Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（...Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（DFT） and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex（Q）, one transition state（TS）, and one intermediate（IM） which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order： GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.展开更多
An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material ...An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, pH titration, and distribution coefficient （Kd） measurement. The acid treatments of Mg2Mn0.5Ti0.5O4 caused Mg^2＋ extractions of more than 81%, whereas the dissolutions of Mn^4＋ and Ti^4＋ were less than 10%. The experimental results proved that the acid-treated sample has a capacity of exchange 56 mg·g^-1 for Li^＋ in the solution. The chemical analysis showed that the Li^＋ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.展开更多
The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G（d）//MP2/6-311G（d） level. The geometric conformations at each stationary point in reaction potential surface were fully optimiz...The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G（d）//MP2/6-311G（d） level. The geometric conformations at each stationary point in reaction potential surface were fully optimized and the transition states were verified by intrinsic reaction coordinate （IRC） and frequency analysis. The energies of all reactants were calculated with CCSD（T）/6-311G（d）//G2MP2 methods. Results indicated that the P1 reaction route with difuoroaldehyde as product is the dominant reaction pathway, which exhibits nucleophilic character. According to NBO analysis, the starting point of insertion reaction is the interaction between carbene LP（C3） and formaldehyde π（Cl-O2）. Besides, the thermodynamic and dynamic properties of dominated reaction （1） at different temperature were studied with statistic thermodynamic method and Eyring transition state theory adjusted by Wigner means, from which the proper temperature （500- 1200 K） of reaction （1） could be estimated. Finally, the thermo- dynamic and dynamic properties of insertion reaction mechanisms （CF2, CX2 （X = Cl, Br） with CH2O） were compared and discussed.展开更多
The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth poly...The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth polymerization of diols,carbonyl sulfide(CoS,or carbon disulfide,CS_(2)),and dichlorides.Diols and dichlorides are common chemicals,and CoS(CS_(2))is released as industrial waste.In addition to abun-dant feedstocks,the method is efficient and performed under mild conditions,using common organic bases as catalysts,and affording unprece-dented polymers.When cos,diols,and dihalides were used as monomers,optimized conditions could completely suppress the oxygen-sulfur exchange reaction,enabling the efficient synthesis of well-defined poly(monothiocarbonate)s with melting points ranging from 48°C to 101°C.These polymers,which have a structure similar to polyethylene with low-density in-chain polar groups,exhibit remarkable toughness and ductili-ty that rival those of high-density polyethylene(melting point:90°C,tensile strength:21.6±0.7 MPa,and elongation at break:576%).Moreover,the obtained poly(monothiocarbonate)s can be chemically degraded by alcoholysis to yield small-molecule diols and dithiols.When CS_(2)was used in place of cos,a pronounced oxygen-sulfur exchange reaction occurred.By optimizing reaction condition,it was found that polymers with-S(C=O)S-and-S(C=S)S-as the main repeating units exhibited high thermal stability and crystallinity.Thus,a new approach for regulat-ing the structure of polythiocarbonates via the oxygen-sulfur exchange reaction is developed.Overall,the polymers hold great potential for green materials due to their facile synthesis,readily available feedstocks,excellent performance,and chemical degradability.展开更多
