水环境下扶椅型单臂碳纳米管内缬氨酸旋光异构及羟自由基致损伤机理

(1.白城师范学院计算机科学学院,吉林 白城 137000; 2.白城师范学院土木工程学院,吉林 白城 137000; 3.白城师范学院物理学院,吉林 白城 137000)

缬氨酸; 旋光异构; 损伤; 碳纳米管; ONIOM方法

Mechanism of optical isomerization and damage of valine moleculesinduced by hydroxyl radicals in armchair single-walled carbon nanotubes in water environment
ZHAO Yu1,WANG Yan2,WANG Zuocheng3*,TONG Hua3,SHENG Shaoxu3,BAI Jie3,ZHANG Xinnan3

(1.College of Computer Science,Baicheng Normal University,Baicheng 137000,China; 2.College of Civil Engineering,Baicheng Normal University,Baicheng 137000,China; 3.College of Physics,Baicheng Normal University,Baicheng 137000,China)

valine; optical isomerism; damage; carbon nanotubes; ONIOM method

DOI: 10.6043/j.issn.0438-0479.201806027

备注

用量子力学与分子力学组合的ONIOM方法,结合自洽反应场的SMD(slovation model density)模型方法,对水环境下单臂碳纳米管(SWCNT)内缬氨酸的旋光异构及羟自由基致损伤机理进行了研究.势能面计算表明:以2个水分子簇作传递质子媒介,氨基氮作质子迁移桥梁时,缬氨酸限域在SWCNT(8,8)和SWCNT(7,7)内旋光异构的决速步能垒分别是115.80和165.64 kJ/mol,水溶剂效应使这2个能垒降到104.34和150.07 kJ/mol.限域在SWCNT(8,8)内的缬氨酸,羟自由基抽氢致其损伤的能垒是13.31 kJ/mol,水分子辅助羟自由基抽氢致其损伤的能垒约15.00 kJ/mol,水溶剂效应使它们相应地上升至18.85和约20.00 kJ/mol.结果表明:SWCNT(8,8)和SWCNT(7,7)的限域对水环境下缬氨酸的旋光异构分别具有正催化和负催化作用,水溶剂具有助催化作用; SWCNT(8,8)的限域对水环境下羟自由基致缬氨酸损伤具有显著的催化作用,水溶剂则会阻碍羟自由基致缬氨酸损伤.

Using ONIOM method combined with quantum mechanics and molecular mechanics, as well as slovation model density(SMD)method based on the self consistent reaction field theory,the mechanism of optical isomerization and damage of valine induced by hydroxyl radicals in armchair single-walled carbon nanotubes(SWCNT)in water environment was studied.Calculations of potential energy surface showed that when valine was confined in SWCNT(8,8)and SWCNT(7,7)with two water molecular clusters as proton transfer medium and amino nitrogen as a proton transfer bridge,the energy barrier of the rate-determining step of optical isomerization was 115.80 kJ/mol and 165.64 kJ/mol,respectively,which decreased to 104.34 kJ/mol and 150.07 kJ/mol under water solvent effect.For valine molecules confined in SWCNT(8,8),the energy barrier of damage induced by H-atom abstraction of hydroxyl radicals was 13.31 kJ/mol,and the corresponding energy barrier of damage induced by H-atom abstraction of hydroxyl radicals assisted with water molecules was about 15.00 kJ/mol,which increased to 18.85 kJ/mol and about 20.00 kJ/mol,respectively under water solvent effect.The results showed that the confinement of SWCNT(8,8)and SWCNT(7,7)had respectively positive and negative catalytic effects on the optical isomerism of valine in water environment and the water solvent had an auxiliary catalytic effect.Moreover,the confinement of SWCNT(8,8)had a significant catalytic effect on the damage of valine induced by hydroxyl radicals in water environment,and the effect of water solvent hindered the damage of valine induced by hydroxyl radicals.