Yucang Liang - Academia.edu (original) (raw)
Papers by Yucang Liang
Acta Crystallographica Section E-structure Reports Online, 2004
ABSTRACT A discrete zinc(II) coordination complex, [Zn(bpy)(H2O)4](tp) [bpy = 2,2′-bipyridine (C... more ABSTRACT A discrete zinc(II) coordination complex, [Zn(bpy)(H2O)4](tp) [bpy = 2,2′-bipyridine (C10H8N2) and tp = terephthalate (C8H4O4)], has been prepared from the hydrothermal reaction of Zn(CH3COO)2·2H2O, bpy and terephthalic acid in water. The zinc ion has a distorted octahedral coordination environment, with two N atoms from bpy and four water molecules. The terephthalate anion does not coordinate to the ZnII metal center. Hydrogen bonds and π–π stacking interactions play important roles in the production of a three-dimensional supramolecular structure.
Journal of Materials Chemistry, 2005
ABSTRACT Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+2Br- (C16-3-1) was exploited as a ... more ABSTRACT Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+2Br- (C16-3-1) was exploited as a structure directing agent (SDA) for the synthesis of highly ordered periodic mesoporous organosilicas (PMOs) from 1,2-bis(triethoxysilyl)ethane (BTEE) as organosilica source under basic conditions. The mesophase structure/symmetry and the phys. parameters could be controlled/optimized by adjusting synthetic parameters such as surfactant and base concn., hydrothermal aging temp. and time, and crucially the type (charge, shape, aliph. tail chain length) of the surfactant. Cubic PMO[KIT-5]-n reveals a face-centered Fm3m symmetry similar to that of the previously reported purely siliceous material KIT-5. Under the applied reaction conditions, lower aging temps. generally afforded PMO[KIT-5] materials with increased BET surface area (max. 840 m2 g-1) and pore vol. (max. 0.93 cm3 g-1), however, similar pore size (ca. 3.0 nm). Lower divalent surfactant concns. (C16-3-1) caused a mesophase transformation from cubic Fm3m to hexagonal P6mm symmetry. Upon relative increase of the base (NaOH) concn., the PMO mesostructure transformed from hexagonal to cubic, then from cubic to hexagonal symmetry. Surfactants [CH3(CH2)17N(CH3)2(CH2)3N(CH3)3]2+2Br- (C18-3-1), [CH3(CH2)15N(CH3)2(CH2)3-N(C2H5)3]2+2Br- (C16-3-2), and [CH3(CH2)15N(CH3)3]+Br- (C16) were found to encode for PMO[SBA-1]-n and PMO[MCM-41]-n with cubic Pm3n (former) and hexagonal P6mm symmetry (latter two), resp. All these periodic mesoporous organosilicas were characterized by powder x-ray diffraction (PXRD), nitrogen physisorption, FTIR spectroscopy, 13C and 29Si solid state NMR spectroscopy, SEM, and transmission electron microscopy (TEM). [on SciFinder (R)]
Chemistry of Materials, 2008
The mesophase structure of ordered periodic mesoporous organosilicas (PMOs) can be easily adjuste... more The mesophase structure of ordered periodic mesoporous organosilicas (PMOs) can be easily adjusted under basic conditions by variation of the sodium hydroxide concentration. PMOs with hexagonal (p6mm, two-dimensional pore system), cubic (Pm3n or Fm3m, three-dimensional cagelike pore system), and disordered hexagonal (MSU-type) symmetry were obtained from 1,2-bis(triethoxysilyl)ethane (BTEE)derived synthesis gels in the presence of binary surfactant mixtures, [CH 3 (CH 2 ) 15 NMe 3 ] + Br -(C 16 TABr) and [CH 3 (CH 2 ) n NMe 2 (CH 2 ) 3 NMe 3 ] 2+ 2Br -(n ) 15, 17), as structure-directing agents. With an increasing amount of NaOH, mesophase-mesophase transitions from p6mm f Pm3n f Fm3m f distorted cubic f MSU-type (3D-network of "wormholelike" mesopores) were evidenced by powder X-ray diffraction analysis and transmission electron microscopy. Slight variations of the NaOH concentration not only affected the PMO mesophase structure via the charge matching principle but also the PMO morphology. Among others, hexagons with smooth faces, regular decaoctahedrons, and spherical particles were found from scanning electron microscopy. The PMO mesophase was further found to be dependent on the carbon chain length of the surfactant. 13 C and 29 Si magic-angle-spinning NMR spectroscopy revealed that intact ethylene moieties were incorporated uniformly into the framework. According to N 2 physisorption measurements, the PMOs display Brunauer-Emmett-Teller surface areas as high as 870 m 2 /g and cage diameters in the [55,63] Å size range. Finally, the hydrothermal stability of three representative PMOs with cubic Pm3n, cubic Fm3m, and hexagonal p6mm symmetry was investigated in detail.
