Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthe...Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate)(PET).It was only used as polycondensation catalyst because it was sensitive to water.For this catalyst,the degree of esterification of the theoretical amount of water was produced up to 95%at 260℃,while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester,polymerized at 280℃,70 Pa for 39 min,was 0.87 dL/g and 23.0μmol/g,respectively.Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.展开更多
Boehmites(Al2O3·xH2O)were hydrothermally prepared from aluminum alkoxide.The effect of temperature on preparation was studied in the range of 100-180℃.The XRD analysis shows that with temperature increasing,the ...Boehmites(Al2O3·xH2O)were hydrothermally prepared from aluminum alkoxide.The effect of temperature on preparation was studied in the range of 100-180℃.The XRD analysis shows that with temperature increasing,the transformation of pseudo-boehmite into well-crystallized boehmite takes place.The micro-morphologies change also from irregular clew to thin cubic platelets.From the mass loss of the samples prepared at different temperatures,the value of x is estimated to vary between 1.06 and 1.67.γ-Al2O3 obtained by subsequent calcination of boehmite at 600℃is also characterized by XRD and its morphology remains unchanged.展开更多
Titanium dioxide(TiO 2) samples of different crystal forms were prepared by hydrolysis tetrabutyl titanate in various water to alkoxide ratios and sintering the hydrolysis product at different temperatures. The photo...Titanium dioxide(TiO 2) samples of different crystal forms were prepared by hydrolysis tetrabutyl titanate in various water to alkoxide ratios and sintering the hydrolysis product at different temperatures. The photocatalysts coated on hollow glass beads and loaded with platinum varying from 0.2% to 2.4% by weight.The photocatalytic degradation rate of sodium pentachlorophenolate (PCP-Na) depends on the preparing conditions such as: sintering temperatures, water to alkoxide ratios( R ), platinum content and the size. The proper conditions of preparation photocatalysts are as follows: the ratio of TiO 2 : sodium silicate : hollow glass beads : platinum is 10:5:20:0.15(w/w), R is 100, sintering temperature is 650℃, and the size of hollow glass is 0.5-1 mm. Under these conditions, the ratio between acatase and rutile of the photocatalyst is 2:1, and the photocatalytic activity is high.展开更多
High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion te...High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.展开更多
In this work, the magnesium aluminum spinel (MgAl2O4) was prepared by Mg and Al as precursors through a method of sol-gel subsequent with high temperature calcination. The wide range of synthetic conditions, including...In this work, the magnesium aluminum spinel (MgAl2O4) was prepared by Mg and Al as precursors through a method of sol-gel subsequent with high temperature calcination. The wide range of synthetic conditions, including organic alcohols, ammonia content, dispersant, alkoxide concentration, hydrolysis time, hydrolysis temperature and calcination temperature were screened over as-prepared samples. This work provides a necessary experimental basis for the synthesis of MgAl2O4 with uniform particle size of spherical structure, which has a potential to be used in many industrial and military applications.展开更多
The fundamental characteristics of varied initial core-sizes of Ba Ti O3（BT） and its influential role on the morphology and dielectric properties of Ba Ti O3@0.6 Ba Ti O3-0.4 Bi Al O3（BT@0.6 BT-0.4 BA） ceramic sam...The fundamental characteristics of varied initial core-sizes of Ba Ti O3（BT） and its influential role on the morphology and dielectric properties of Ba Ti O3@0.6 Ba Ti O3-0.4 Bi Al O3（BT@0.6 BT-0.4 BA） ceramic samples were studied. Alkoxide sol-precipitation method was adopted as revised chemical route to synthesize the constituent ＂core＂ BT powders in a dispersed phase, whereas the distinctive initial nano-sized particles were affected by the pre-calcination temperatures（600-900 ℃）.The microstructure of the uncoated BT ceramics revealed an exaggerated grain growth with an optimized dielectric constant（ε（max） 〉9 000） whilst the coated ceramics behaved otherwise（grain growth inhibited） when sintered at an elevated temperature. Regardless of the previously studied solubility limit（about 0.1%） of BT-BA samples, BT@0.6 BT-0.4 BA maintained a maximum dielectric constant（ε（max）） ranging from 1 592 to 1 708 and tan δ less than 2% under a unit mole ratio at room temperature. In view of all these analyses, the initial nanometer sizes of the as-prepared BT-core powders combined with the increase effect of cation substitutions of Bi^（3＋） and Al^（3＋） in the shell content, induced the diffuse transition phase of BT@0.6 BT-0.4 BA composition.展开更多
