INADEQUATE(Incredible Natural Abundance DoublE QUAntum Transfer Experiment)is one of the most important techniques in revealing the carbon skeleton of organic solids in solid-state NMR spectroscopy.Nevertheless,its us...INADEQUATE(Incredible Natural Abundance DoublE QUAntum Transfer Experiment)is one of the most important techniques in revealing the carbon skeleton of organic solids in solid-state NMR spectroscopy.Nevertheless,its use for structural analysis is quite limited due to the low natural abundance of^(13)C-^(13)C connectivity(~0.01%)and thus low sensitivity.Particularly,in semi-solids like rubbers,the sensitivity will be further significantly reduced by the inefficient cross polarization from 1H to^(13)C due to molecular motions induced averaging of^(1)H-^(13)C dipolar couplings.Herein,in this study,we demonstrate that transient nuclear Overhauser effect(NOE)can be used to efficiently enhance^(13)C signals,and thus enable rapid acquisition of two-dimensional(2D)^(13)C INADEQUATE spectra of rubbers.Using chlorobutyl rubber as the model system,it is found that an overall signalto-noise ratio(SNR)enhancement about 22%can be achieved,leading to significant timesaving by about 33%as compared to the direct polarization-based INADEQUATE experiment.Further experimental results on natural rubber and ethylene propylene diene monomer(EPDM)rubber are also shown to demonstrate the robust performance of transient NOE enhanced INADEQUATE experiment.展开更多
The author discussed the extent of NOE concerning adjustment of GDP. The author thought that value added of NOE and value added of concealment should be added to GDP, and studied the method about estimation of NOE.
The concept of base stacking of nucleotides in solutions has been well accepted.However,direct evidence has not been found.Here we report for the first time the intermolecular NOE cross peaks between ATP (adenosine 5...The concept of base stacking of nucleotides in solutions has been well accepted.However,direct evidence has not been found.Here we report for the first time the intermolecular NOE cross peaks between ATP (adenosine 5′triphosphate) and GTP (guanosine 5′triphosphate),which unambiguously indicates the base stacking of nucleotides in solutions.In 400 mmol·L -1 ATPGTP solutions,the base protons of ATP,AH2 and AH8,show NOE cross peaks with the sugar protons of GTP,GH1′,GH2′ and GH3′.Also there are NOE cross peaks between the base proton of GTP (GH8) and the sugar protons of ATP.Possible conformations of base stacking in solutions have been discussed,and the distance between the stacked bases is estimated.展开更多
基金support of National Natural Science Foundation of China(No.22173033,and 22241501)Natural Science Foundation of Guangdong Province,China(No.2023A1515011395).
文摘INADEQUATE(Incredible Natural Abundance DoublE QUAntum Transfer Experiment)is one of the most important techniques in revealing the carbon skeleton of organic solids in solid-state NMR spectroscopy.Nevertheless,its use for structural analysis is quite limited due to the low natural abundance of^(13)C-^(13)C connectivity(~0.01%)and thus low sensitivity.Particularly,in semi-solids like rubbers,the sensitivity will be further significantly reduced by the inefficient cross polarization from 1H to^(13)C due to molecular motions induced averaging of^(1)H-^(13)C dipolar couplings.Herein,in this study,we demonstrate that transient nuclear Overhauser effect(NOE)can be used to efficiently enhance^(13)C signals,and thus enable rapid acquisition of two-dimensional(2D)^(13)C INADEQUATE spectra of rubbers.Using chlorobutyl rubber as the model system,it is found that an overall signalto-noise ratio(SNR)enhancement about 22%can be achieved,leading to significant timesaving by about 33%as compared to the direct polarization-based INADEQUATE experiment.Further experimental results on natural rubber and ethylene propylene diene monomer(EPDM)rubber are also shown to demonstrate the robust performance of transient NOE enhanced INADEQUATE experiment.
文摘The author discussed the extent of NOE concerning adjustment of GDP. The author thought that value added of NOE and value added of concealment should be added to GDP, and studied the method about estimation of NOE.
文摘The concept of base stacking of nucleotides in solutions has been well accepted.However,direct evidence has not been found.Here we report for the first time the intermolecular NOE cross peaks between ATP (adenosine 5′triphosphate) and GTP (guanosine 5′triphosphate),which unambiguously indicates the base stacking of nucleotides in solutions.In 400 mmol·L -1 ATPGTP solutions,the base protons of ATP,AH2 and AH8,show NOE cross peaks with the sugar protons of GTP,GH1′,GH2′ and GH3′.Also there are NOE cross peaks between the base proton of GTP (GH8) and the sugar protons of ATP.Possible conformations of base stacking in solutions have been discussed,and the distance between the stacked bases is estimated.
