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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Cis/Trans Isomeric Valence Tautomeric Compounds with Guest-Driven Conformational Adaptation in Pillar[5]arene
Ling-Tai Yue1, Jie-Sheng Hu1, Yu-Meng Zhao1
1Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China.
Abstract:
The pursuit of ancillary ligands is crucial for constructing new valence tautomeric (VT) complexes based on the dioxolene-cobalt(II/III) moiety. In this study, we adopted pillar[5]arene derivatives with guest-adaptable conformations─specifically, phenylpyridine-containing pillar[5]arene (pyphp[5]) and alkynylpyridine-containing pillar[5]arene (pyetp[5])─as ancillary and bridging ligands to synthesize a series of cobalt-based VT complexes: [CoIII(Sq•-)(Cat2-)(pyphp[5])]·2CH2Cl2·2CH3OH (1a·), [CoIII(Sq•-)(Cat2-)(pyphp[5])]·4Cl2CH2CH2Cl2·2CH3OH (1b·), [CoIII(Sq•-)(Cat2-)(pyetp[5])]·2CH2Cl2·3CH3OH (2a·), and [CoIII(Sq•-)(Cat2-)(pyetp[5])]·3Cl2CH2CH2Cl2·2CH3OH (2b·) (Sq•- = 3,5-di-tert-butylsemiquinonate, Cat2- = 3,5-di-tert-butyl-catecholate). Single-crystal X-ray diffraction analyses revealed that all complexes possess one-dimensional structures. Complexes 1a· and 1b· exhibit the common trans configuration (trans(N)-trans(Bu)) of the cobalt-dioxolene-pyridine species, whereas 2a· and 2b· adopt a rare C2h-symmetric cis one (trans(N)-cis(Bu)). Variations in guest molecule size and host-guest interactions within the pillar[5]arene cavity led to distinct pore conformations and stacking patterns. This work represents the first example of both the trans and C2h-symmetric cis isomers of the cobalt-dioxolene-pyridine moiety being obtained through synthesis. Our findings highlight the potential to synthesize VT isomers and the critical role of host-guest interactions in modulating VT behavior, offering valuable insights into the design of multifunctional materials with controllable magnetic properties.
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