title: Bulky metallocavitands with a chiral cavity constructed by aluminum and magnesium atrane-likes: enantioselective recognition and separation of racemic alcohols.
abstract: Seven new type metallocavitand complexes 1–7 were synthesized via the self-assembly of aluminum and magnesium atrane-likes. The recognition of R-2-butanol from racemic 2-butanol can be achieved in the chiral cavity of metallocavitand complex 5. The crystal structure of complex 5 showed that the enantioselectivity of the center cavity for the inclusion of two 2-butanol molecules is higher than that of the groups at the outer rim, which indicates that the size-limited cavity is more sensitive to the chirality of 2-butanol. Furthermore, desorption of R-2-butanol is successful through vacuumization which afforded complex 6 and gives R-2-butanol with an enantiomeric excess (ee) value of 53(±1)%. The reaction of enantiopure H3L2, MgnBu2, and racemic 1-phenylethanol afforded complex 7. The structure of complex 7 showed that the center cavity was occupied by three H2O molecules and one molecular R-1-phenylethanol suspended in the outer rim of the metallocavitand via a hydrogen bond, which indicated that 1-phenylethanol is too bulky for the size-limited cavity. Because a certain amount of racemic 1-phenylethanol is also co-crystallized in the unit cell, the final separated 1-phenylethanol has an ee value of 33(±1)%. The host–guest mechanism for the separation is clearly determined through X-ray crystal structural analysis.
authors.affiliation: Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China. wujc@lzu.edu.cn.
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Li
authors.forename: Dawei
authors.initials: D
authors.lastname: Yu
authors.forename: Zhongran
authors.initials: Z
authors.lastname: Dai
authors.forename: Jinjin
authors.initials: J
authors.lastname: Zhang
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Shao
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Jincai
authors.initials: J
authors.lastname: Wu