A new wave-like infinite chain coordination polymer [Cu3（CN）3（PPh3）4]n（1,PPh3=triphenylphosphine） has been synthesized by solution reaction and characterized by X-ray single-crystal structure diffraction analysi...A new wave-like infinite chain coordination polymer [Cu3（CN）3（PPh3）4]n（1,PPh3=triphenylphosphine） has been synthesized by solution reaction and characterized by X-ray single-crystal structure diffraction analysis.The complex crystallizes in space group P1 with a=13.343（6）,b=13.429（7）,c=20.694（10）A,α=103.163（4）,β=96.704（5）,γ=101.981（6）o,V=3479（3）A^3,Z=2,C75H60Cu3N3P4,Mr=1317.76,Dc=1.258 g/cm^3,F（000）=1356,μ=1.043 mm^-1,the final R=0.0680 and wR=0.1305 for 9232 observed reflections with I〉2σ（I）.The infinite chain is linked by C-H…π H bonding interactions to form a 2-D supramolecular network.Luminescent study reveals that the complex has green-light emission.展开更多
A new Schiff base, N-phenyl-(2S)-hydroxy-3-[(2-hydroxybenzylidene)amino]pro- pionamide, has been synthesized by using (S)-isoserine as the starting material. Its crystal struc- ture with solvent benzene was determined...A new Schiff base, N-phenyl-(2S)-hydroxy-3-[(2-hydroxybenzylidene)amino]pro- pionamide, has been synthesized by using (S)-isoserine as the starting material. Its crystal struc- ture with solvent benzene was determined by X-ray single-crystal diffraction, elemental analysis and 1H NMR. The crystal belongs to the monoclinic system with space group P21, a = 5.673(3), b = 15.486(8), c = 18.753(9) ?, β = 90.086(7)o, C16H16O3N2?1/2C6H6, Mr = 323.36, V = 1647.7(14) ?3, Z = 4, Dc = 1.304 g/cm3, μ = 0.089 cm-1, F(000) = 684.00, the final R = 0.0624 and wR = 0.1320 for 2613 observed reflections (I > 2σ(I)). The asymmetric unit of the crystal has two crystallographically different molecules with the same configuration and one solvent benzene molecule, and they are not planar. In the crystal, molecules are stacked through H-bonds along [100] and the stacks are laterally interacted through H-bonds and extended along [010]. In the third direction [101], molecules interact through C–H…π interaction, which is one of the major factors stabilizing the crystal structure.展开更多
The title compounds,C9H13ClN6O2S 1 and C15H17ClN6O2S 2,were synthesized and structurally characterized by elemental analysis,IR,1H NMR spectra and single-crystal X-ray diffraction.Compound 1 is in the monoclinic syste...The title compounds,C9H13ClN6O2S 1 and C15H17ClN6O2S 2,were synthesized and structurally characterized by elemental analysis,IR,1H NMR spectra and single-crystal X-ray diffraction.Compound 1 is in the monoclinic system,space group P21/c with a=13.7711（5）,b=10.3883（4）,c=9.7623（2）,V=1344.47（8）3,Dc=1.506 g/cm3,C9H13ClN6O2S,Mr=304.76,F（000）=632,μ=0.448 mm-1,Z=4,S=1.084,R=0.0497 and wR=0.1328 for 2640 unique reflections（Rint=0.0787） with 2089 observed ones（I2σ（I））.Compound 2 belongs to the monoclinic system,space group P21/n with a=8.3828（5）,b=14.5285（7）,c=14.2456（4）,V=1729.74（14）3,Dc=1.462 g/cm3,C15H17ClN6O2S,Mr=380.86,F（000）=792,μ=0.364 mm-1,Z=4,S=1.057,R=0.0598 and wR=0.1582 for 3384 unique reflections（Rint=0.0469） with 2833 observed ones（I2σ（I））.Compounds 1 and 2 are homologues and stabilized by intermolecular and intramolecular hydrogen bonds.Moreover,compound 2 containing C（2）–H（2）…π（thiazole） interaction is more stable than 1.展开更多