用Mg-Al基复合物催化环氧丙烷（PO）一步嵌入乙酸酐（AA）合成了1,2-丙二醇二乙酸酯（PGDA）,经红外光谱、电喷雾质谱鉴定得到了预期产物。研究了反应温度、n（PO）/n（AA）、PO滴加或一次性投入方式对单PO加成选择性的影响。实验结果表...用Mg-Al基复合物催化环氧丙烷（PO）一步嵌入乙酸酐（AA）合成了1,2-丙二醇二乙酸酯（PGDA）,经红外光谱、电喷雾质谱鉴定得到了预期产物。研究了反应温度、n（PO）/n（AA）、PO滴加或一次性投入方式对单PO加成选择性的影响。实验结果表明,当Mg-Al基复合物用量为1.6 g/100 g AA,n（PO）/n（AA）=1,以0.75g/min滴加PO,反应温度130-135℃时,单PO加成选择性达到ω（PGDA）=98.2%。与传统合成二元醇二酯的方法相比,该路线无需过量加入AA原料,亦不生成副产物,是一条具有工业化前景的合成二元醇二酯的高原子经济性的绿色化学途径。展开更多
Although the lead-free halide double perovskites(DPs)have shown great promise for the photocatalytic reduction of CO_(2),the catalytic performance is still far from satisfactory.In this work,lead-free Cs_(2)AgSbX_(6)(...Although the lead-free halide double perovskites(DPs)have shown great promise for the photocatalytic reduction of CO_(2),the catalytic performance is still far from satisfactory.In this work,lead-free Cs_(2)AgSbX_(6)(X=Cl,Br,I)DPs nanocrystals(NCs)are prepared by a modified ligand-assisted reprecipitation(LARP)approach at room temperature.The crystal surface,shape,and optoelectronic properties of the AgSb-based DPs are modified using halogen modulation technique.Moreover,a series of Cs_(2)AgSbX_(6) perovskites NCs are utilized as efficient catalysts for the photocatalytic CO_(2) reduction.Among them,the Cs_(2)AgSbBr_(6) NCs demonstrate the optimal CO_(2) photoreduction activity with CO and CH_(4) evolutions of 366 and 49μmol g^(-1) respectively under 3h irradiation.Additionally,using the in-situ DRIFTS research,the surface reaction intermediates were precisely identified and dynamically tracked.This study suggests the potential of the lead-free halide DPs NCs as an important platform for the practical solar-to-fuel conversions.展开更多
基金supported by the National Natural Science Foundation Committee of China(No.21103145)the Natural Science Foundation of Shandong Province(No.ZR2009BQ006)+3 种基金the Fund for Doctor of Yantai University(No.HY05B30)the Special Foundation of Youth Academic Backbone of Yantai Universitysupport by the Open fund(sklssm201418)of the State Key Laboratory of Supramolecular Structure and Materials,Jilin Universitythe Graduate Innovation Foundation of Yantai University,GIFYTU
文摘Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（DFT） and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex（Q）, one transition state（TS）, and one intermediate（IM） which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order： GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.
文摘An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, pH titration, and distribution coefficient （Kd） measurement. The acid treatments of Mg2Mn0.5Ti0.5O4 caused Mg^2＋ extractions of more than 81%, whereas the dissolutions of Mn^4＋ and Ti^4＋ were less than 10%. The experimental results proved that the acid-treated sample has a capacity of exchange 56 mg·g^-1 for Li^＋ in the solution. The chemical analysis showed that the Li^＋ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.
基金the Research Foundation of Education Bureau of Gansu Province(0708-11)
文摘The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G（d）//MP2/6-311G（d） level. The geometric conformations at each stationary point in reaction potential surface were fully optimized and the transition states were verified by intrinsic reaction coordinate （IRC） and frequency analysis. The energies of all reactants were calculated with CCSD（T）/6-311G（d）//G2MP2 methods. Results indicated that the P1 reaction route with difuoroaldehyde as product is the dominant reaction pathway, which exhibits nucleophilic character. According to NBO analysis, the starting point of insertion reaction is the interaction between carbene LP（C3） and formaldehyde π（Cl-O2）. Besides, the thermodynamic and dynamic properties of dominated reaction （1） at different temperature were studied with statistic thermodynamic method and Eyring transition state theory adjusted by Wigner means, from which the proper temperature （500- 1200 K） of reaction （1） could be estimated. Finally, the thermo- dynamic and dynamic properties of insertion reaction mechanisms （CF2, CX2 （X = Cl, Br） with CH2O） were compared and discussed.
