A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear reg...A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.展开更多
After the geometry optimization at B3LYP/6-31＋G（d,p） level,the calculations of the NMR chemical shifts of a series of stilbene analogues were carried out by means of Gauge Including Atomic Orbitals（GIAO） method a...After the geometry optimization at B3LYP/6-31＋G（d,p） level,the calculations of the NMR chemical shifts of a series of stilbene analogues were carried out by means of Gauge Including Atomic Orbitals（GIAO） method at HF/6-31＋G（d） level and B3LYP/6-311G＋（2d,p） level,respectively.The 13C NMR chemical shifts calculated at both HF/6-31＋G（d） and B3LYP/6-31＋G（d,p） levels are in agreement with the observed values.By virtue of a series of linear correction equations（δpred.=a＋bδcalcd.） of the 13C chemical shifts,accurate prediction of 13C chemical shifts was achieved for the new stilbene compounds.For the 13C NMR chemical shifts calculated at HF/6-31＋G（d） level,the linear correlation of δpred.with δexptl.is excellent,and the square of correlation coefficient,r2,is 0.9985.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.3,and the root-mean-square error between δpred.and δexptl.is 0.98.In the meantime,for those obtained at B3LYP/6-31＋G（d,p） level,the linear correlation of δpred.with δexptl.is also excellent,and the square of correlation coefficient,r2,is up to 0.9987.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.2,and the root-mean-square error between δpred.and δexptl.is only 0.88.展开更多
After the geometry optimizations at the B3LYP/6-31＋G（d,p） level, the NMR calculations of a series of 9,10-dihydrophenanthrene analogues have been carried out by GIAO method at the HF/6-31＋G（d） level. The calcula...After the geometry optimizations at the B3LYP/6-31＋G（d,p） level, the NMR calculations of a series of 9,10-dihydrophenanthrene analogues have been carried out by GIAO method at the HF/6-31＋G（d） level. The calculated ^13C NMR chemical shifts are in agreement with the observed values. By a series of linear correlation equations （δpred = a ＋ bδcal.c） of the ^13C chemical shifts, accurate prediction of ^13C chemical shifts was achieved for the new 9,10- dihydrophenanthrene compound, for which the predicted ^13C NMR chemical shifts are in quite good agreement with the experimental values. The linear correlation between δpred and δexptl is excellent, and the square of correlation coefficient, r^2, is up to 0.9973. The maximum absolute difference between δpred and δexptl, △δ, is 4.5 ppm, and the rms error between δpred and δexpt is 2.55 ppm. In the meantime, according to the theoretical predicted result, we could confirm that the new 9,10-dihydrophenanthrene analogue is erianthridin （2,7-dihydroxy-3,4-dimethoxy-9,10-dihydro- phenanthrene）.展开更多
用原子电性距离矢量(atom ic electronegativity d istance vector,AEDV)和原子杂化状态指数(atom ic hybrid i-zation state index,AHSI)对13个雄甾烯酮化合物中247个碳原子进行了结构表征,并与其核磁共振碳谱(13CNMR)建立了多元线性...用原子电性距离矢量(atom ic electronegativity d istance vector,AEDV)和原子杂化状态指数(atom ic hybrid i-zation state index,AHSI)对13个雄甾烯酮化合物中247个碳原子进行了结构表征,并与其核磁共振碳谱(13CNMR)建立了多元线性定量构谱相关(QSSR)模型;运用逐步回归结合统计检测,对模型变量进行了筛选,建模计算值、留一法(leave-one-out,LOO)交互校验(cross-validation,CV)预测值和留分法(leave-molecu le-out,LMO)交互校验预测值的复相关系数(R)分别为0.989 6,0.989 1和0.989 4。结果表明:AEDV,AHSI与13CNMR谱化学位移显著相关。展开更多
Three ethylene-vinyl alcohol copolymers were studied by means of the substituent chemical shift (SCS) method. The SCS parameters of hydroxy (-OH) in two different solvents were obtained: in deuterium oxide/phenol (20/...Three ethylene-vinyl alcohol copolymers were studied by means of the substituent chemical shift (SCS) method. The SCS parameters of hydroxy (-OH) in two different solvents were obtained: in deuterium oxide/phenol (20/80 W/W ) the parameters are S_1 = 42.77±0.08ppm, S_2 = 7.15±0.06 ppm, S_3 (s)= -4.08±0.02ppm, S_3 (t) =-3.09±0.20ppm,S_4 = 0.48±0.03ppm, S_5 = 0.26±0.05ppm. In o-dichloro-benzen-d_4 S_1(s)=44.79±0.61ppm, S_2=7.40±0.00ppm, S_3(s)=-4.51±0.17ppm, S_3(t)=-3.13 ±0.00 ppm, S_4 =0.63±0.04ppm, S_5=0.36±0.00ppm.Simultaneously the ^(13)CNMR spectra of EVA copolymers were assigned by using the SCS parameters obtained.展开更多
The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above a...The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above and the DEPT technique, we then entirely assigned the 13 C NMR spectra of the ethylene/propylene/octene 1 terpolymers synthesized in the presence of the same heterogeneous supported Ziegler Natta catalyst, TiCl 4/MgCl 2/ i Bu 3Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene 1 terpolymers.展开更多
^1H and ^13C NMR chemical shifts were determined to investigate the interactions of acetone with a room temperature ionic liquid 1-hexyl-3- methylimidazolium bromide [C6mim]Br at various mole fractions. Changes in che...^1H and ^13C NMR chemical shifts were determined to investigate the interactions of acetone with a room temperature ionic liquid 1-hexyl-3- methylimidazolium bromide [C6mim]Br at various mole fractions. Changes in chemical shifts of hydrogen nuclei and of carbon nuclei with the acetone concentration indicated the formation of hydrogen bond between anion of the ionic liquid and methyl protons of acetone. The NMR results were in good agreement with the ab initio computational results.展开更多
基金Projects(20775010, 21075011) supported by the National Natural Science Foundation of ChinaProject(2008AA05Z405) supported by the National High-tech Research and Development Program of China+2 种基金Project(09JJ3016) supported by the Natural Science Foundation of Hunan Province, ChinaProject(09C066) supported by the Scientific Research Fund of Hunan Provincial Education Department, ChinaProject(2010CL01) supported by the Foundation of Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, China
文摘A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.
