Experiments indicate that a catalytic amount of Cul plays an important role in the siloxane-mediated Pd-catalyzed cross-coupling reactions with the direct use of organolithium reagents.Addition of organolithium to the...Experiments indicate that a catalytic amount of Cul plays an important role in the siloxane-mediated Pd-catalyzed cross-coupling reactions with the direct use of organolithium reagents.Addition of organolithium to the siloxane transfer agent generates an organosilicon intermediate.DFT calculations indicate that Cul initially accelerates the Si-Pd(Ⅱ) transmetalation of the organosilicon intermediate by the formation of CuI_(2)^(-).Subsequently,CuI_(2)^(-)works as a shuttle between the Si-Cu(Ⅰ) and Cu(Ⅰ)-Pd(Ⅱ)transmetalation processes.展开更多
We computationally investigate the impact of crystal strain on the formation of native point defects likely to be formed in halide perovskites;A-site cation antisite(I_(A)),Pb antisite(I_(Pb)),A-site cation vacany(V_(...We computationally investigate the impact of crystal strain on the formation of native point defects likely to be formed in halide perovskites;A-site cation antisite(I_(A)),Pb antisite(I_(Pb)),A-site cation vacany(V_(A)),I vacancy(V_(I)),Pb vacancy(V_(Pb)),and I interstitial(I_(i)).We systematically identify compressive and tensile strain to CsPbI_(3),FAPbI_(3),and MAPbI_(3)perovskite structures.We observe that while each type of defect has a unique behaviour,overall,the defect formation in FAPbI3 is much more sensitive to the strain.The compressive strain can enhance the formation energy of neutral I_(Pb)and I_(i)up to 15%for FAPbI_(3),depending on the growth conditions.We show that the strain not only controls the formation of defects but also their transition levels in the band gap:A deep level can be transformed into a shallow level by the strain.We anticipate that tailoring the lattice strain can be used as a defect passivation mechanism for future studies.展开更多
The catalysis of the Hajos-Parrish reaction by cis-and trans-4,5-ethano-proline was explored experimentally and computationally with DFT(ωB97X-D and MN15)and DLPNO-CCSD(T).Both of the new catalysts are as active as p...The catalysis of the Hajos-Parrish reaction by cis-and trans-4,5-ethano-proline was explored experimentally and computationally with DFT(ωB97X-D and MN15)and DLPNO-CCSD(T).Both of the new catalysts are as active as proline or cis-and trans-4,5-methano-proline,with the trans-ethano-proline being as enantioselective as proline.A thorough theoretical analysis of the electronic factors influencing catalysis is reported.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21803030)the Fundamental Research Funds for the Central Universities,the National Thousand Young Talents Program+3 种基金the Jiangsu Innovation&Entrepreneurship Talents Planthe NSF of Jiangsu Province(No.BK20170631)in Chinathe National Institutes of Health(No.CA-019033)the National Science Foundation in USA(No.CHE-1361104)。
文摘Experiments indicate that a catalytic amount of Cul plays an important role in the siloxane-mediated Pd-catalyzed cross-coupling reactions with the direct use of organolithium reagents.Addition of organolithium to the siloxane transfer agent generates an organosilicon intermediate.DFT calculations indicate that Cul initially accelerates the Si-Pd(Ⅱ) transmetalation of the organosilicon intermediate by the formation of CuI_(2)^(-).Subsequently,CuI_(2)^(-)works as a shuttle between the Si-Cu(Ⅰ) and Cu(Ⅰ)-Pd(Ⅱ)transmetalation processes.
基金supported by the National Science Foundation(CHE1764328)S.T.and Y.Y.were supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Solar Energy Technologies Office under award DE-EE0008751.
文摘We computationally investigate the impact of crystal strain on the formation of native point defects likely to be formed in halide perovskites;A-site cation antisite(I_(A)),Pb antisite(I_(Pb)),A-site cation vacany(V_(A)),I vacancy(V_(I)),Pb vacancy(V_(Pb)),and I interstitial(I_(i)).We systematically identify compressive and tensile strain to CsPbI_(3),FAPbI_(3),and MAPbI_(3)perovskite structures.We observe that while each type of defect has a unique behaviour,overall,the defect formation in FAPbI3 is much more sensitive to the strain.The compressive strain can enhance the formation energy of neutral I_(Pb)and I_(i)up to 15%for FAPbI_(3),depending on the growth conditions.We show that the strain not only controls the formation of defects but also their transition levels in the band gap:A deep level can be transformed into a shallow level by the strain.We anticipate that tailoring the lattice strain can be used as a defect passivation mechanism for future studies.
基金We thank NSERC for financial assistance.We also thank Thierry Maris and Michel Simard from the X-ray diffraction laboratory of the Universitéde Montréal for X-ray analysis。
文摘The catalysis of the Hajos-Parrish reaction by cis-and trans-4,5-ethano-proline was explored experimentally and computationally with DFT(ωB97X-D and MN15)and DLPNO-CCSD(T).Both of the new catalysts are as active as proline or cis-and trans-4,5-methano-proline,with the trans-ethano-proline being as enantioselective as proline.A thorough theoretical analysis of the electronic factors influencing catalysis is reported.