基金supported by the National Natural Science Foundation of China(Nos.223B2119,U23A2083,52373014,52203129).
文摘The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth polymerization of diols,carbonyl sulfide(CoS,or carbon disulfide,CS_(2)),and dichlorides.Diols and dichlorides are common chemicals,and CoS(CS_(2))is released as industrial waste.In addition to abun-dant feedstocks,the method is efficient and performed under mild conditions,using common organic bases as catalysts,and affording unprece-dented polymers.When cos,diols,and dihalides were used as monomers,optimized conditions could completely suppress the oxygen-sulfur exchange reaction,enabling the efficient synthesis of well-defined poly(monothiocarbonate)s with melting points ranging from 48°C to 101°C.These polymers,which have a structure similar to polyethylene with low-density in-chain polar groups,exhibit remarkable toughness and ductili-ty that rival those of high-density polyethylene(melting point:90°C,tensile strength:21.6±0.7 MPa,and elongation at break:576%).Moreover,the obtained poly(monothiocarbonate)s can be chemically degraded by alcoholysis to yield small-molecule diols and dithiols.When CS_(2)was used in place of cos,a pronounced oxygen-sulfur exchange reaction occurred.By optimizing reaction condition,it was found that polymers with-S(C=O)S-and-S(C=S)S-as the main repeating units exhibited high thermal stability and crystallinity.Thus,a new approach for regulat-ing the structure of polythiocarbonates via the oxygen-sulfur exchange reaction is developed.Overall,the polymers hold great potential for green materials due to their facile synthesis,readily available feedstocks,excellent performance,and chemical degradability.
文摘用Mg-Al基复合物催化环氧丙烷（PO）一步嵌入乙酸酐（AA）合成了1,2-丙二醇二乙酸酯（PGDA）,经红外光谱、电喷雾质谱鉴定得到了预期产物。研究了反应温度、n（PO）/n（AA）、PO滴加或一次性投入方式对单PO加成选择性的影响。实验结果表明,当Mg-Al基复合物用量为1.6 g/100 g AA,n（PO）/n（AA）=1,以0.75g/min滴加PO,反应温度130-135℃时,单PO加成选择性达到ω（PGDA）=98.2%。与传统合成二元醇二酯的方法相比,该路线无需过量加入AA原料,亦不生成副产物,是一条具有工业化前景的合成二元醇二酯的高原子经济性的绿色化学途径。
基金supported by the National Natural Science Foundation of China(62375032,22408362)The China National Postdoctoral Program for Innovative Talents(Certificate Number:BX20230355)+3 种基金The China Postdoctoral Science Foundation(Certificate Number:2024M753165)The Natural Science Foundation of Chongqing(No.CSTB2023TIAD-KPX0017)The Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)Department of Education of Guizhou Province(Guizhou Teaching and Technology[2023]015).
文摘Although the lead-free halide double perovskites(DPs)have shown great promise for the photocatalytic reduction of CO_(2),the catalytic performance is still far from satisfactory.In this work,lead-free Cs_(2)AgSbX_(6)(X=Cl,Br,I)DPs nanocrystals(NCs)are prepared by a modified ligand-assisted reprecipitation(LARP)approach at room temperature.The crystal surface,shape,and optoelectronic properties of the AgSb-based DPs are modified using halogen modulation technique.Moreover,a series of Cs_(2)AgSbX_(6) perovskites NCs are utilized as efficient catalysts for the photocatalytic CO_(2) reduction.Among them,the Cs_(2)AgSbBr_(6) NCs demonstrate the optimal CO_(2) photoreduction activity with CO and CH_(4) evolutions of 366 and 49μmol g^(-1) respectively under 3h irradiation.Additionally,using the in-situ DRIFTS research,the surface reaction intermediates were precisely identified and dynamically tracked.This study suggests the potential of the lead-free halide DPs NCs as an important platform for the practical solar-to-fuel conversions.