Two complexes, [Cu2（Htdb）4（H2O）2] （1） and [Cd（bipy）2（Hmcmbc）2] （2） （H2tdb = 2,2-thiodibenzoic acid, H2mcmbc = m-（carboxyl-methyloxy）-benzenecarboxylic acid, bipy = 4,4＇-bipyridine）, have been prepared...Two complexes, [Cu2（Htdb）4（H2O）2] （1） and [Cd（bipy）2（Hmcmbc）2] （2） （H2tdb = 2,2-thiodibenzoic acid, H2mcmbc = m-（carboxyl-methyloxy）-benzenecarboxylic acid, bipy = 4,4＇-bipyridine）, have been prepared, and were characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction. Structures indicate that complex 1 is a single molecule, and 2 is a one-dimensional chain. Their two-and three-dimensional frameworks are constructed through hydrogen bonding, π…π or C–H…π stacking, and such other weak interactions. The cyclic voltametric behavior of complex 1 and luminescence property of complex 2 were investigated. 1 belongs to the triclinic system, space group P with a = 7.8607（6）, b = 11.7619（9）, c = 15.3481（12） , α = 109.3670（10）, β = 92.4420（10）, γ = 92.0450（10）°, V = 1335.65（18） 3, Mr = 1256.26, Dc = 1.5619（2） g/cm3, F（000） = 642, μ = 1.029 mm–1, Z = 1, the final R = 0.0289 and wR = 0.0763 for 5199 observed reflections with I 2σ（I）. Complex 2 crystallizes in triclinic, space group P with a = 9.6378（10）, b = 9.7508（10）, c = 19.055（2） , α = 88.7020（10）, β = 80.5260（10）, γ = 69.2000（10）o, V = 1649.9（3） 3, Mr = 815.07, Dc = 1.641 g/cm3, μ = 0.732 mm-1, F（000） = 828, Z = 2, the final R = 0.0511 and wR = 0.1149 for 4729 observed reflections （I 2σ（I））.展开更多
The title compound l-benzyl-5-（（4-methoxyphenyl）ethynyl）-4-phenyl-1H-1,2,3-triazole（C24H19N3O） was designed and synthesized using one-pot strategy and structural characterization was done by single-crystal X-ray...The title compound l-benzyl-5-（（4-methoxyphenyl）ethynyl）-4-phenyl-1H-1,2,3-triazole（C24H19N3O） was designed and synthesized using one-pot strategy and structural characterization was done by single-crystal X-ray diffraction,NMR,IR and MS.This compound was crystallized out from an ethanolic solution in triclinic system,space group P1 with a =9.9038（9）,b = 10.2928（9）,c = 18.8715（19）A°,α = 103.541（6）,β = 90.507（7）,γ = 97.157（7）°,V =1854.2（3） A°3,Z = 4,crystal size（mm） = 0.25 × 0.1 × 0.1 and R（int） = 0.068.Its asymmetric unit contains two independent molecules.The crystal structure of the title compound is stabilized by intramolecular interactions of types C-H…N and C-H…O.Additionally,X-ray analysis reveals obvious C-H…π,π-π stacking interactions between two adjacent aromatic ring planes.展开更多
Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneo...Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.展开更多
Heterogenization of organic-macrocyclic metal catalysts is one of the simplest and most efficient methods for effective separation of products and cyclic application of a catalyst.By using an environmentally friendly ...Heterogenization of organic-macrocyclic metal catalysts is one of the simplest and most efficient methods for effective separation of products and cyclic application of a catalyst.By using an environmentally friendly Mn-corrolazine catalyst as the building unit,which can directly oxidize organic substrates under oxygen atmosphere and mild conditions,we theoretically constructed a novel two-dimensional(2D)Mn-corrolazine nanocatalytic material with high catalytic activity.In this material,each Mn atom maintains its electronic configuration in the monomer and can directly activate O2 as the single-atom catalyst(SAC)center to form a radical-like[Mn]-O-O under mild visible-light irradiation conditions.The newly generated[Mn]–O–O can efficiently and selectively oxidize C–H bonds to form alcohol species through H-abstraction and the rebound reaction.Moreover,the catalytic reaction is easily regulated by an external electric field along its intrinsic Mn–O–O reaction axis.The current study provides a theoretical foundation for further experimental studies and practical applications of the Mn-corrolazine-based SAC.展开更多