New 3 -oxo-benzoisothiazoline-2-acetamide 1, 1-dioxides (IIa-b) ware synthesizedand whose reaction with alkoxides was studied. The reaction results indicated that differentproducts were obtained owing to the different...New 3 -oxo-benzoisothiazoline-2-acetamide 1, 1-dioxides (IIa-b) ware synthesizedand whose reaction with alkoxides was studied. The reaction results indicated that differentproducts were obtained owing to the different time of reaction with alkoxides展开更多
Reaction of (MeC 5H 4) 3Ln with HOCH 2CH 2NMe 2 in tetrahydrofuran(THF) gives the new complexes [(MeC 5H 4) 2Ln(μ OCH 2CH 2NMe 2)] 2 (Ln=Sm, Y, Nd) with nitrogen functionalized μ alkoxide ligand. The ...Reaction of (MeC 5H 4) 3Ln with HOCH 2CH 2NMe 2 in tetrahydrofuran(THF) gives the new complexes [(MeC 5H 4) 2Ln(μ OCH 2CH 2NMe 2)] 2 (Ln=Sm, Y, Nd) with nitrogen functionalized μ alkoxide ligand. The complexes were characterized by elemental analysis and IR, and [(MeC 5H 4) 2Sm(μ OCH 2CH 2NMe 2)] 2 was structurally characterized by the X ray diffraction to be a dimer formed by two unsymmetric oxygen bridges. The complex has a tricyclic skeleton with the additional two Sm-N bonds via intramolecular coordination of OCH 2CH 2NMe 2. The coordination number of the central metal Sm is nine. The title complexes show good catalytic activity for ring opening polymerization of ε caprolactone.展开更多
The mixed-metal cluster Yb4O4（OiPr）16Na12 has been synthesized and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. The crystal belongs to the cubic system, space group P23 wi...The mixed-metal cluster Yb4O4（OiPr）16Na12 has been synthesized and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. The crystal belongs to the cubic system, space group P23 with a = b = c = 13.9788（3）A, V = 2731.55（10）A3, Z = 1, Dc = 1.202 g/cm3, Mr = 1977.42,/J = 3.480 mm-1, F（000） = 972, the final R = 0.0288 and wR = 0.1511 for 1677 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that Yb4O4（Oipr）16Na12 is centrosym- metric and the structure contains four ytterbium metals and twelve sodium metals, and each ytterbium atom is coordinated by six oxygen atoms. In addition, an ancillary computational analysis of the optimized molecular unit was provided. The large energy gap （3,31 eV） between HOMO and LUMO indicates that the structure framework is particularly stable.展开更多
Three new chiral binuclear organolanthanide alkoxides containing cyclopentadienyl ligand have been synthesised by the reaction of Cp3Ln (Cp=C5H5; Ln=Yb, Y, Dy ) with 0.5equimolar chiral diol in THF (tetrahydrofuran) a...Three new chiral binuclear organolanthanide alkoxides containing cyclopentadienyl ligand have been synthesised by the reaction of Cp3Ln (Cp=C5H5; Ln=Yb, Y, Dy ) with 0.5equimolar chiral diol in THF (tetrahydrofuran) at -78℃ at room temperature. All the complexes were characterized by elemental analysis, IR and MS spectra.展开更多
The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relati...The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relationship between frontier orbitals and organic chemical reactions. Based on the above results. properexperimental conditions for the preparation of homogeneous ultra-purity. submicro high-T_cYBa_2Cu_3O_(7-δ) superconducting powders are proposed.展开更多
The reaction of 2-formylpyrrole acetals with sodium alkoxide in alcohols at reflux temperature smoothly proceeded to generate corresponding transacetalization products in nearly quantitative yields.A plausible mechani...The reaction of 2-formylpyrrole acetals with sodium alkoxide in alcohols at reflux temperature smoothly proceeded to generate corresponding transacetalization products in nearly quantitative yields.A plausible mechanism involving the formation of a highly reactive intermediate azafulvene species was proposed to explain the observed transformation.展开更多
Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route.These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission...Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route.These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy.Moreover,the presence of the alkoxide moieties has been unambiguously demonstrated by means of thermogravimetric analysis coupled to a mass spectrometer.These NiFe-LDHs can be exfoliated in water or organic solvents and processed into homogeneous ultra-thin films(<3 nm thick)with the assistance of O_(2)-plasma.The study of their behaviour as water oxidation electrocatalysts has shown an outstanding performance at basic pHs(small overpotential of ca.249 mV and Tafel slopes in the range of 52–55 mV per decade).展开更多
Hollow cobalt nickel oxide microspheres assembled by ultrathin porous nanosheets with tunable Co/Ni molar ratios have been successfully synthesized via a facile“self-template”method,taking solid bimetallic alkoxide ...Hollow cobalt nickel oxide microspheres assembled by ultrathin porous nanosheets with tunable Co/Ni molar ratios have been successfully synthesized via a facile“self-template”method,taking solid bimetallic alkoxide microspheres as a precursor.The compositions and the sizes of the hollow cavities of cobalt nickel oxides can be easily controlled by the Co/Ni molar ratios and the size of bimetallic alkoxide microspheres,respectively.The electrochemical measurements indicate that the cobalt nickel oxide catalysts exhibit greatly enhanced oxygen evolution reaction(OER)activity in alkaline media,and Co_(2)-Ni_(1)-O microspheres with the optimal composition show the lowest overpotential(∼310 mV for 10 mA cm^(-2))and the smallest Tafel slope(57 mV per decade).This is attributed to the large electrochemically reactive surface and good charge conduction offered by the synergetic effects between their unique structural features and tunable compositions.The hollow cobalt nickel oxide microspheres may serve as promising noble-metal-free OER electrocatalysts to replace IrO_(x)material,and the synthetic strategy that directs structural design can be applied to prepare other multifunctional materials.展开更多
We report a new octahedral[Dy(OCPh_(3))_(2)(THF)_(4)][BPh_(4)]luminescent Single-Molecule Magnet(SMM)exhibiting massive crystal-field splitting and an anisotropic barrier of 1385 cm^(−1).Magnetic measurements combined...We report a new octahedral[Dy(OCPh_(3))_(2)(THF)_(4)][BPh_(4)]luminescent Single-Molecule Magnet(SMM)exhibiting massive crystal-field splitting and an anisotropic barrier of 1385 cm^(−1).Magnetic measurements combined with ab initio analysis reveal a novel mechanism behind the high blocking barrier based on the quenching of one-phonon transitions between the three low-lying crystal-field multiplets due to large energy gaps between them exceeding the available phonon energies and forcing the activated relaxation to proceed through the fourth doublet.The observed nonetheless short relaxation time is due to appreciable non-axial anisotropy,which opens a tunnelling relaxation path via interaction with the nuclear spins.Reducing the equatorial crystal-field quenches drastically the quantum tunnelling of magnetization,allowing for full exploitation of the high blocking barrier of the complex as in the best known SMMs.展开更多
Functional nanostructured oxides are important inorganic materials for various energy-and environmentrelated applications,such as photocatalysis and lithium ion batteries.To optimize their properties/functions,synthet...Functional nanostructured oxides are important inorganic materials for various energy-and environmentrelated applications,such as photocatalysis and lithium ion batteries.To optimize their properties/functions,synthetic methods that can lead to nanomaterials with unique composition,morphology and size are highly desirable.In this review,we summarize recent research efforts towards the construction of nanostructured solid-state metal alkoxides-a family of inorganic-organic hybrid compounds and their conversion into functional inorganic nanomaterials.The chemical transformation from metal alkoxides to nanostructured oxides represents a novel precursor-directed synthetic route to functional inorganic nanomaterials.The uniqueness of this method mainly lies in:(i)the crystal/molecular structure of metal alkoxides which plays a crucial role in their nanosized structures;(ii)the use of metal alkoxides as precursor materials which determines the composition and(micro)structure of the finally-obtained oxide nanomaterials;and(iii)that this method can be employed to synthesize nanomaterials that cannot be readily achieved using other approaches.展开更多
