nanocomposite [(O3SCF3)Ag(PPh3)(HOC5H4N)][SiO2] (n) affords the firstly-reported materials containing Ag2O along with SiO2 nanoparticles.}, keywords = {bridged catalyst, copper cyclotriphospahzenes, mesoporous metallic nanoparticles, nanostructures, phosphoric-acid polysilsesquioxanes, precursors, silica, sol-gel sol-gel, synthesis, thermolytic thin-films, transformation, xerogel}, pubstate = {published}, tppubtype = {article} } Organometallic derivatives of the cyclotriphosphazene N3P3[OC6H4CH2CN center dot TiClCp2](6) (1), N3P3(O6H5)(5)[OC6H4N center dot W(CO)(5)] (2), N3P3[OC6H4CH2CN center dot Mo(CO)(5)](6) (3), [N3P3(O6H5)(5)(OC5H4N center dot CpRu(PPh3)(2))][PF6] (4), [N3P3(O2C12H8)(2)OC5H4N center dot Ag(PPh3)][OSO2CF3] (5), N3P3[OC6H5](5) [OC5H4N center dot Cu][PF6] (6) and N3P3[OC6H4CH2CN center dot CuCl](6)[PF6](6) (7),were incorporated inside SiO2 through the sol-gel method. The metal-organic nanocomposites of the general formula N3P3[OC6H4CH2CN center dot TiClCp2](6)center dot nSiO(2) (G (1) ), N3P3[OC6H4N center dot W(CO)(5)]center dot nSiO(2) (G (2) ), N3P3[OC6H4CH2CN center dot Mo(CO)(5)](6)center dot nSiO(2) (G (3) ), N3P3(O6H5)(5)OC5H4N center dot CpRu(PPh3)(2)][PF6]center dot nSiO(2) (G (4) ), [N3P3(O2C12H8)(2)OC5H4N center dot Ag(PPh3)][OSO2CF3]center dot nSiO(2) (G (5) ), N3P3[OC6H5](5)[OC5H4N center dot Cu][PF6]center dot(SiO2) (n) (G (6) ), and N3P3[OC6H4CH2CN center dot CuCl](6)[PF6](6)center dot(SiO2) (n) (G (7) ), were characterized by IR spectroscopy; C-12, (31) P and Si-29 MAS NMR measurements as well as UV-Visible diffuse reflectance spectra, indicating the presence of the respective organometallic derivatives of the cyclotriphosphazene incorporated into SiO2. Pyrolysis of these nanocomposites under air at 800 A degrees C gives rise to nanostructured metal-oxides and metal phosphates incorporated into amorphous SiO2, with the presence in some cases of complexes phase mixtures. From some precursors, we obtained metal-oxides/phosphates nanoparticles separated from the SiO2 nanoparticles instead the oxides/phosphates nanoparticles inside the SiO2 matrix. Additionally and for comparison purposes, we used the compound N3P3[NH(CH2)(3)Si(OEt)(3)](6) as gelator. Nanocomposites (G' (1) ), (G' (2) ) and (G' (3) ) exhibited mainly morphological differences while in some cases composition differences when using TEOS as gelator., Some simple metal-containing compounds as (O3SCF3)Ag(PPh3)(HOC5H4N), [CuCl2 center dot NC5H4OH] and [CuCl2 center dot NCCH2C6H4OH]-which are useful models of the most complexes (G (5) ), (G (6) ) and (G (7) ) were also prepared and incorporated in amorphous silica. Their pyrolytic products were compared with those of more complex cyclotriphosphazene analogous. Interestingly, the pyrolysis of the nanocomposite [(O3SCF3)Ag(PPh3)(HOC5H4N)][SiO2] (n) affords the firstly-reported materials containing Ag2O along with SiO2 nanoparticles. |
Publicaciones 2011-2020