The dynamic behaviors of water contained in calcium-silicate-hydrate（C-S-H） gel with different water content values from 10%to 30%（by weight）,are studied by using an empirical diffusion model（EDM） to analyze the...The dynamic behaviors of water contained in calcium-silicate-hydrate（C-S-H） gel with different water content values from 10%to 30%（by weight）,are studied by using an empirical diffusion model（EDM） to analyze the experimental data of quasi-elastic neutron scattering（QENS） spectra at measured temperatures ranging from 230 K to 280 K.In the study,the experimental QENS spectra with the whole Q-range are considered.Several important parameters including the bound/immobile water elastic coefficient A,the bound water index BWI,the Lorentzian with a half-width at half-maximum（HWHM） Γ;（Q） and Γ;（Q）,the self-diffusion coefficients D;and D;of water molecules,the average residence times τ;and τ;,and the proton mean squared displacement（MSD）(u;) are obtained.The results show that the QENS spectra can be fitted very well not only for small Q（≤1 A;） but also for large Q.The bound/immobile water fraction in a C-S-H gel sample can be shown by the fitted BWI.The distinction between bound/immobile and mobile water,which includes confined water and ultra-confined water,can be seen by the fitted MSD.All the MSD tend to be the smallest value below 0.25 A;（the MSD of bound/immobile water） as the Q increases to 1.9 A;no matter what the temperature and water content are.Furthermore,by the abrupt changes of the fitted values of D;,τ;,and Γ;（Q）,a crossover temperature at 250 K,namely the liquid-to-crystal-like transition temperature,can be identified for confined water in large gel pores（LGPs） and/or small gel pores（SGPs） contained in the C-S-H gel sample with 30% water content.展开更多
The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(>...The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.展开更多
Dioxygen activations constitute one of core issues in copper-dependent metalloenzymes. Upon O_(2) activation, copper-dependent metalloenzymes such as particulate methane monooxygenases(pM MOs), lytic polysaccharide mo...Dioxygen activations constitute one of core issues in copper-dependent metalloenzymes. Upon O_(2) activation, copper-dependent metalloenzymes such as particulate methane monooxygenases(pM MOs), lytic polysaccharide monooxygenases(LPMOs) and binuclear copper enzymes PHM and DβM, are able to perform various challenging C–H bond activations. Meanwhile, various copper-oxygen core containing complexes have been synthetized to mimic the active species of metalloenzymes. Dioxygen activation by mononuclear copper active site may generate various copper-oxygen intermediates, including Cu(Ⅱ)-superoxo, Cu(Ⅱ)-hydroperoxo, Cu(Ⅱ)-oxyl as well as the Cu(Ⅲ)-hydroxide species. Intriguingly, all these species have been invoked as the potential active intermediates for C–H/O–H activations in either biological or synthetic systems. Due to the poor understanding on reactivities of copper-oxygen complex, the nature of active species in both biological and synthetic systems are highly controversial. In this account, we will compare the reactivities of various mononuclear copper-oxygen species between biological systems and the synthetic systems. The present study is expected to provide the consistent understanding on reactivities of various copper-oxygen active species in both biological and synthetic systems.展开更多
The title complex [Cu（L1）（L2）（H2O）]·H2O（1,HL1 = N-（imino（pyridin-2-yl）me-thyl）picolinamidine）,HL2 = salicylic acid） has been obtained by volatilization method with L1 prepared from 2,4,6-tripyridyl-1...The title complex [Cu（L1）（L2）（H2O）]·H2O（1,HL1 = N-（imino（pyridin-2-yl）me-thyl）picolinamidine）,HL2 = salicylic acid） has been obtained by volatilization method with L1 prepared from 2,4,6-tripyridyl-1,3,5-triazine in situ.1 was fully characterized by single-crystal X-ray diffraction,elemental analysis and FT-IR.This complex exhibits a three-dimensional frame-work constructed through hydrogen bonding and C-H···π stacking interactions.The cyclic voltametric behavior of complex 1 was also investigated.1 belongs to the monoclinic system,space group P21/c with a = 15.112（5）,b = 7.115（2）,c = 19.899（6） ,β = 112.32°,V = 1979.4（11） 3,Mr = 460.94,Dc = 1.540 g/cm3,F（000） = 948,μ = 1.146 mm-1,Z = 4,the final R = 0.0612 and wR = 0.1813 for 2510 observed reflections with I 2σ（I）.展开更多
