The intramolecular acetate rearrangement of the aminocarboxylate metal chelates with the hexdentate-coordinate has been investigated by dynamic NMR in recent years. However, the intramolecular processes of the metal q...The intramolecular acetate rearrangement of the aminocarboxylate metal chelates with the hexdentate-coordinate has been investigated by dynamic NMR in recent years. However, the intramolecular processes of the metal quinquedentate chelates have not been studied up to now. Here is reported the configurational reversion展开更多
The dynamic ~1H and ^(13)C-NMR studies on [Li(2D)][Nd(η~8-C_3H_5)_4] (D=dioxane)were reported The four allyls coordinated to Hd^(8+) ion are equivalent and hydrogens appear as three groups in ~1H-NMR spectra with the...The dynamic ~1H and ^(13)C-NMR studies on [Li(2D)][Nd(η~8-C_3H_5)_4] (D=dioxane)were reported The four allyls coordinated to Hd^(8+) ion are equivalent and hydrogens appear as three groups in ~1H-NMR spectra with their chemical shifts changing with temperature.C_1 and Ca are equivalent showing the characteristic of η~2=-allyl.The paramagnetic shifts of carbons in allyls induced by Nd^(2+) ere separated sucessfully.C_1 and C_3 located on the zero-dipolar cone.The content of contact shift is greater than that of dipolar slift to Co.展开更多
By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bo...By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1 gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.展开更多
The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top...The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and R states.展开更多
G-protein-coupled receptors(GPCRs)mediate a wide range of cellular responses to various ligands or stimuli,and are the most important drug targets associated with human diseases.While major advances in GPCR structural...G-protein-coupled receptors(GPCRs)mediate a wide range of cellular responses to various ligands or stimuli,and are the most important drug targets associated with human diseases.While major advances in GPCR structural biology have greatly deepened our understanding of its activation mechanism,the highly complex changes in the structural dynamics of GPCRs during activation remain underdetermined and their links to physiological functions largely unknown.Solution nuclear magnetic resonance(NMR)spectroscopy is an essential technique that allows the characterization of protein structural dynamics at atomic level,and has been applied in the studies of GPCR structural-function relationship in the past decade.Herein,we summarize a few specific studies in which solution NMR methods were employed and provided novel insights into questions difficult to be addressed by other methods.展开更多
Synthesis of N-（1H-imidazoline-2-yl）-lH-benzimidazol-2-amine was carried out under microwave irradiation （MWI） conditions. Dynamic 1H NMR investigation of N-（lH-imidazoline-2-yl）-lH-benzimidazol-2-amine compound...Synthesis of N-（1H-imidazoline-2-yl）-lH-benzimidazol-2-amine was carried out under microwave irradiation （MWI） conditions. Dynamic 1H NMR investigation of N-（lH-imidazoline-2-yl）-lH-benzimidazol-2-amine compound was reported at temperature range of 223--333 K in DMF-d7. Some physical parameters, such as coalescence temperature （Tc）, the free energy of activation （△G＊） and rate constant （k） values were calculated from its IH NMR spectra at various temperatures. Electrochemical feature of this compound was investigated by cyclic （CV） and square wave voltammetry （SWV）.展开更多
The zwitterionic intermediate generated from the reaction of triphenylphosphine with electron deficient acety- lenic compounds was trapped by various NH acids. The synthesis resulted in a new class of highly functiona...The zwitterionic intermediate generated from the reaction of triphenylphosphine with electron deficient acety- lenic compounds was trapped by various NH acids. The synthesis resulted in a new class of highly functionalized heterocyclic compounds. Some of the reactions produced E and Z isomers. And the stability and transformation of them were studied by dynamic 1H NMR and density functional theory （DFT） calculations.展开更多
基金Supported by the National Natural Science Foundation of China
文摘The intramolecular acetate rearrangement of the aminocarboxylate metal chelates with the hexdentate-coordinate has been investigated by dynamic NMR in recent years. However, the intramolecular processes of the metal quinquedentate chelates have not been studied up to now. Here is reported the configurational reversion
文摘The dynamic ~1H and ^(13)C-NMR studies on [Li(2D)][Nd(η~8-C_3H_5)_4] (D=dioxane)were reported The four allyls coordinated to Hd^(8+) ion are equivalent and hydrogens appear as three groups in ~1H-NMR spectra with their chemical shifts changing with temperature.C_1 and Ca are equivalent showing the characteristic of η~2=-allyl.The paramagnetic shifts of carbons in allyls induced by Nd^(2+) ere separated sucessfully.C_1 and C_3 located on the zero-dipolar cone.The content of contact shift is greater than that of dipolar slift to Co.
文摘By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1 gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.
基金Supported by the National Natural Science Foundation of China
文摘The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and R states.
文摘G-protein-coupled receptors(GPCRs)mediate a wide range of cellular responses to various ligands or stimuli,and are the most important drug targets associated with human diseases.While major advances in GPCR structural biology have greatly deepened our understanding of its activation mechanism,the highly complex changes in the structural dynamics of GPCRs during activation remain underdetermined and their links to physiological functions largely unknown.Solution nuclear magnetic resonance(NMR)spectroscopy is an essential technique that allows the characterization of protein structural dynamics at atomic level,and has been applied in the studies of GPCR structural-function relationship in the past decade.Herein,we summarize a few specific studies in which solution NMR methods were employed and provided novel insights into questions difficult to be addressed by other methods.
文摘Synthesis of N-（1H-imidazoline-2-yl）-lH-benzimidazol-2-amine was carried out under microwave irradiation （MWI） conditions. Dynamic 1H NMR investigation of N-（lH-imidazoline-2-yl）-lH-benzimidazol-2-amine compound was reported at temperature range of 223--333 K in DMF-d7. Some physical parameters, such as coalescence temperature （Tc）, the free energy of activation （△G＊） and rate constant （k） values were calculated from its IH NMR spectra at various temperatures. Electrochemical feature of this compound was investigated by cyclic （CV） and square wave voltammetry （SWV）.
文摘The zwitterionic intermediate generated from the reaction of triphenylphosphine with electron deficient acety- lenic compounds was trapped by various NH acids. The synthesis resulted in a new class of highly functionalized heterocyclic compounds. Some of the reactions produced E and Z isomers. And the stability and transformation of them were studied by dynamic 1H NMR and density functional theory （DFT） calculations.