Journal of Materials Chemistry, 2007
RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/B700545H (... more RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/B700545H (Paper) J. Mater. Chem., 2007, 17, 2506-2516. Disilazane functionalization of large-pore hybrid periodic mesoporous organosilicas†. ...
Chemical Communications, 2005
Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ - 2Br- (C16-3-1) was used as a structure d... more Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ - 2Br- (C16-3-1) was used as a structure directing agent (SDA) for the synthesis of highly ordered periodic mesoporous organosilicas (PMOs) with cubic Fm3m symmetry from 1,2-bis(triethoxylsilyl)ethane (BTEE) under basic conditions.
Chemistry of Materials, 2007
ABSTRACT Periodic mesoporous silicas SBA-1, SBA-2, and SBA-16 feature a unique cagelike pore topo... more ABSTRACT Periodic mesoporous silicas SBA-1, SBA-2, and SBA-16 feature a unique cagelike pore topol. consisting of large supercages interconnected by smaller windows. Compared to channel-like mesoporous silica MCM-48, these cagelike silicas display a distinct reactivity toward magnesium silylamides {Mg[N(SiHMe2)2]2}2 and {Mg[N(SiMe3)2]2}2. All surface silanol groups ==Si-OH of MCM-48 can be derivatized with the magnesium grafting precursors, forming stable silicon-oxygen-magnesium linkages. The completeness of the reaction is evidenced by a dramatic loss of specific pore vol. (0.92 -> 0.27 and 0.30 cm3 g-1), disappearance of the OH stretching vibration in the IR spectrum and the magnesium content (3.5 and 4.0 wt %) of the hybrid materials Mg[N(SiHMe2)2]x@MCM-48 and Mg[N(SiMe3)2]x@MCM-48. In contrast, the amt. of magnesium that can be grafted onto the surface of cagelike silica SBA-1 does not exceed 0.3 wt %. The specific pore vol. of SBA-1 hybrid materials is only slightly decreased compared to the MCM-48 materials and the majority of the SiOH groups is still visible in the IR spectrum. We assume that the surface reaction is limited to the external surface of the SBA-1 silica particles. The remaining silanol functional groups located at the internal surface of SBA-1 are prone to further derivatization with small silylating reagents or small metalorg. compds. such as HN(SiHMe2)2 or Ti(NMe2)4 yielding org./metalorg. or heterobimetallic hybrid materials, resp. [on SciFinder (R)]
Chemistry-a European Journal, 2007
A series of functionalized mesoporous silicas with cagelike pore topology has been synthesized an... more A series of functionalized mesoporous silicas with cagelike pore topology has been synthesized and screened for size-selective catalytic transformations. The aluminum-catalyzed Meerwein–Ponndorf–Verley (MPV) reduction of differently sized aromatic aldehydes (benzaldehyde and 1-pyrenecarbox-aldehyde) has been investigated as a test reaction. The catalysts were synthesized in a two-step grafting sequence comprising pore-size engineering of mesoporous silicas (SBA-1, SBA-2, SBA-16) with long-chain alkyl dimethylaminosilanes and surface organoaluminum chemistry with triethylaluminum [{Al(CH2CH3)3}2]. Size-selective reaction behavior was found for small pore SBA-1 materials, and the selectivity could be efficiently tuned by selecting a silylating reagent of appropriate size. The results are compared with the catalytic performance of a large-pore periodic mesoporous organosilica PMO[SBA-1] and the nonporous high-surface-area silicas Aerosil 300/380.