A novel {[bis（pyridine-κN）bis（3,5-dinitrosalicylato κ-O,O＇）Zn（Ⅱ）][bis（pyridine-κN）Zn（Ⅱ）]}（C_（34）H_（24）N_8O_（14）Zn_2） was synthesized by a self-assemble method at room temperature. The molecular...A novel {[bis（pyridine-κN）bis（3,5-dinitrosalicylato κ-O,O＇）Zn（Ⅱ）][bis（pyridine-κN）Zn（Ⅱ）]}（C_（34）H_（24）N_8O_（14）Zn_2） was synthesized by a self-assemble method at room temperature. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P2_1/n with a = 12.2156, b = 13.5696, c = 22.5602 A, β = 90.061o, Z = 4 and V = 3739.6（3）A^3. The new 1D binuclear coordination polymer {[bis（py-κN）bis（3,5-dinitrosal κ-O,O′） Zn（Ⅱ）][bis（py-κN）Zn（Ⅱ）]} resulted from two different types of moieties. The polymer [bis（py-κN）bis（3,5-dinitrosal κ-O,O′）Zn（Ⅱ）] unit is connected with [bis（py-κN） Zn（Ⅱ）] by zigzag topology. One zinc（Ⅱ） cation has a six-fold coordination environment, in which the metal atom is connected with four oxygen atoms of two 3,5-dinitrosalicylic acids to form equatorial bonds and two nitrogen atoms of pyridine to generate the axial bonds. Other four-fold nucleus contain two Zn-O bonds from different 3,5-dinitrosalicylic acids and two bonds with the Natom of pyridine. Antimicrobial assay results indicated that the compound showed moderate activities against different bacterial and fungal strains.展开更多
The structure of 1-hydroxy-3,5-dimethoxy-9 H-xanthen-9-one isolated from chloroform extract of Ajuga bracteosa root was analyzed by single-crystal X-ray diffraction. DPPH(1,1-diphenyl-2-picryl hydrazyl), ABTS(2,2?-azi...The structure of 1-hydroxy-3,5-dimethoxy-9 H-xanthen-9-one isolated from chloroform extract of Ajuga bracteosa root was analyzed by single-crystal X-ray diffraction. DPPH(1,1-diphenyl-2-picryl hydrazyl), ABTS(2,2?-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities(RSA) and Fe2+ chelating activities were carried out to determine the antioxidant potential of the compound. RSA values for the compound were 96%, 96% and 96% for all the three activities respectively at maximum concentration of the compound(100 μ gmL-1) with the IC50 values of 3.40, 4.86 and 0.10(μ gmL-1). Antidiabetic activities including antiglycation and α-glucosidase inhibition were also performed where the antiglycation activity was performed using two techniques including spectrofluorometric as well as spectrophotometric technique. Spectrofluorometric technique provided 97% antiglycation potential while 92% antiglycation potential was observed by spectrophotometric technique for the isolated compound. The compound at a concentration of 10 μ gmL-1 exhibited 31% α-glucosidase inhibitory potential with IC50 of 15.56 μ gmL-1. Antimicrobial activity data showed that the compound was active against all the studied pathogenic bacteria.展开更多
基金supported by the National Natural Science Foundation of China (20873150, 20821061, and 50772113)the Natural Science Foundation of Fujian Province (2007F3116, 2007HZ0001-1)the Chinese Academy of Sciences (KJCX2-YW-M05)
文摘A new wave-like infinite chain coordination polymer [Cu3（CN）3（PPh3）4]n（1,PPh3=triphenylphosphine） has been synthesized by solution reaction and characterized by X-ray single-crystal structure diffraction analysis.The complex crystallizes in space group P1 with a=13.343（6）,b=13.429（7）,c=20.694（10）A,α=103.163（4）,β=96.704（5）,γ=101.981（6）o,V=3479（3）A^3,Z=2,C75H60Cu3N3P4,Mr=1317.76,Dc=1.258 g/cm^3,F（000）=1356,μ=1.043 mm^-1,the final R=0.0680 and wR=0.1305 for 9232 observed reflections with I〉2σ（I）.The infinite chain is linked by C-H…π H bonding interactions to form a 2-D supramolecular network.Luminescent study reveals that the complex has green-light emission.
