物理化学学报2018，Vol.34Issue(10)：1171-1178,8.DOI:10.3866/PKU.WHXB201803024
含偶氮苯主-客体复合物的光致异构化反应对结合能与几何构象的影响
Influence of Photoisomerization on Binding Energy and Conformation of Azobenzene-Containing Host-Guest Complex
摘要
Abstract
The construction of a photo-controllable artificial molecular machine capable of realizing the light-driven motion on a molecular scale and of performing a specific function is a fascinating topic in supramolecular chemistry.The bistable switchable molecule,azobenzene (AZO),has been introduced into the supramolecular architecture as a key building block,owing to its efficient and reversible trans (E)-cis (Z) photoisomerization.The binding strength of the dibenzo[24]crown-8 (DB24C8) host and dialkylammonium-based rod-like guest consisting of an AZO moiety and the Z→E photoisomerization process in an interlocked host-guest complex have been investigated by the density functional theory (DFT) calculations and the reactive molecular dynamics (RMD) simulations by considering both torsion and inversion paths.The strong host-guest binding strength provides a necessary premise to stabilize the complex during the E-Z photoisomerization of the AZO unit,which is a terminal stopper to control the directional motion of the guest.A stronger binding strength for the Z isomer can be induced by the stronger hydrogen-bonding interaction.The steric effect is introduced into the Z isomer to force the ring slipping exclusively over the cyclopentyl terminal (pseudostopper).The host-guest complexation has a slight effect on the conformation of the AZO functional subunit for the two isomers.The faster Z→E photoisomerization process within the picosecond timescale is kinetically more favored than the dethreading of the ring through the pseudostopper subunit of the rod.After isomerization,a structure relaxation is observed for the crown ether ring within 500 ps.The flexible backbone of the crown ether ring is helpful in realizing steady and stable host-guest recognition during photoisomerization.Moreover,the orthogonality of the site-specific binding interaction is revealed by the similar binding energies obtained at similar hydrogen bonding recognition sites for various interlocked host-guest supramolecular systems although the constituents of the guests are different from each other.The introduction of two stereoisomers of the AZO subunit has little influence on the other conformations of guest subunits.These results are useful for the rational design of more sophisticated stimuli-controlled artificial molecular machines.关键词
光致异构化/反应性分子动力学/偶氮苯/分子马达/准轮烷/超分子化学Key words
Photoisomerization/Reactive molecular dynamics model/Azobenzene/Nanomotors/Pseudorotaxane/Supramolecular chemistry分类
化学化工引用本文复制引用
柳平英,刘春艳,刘倩,马晶..含偶氮苯主-客体复合物的光致异构化反应对结合能与几何构象的影响[J].物理化学学报,2018,34(10):1171-1178,8.基金项目
The project was supported by the National Natural Science Foundation of China (21673111,21661017) and Natural Science Foundation of Jiangxi Province,China (20161BAB203081).国家自然科学基金(21673111,21661017)和江西省自然科学基金(20161BAB203081)资助项目 （21673111,21661017）