Microporous and Mesoporous Materials, 2004
A series of mesoporous organosilicas (MOs) in the ½3:2; 11:1 nm pore diameter range has been obta... more A series of mesoporous organosilicas (MOs) in the ½3:2; 11:1 nm pore diameter range has been obtained in basic media by using 1,2-bis(triethoxysilyl)ethane (BTEE) or 1,2-bis(trimethoxysilyl)ethane (BTME) as a silica source, binary surfactant mixtures [CH 3 (CH 2 ) 17 NMe 2 (CH 2 ) 3 NMe 3 ] 2þ 2Br À (C 18-3-1 ) and [CH 3 (CH 2 ) 15 NMe 3 ] þ Br À (C 16 TABr) as structure-directing agents (SDAs), and TMB (mesitylene) or TPB (1,3,5-triisopropylbenzene) as swelling agents. Pore size control has been achieved via variation of (i) the binary surfactant ratio, (ii) base (sodium hydroxide) concentration, (iii) reaction time and temperature, and (iv) type of expander molecule. The surface morphology and silanol population of the dehydrated MOs was examined by TMDS (tetramethyldisilazane) silylation. The parent and functionalized MOs were characterized by powder X-ray diffraction, N 2 physisorption, elemental analysis, FTIR, and solid-state ( 1 H, 13 C, 29 Si) NMR spectroscopy. According to their PXRD patterns, the pore-enlarged MO materials do not display any long-range order, however, pore volumes >2 cm 3 /g. The type of hysteresis loop exhibited by the N 2 adsorption and desorption isotherm changed remarkably for MOs synthesized at low concentrations of divalent surfactant as well as base, which can be attributed to a change of pore topology. 29 Si MAS NMR spectroscopy revealed the prominent T 2 and T 3 peaks at )58and)58 and )58and)64 ppm, respectively, indicative of an intact wall and surface structure. The silyl group coverage was determined as 0.8-1.3 SiHMe 2 groups per nm 2 corresponding to approximately half of that found on purely siliceous periodic mesoporous silicas such as MCM-41 or MCM-48.
Journal of Materials Chemistry, 2006
Journal of The Chemical Society-dalton Transactions, 2001
Hydrothermal reactions of rare earth ions(III) with a flexible building unit (1,3,4-thiadiazole-2... more Hydrothermal reactions of rare earth ions(III) with a flexible building unit (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H 2 tzda) lead to five novel coordination polymers with 1D chain and 3D network structures, namely, {[Y 2 (tzda) 3 (H 2 O) 10 ] AE 5H 2 O} n (1) and [Ln 2 (tzda) 3 (H 2 O) 5 ] n [Ln = Er (2), Pr (3), Nd (4), Eu ]. Compound 1 has one-dimensional ribbon-like chain structure constructed by [Y 2 (tzda) 3 ] units through the syn-anti bidentate bridging mode of carboxylate groups. Compounds 2-5 possess compact three-dimensional network structures which are made up of [Ln 2 (tzda) 3 ] (Ln = Er, Pr, Nd and Eu) units bridged by carboxylate groups. In these compounds, the flexible tzda 2À ligand is versatile and displays six different coordination fashions to meet the requirement of the coordination preference of the metal center. Furthermore, the magnetic behaviors for 2-5 in the temperature range of 5.0-300 K and photoluminescent property of 5 are significantly investigated in this paper.
Angewandte Chemie-international Edition, 2000
2 O (3) {1,3-tpbd = 1,3bis[bis(2-pyridylmethyl)amino]benzene} were synthesised and structurally c... more 2 O (3) {1,3-tpbd = 1,3bis[bis(2-pyridylmethyl)amino]benzene} were synthesised and structurally characterised by X-ray diffraction. Variabletemperature (2.0−290 K) magnetic susceptibility measurements on these complexes as well as on the dinuclear cop- [a]
Chemistry Letters, 2001
ABSTRACT
Acta Crystallographica Section E-structure Reports Online, 2001
... Although some complexes containing the pyridine-2,5-dicarboxylic acid ligand have been report... more ... Although some complexes containing the pyridine-2,5-dicarboxylic acid ligand have been reported (Plater et al., 1998 [Plater, MJ, Forman, MR St J., Howie, RA & Lachowski, EE (1998). ... [CrossRef] [details] Plater, MJ, Forman, MR St J., Howie, RA & Lachowski, EE (1998). ...
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Acta Crystallographica Section E-structure Reports Online, 2001
ABSTRACT
Journal of The Chemical Society-dalton Transactions, 2002
ABSTRACT
Acta Crystallographica Section C-crystal Structure Communications, 2000
The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hyd... more The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hydrothermal reaction of CuCl(2), 1,4-dicyanobenzene, 1,10-phenanthroline and water at 443 K. The compound is a dimer in which the cation lies about an inversion center. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu-O distances of 1.955 (2) and 2.815 (2) A, and Cu-N distances of 2.008 (2) to 2.216 (2) A.