基金This work was supported by the Key Laboratory of Organic Synthesis of Jiangsu Province
文摘A new Schiff base, N-phenyl-(2S)-hydroxy-3-[(2-hydroxybenzylidene)amino]pro- pionamide, has been synthesized by using (S)-isoserine as the starting material. Its crystal struc- ture with solvent benzene was determined by X-ray single-crystal diffraction, elemental analysis and 1H NMR. The crystal belongs to the monoclinic system with space group P21, a = 5.673(3), b = 15.486(8), c = 18.753(9) ?, β = 90.086(7)o, C16H16O3N2?1/2C6H6, Mr = 323.36, V = 1647.7(14) ?3, Z = 4, Dc = 1.304 g/cm3, μ = 0.089 cm-1, F(000) = 684.00, the final R = 0.0624 and wR = 0.1320 for 2613 observed reflections (I > 2σ(I)). The asymmetric unit of the crystal has two crystallographically different molecules with the same configuration and one solvent benzene molecule, and they are not planar. In the crystal, molecules are stacked through H-bonds along [100] and the stacks are laterally interacted through H-bonds and extended along [010]. In the third direction [101], molecules interact through C–H…π interaction, which is one of the major factors stabilizing the crystal structure.
基金Supported by the NNSFC (No 20672073)Shanghai Key Laboratory of Thulium Functional Materials (07d222303)
文摘The title compounds,C9H13ClN6O2S 1 and C15H17ClN6O2S 2,were synthesized and structurally characterized by elemental analysis,IR,1H NMR spectra and single-crystal X-ray diffraction.Compound 1 is in the monoclinic system,space group P21/c with a=13.7711（5）,b=10.3883（4）,c=9.7623（2）,V=1344.47（8）3,Dc=1.506 g/cm3,C9H13ClN6O2S,Mr=304.76,F（000）=632,μ=0.448 mm-1,Z=4,S=1.084,R=0.0497 and wR=0.1328 for 2640 unique reflections（Rint=0.0787） with 2089 observed ones（I2σ（I））.Compound 2 belongs to the monoclinic system,space group P21/n with a=8.3828（5）,b=14.5285（7）,c=14.2456（4）,V=1729.74（14）3,Dc=1.462 g/cm3,C15H17ClN6O2S,Mr=380.86,F（000）=792,μ=0.364 mm-1,Z=4,S=1.057,R=0.0598 and wR=0.1582 for 3384 unique reflections（Rint=0.0469） with 2833 observed ones（I2σ（I））.Compounds 1 and 2 are homologues and stabilized by intermolecular and intramolecular hydrogen bonds.Moreover,compound 2 containing C（2）–H（2）…π（thiazole） interaction is more stable than 1.
基金supported by the University Science Foundation of Anhui Province (No. KJ2011Z271)the Applied Chemistry Key Constructing Subject of Anhui Province (No. 200802187C)
文摘Two complexes, [Cu2（Htdb）4（H2O）2] （1） and [Cd（bipy）2（Hmcmbc）2] （2） （H2tdb = 2,2-thiodibenzoic acid, H2mcmbc = m-（carboxyl-methyloxy）-benzenecarboxylic acid, bipy = 4,4＇-bipyridine）, have been prepared, and were characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction. Structures indicate that complex 1 is a single molecule, and 2 is a one-dimensional chain. Their two-and three-dimensional frameworks are constructed through hydrogen bonding, π…π or C–H…π stacking, and such other weak interactions. The cyclic voltametric behavior of complex 1 and luminescence property of complex 2 were investigated. 1 belongs to the triclinic system, space group P with a = 7.8607（6）, b = 11.7619（9）, c = 15.3481（12） , α = 109.3670（10）, β = 92.4420（10）, γ = 92.0450（10）°, V = 1335.65（18） 3, Mr = 1256.26, Dc = 1.5619（2） g/cm3, F（000） = 642, μ = 1.029 mm–1, Z = 1, the final R = 0.0289 and wR = 0.0763 for 5199 observed reflections with I 2σ（I）. Complex 2 crystallizes in triclinic, space group P with a = 9.6378（10）, b = 9.7508（10）, c = 19.055（2） , α = 88.7020（10）, β = 80.5260（10）, γ = 69.2000（10）o, V = 1649.9（3） 3, Mr = 815.07, Dc = 1.641 g/cm3, μ = 0.732 mm-1, F（000） = 828, Z = 2, the final R = 0.0511 and wR = 0.1149 for 4729 observed reflections （I 2σ（I））.