Owing to their unique mechanical properties and excellent thermal and chemical stability,Al_(2)O_(3)nanofibers are highly desirable for practical applications as functional and structural building blocks.However,the s...Owing to their unique mechanical properties and excellent thermal and chemical stability,Al_(2)O_(3)nanofibers are highly desirable for practical applications as functional and structural building blocks.However,the scalable production of Al,O3 nanofibers has always faced significant challenges,namely,high cost and complicated processes.This work explores a feasible and straightforward dealloying strategy for the batch synthesis of Al_(2)O_(3)nanofibers.When a binary Al-Li alloy is immersed in alcohol,the alkoxide nanofibers spontaneously grow following the mechanism of boundary strain energy minimization.The results indicate that by dissolving Li in Al-Li alloys,the continuous exposure of a fresh Al surface renders the remaining unsaturated bonds of Al sufficiently reactive,providing the conditions for the subsequent reaction with alcohols and thus inducing the formation of alcohol-aluminum compounds.These nanofibers were calcined in air to obtain monocrystallineα-Al_(2)O_(3)and polycrystalline y-Al_(2)O_(3)nanofibers.We investigated the evolution of the alloy into nanofibers in dry ethanol and the influence of different Al-Li alloy compositions and calcination temperatures on the crystal structure and morphology of the resulting Al_(2)O_(3)nanofibers.The study revealed thatγ-Al_(2)O_(3)with diameters of approximately 50-80 nm and lengths of approximately 20-30μm andα-Al_(2)O_(3)with diameters of approximately 100-150 nm and lengths of approximately 15-20μm were successfully prepared via this technique route.The approach reported in this study is anticipated to open new paths for the efficient and economical synthesis of advanced metal oxide nanofibers and lay the foundation for their extensive application in current industrial sectors.展开更多
A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF...A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF3CH2O)(3)Y(THF)(3) (7) were synthesized and they have good activity for the oligomerization of phenyl isocyanate. Among-them 5 shows,the highest activity. The conversion is as high as 96.2%, with 1/2500 of the molar ratio of cat. / PhNCO. The main components in oligomer were characterized to be a cyclodimer and a cyclotrimer. The ratio of cyclodimer,to cyclotrimer depends on the lanthanide complexes:used. 7 gave 85.2% cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40 V for 0.5 h, while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat. /PhNCO at 40 degreesC for 4 h.展开更多
Carbonyl sulfide （COS）, an analogue of carbon dioxide （CO2）, can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly（monothiocarbonate）s, whi...Carbonyl sulfide （COS）, an analogue of carbon dioxide （CO2）, can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly（monothiocarbonate）s, which are difficult to synthesize by traditional methods. Herein, for the first time, we describe an anionic copolymerization of COS with epoxides using alkali metal alkoxides as the catalysts （initiators）, affording poly（monothiocarbonate）s with 100% alternating degree, 〉99% tail-to-head （T-H） content, high number-average molecular weights （Mns, up to 90.3 kg/mol） with narrow molecular weight distributions （D=Mw/Mn, 1.05-1.31 for COS/propylene oxide copolymers） under solvent-free and mild conditions. Oxygen-sulfur exchange reaction （O/S ER）, which can result in the production of contaminated dithiocarbonate and carbonate units in the main chain, was nearly completely depressed at 0 ℃. In addition, in contrast to previously reported salen chromium （iron） complexes that required multiple synthetic steps, this work provides simple, low-cost, and effective catalysts for making colorless sulfur-containing polymers.展开更多
文摘Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate)(PET).It was only used as polycondensation catalyst because it was sensitive to water.For this catalyst,the degree of esterification of the theoretical amount of water was produced up to 95%at 260℃,while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester,polymerized at 280℃,70 Pa for 39 min,was 0.87 dL/g and 23.0μmol/g,respectively.Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.