Bulletin of The Chemical Society of Japan, 2002
ABSTRACT The hydrothermal reactions of Ln2O3, Zn(NO3)2.6H2O, pyrazine-2,3-dicarboxylic acid (H2pz... more ABSTRACT The hydrothermal reactions of Ln2O3, Zn(NO3)2.6H2O, pyrazine-2,3-dicarboxylic acid (H2pzdc) and H2O gave three isostructural coordination polymers [Ln2Zn(pzdc)4(H2O)6.2H2O]n (Ln = Gd, 1; Nd, 2; and Sm, 3). The crystal structures of complexes 1 and 2 were detd. by x-ray diffraction methods. Compds. 1, 2 and 3 are isomorphous and crystallize in the monoclinic space group P21/n with a 6.1196(2), b 22.5318(8), c 11.9617(1) .ANG., beta 91.766(2) Deg, Z = 2 for 1, and a 6.1644(3), b 22.6577(12), c 12.0384(6) .ANG., beta 91.513(2) Deg, Z = 2 for 2. X-ray diffraction analyses confirm that complexes 1 and 2 possess a 3-dimensional brick-like framework structure, each framework being surround by metal atoms, with a size of 16.37 * 6.12 .ANG., accommodating two water mols. as guests. The Ln(III) ions in compds. 1 to 3 are coordinated by seven oxygen and two nitrogen atoms. In addn., the zinc(II) ions are bonded by two carboxyl oxygen, two nitrogen and two apical carboxyl oxygen atoms in an octahedral geometry. The excitation spectrum and luminescent properties of 1 and 3 were studied qual. [on SciFinder (R)]
Inorganic Chemistry Communications, 2002
Two novel three dimension Ln(III)-Cu(II) coordination polymers ½Gd 2 CuðpydcÞ 4 ðH 2 OÞ 6 n and ½... more Two novel three dimension Ln(III)-Cu(II) coordination polymers ½Gd 2 CuðpydcÞ 4 ðH 2 OÞ 6 n and ½Sm 2 Cu 3 ðpydcÞ 6 ðH 2 OÞ 6 n were prepared by the hydrothermal reactions of CuO, Ln 2 O 3 (Ln ¼ Gd, Sm), H 2 pydc (H 2 pydc ¼ 2,4-pyridinedicarboxylic acid) and characterized by single-crystal X-ray diffraction analysis. Ó
Acta Crystallographica Section C-crystal Structure Communications, 2000
The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hyd... more The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hydrothermal reaction of CuCl(2), 1,4-dicyanobenzene, 1,10-phenanthroline and water at 443 K. The compound is a dimer in which the cation lies about an inversion center. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu-O distances of 1.955 (2) and 2.815 (2) A, and Cu-N distances of 2.008 (2) to 2.216 (2) A.
Inorganic Chemistry, 2001
The hydrothermal reaction of Ln2O3 (Ln = Er, Gd, and Sm), pyridine-2,5-dicarboxylic acid (H2pydc)... more The hydrothermal reaction of Ln2O3 (Ln = Er, Gd, and Sm), pyridine-2,5-dicarboxylic acid (H2pydc), and Cu(II) reagents (CuO, Cu(OAc)2-2H2O, or CuCl2-2H2O) with a mole ratio of 1:2:4 resulted in the formation of six polymeric Cu(II)-Ln(III) complexes, [(Ln2Cu3(pydc)6(H2O)12)-4H2O]n (Ln = Er (1); Ln = Gd (2)), [(Ln4Cu2(pydc)8(H2O)12)-4H2O]n (Ln = Sm (3); Ln = Gd (4); Ln = Er (5)), and [(Gd2Cu2(pydc)4(H2O)8)-Cu(pydc)2-12H2O]n (6). 1 and 2 are isomorphous and crystallize in triclinic space group Ponebar. Compounds 3-5 are isomorphous and crystallize in monoclinic space group P2(1)/c. Compound 6 crystallizes in triclinic space group Ponebar. Complexes 1 and 2 have one-dimensional zigzag chain structures and compounds 3-5 display three-dimensional wavelike polymeric structures, while 6 has an infinite sandwich-type structure. The different structures of the complexes are induced by the different forms of Cu(II) reagents; the reactions of Cu(OAc)2-2H2O yield high Cu/Ln ratio products 1, 2, and 6, while the reactions of CuO or CuCl2-2H2O/2,2'-bipyridine results in low Cu/Ln ratio compounds 3-5. Temperature-dependent magnetic susceptibilities for 2, 4, and 5 were studied, and the thermal stabilities of complexes 2 and 4 were examined.