基金supported by the Higher Education Commision(HEC),Govt.of Pakistan
文摘The title compound l-benzyl-5-（（4-methoxyphenyl）ethynyl）-4-phenyl-1H-1,2,3-triazole（C24H19N3O） was designed and synthesized using one-pot strategy and structural characterization was done by single-crystal X-ray diffraction,NMR,IR and MS.This compound was crystallized out from an ethanolic solution in triclinic system,space group P1 with a =9.9038（9）,b = 10.2928（9）,c = 18.8715（19）A°,α = 103.541（6）,β = 90.507（7）,γ = 97.157（7）°,V =1854.2（3） A°3,Z = 4,crystal size（mm） = 0.25 × 0.1 × 0.1 and R（int） = 0.068.Its asymmetric unit contains two independent molecules.The crystal structure of the title compound is stabilized by intramolecular interactions of types C-H…N and C-H…O.Additionally,X-ray analysis reveals obvious C-H…π,π-π stacking interactions between two adjacent aromatic ring planes.
基金supported by National Natural Science Foundation of China(21606222,21776270)Postdoctoral Science Foundation(2017M621170,2016M601350)~~
文摘Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.
文摘Heterogenization of organic-macrocyclic metal catalysts is one of the simplest and most efficient methods for effective separation of products and cyclic application of a catalyst.By using an environmentally friendly Mn-corrolazine catalyst as the building unit,which can directly oxidize organic substrates under oxygen atmosphere and mild conditions,we theoretically constructed a novel two-dimensional(2D)Mn-corrolazine nanocatalytic material with high catalytic activity.In this material,each Mn atom maintains its electronic configuration in the monomer and can directly activate O2 as the single-atom catalyst(SAC)center to form a radical-like[Mn]-O-O under mild visible-light irradiation conditions.The newly generated[Mn]–O–O can efficiently and selectively oxidize C–H bonds to form alcohol species through H-abstraction and the rebound reaction.Moreover,the catalytic reaction is easily regulated by an external electric field along its intrinsic Mn–O–O reaction axis.The current study provides a theoretical foundation for further experimental studies and practical applications of the Mn-corrolazine-based SAC.
文摘The dynamic behaviors of water contained in calcium-silicate-hydrate（C-S-H） gel with different water content values from 10%to 30%（by weight）,are studied by using an empirical diffusion model（EDM） to analyze the experimental data of quasi-elastic neutron scattering（QENS） spectra at measured temperatures ranging from 230 K to 280 K.In the study,the experimental QENS spectra with the whole Q-range are considered.Several important parameters including the bound/immobile water elastic coefficient A,the bound water index BWI,the Lorentzian with a half-width at half-maximum（HWHM） Γ;（Q） and Γ;（Q）,the self-diffusion coefficients D;and D;of water molecules,the average residence times τ;and τ;,and the proton mean squared displacement（MSD）(u;) are obtained.The results show that the QENS spectra can be fitted very well not only for small Q（≤1 A;） but also for large Q.The bound/immobile water fraction in a C-S-H gel sample can be shown by the fitted BWI.The distinction between bound/immobile and mobile water,which includes confined water and ultra-confined water,can be seen by the fitted MSD.All the MSD tend to be the smallest value below 0.25 A;（the MSD of bound/immobile water） as the Q increases to 1.9 A;no matter what the temperature and water content are.Furthermore,by the abrupt changes of the fitted values of D;,τ;,and Γ;（Q）,a crossover temperature at 250 K,namely the liquid-to-crystal-like transition temperature,can be identified for confined water in large gel pores（LGPs） and/or small gel pores（SGPs） contained in the C-S-H gel sample with 30% water content.
基金the financial support from the Ministry of Science and Technology of China (Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China (Nos.21890753, 21573220 and 21802124)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (No.QYZDB-SSW-JSC020)the DNL Cooperation Fund, CAS (No.DNL180201)the financial and technique supports from the Westlake Education Foundation, Supercomputing Systems in the Information Technology Center of Westlake University
文摘The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.