基金Supported by the Scientific Research Foundation of Department of Education of Yunnan Province,China(No.09Y0181)
文摘After the geometry optimization at B3LYP/6-31＋G（d,p） level,the calculations of the NMR chemical shifts of a series of stilbene analogues were carried out by means of Gauge Including Atomic Orbitals（GIAO） method at HF/6-31＋G（d） level and B3LYP/6-311G＋（2d,p） level,respectively.The 13C NMR chemical shifts calculated at both HF/6-31＋G（d） and B3LYP/6-31＋G（d,p） levels are in agreement with the observed values.By virtue of a series of linear correction equations（δpred.=a＋bδcalcd.） of the 13C chemical shifts,accurate prediction of 13C chemical shifts was achieved for the new stilbene compounds.For the 13C NMR chemical shifts calculated at HF/6-31＋G（d） level,the linear correlation of δpred.with δexptl.is excellent,and the square of correlation coefficient,r2,is 0.9985.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.3,and the root-mean-square error between δpred.and δexptl.is 0.98.In the meantime,for those obtained at B3LYP/6-31＋G（d,p） level,the linear correlation of δpred.with δexptl.is also excellent,and the square of correlation coefficient,r2,is up to 0.9987.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.2,and the root-mean-square error between δpred.and δexptl.is only 0.88.
基金supported by the Scientific Research Foundation of Department of Education of Yunnan Province (No. 2010Z035)
文摘After the geometry optimizations at the B3LYP/6-31＋G（d,p） level, the NMR calculations of a series of 9,10-dihydrophenanthrene analogues have been carried out by GIAO method at the HF/6-31＋G（d） level. The calculated ^13C NMR chemical shifts are in agreement with the observed values. By a series of linear correlation equations （δpred = a ＋ bδcal.c） of the ^13C chemical shifts, accurate prediction of ^13C chemical shifts was achieved for the new 9,10- dihydrophenanthrene compound, for which the predicted ^13C NMR chemical shifts are in quite good agreement with the experimental values. The linear correlation between δpred and δexptl is excellent, and the square of correlation coefficient, r^2, is up to 0.9973. The maximum absolute difference between δpred and δexptl, △δ, is 4.5 ppm, and the rms error between δpred and δexpt is 2.55 ppm. In the meantime, according to the theoretical predicted result, we could confirm that the new 9,10-dihydrophenanthrene analogue is erianthridin （2,7-dihydroxy-3,4-dimethoxy-9,10-dihydro- phenanthrene）.
文摘用原子电性距离矢量(atom ic electronegativity d istance vector,AEDV)和原子杂化状态指数(atom ic hybrid i-zation state index,AHSI)对13个雄甾烯酮化合物中247个碳原子进行了结构表征,并与其核磁共振碳谱(13CNMR)建立了多元线性定量构谱相关(QSSR)模型;运用逐步回归结合统计检测,对模型变量进行了筛选,建模计算值、留一法(leave-one-out,LOO)交互校验(cross-validation,CV)预测值和留分法(leave-molecu le-out,LMO)交互校验预测值的复相关系数(R)分别为0.989 6,0.989 1和0.989 4。结果表明:AEDV,AHSI与13CNMR谱化学位移显著相关。
文摘Three ethylene-vinyl alcohol copolymers were studied by means of the substituent chemical shift (SCS) method. The SCS parameters of hydroxy (-OH) in two different solvents were obtained: in deuterium oxide/phenol (20/80 W/W ) the parameters are S_1 = 42.77±0.08ppm, S_2 = 7.15±0.06 ppm, S_3 (s)= -4.08±0.02ppm, S_3 (t) =-3.09±0.20ppm,S_4 = 0.48±0.03ppm, S_5 = 0.26±0.05ppm. In o-dichloro-benzen-d_4 S_1(s)=44.79±0.61ppm, S_2=7.40±0.00ppm, S_3(s)=-4.51±0.17ppm, S_3(t)=-3.13 ±0.00 ppm, S_4 =0.63±0.04ppm, S_5=0.36±0.00ppm.Simultaneously the ^(13)CNMR spectra of EVA copolymers were assigned by using the SCS parameters obtained.
基金Supported by the Foundation of Educational Ministry of China.
文摘The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above and the DEPT technique, we then entirely assigned the 13 C NMR spectra of the ethylene/propylene/octene 1 terpolymers synthesized in the presence of the same heterogeneous supported Ziegler Natta catalyst, TiCl 4/MgCl 2/ i Bu 3Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene 1 terpolymers.
基金Ⅴ. ACKN0WLEDGMENTS This work was supported Science Foundation of China by the National Natural （No.20273019）.
文摘^1H and ^13C NMR chemical shifts were determined to investigate the interactions of acetone with a room temperature ionic liquid 1-hexyl-3- methylimidazolium bromide [C6mim]Br at various mole fractions. Changes in chemical shifts of hydrogen nuclei and of carbon nuclei with the acetone concentration indicated the formation of hydrogen bond between anion of the ionic liquid and methyl protons of acetone. The NMR results were in good agreement with the ab initio computational results.