Acta Crystallographica Section E-structure Reports Online, 2004
ABSTRACT A discrete zinc(II) coordination complex, [Zn(bpy)(H2O)4](tp) [bpy = 2,2′-bipyridine (C... more ABSTRACT A discrete zinc(II) coordination complex, [Zn(bpy)(H2O)4](tp) [bpy = 2,2′-bipyridine (C10H8N2) and tp = terephthalate (C8H4O4)], has been prepared from the hydrothermal reaction of Zn(CH3COO)2·2H2O, bpy and terephthalic acid in water. The zinc ion has a distorted octahedral coordination environment, with two N atoms from bpy and four water molecules. The terephthalate anion does not coordinate to the ZnII metal center. Hydrogen bonds and π–π stacking interactions play important roles in the production of a three-dimensional supramolecular structure.
Journal of Materials Chemistry, 2005
ABSTRACT Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+2Br- (C16-3-1) was exploited as a ... more ABSTRACT Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+2Br- (C16-3-1) was exploited as a structure directing agent (SDA) for the synthesis of highly ordered periodic mesoporous organosilicas (PMOs) from 1,2-bis(triethoxysilyl)ethane (BTEE) as organosilica source under basic conditions. The mesophase structure/symmetry and the phys. parameters could be controlled/optimized by adjusting synthetic parameters such as surfactant and base concn., hydrothermal aging temp. and time, and crucially the type (charge, shape, aliph. tail chain length) of the surfactant. Cubic PMO[KIT-5]-n reveals a face-centered Fm3m symmetry similar to that of the previously reported purely siliceous material KIT-5. Under the applied reaction conditions, lower aging temps. generally afforded PMO[KIT-5] materials with increased BET surface area (max. 840 m2 g-1) and pore vol. (max. 0.93 cm3 g-1), however, similar pore size (ca. 3.0 nm). Lower divalent surfactant concns. (C16-3-1) caused a mesophase transformation from cubic Fm3m to hexagonal P6mm symmetry. Upon relative increase of the base (NaOH) concn., the PMO mesostructure transformed from hexagonal to cubic, then from cubic to hexagonal symmetry. Surfactants [CH3(CH2)17N(CH3)2(CH2)3N(CH3)3]2+2Br- (C18-3-1), [CH3(CH2)15N(CH3)2(CH2)3-N(C2H5)3]2+2Br- (C16-3-2), and [CH3(CH2)15N(CH3)3]+Br- (C16) were found to encode for PMO[SBA-1]-n and PMO[MCM-41]-n with cubic Pm3n (former) and hexagonal P6mm symmetry (latter two), resp. All these periodic mesoporous organosilicas were characterized by powder x-ray diffraction (PXRD), nitrogen physisorption, FTIR spectroscopy, 13C and 29Si solid state NMR spectroscopy, SEM, and transmission electron microscopy (TEM). [on SciFinder (R)]
Chemistry of Materials, 2008
The mesophase structure of ordered periodic mesoporous organosilicas (PMOs) can be easily adjuste... more The mesophase structure of ordered periodic mesoporous organosilicas (PMOs) can be easily adjusted under basic conditions by variation of the sodium hydroxide concentration. PMOs with hexagonal (p6mm, two-dimensional pore system), cubic (Pm3n or Fm3m, three-dimensional cagelike pore system), and disordered hexagonal (MSU-type) symmetry were obtained from 1,2-bis(triethoxysilyl)ethane (BTEE)derived synthesis gels in the presence of binary surfactant mixtures, [CH 3 (CH 2 ) 15 NMe 3 ] + Br -(C 16 TABr) and [CH 3 (CH 2 ) n NMe 2 (CH 2 ) 3 NMe 3 ] 2+ 2Br -(n ) 15, 17), as structure-directing agents. With an increasing amount of NaOH, mesophase-mesophase transitions from p6mm f Pm3n f Fm3m f distorted cubic f MSU-type (3D-network of "wormholelike" mesopores) were evidenced by powder X-ray diffraction analysis and transmission electron microscopy. Slight variations of the NaOH concentration not only affected the PMO mesophase structure via the charge matching principle but also the PMO morphology. Among others, hexagons with smooth faces, regular decaoctahedrons, and spherical particles were found from scanning electron microscopy. The PMO mesophase was further found to be dependent on the carbon chain length of the surfactant. 13 C and 29 Si magic-angle-spinning NMR spectroscopy revealed that intact ethylene moieties were incorporated uniformly into the framework. According to N 2 physisorption measurements, the PMOs display Brunauer-Emmett-Teller surface areas as high as 870 m 2 /g and cage diameters in the [55,63] Å size range. Finally, the hydrothermal stability of three representative PMOs with cubic Pm3n, cubic Fm3m, and hexagonal p6mm symmetry was investigated in detail.
