title: A thiourea-functionalized metal-organic macrocycle for the catalysis of Michael additions and prominent size-selective effect.
abstract: A discrete tetranuclear thiourea-based metal-organic macrocycle (MOM) with a large size was constructed by a well-designed organic ligand and nickel(ii) ions via self-assembly. Incorporating thiourea groups as hydrogen-bond donors into a metal-organic complex system leads to a new approach for synthesizing functionalized heterogeneous catalysts, as this not only introduces coordination sites serving as chelators, but also overcomes the issues of self-association via intermolecular H-bonding, often occurring in homogeneous systems. The packing structure of this material formed a confined environment suitable for the access of substrate molecules dragged by the strong hydrogen-bond interactions from the thiourea groups, thus achieving a high catalytic performance in Michael additions of nitrostyrenes to nitroalkanes, with remarkable yields and size-selectivity in heterogeneous phase. Moreover, a comparison of the IR spectrum of Ni-SPT with the spectra of dimethyl malonate- and β-nitrostyrene-impregnated Ni-SPT indicated that both substrate molecules, β-nitrostyrene and dimethyl malonate, were able to access the cavity of the trimeric subunit.
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Lu
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Cheng
authors.identifier: http://orcid.org/0000-0002-1426-0124
authors.initials: C
authors.lastname: He
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian, 116012, China. hecheng@dlut.edu.cn.
authors.forename: Chunying
authors.initials: C
authors.lastname: Duan