基金Project(50974026)supported by the National Natural Science Foundation of China
文摘Boehmites(Al2O3·xH2O)were hydrothermally prepared from aluminum alkoxide.The effect of temperature on preparation was studied in the range of 100-180℃.The XRD analysis shows that with temperature increasing,the transformation of pseudo-boehmite into well-crystallized boehmite takes place.The micro-morphologies change also from irregular clew to thin cubic platelets.From the mass loss of the samples prepared at different temperatures,the value of x is estimated to vary between 1.06 and 1.67.γ-Al2O3 obtained by subsequent calcination of boehmite at 600℃is also characterized by XRD and its morphology remains unchanged.
文摘Titanium dioxide(TiO 2) samples of different crystal forms were prepared by hydrolysis tetrabutyl titanate in various water to alkoxide ratios and sintering the hydrolysis product at different temperatures. The photocatalysts coated on hollow glass beads and loaded with platinum varying from 0.2% to 2.4% by weight.The photocatalytic degradation rate of sodium pentachlorophenolate (PCP-Na) depends on the preparing conditions such as: sintering temperatures, water to alkoxide ratios( R ), platinum content and the size. The proper conditions of preparation photocatalysts are as follows: the ratio of TiO 2 : sodium silicate : hollow glass beads : platinum is 10:5:20:0.15(w/w), R is 100, sintering temperature is 650℃, and the size of hollow glass is 0.5-1 mm. Under these conditions, the ratio between acatase and rutile of the photocatalyst is 2:1, and the photocatalytic activity is high.
基金the staff at Beamline (BL08U1-A and BL11B)of the Shanghai Synchrotron Radiation Facility (SSRF)the support from the National Key Research&Development Program of China (2022YFB3803700)+2 种基金the National Natural Science Foundation of China (52171186)the support through the Overseas Outstanding Youth Fund and Shanghai Pujiang Talent Project (21PJ1408500)the financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.
文摘In this work, the magnesium aluminum spinel (MgAl2O4) was prepared by Mg and Al as precursors through a method of sol-gel subsequent with high temperature calcination. The wide range of synthetic conditions, including organic alcohols, ammonia content, dispersant, alkoxide concentration, hydrolysis time, hydrolysis temperature and calcination temperature were screened over as-prepared samples. This work provides a necessary experimental basis for the synthesis of MgAl2O4 with uniform particle size of spherical structure, which has a potential to be used in many industrial and military applications.
基金Funded by NSFC-Guangdong Joint Funds of the Natural Science Foundation of China(No.U1601209)the National Key Basic Research Program of China(973 Program)(No.2015CB654601)National Natural Science Foundation of China(No.51372191)
文摘The fundamental characteristics of varied initial core-sizes of Ba Ti O3（BT） and its influential role on the morphology and dielectric properties of Ba Ti O3@0.6 Ba Ti O3-0.4 Bi Al O3（BT@0.6 BT-0.4 BA） ceramic samples were studied. Alkoxide sol-precipitation method was adopted as revised chemical route to synthesize the constituent ＂core＂ BT powders in a dispersed phase, whereas the distinctive initial nano-sized particles were affected by the pre-calcination temperatures（600-900 ℃）.The microstructure of the uncoated BT ceramics revealed an exaggerated grain growth with an optimized dielectric constant（ε（max） 〉9 000） whilst the coated ceramics behaved otherwise（grain growth inhibited） when sintered at an elevated temperature. Regardless of the previously studied solubility limit（about 0.1%） of BT-BA samples, BT@0.6 BT-0.4 BA maintained a maximum dielectric constant（ε（max）） ranging from 1 592 to 1 708 and tan δ less than 2% under a unit mole ratio at room temperature. In view of all these analyses, the initial nanometer sizes of the as-prepared BT-core powders combined with the increase effect of cation substitutions of Bi^（3＋） and Al^（3＋） in the shell content, induced the diffuse transition phase of BT@0.6 BT-0.4 BA composition.