Journal of Materials Chemistry, 2007
RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/B700545H (... more RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/B700545H (Paper) J. Mater. Chem., 2007, 17, 2506-2516. Disilazane functionalization of large-pore hybrid periodic mesoporous organosilicas†. ...
Chemical Communications, 2005
Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ - 2Br- (C16-3-1) was used as a structure d... more Divalent surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ - 2Br- (C16-3-1) was used as a structure directing agent (SDA) for the synthesis of highly ordered periodic mesoporous organosilicas (PMOs) with cubic Fm3m symmetry from 1,2-bis(triethoxylsilyl)ethane (BTEE) under basic conditions.
Chemistry of Materials, 2007
ABSTRACT Periodic mesoporous silicas SBA-1, SBA-2, and SBA-16 feature a unique cagelike pore topo... more ABSTRACT Periodic mesoporous silicas SBA-1, SBA-2, and SBA-16 feature a unique cagelike pore topol. consisting of large supercages interconnected by smaller windows. Compared to channel-like mesoporous silica MCM-48, these cagelike silicas display a distinct reactivity toward magnesium silylamides {Mg[N(SiHMe2)2]2}2 and {Mg[N(SiMe3)2]2}2. All surface silanol groups ==Si-OH of MCM-48 can be derivatized with the magnesium grafting precursors, forming stable silicon-oxygen-magnesium linkages. The completeness of the reaction is evidenced by a dramatic loss of specific pore vol. (0.92 -> 0.27 and 0.30 cm3 g-1), disappearance of the OH stretching vibration in the IR spectrum and the magnesium content (3.5 and 4.0 wt %) of the hybrid materials Mg[N(SiHMe2)2]x@MCM-48 and Mg[N(SiMe3)2]x@MCM-48. In contrast, the amt. of magnesium that can be grafted onto the surface of cagelike silica SBA-1 does not exceed 0.3 wt %. The specific pore vol. of SBA-1 hybrid materials is only slightly decreased compared to the MCM-48 materials and the majority of the SiOH groups is still visible in the IR spectrum. We assume that the surface reaction is limited to the external surface of the SBA-1 silica particles. The remaining silanol functional groups located at the internal surface of SBA-1 are prone to further derivatization with small silylating reagents or small metalorg. compds. such as HN(SiHMe2)2 or Ti(NMe2)4 yielding org./metalorg. or heterobimetallic hybrid materials, resp. [on SciFinder (R)]
Chemistry-a European Journal, 2007
A series of functionalized mesoporous silicas with cagelike pore topology has been synthesized an... more A series of functionalized mesoporous silicas with cagelike pore topology has been synthesized and screened for size-selective catalytic transformations. The aluminum-catalyzed Meerwein–Ponndorf–Verley (MPV) reduction of differently sized aromatic aldehydes (benzaldehyde and 1-pyrenecarbox-aldehyde) has been investigated as a test reaction. The catalysts were synthesized in a two-step grafting sequence comprising pore-size engineering of mesoporous silicas (SBA-1, SBA-2, SBA-16) with long-chain alkyl dimethylaminosilanes and surface organoaluminum chemistry with triethylaluminum [{Al(CH2CH3)3}2]. Size-selective reaction behavior was found for small pore SBA-1 materials, and the selectivity could be efficiently tuned by selecting a silylating reagent of appropriate size. The results are compared with the catalytic performance of a large-pore periodic mesoporous organosilica PMO[SBA-1] and the nonporous high-surface-area silicas Aerosil 300/380.
