The electronic structure and ferroelectric mechanism of trichloroacetamide were studied using first principles calculations and density functional theory within the generalized gradient approximation.Using both Bader ...The electronic structure and ferroelectric mechanism of trichloroacetamide were studied using first principles calculations and density functional theory within the generalized gradient approximation.Using both Bader charge and electron deformation density,large molecular spontaneous polarization is found to originate from the charge transfer cause by the strong“push-pull”effect of electron-releasing interacting with electron-withdrawing groups.The intermolecular hydrogen bonds,Ne-H…O,produce dipole moments in adjacent molecules to be aligned with each other.They also reduce the potential energy of the molecular chain threaded by hydrogen bonds.Due to the symmetric crystalline properties,however,the polarization of trichloroacetamide is mostly compensated and therefore small.Using the Berry Phase method,the spontaneous polarization of trichloroacetamide was simulated,and good agreement with the experimental values was found.Considering the polarization characteristics of trichloroacetamide,we constructed a one-dimensional ferroelectric Hamiltonian model to calculate the ferroelectric properties of TCAA.Using the Hamiltonian model,the thermal properties and ferroelectricity of trichloroacetamide were studied using the Monte Carlo method,and the Tc value was calculated.展开更多
Triphenylphosphine coupled with trichloroacetamide was determined to be an effective reagent for the conversion of 2,3,4,6-tetra-O-benzyl-D-glucopyranose as a glycosyl hemiacetal to the corresponding glycosyl chloride...Triphenylphosphine coupled with trichloroacetamide was determined to be an effective reagent for the conversion of 2,3,4,6-tetra-O-benzyl-D-glucopyranose as a glycosyl hemiacetal to the corresponding glycosyl chloride in excellent yield under mild and neutral conditions. Subsequently, the glycosyl chloride was reacted with alcohol or glycosyl acceptors in the presence of zinc（ll） bromide and molecular sieve 5 A to afford the corresponding glycosides in high yields and a-selectivity. This practical and convenient protocol can be utilized for the one-pot glycosylation of glycosyl hemiacetals.展开更多
基金Research supported by the National Science Foundation of China(Grant Nos.11474088,11504099 and 11274103)Natural Science Foundation of Hubei Provincial Department of Education(Grant No.Q20141005)the Applied Basic Research Programs of Wuhan City(Grant No.2014010101010006).
文摘The electronic structure and ferroelectric mechanism of trichloroacetamide were studied using first principles calculations and density functional theory within the generalized gradient approximation.Using both Bader charge and electron deformation density,large molecular spontaneous polarization is found to originate from the charge transfer cause by the strong“push-pull”effect of electron-releasing interacting with electron-withdrawing groups.The intermolecular hydrogen bonds,Ne-H…O,produce dipole moments in adjacent molecules to be aligned with each other.They also reduce the potential energy of the molecular chain threaded by hydrogen bonds.Due to the symmetric crystalline properties,however,the polarization of trichloroacetamide is mostly compensated and therefore small.Using the Berry Phase method,the spontaneous polarization of trichloroacetamide was simulated,and good agreement with the experimental values was found.Considering the polarization characteristics of trichloroacetamide,we constructed a one-dimensional ferroelectric Hamiltonian model to calculate the ferroelectric properties of TCAA.Using the Hamiltonian model,the thermal properties and ferroelectricity of trichloroacetamide were studied using the Monte Carlo method,and the Tc value was calculated.
文摘Triphenylphosphine coupled with trichloroacetamide was determined to be an effective reagent for the conversion of 2,3,4,6-tetra-O-benzyl-D-glucopyranose as a glycosyl hemiacetal to the corresponding glycosyl chloride in excellent yield under mild and neutral conditions. Subsequently, the glycosyl chloride was reacted with alcohol or glycosyl acceptors in the presence of zinc（ll） bromide and molecular sieve 5 A to afford the corresponding glycosides in high yields and a-selectivity. This practical and convenient protocol can be utilized for the one-pot glycosylation of glycosyl hemiacetals.
