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Published September 2, 2015 | Supplemental Material
Journal Article Open

Redox Control of the Binding Modes of an Organic Receptor


The modulation of noncovalent bonding interactions by redox processes is a central theme in the fundamental understanding of biological systems as well as being ripe for exploitation in supramolecular science. In the context of host–guest systems, we demonstrate in this article how the formation of inclusion complexes can be controlled by manipulating the redox potential of a cyclophane. The four-electron reduction of cyclobis(paraquat-p-phenylene) to its neutral form results in altering its binding properties while heralding a significant change in its stereoelectronic behavior. Quantum mechanics calculations provide the energetics for the formation of the inclusion complexes between the cyclophane in its various redox states with a variety of guest molecules, ranging from electron-poor to electron-rich. The electron-donating properties displayed by the cyclophane were investigated by probing the interaction of this host with electron-poor guests, and the formation of inclusion complexes was confirmed by single-crystal X-ray diffraction analysis. The dramatic change in the binding mode depending on the redox state of the cyclophane leads to (i) aromatic donor–acceptor interactions in its fully oxidized form and (ii) van der Waals interactions when the cyclophane is fully reduced. These findings lay the foundation for the potential use of this class of cyclophane in various arenas, all the way from molecular electronics to catalysis, by virtue of its electronic properties. The extension of the concept presented herein into the realm of mechanically interlocked molecules will lead to the investigation of novel structures with redox control being expressed over the relative geometries of their components.

Additional Information

© 2015 American Chemical Society. Received: May 31, 2015; Published: August 3, 2015. We thank Dr. Amy Sarjeant and Charlotte C. Stern for solving the single-crystal X-ray structures. This research is part (Project 32-949) of the Joint Center of Excellence in Integrated Nano-Systems (JCIN) at King Abdulaziz City for Science and Technology (KACST) and Northwestern University (NU). The authors thank both KACST and NU for their continued support of this research. M.R.W. and S.M.D. acknowledge support from the National Science Foundation (NSF) under Grant No. CHE-1266201. W.G.L. and W.A.G. were supported by NSF-EFRI-ODISSEI 1332411. Y.W. thanks the Fulbright Scholar Program for a Research Fellowship and also acknowledges additional support from a Ryan Fellowship awarded under the auspices of the NU International Institute of Nanotechnology (IIN). The authors declare no competing financial interest.

Attached Files

Supplemental Material - ja5b05618_si_001.pdf

Supplemental Material - ja5b05618_si_002.cif

Supplemental Material - ja5b05618_si_003.cif

Supplemental Material - ja5b05618_si_004.cif

Supplemental Material - ja5b05618_si_005.cif


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August 20, 2023
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