Microporous and Mesoporous Materials, 2004
A series of mesoporous organosilicas (MOs) in the ½3:2; 11:1 nm pore diameter range has been obta... more A series of mesoporous organosilicas (MOs) in the ½3:2; 11:1 nm pore diameter range has been obtained in basic media by using 1,2-bis(triethoxysilyl)ethane (BTEE) or 1,2-bis(trimethoxysilyl)ethane (BTME) as a silica source, binary surfactant mixtures [CH 3 (CH 2 ) 17 NMe 2 (CH 2 ) 3 NMe 3 ] 2þ 2Br À (C 18-3-1 ) and [CH 3 (CH 2 ) 15 NMe 3 ] þ Br À (C 16 TABr) as structure-directing agents (SDAs), and TMB (mesitylene) or TPB (1,3,5-triisopropylbenzene) as swelling agents. Pore size control has been achieved via variation of (i) the binary surfactant ratio, (ii) base (sodium hydroxide) concentration, (iii) reaction time and temperature, and (iv) type of expander molecule. The surface morphology and silanol population of the dehydrated MOs was examined by TMDS (tetramethyldisilazane) silylation. The parent and functionalized MOs were characterized by powder X-ray diffraction, N 2 physisorption, elemental analysis, FTIR, and solid-state ( 1 H, 13 C, 29 Si) NMR spectroscopy. According to their PXRD patterns, the pore-enlarged MO materials do not display any long-range order, however, pore volumes >2 cm 3 /g. The type of hysteresis loop exhibited by the N 2 adsorption and desorption isotherm changed remarkably for MOs synthesized at low concentrations of divalent surfactant as well as base, which can be attributed to a change of pore topology. 29 Si MAS NMR spectroscopy revealed the prominent T 2 and T 3 peaks at )58and)58 and )58and)64 ppm, respectively, indicative of an intact wall and surface structure. The silyl group coverage was determined as 0.8-1.3 SiHMe 2 groups per nm 2 corresponding to approximately half of that found on purely siliceous periodic mesoporous silicas such as MCM-41 or MCM-48.
Journal of Materials Chemistry, 2006
Journal of The Chemical Society-dalton Transactions, 2001
Hydrothermal reactions of rare earth ions(III) with a flexible building unit (1,3,4-thiadiazole-2... more Hydrothermal reactions of rare earth ions(III) with a flexible building unit (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H 2 tzda) lead to five novel coordination polymers with 1D chain and 3D network structures, namely, {[Y 2 (tzda) 3 (H 2 O) 10 ] AE 5H 2 O} n (1) and [Ln 2 (tzda) 3 (H 2 O) 5 ] n [Ln = Er (2), Pr (3), Nd (4), Eu ]. Compound 1 has one-dimensional ribbon-like chain structure constructed by [Y 2 (tzda) 3 ] units through the syn-anti bidentate bridging mode of carboxylate groups. Compounds 2-5 possess compact three-dimensional network structures which are made up of [Ln 2 (tzda) 3 ] (Ln = Er, Pr, Nd and Eu) units bridged by carboxylate groups. In these compounds, the flexible tzda 2À ligand is versatile and displays six different coordination fashions to meet the requirement of the coordination preference of the metal center. Furthermore, the magnetic behaviors for 2-5 in the temperature range of 5.0-300 K and photoluminescent property of 5 are significantly investigated in this paper.
Angewandte Chemie-international Edition, 2000
2 O (3) {1,3-tpbd = 1,3bis[bis(2-pyridylmethyl)amino]benzene} were synthesised and structurally c... more 2 O (3) {1,3-tpbd = 1,3bis[bis(2-pyridylmethyl)amino]benzene} were synthesised and structurally characterised by X-ray diffraction. Variabletemperature (2.0−290 K) magnetic susceptibility measurements on these complexes as well as on the dinuclear cop- [a]
Chemistry Letters, 2001
ABSTRACT
Acta Crystallographica Section E-structure Reports Online, 2001
... Although some complexes containing the pyridine-2,5-dicarboxylic acid ligand have been report... more ... Although some complexes containing the pyridine-2,5-dicarboxylic acid ligand have been reported (Plater et al., 1998 [Plater, MJ, Forman, MR St J., Howie, RA & Lachowski, EE (1998). ... [CrossRef] [details] Plater, MJ, Forman, MR St J., Howie, RA & Lachowski, EE (1998). ...
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Acta Crystallographica Section E-structure Reports Online, 2001
ABSTRACT
Journal of The Chemical Society-dalton Transactions, 2002
ABSTRACT
Acta Crystallographica Section C-crystal Structure Communications, 2000
The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hyd... more The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hydrothermal reaction of CuCl(2), 1,4-dicyanobenzene, 1,10-phenanthroline and water at 443 K. The compound is a dimer in which the cation lies about an inversion center. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu-O distances of 1.955 (2) and 2.815 (2) A, and Cu-N distances of 2.008 (2) to 2.216 (2) A.
