摘要
用量子化学ONIOM(B3LYP/6-31++g*:UFF)方法,考察扶椅型单壁碳纳米管SWCNT(5,5),(6,6),(7,7)、锯齿型SWCNT(9,0),(10,0),(11,0)和螺旋型SWCNT(8,2),(8,3),(8,4),(9,1),(9,2),(9,3)中的α-Ala分子结构和手性转变机制.结果表明:与单体相比,当α-Ala分子限域在直径小的SWCNT中时,其C—C—C键角、C—C—N—C二面角和H—N—H键角增加较大,其他结构参数值略有增减;只存在H先在羧基内转移,手性碳上的H再以羰基11O为桥梁转移的反应通道;当α-Ala分子限域在SWCNT(5,5),(9,0),(8,2),(9,1)中时,羧基内H转移和H从手性碳转移到羰基的能垒较低;α-Ala分子限域在SWCNT中的H转移反应能垒随管径的减小而降低;不同手性的SWCNT对H转移反应能垒影响较小.
The molecular structure and chiral shift mechanism ofα-alanine inside single-walled armchair SWCNT（5,5）,（6,6）,（7,7）,zigzag SWCNT（9,0）,（10,0）,（11,0）,spiral SWCNT（8,2）,（8,3）,（8,4）,（9,1）,（9,2）and（9,3）were studied by the combined method of quantum chemistry ONIOM（B3LYP/6-31＋＋g＊：UFF）.The analysis of molecular structure shows that compared with that of the monomerα-alanine,the molecular structure ofα-alanine which is limited to the carbon nanotube of small diameter is significantly stretched along the axial direction of the nanotube.The bond angle of skeleton C—C—C and H—N—H significantly increased.The dihedral angles of skeleton C—C—N—C significantly increased.The researches on the reaction channel and paths ofchiral shift show that there is a channel with the help of which hydrogen first transfers inside hydroxyl and then hydrogen in chiral carbon transfers,making hydroxyl 11 Oas a bridge.The calculation of potential energy surface in chiral shift reaction shows that whenα-alanine is limited to the small diameter of the SWCNT（5,5）,（9,0）,（8,2）,（9,1）,the energy barriers of hydrogen transfer inside the carboxyl and hydrogen transfer from the chiral carbon to the carbonyl group are significantly reduced.The results show that whenα-alanines are limited to carbon nanotubes,the energy barriers of hydrogen transfer of chiral transition decreases with the decreasing diameter of carbon nanotubes.The difference in nanotube chirality makes little effect on energy barrier in the process of hydrogen transfer.
出处
《吉林大学学报（理学版）》
CAS
CSCD
北大核心
2015年第4期791-801,共11页
Journal of Jilin University:Science Edition
基金
吉林省科技发展计划项目(批准号:20130101131JC)
国家自然科学基金(批准号:11004076)
关键词
单壁碳纳米管
Α-丙氨酸
手性转变
密度泛函理论
过渡态
ONIOM方法
single-walled carbon nanotubes（SWCNT）
α-alanine
chiral transition
density functional theory
transition state
ONIOM method