文摘New 3 -oxo-benzoisothiazoline-2-acetamide 1, 1-dioxides (IIa-b) ware synthesizedand whose reaction with alkoxides was studied. The reaction results indicated that differentproducts were obtained owing to the different time of reaction with alkoxides
文摘Reaction of (MeC 5H 4) 3Ln with HOCH 2CH 2NMe 2 in tetrahydrofuran(THF) gives the new complexes [(MeC 5H 4) 2Ln(μ OCH 2CH 2NMe 2)] 2 (Ln=Sm, Y, Nd) with nitrogen functionalized μ alkoxide ligand. The complexes were characterized by elemental analysis and IR, and [(MeC 5H 4) 2Sm(μ OCH 2CH 2NMe 2)] 2 was structurally characterized by the X ray diffraction to be a dimer formed by two unsymmetric oxygen bridges. The complex has a tricyclic skeleton with the additional two Sm-N bonds via intramolecular coordination of OCH 2CH 2NMe 2. The coordination number of the central metal Sm is nine. The title complexes show good catalytic activity for ring opening polymerization of ε caprolactone.
基金Supported by the National Natural Science Foundation of China(No.20902001 and 21102001)the Natural Science Foundation of Anhui Province(No.090416220)the 211 Project of Anhui University
文摘The mixed-metal cluster Yb4O4（OiPr）16Na12 has been synthesized and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. The crystal belongs to the cubic system, space group P23 with a = b = c = 13.9788（3）A, V = 2731.55（10）A3, Z = 1, Dc = 1.202 g/cm3, Mr = 1977.42,/J = 3.480 mm-1, F（000） = 972, the final R = 0.0288 and wR = 0.1511 for 1677 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that Yb4O4（Oipr）16Na12 is centrosym- metric and the structure contains four ytterbium metals and twelve sodium metals, and each ytterbium atom is coordinated by six oxygen atoms. In addition, an ancillary computational analysis of the optimized molecular unit was provided. The large energy gap （3,31 eV） between HOMO and LUMO indicates that the structure framework is particularly stable.
文摘Three new chiral binuclear organolanthanide alkoxides containing cyclopentadienyl ligand have been synthesised by the reaction of Cp3Ln (Cp=C5H5; Ln=Yb, Y, Dy ) with 0.5equimolar chiral diol in THF (tetrahydrofuran) at -78℃ at room temperature. All the complexes were characterized by elemental analysis, IR and MS spectra.
文摘The structural characteristics of different alkoxides of Y. Ba and Cu are studied with quantum chemi-cal CNDO /2 calculations. The relative hydrolysis rate coefficients k_M of them are obtained according tothe relationship between frontier orbitals and organic chemical reactions. Based on the above results. properexperimental conditions for the preparation of homogeneous ultra-purity. submicro high-T_cYBa_2Cu_3O_(7-δ) superconducting powders are proposed.
基金The Ministry of Education of The People's Republic of ChinaDepartment of education of Jiangxi ProvinceJiangxi Provincial Natural Science Foundation for financial support
文摘The reaction of 2-formylpyrrole acetals with sodium alkoxide in alcohols at reflux temperature smoothly proceeded to generate corresponding transacetalization products in nearly quantitative yields.A plausible mechanism involving the formation of a highly reactive intermediate azafulvene species was proposed to explain the observed transformation.
基金Financial support from the EU(FET-OPEN 2D-INK,grant agreement 664878,Graphene Flagship,grant agreement 604391 and ERC Starting Investigator Award STEMOX,grant agreement 239739)the Spanish MINECO(Project MAT2014-56143-R and Excellence Unit Maria de Maeztu,MDM-2015-0538)+3 种基金the Generalitat Valenciana(Prometeo and ISIC-Nano Programs)is gratefully acknowledgedCo-funding from UE is also acknowledged.Electron microscopy observations carried out at the Centro Nacional de Microscopía Electrónica,Universidad Complutense de Madridthe Universidad de Valencia for support from VLC/CAMPUS and INNCIDE program,and for a predoctoral grant(to J.A.C.)the EU for a Marie Curie Fellowship(FP7/2013-IEF-627386).