Bulletin of The Chemical Society of Japan, 2002
ABSTRACT The hydrothermal reactions of Ln2O3, Zn(NO3)2.6H2O, pyrazine-2,3-dicarboxylic acid (H2pz... more ABSTRACT The hydrothermal reactions of Ln2O3, Zn(NO3)2.6H2O, pyrazine-2,3-dicarboxylic acid (H2pzdc) and H2O gave three isostructural coordination polymers [Ln2Zn(pzdc)4(H2O)6.2H2O]n (Ln = Gd, 1; Nd, 2; and Sm, 3). The crystal structures of complexes 1 and 2 were detd. by x-ray diffraction methods. Compds. 1, 2 and 3 are isomorphous and crystallize in the monoclinic space group P21/n with a 6.1196(2), b 22.5318(8), c 11.9617(1) .ANG., beta 91.766(2) Deg, Z = 2 for 1, and a 6.1644(3), b 22.6577(12), c 12.0384(6) .ANG., beta 91.513(2) Deg, Z = 2 for 2. X-ray diffraction analyses confirm that complexes 1 and 2 possess a 3-dimensional brick-like framework structure, each framework being surround by metal atoms, with a size of 16.37 * 6.12 .ANG., accommodating two water mols. as guests. The Ln(III) ions in compds. 1 to 3 are coordinated by seven oxygen and two nitrogen atoms. In addn., the zinc(II) ions are bonded by two carboxyl oxygen, two nitrogen and two apical carboxyl oxygen atoms in an octahedral geometry. The excitation spectrum and luminescent properties of 1 and 3 were studied qual. [on SciFinder (R)]
Inorganic Chemistry Communications, 2002
Two novel three dimension Ln(III)-Cu(II) coordination polymers ½Gd 2 CuðpydcÞ 4 ðH 2 OÞ 6 n and ½... more Two novel three dimension Ln(III)-Cu(II) coordination polymers ½Gd 2 CuðpydcÞ 4 ðH 2 OÞ 6 n and ½Sm 2 Cu 3 ðpydcÞ 6 ðH 2 OÞ 6 n were prepared by the hydrothermal reactions of CuO, Ln 2 O 3 (Ln ¼ Gd, Sm), H 2 pydc (H 2 pydc ¼ 2,4-pyridinedicarboxylic acid) and characterized by single-crystal X-ray diffraction analysis. Ó
Acta Crystallographica Section C-crystal Structure Communications, 2000
The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hyd... more The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hydrothermal reaction of CuCl(2), 1,4-dicyanobenzene, 1,10-phenanthroline and water at 443 K. The compound is a dimer in which the cation lies about an inversion center. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu-O distances of 1.955 (2) and 2.815 (2) A, and Cu-N distances of 2.008 (2) to 2.216 (2) A.
Inorganic Chemistry, 2001
The hydrothermal reaction of Ln2O3 (Ln = Er, Gd, and Sm), pyridine-2,5-dicarboxylic acid (H2pydc)... more The hydrothermal reaction of Ln2O3 (Ln = Er, Gd, and Sm), pyridine-2,5-dicarboxylic acid (H2pydc), and Cu(II) reagents (CuO, Cu(OAc)2-2H2O, or CuCl2-2H2O) with a mole ratio of 1:2:4 resulted in the formation of six polymeric Cu(II)-Ln(III) complexes, [(Ln2Cu3(pydc)6(H2O)12)-4H2O]n (Ln = Er (1); Ln = Gd (2)), [(Ln4Cu2(pydc)8(H2O)12)-4H2O]n (Ln = Sm (3); Ln = Gd (4); Ln = Er (5)), and [(Gd2Cu2(pydc)4(H2O)8)-Cu(pydc)2-12H2O]n (6). 1 and 2 are isomorphous and crystallize in triclinic space group Ponebar. Compounds 3-5 are isomorphous and crystallize in monoclinic space group P2(1)/c. Compound 6 crystallizes in triclinic space group Ponebar. Complexes 1 and 2 have one-dimensional zigzag chain structures and compounds 3-5 display three-dimensional wavelike polymeric structures, while 6 has an infinite sandwich-type structure. The different structures of the complexes are induced by the different forms of Cu(II) reagents; the reactions of Cu(OAc)2-2H2O yield high Cu/Ln ratio products 1, 2, and 6, while the reactions of CuO or CuCl2-2H2O/2,2'-bipyridine results in low Cu/Ln ratio compounds 3-5. Temperature-dependent magnetic susceptibilities for 2, 4, and 5 were studied, and the thermal stabilities of complexes 2 and 4 were examined.