title: Redox Control of the Binding Modes of an Organic Receptor.
abstract: 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.
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Marco
authors.initials: M
authors.lastname: Frasconi
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Isurika R
authors.initials: IR
authors.lastname: Fernando
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Zhichang
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Materials and Process Simulation Center, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Wei-Guang
authors.initials: WG
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Dyar
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Gokhan
authors.initials: G
authors.lastname: Barin
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski
authors.affiliation: Materials and Process Simulation Center, California Institute of Technology , Pasadena, California 91125, United States.|NanoCentury KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea.
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.affiliation: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D004988:Ethers, Cyclic / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010269:Paraquat / Q000031:analogs & derivatives / Q000737:chemistry*; D010880:Piperidines / Q000737:chemistry*; D011789:Quantum Theory; D000097566:Cyclophanes
chemical_list: D004988:Ethers, Cyclic; D010269:Paraquat; D010880:Piperidines; C121239:cyclophane 1; D000097566:Cyclophanes