文摘Dioxygen activations constitute one of core issues in copper-dependent metalloenzymes. Upon O_(2) activation, copper-dependent metalloenzymes such as particulate methane monooxygenases(pM MOs), lytic polysaccharide monooxygenases(LPMOs) and binuclear copper enzymes PHM and DβM, are able to perform various challenging C–H bond activations. Meanwhile, various copper-oxygen core containing complexes have been synthetized to mimic the active species of metalloenzymes. Dioxygen activation by mononuclear copper active site may generate various copper-oxygen intermediates, including Cu(Ⅱ)-superoxo, Cu(Ⅱ)-hydroperoxo, Cu(Ⅱ)-oxyl as well as the Cu(Ⅲ)-hydroxide species. Intriguingly, all these species have been invoked as the potential active intermediates for C–H/O–H activations in either biological or synthetic systems. Due to the poor understanding on reactivities of copper-oxygen complex, the nature of active species in both biological and synthetic systems are highly controversial. In this account, we will compare the reactivities of various mononuclear copper-oxygen species between biological systems and the synthetic systems. The present study is expected to provide the consistent understanding on reactivities of various copper-oxygen active species in both biological and synthetic systems.
基金supported by the University Science Foundation of Anhui Province (No.KJ2009B104)the Applied Chemistry Key Constructing Subject of Anhui Province (No.200802187C)
文摘The title complex [Cu（L1）（L2）（H2O）]·H2O（1,HL1 = N-（imino（pyridin-2-yl）me-thyl）picolinamidine）,HL2 = salicylic acid） has been obtained by volatilization method with L1 prepared from 2,4,6-tripyridyl-1,3,5-triazine in situ.1 was fully characterized by single-crystal X-ray diffraction,elemental analysis and FT-IR.This complex exhibits a three-dimensional frame-work constructed through hydrogen bonding and C-H···π stacking interactions.The cyclic voltametric behavior of complex 1 was also investigated.1 belongs to the monoclinic system,space group P21/c with a = 15.112（5）,b = 7.115（2）,c = 19.899（6） ,β = 112.32°,V = 1979.4（11） 3,Mr = 460.94,Dc = 1.540 g/cm3,F（000） = 948,μ = 1.146 mm-1,Z = 4,the final R = 0.0612 and wR = 0.1813 for 2510 observed reflections with I 2σ（I）.
文摘A novel {[bis（pyridine-κN）bis（3,5-dinitrosalicylato κ-O,O＇）Zn（Ⅱ）][bis（pyridine-κN）Zn（Ⅱ）]}（C_（34）H_（24）N_8O_（14）Zn_2） was synthesized by a self-assemble method at room temperature. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P2_1/n with a = 12.2156, b = 13.5696, c = 22.5602 A, β = 90.061o, Z = 4 and V = 3739.6（3）A^3. The new 1D binuclear coordination polymer {[bis（py-κN）bis（3,5-dinitrosal κ-O,O′） Zn（Ⅱ）][bis（py-κN）Zn（Ⅱ）]} resulted from two different types of moieties. The polymer [bis（py-κN）bis（3,5-dinitrosal κ-O,O′）Zn（Ⅱ）] unit is connected with [bis（py-κN） Zn（Ⅱ）] by zigzag topology. One zinc（Ⅱ） cation has a six-fold coordination environment, in which the metal atom is connected with four oxygen atoms of two 3,5-dinitrosalicylic acids to form equatorial bonds and two nitrogen atoms of pyridine to generate the axial bonds. Other four-fold nucleus contain two Zn-O bonds from different 3,5-dinitrosalicylic acids and two bonds with the Natom of pyridine. Antimicrobial assay results indicated that the compound showed moderate activities against different bacterial and fungal strains.
基金supported by Higher Education Commission(HEC)Govt.of Pakistan
文摘The structure of 1-hydroxy-3,5-dimethoxy-9 H-xanthen-9-one isolated from chloroform extract of Ajuga bracteosa root was analyzed by single-crystal X-ray diffraction. DPPH(1,1-diphenyl-2-picryl hydrazyl), ABTS(2,2?-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities(RSA) and Fe2+ chelating activities were carried out to determine the antioxidant potential of the compound. RSA values for the compound were 96%, 96% and 96% for all the three activities respectively at maximum concentration of the compound(100 μ gmL-1) with the IC50 values of 3.40, 4.86 and 0.10(μ gmL-1). Antidiabetic activities including antiglycation and α-glucosidase inhibition were also performed where the antiglycation activity was performed using two techniques including spectrofluorometric as well as spectrophotometric technique. Spectrofluorometric technique provided 97% antiglycation potential while 92% antiglycation potential was observed by spectrophotometric technique for the isolated compound. The compound at a concentration of 10 μ gmL-1 exhibited 31% α-glucosidase inhibitory potential with IC50 of 15.56 μ gmL-1. Antimicrobial activity data showed that the compound was active against all the studied pathogenic bacteria.