文摘Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route.These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy.Moreover,the presence of the alkoxide moieties has been unambiguously demonstrated by means of thermogravimetric analysis coupled to a mass spectrometer.These NiFe-LDHs can be exfoliated in water or organic solvents and processed into homogeneous ultra-thin films(<3 nm thick)with the assistance of O_(2)-plasma.The study of their behaviour as water oxidation electrocatalysts has shown an outstanding performance at basic pHs(small overpotential of ca.249 mV and Tafel slopes in the range of 52–55 mV per decade).
基金supported by the Natural Science Foundation of Hebei Province(B2016208108)the Foundation of Educational Committee of Hebei Province(QN2016061)+1 种基金the Foundation of Hebei University of Science and Technology(Grant No.1181156,2014PT94)the Key Laboratory Project Fund of Jilin University(Grant No.2015-21).
文摘Hollow cobalt nickel oxide microspheres assembled by ultrathin porous nanosheets with tunable Co/Ni molar ratios have been successfully synthesized via a facile“self-template”method,taking solid bimetallic alkoxide microspheres as a precursor.The compositions and the sizes of the hollow cavities of cobalt nickel oxides can be easily controlled by the Co/Ni molar ratios and the size of bimetallic alkoxide microspheres,respectively.The electrochemical measurements indicate that the cobalt nickel oxide catalysts exhibit greatly enhanced oxygen evolution reaction(OER)activity in alkaline media,and Co_(2)-Ni_(1)-O microspheres with the optimal composition show the lowest overpotential(∼310 mV for 10 mA cm^(-2))and the smallest Tafel slope(57 mV per decade).This is attributed to the large electrochemically reactive surface and good charge conduction offered by the synergetic effects between their unique structural features and tunable compositions.The hollow cobalt nickel oxide microspheres may serve as promising noble-metal-free OER electrocatalysts to replace IrO_(x)material,and the synthetic strategy that directs structural design can be applied to prepare other multifunctional materials.
基金the Russian Science Foundation(grant 17-73-30036)the Natural Science Basic Research Program of Shaanxi(program no.2020JQ-136)+1 种基金the Fundamental Research Funds for the Central Universities(G2020KY0519).funded by the Researchers Supporting Project Number(RSP-2020/267)King Saud University,Riyadh,Saudi Arabia.
文摘We report a new octahedral[Dy(OCPh_(3))_(2)(THF)_(4)][BPh_(4)]luminescent Single-Molecule Magnet(SMM)exhibiting massive crystal-field splitting and an anisotropic barrier of 1385 cm^(−1).Magnetic measurements combined with ab initio analysis reveal a novel mechanism behind the high blocking barrier based on the quenching of one-phonon transitions between the three low-lying crystal-field multiplets due to large energy gaps between them exceeding the available phonon energies and forcing the activated relaxation to proceed through the fourth doublet.The observed nonetheless short relaxation time is due to appreciable non-axial anisotropy,which opens a tunnelling relaxation path via interaction with the nuclear spins.Reducing the equatorial crystal-field quenches drastically the quantum tunnelling of magnetization,allowing for full exploitation of the high blocking barrier of the complex as in the best known SMMs.
基金supported by the NSFC(21371070,21401066)the National Basic Research Program of China(2013CB632403)+1 种基金Jilin province science and technology development projects(20140101041JC,20130204001GX)Graduate Innovation Fund of Jilin University(2014052).
文摘Functional nanostructured oxides are important inorganic materials for various energy-and environmentrelated applications,such as photocatalysis and lithium ion batteries.To optimize their properties/functions,synthetic methods that can lead to nanomaterials with unique composition,morphology and size are highly desirable.In this review,we summarize recent research efforts towards the construction of nanostructured solid-state metal alkoxides-a family of inorganic-organic hybrid compounds and their conversion into functional inorganic nanomaterials.The chemical transformation from metal alkoxides to nanostructured oxides represents a novel precursor-directed synthetic route to functional inorganic nanomaterials.The uniqueness of this method mainly lies in:(i)the crystal/molecular structure of metal alkoxides which plays a crucial role in their nanosized structures;(ii)the use of metal alkoxides as precursor materials which determines the composition and(micro)structure of the finally-obtained oxide nanomaterials;and(iii)that this method can be employed to synthesize nanomaterials that cannot be readily achieved using other approaches.
