Methylenedioxyphenyl unit displays a significant stereoelectronic effect in some key transformations in the total synthesis of cephalotaxine. The ring-strain of methylenedioxy ring may account for some important facil...Methylenedioxyphenyl unit displays a significant stereoelectronic effect in some key transformations in the total synthesis of cephalotaxine. The ring-strain of methylenedioxy ring may account for some important facile ring-skeleton rearrangements.展开更多
A mechanism about the origin of the selectivities for the cleavage of dioxolane five-membered rings on pyranoside rings was suggested. Quantum chemical studies were performed to testify the rationality of the mechanis...A mechanism about the origin of the selectivities for the cleavage of dioxolane five-membered rings on pyranoside rings was suggested. Quantum chemical studies were performed to testify the rationality of the mechanism. It is thus suggested that the selectivities should be dependent on the differences of the free energy at the transition states when the five-membered ring cleaves. Natural bond orbital（NBO） analysis was further made to assess the influence of stereoelectronic effects on the selectivities.展开更多
Monitoring the structural transitions of individual molecules is of great significance because it helps to in depth explore the properties of molecules and provide diverse possibilities for molecular applications in t...Monitoring the structural transitions of individual molecules is of great significance because it helps to in depth explore the properties of molecules and provide diverse possibilities for molecular applications in the fields of chemistry,biology and material science.This review summarizes the strategy of using single-molecule electrical approaches to study molecular structure transitions at the single-molecule level in real time.Specifically,through the use of stable single-molecule devices for real-time electrical monitoring,the process of molecular structure transitions of a single molecule can be investigated,which helps to explore the nature of molecules in chemical and biological systems.In particular,the detection methods have been extended to the investigation of biological macromolecules for monitoring the conformational changes of nucleotide chains in different systems,such as double helix DNA,aptamer and DNA enzyme.In the end,we discuss the future challenges of probing structural transitions of single molecules,and provide prospects for further breakthroughs in this field.展开更多
基金This work was financially supported by the National Natural Science Foundation (DistinguishedYouth Fund 29925204) Fok Ying Tung Education Foundaiton (Fund 71012).
文摘Methylenedioxyphenyl unit displays a significant stereoelectronic effect in some key transformations in the total synthesis of cephalotaxine. The ring-strain of methylenedioxy ring may account for some important facile ring-skeleton rearrangements.
基金Supported by the National Natural Science Foundation of China（No.20973077）, the Program for New Century Excellent Talents in University of China（No.NCET-07-0358） and the Brain Gain Fund of Huazhong University of Science and Technology, China.
文摘A mechanism about the origin of the selectivities for the cleavage of dioxolane five-membered rings on pyranoside rings was suggested. Quantum chemical studies were performed to testify the rationality of the mechanism. It is thus suggested that the selectivities should be dependent on the differences of the free energy at the transition states when the five-membered ring cleaves. Natural bond orbital（NBO） analysis was further made to assess the influence of stereoelectronic effects on the selectivities.
基金We acknowledge primary financial supports from the National Key R&D Program of China(2017YFA0204901)NSFC(21727806 and 21933001)+1 种基金NSFB(Z181100004418003)the Tencent Foundation through the EXPLORER PRIZE.
文摘Monitoring the structural transitions of individual molecules is of great significance because it helps to in depth explore the properties of molecules and provide diverse possibilities for molecular applications in the fields of chemistry,biology and material science.This review summarizes the strategy of using single-molecule electrical approaches to study molecular structure transitions at the single-molecule level in real time.Specifically,through the use of stable single-molecule devices for real-time electrical monitoring,the process of molecular structure transitions of a single molecule can be investigated,which helps to explore the nature of molecules in chemical and biological systems.In particular,the detection methods have been extended to the investigation of biological macromolecules for monitoring the conformational changes of nucleotide chains in different systems,such as double helix DNA,aptamer and DNA enzyme.In the end,we discuss the future challenges of probing structural transitions of single molecules,and provide prospects for further breakthroughs in this field.
