Allosterically Regulated Guest Binding Determines Framework Symmetry for an FeII4L4 Cage |
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| Authors: | Dr Weichao Xue Dr Kai Wu Nianfeng Ouyang Dr Thierry Brotin Prof?Dr Jonathan R Nitschke |
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| Institution: | 1. Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW UK;2. Laboratoire de chimie, Université Lyon, Ens de Lyon, CNRS UMR 5182, 69342 Lyon, France |
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| Abstract: | Self-assembly of a flexible tritopic aniline and 3-substituted 2-formylpyridine subcomponents around iron(II) templates gave rise to a low-spin FeII4L4 capsule, whereas a high-spin FeII3L2 sandwich species formed when a sterically hindered 6-methyl-2-formylpyridine was used. The FeII4L4 cage adopted a new structure type with S4 symmetry, having two mer-Δ and two mer-? metal vertices, as confirmed by NMR and X-ray crystallographic analysis. The flexibility of the face-capping ligand endows the resulting FeII4L4 framework with conformational plasticity, enabling it to adapt structurally from S4 to T or C3 symmetry upon guest binding. The cage also displayed negative allosteric cooperativity in simultaneously binding different guests within its cavity and at the apertures between its faces. |
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| Keywords: | Allosteric Regulation Host–Guest Chemistry Metal-Organic Cages Structural Adaptation Symmetry |
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