基金supported by the National Natural Science Foundation of China(No.U2469213)the Beijing Natural Science Foundation(Nos.2252051 and 2234093)+1 种基金the Fundamental Research Funds for the Central Universities(No.2022XKRC016),the Hebei Natural Science Foundation(No.E2024105074)the Research Fund for Commercialization of Major Scientific and Technological Achievements of Hebei Province(No.22281006Z and 23267601Z).
文摘Owing to their unique mechanical properties and excellent thermal and chemical stability,Al_(2)O_(3)nanofibers are highly desirable for practical applications as functional and structural building blocks.However,the scalable production of Al,O3 nanofibers has always faced significant challenges,namely,high cost and complicated processes.This work explores a feasible and straightforward dealloying strategy for the batch synthesis of Al_(2)O_(3)nanofibers.When a binary Al-Li alloy is immersed in alcohol,the alkoxide nanofibers spontaneously grow following the mechanism of boundary strain energy minimization.The results indicate that by dissolving Li in Al-Li alloys,the continuous exposure of a fresh Al surface renders the remaining unsaturated bonds of Al sufficiently reactive,providing the conditions for the subsequent reaction with alcohols and thus inducing the formation of alcohol-aluminum compounds.These nanofibers were calcined in air to obtain monocrystallineα-Al_(2)O_(3)and polycrystalline y-Al_(2)O_(3)nanofibers.We investigated the evolution of the alloy into nanofibers in dry ethanol and the influence of different Al-Li alloy compositions and calcination temperatures on the crystal structure and morphology of the resulting Al_(2)O_(3)nanofibers.The study revealed thatγ-Al_(2)O_(3)with diameters of approximately 50-80 nm and lengths of approximately 20-30μm andα-Al_(2)O_(3)with diameters of approximately 100-150 nm and lengths of approximately 15-20μm were successfully prepared via this technique route.The approach reported in this study is anticipated to open new paths for the efficient and economical synthesis of advanced metal oxide nanofibers and lay the foundation for their extensive application in current industrial sectors.
文摘A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF3CH2O)(3)Y(THF)(3) (7) were synthesized and they have good activity for the oligomerization of phenyl isocyanate. Among-them 5 shows,the highest activity. The conversion is as high as 96.2%, with 1/2500 of the molar ratio of cat. / PhNCO. The main components in oligomer were characterized to be a cyclodimer and a cyclotrimer. The ratio of cyclodimer,to cyclotrimer depends on the lanthanide complexes:used. 7 gave 85.2% cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40 V for 0.5 h, while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat. /PhNCO at 40 degreesC for 4 h.
基金X. H. Z gratefully thanks the financial support of the Distinguished Young Investigator Fund of Zhejiang Province （No. LR16B040001） and the National Natural Science Foundation of China （No. 21774108）.
文摘Carbonyl sulfide （COS）, an analogue of carbon dioxide （CO2）, can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly（monothiocarbonate）s, which are difficult to synthesize by traditional methods. Herein, for the first time, we describe an anionic copolymerization of COS with epoxides using alkali metal alkoxides as the catalysts （initiators）, affording poly（monothiocarbonate）s with 100% alternating degree, 〉99% tail-to-head （T-H） content, high number-average molecular weights （Mns, up to 90.3 kg/mol） with narrow molecular weight distributions （D=Mw/Mn, 1.05-1.31 for COS/propylene oxide copolymers） under solvent-free and mild conditions. Oxygen-sulfur exchange reaction （O/S ER）, which can result in the production of contaminated dithiocarbonate and carbonate units in the main chain, was nearly completely depressed at 0 ℃. In addition, in contrast to previously reported salen chromium （iron） complexes that required multiple synthetic steps, this work provides simple, low-cost, and effective catalysts for making colorless sulfur-containing polymers.
