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Guest shape-responsive fitting of porous coordination polymer with shrinkable framework
Ryotaro Matsuda1, Ryo Kitaura, Susumu Kitagawa
1Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
Journal of the American Chemical Society
|October 28, 2004
Summary
Porous coordination polymers exhibit a "shape-responsive fitting" transformation upon benzene adsorption, contracting to create optimal pore structures. This discovery offers new design principles for flexible framework materials.
Area of Science:
- Materials Science
- Crystallography
- Supramolecular Chemistry
Background:
- Porous coordination polymers (PCPs) are crystalline materials with tunable structures and pore sizes.
- Understanding guest molecule interactions within PCPs is crucial for designing selective adsorption materials.
- The flexibility and structural response of PCPs to guest molecules remain an active area of research.
Purpose of the Study:
- To investigate the structural changes in porous coordination polymers upon guest molecule adsorption.
- To characterize the mechanism of crystal transformation induced by benzene adsorption in [[Cu(2)(pzdc)(2)(bpy)].G].
- To establish design principles for creating shape-responsive porous materials.
Main Methods:
- In situ synchrotron X-ray powder diffraction was employed to monitor structural changes.
- Rietveld analysis was used to determine the crystal structures of the apohost and benzene-loaded phases.
- Adsorption experiments were conducted to study the interaction of benzene with the PCP framework.
Main Results:
- Adsorption of benzene in [[Cu(2)(pzdc)(2)(bpy)].G] induced a significant contraction of the crystal structure (b-axis: 6.8%, volume: 4.9%).
- Despite channel occupation by benzene, the framework underwent a transformation to a new pore structure.
- This phenomenon was termed 'shape-responsive fitting', where the pore adapts to the guest molecule.
Conclusions:
- Porous coordination polymers can undergo significant structural transformations in response to guest molecules.
- The 'shape-responsive fitting' mechanism highlights the dynamic nature of these materials.
- Frameworks composed of flexible and stiff motifs linked appropriately can lead to adaptive pore structures.
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