Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water ...Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water complexes. The results show that the ground state complexes have strong hydrogen bonding interaction with -20.99, -16.73 and -15.31 kJ/mol after basis set superposition error and zero-point vibration energy correction for pyridazine-water, pyrimidine-water and pyrazine-water, respectively, and large red-shift for the symmetric H-O stretching vibration frequencies due to the formation of N…H-O hydrogen bond in the diazine-water complexes. The NBO analysis indicates that intermolecular charge transfer are 0.0316, 0.0255 and 0.0265 e respectively. In addition, the first singlet （n,n＊） vertical excitation energy of the monomer and the hydrogen bonding complexes between diazines and water was investigated by time-dependent density functional theory.展开更多
Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for ...Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for the determination of glyoxal in acetaldehyde solution.Glyoxal was derivatised from MBTH and the derivatives(diazine)were analyzed by HPLC for identification and quantification.The determination was performed on a ZORBAX Eclipse XDB-C18 column(4.6250 mm,5 mm)at 35℃ with an injection volume of 10 mL,using a mixture of acetonitrile-water solvent(99∶5,v∶v)as a mobile phase with a flow rate of 0.8 mL·min^(–1).The proper derivative reaction conditions were the temperature of 70℃,MBTH to carbonyl molar ratio of 12,and reaction time of 110 min.The glyoxal diazine was a yellow dye with a maximum molar absorptivity at 401 nm and its retention time was 5.2 min under optimal HPLC conditions.The standard curve for glyoxal had a strong linear relationship with a regression coefficient(R2=0.999)in the range of 0.002–0.020 g·L^(–1).The analysis of glyoxal in an oxidising solution gave accurate results with a relative standard deviation(RSD)value of 0.55%.The average relative recovery was 102%.This efficient HPLC technique is also proposed for detecting other dicarbonyl compounds besides glyoxal.展开更多
基金Project supported by the Scientific Foundation for Youth of Sichuan Province （No. 06ZQ026-019） and the Natural Science Foundation of Education Department of Sichuan Province （No, 2005A102）.
文摘Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water complexes. The results show that the ground state complexes have strong hydrogen bonding interaction with -20.99, -16.73 and -15.31 kJ/mol after basis set superposition error and zero-point vibration energy correction for pyridazine-water, pyrimidine-water and pyrazine-water, respectively, and large red-shift for the symmetric H-O stretching vibration frequencies due to the formation of N…H-O hydrogen bond in the diazine-water complexes. The NBO analysis indicates that intermolecular charge transfer are 0.0316, 0.0255 and 0.0265 e respectively. In addition, the first singlet （n,n＊） vertical excitation energy of the monomer and the hydrogen bonding complexes between diazines and water was investigated by time-dependent density functional theory.
基金Financial support by the China Petroleum and Chemical Corporation is gratefully acknowledged.
文摘Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for the determination of glyoxal in acetaldehyde solution.Glyoxal was derivatised from MBTH and the derivatives(diazine)were analyzed by HPLC for identification and quantification.The determination was performed on a ZORBAX Eclipse XDB-C18 column(4.6250 mm,5 mm)at 35℃ with an injection volume of 10 mL,using a mixture of acetonitrile-water solvent(99∶5,v∶v)as a mobile phase with a flow rate of 0.8 mL·min^(–1).The proper derivative reaction conditions were the temperature of 70℃,MBTH to carbonyl molar ratio of 12,and reaction time of 110 min.The glyoxal diazine was a yellow dye with a maximum molar absorptivity at 401 nm and its retention time was 5.2 min under optimal HPLC conditions.The standard curve for glyoxal had a strong linear relationship with a regression coefficient(R2=0.999)in the range of 0.002–0.020 g·L^(–1).The analysis of glyoxal in an oxidising solution gave accurate results with a relative standard deviation(RSD)value of 0.55%.The average relative recovery was 102%.This efficient HPLC technique is also proposed for detecting other dicarbonyl compounds besides glyoxal.
