title: Mechanically stabilized tetrathiafulvalene radical dimers.
abstract: Two donor-acceptor [3]catenanes-composed of a tetracationic molecular square, cyclobis(paraquat-4,4'-biphenylene), as the π-electron deficient ring and either two tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) containing macrocycles or two TTF-butadiyne-containing macrocycles as the π-electron rich components-have been investigated in order to study their ability to form TTF radical dimers. It has been proven that the mechanically interlocked nature of the [3]catenanes facilitates the formation of the TTF radical dimers under redox control, allowing an investigation to be performed on these intermolecular interactions in a so-called "molecular flask" under ambient conditions in considerable detail. In addition, it has also been shown that the stability of the TTF radical-cation dimers can be tuned by varying the secondary binding motifs in the [3]catenanes. By replacing the DNP station with a butadiyne group, the distribution of the TTF radical-cation dimer can be changed from 60% to 100%. These findings have been established by several techniques including cyclic voltammetry, spectroelectrochemistry and UV-vis-NIR and EPR spectroscopies, as well as with X-ray diffraction analysis which has provided a range of solid-state crystal structures. The experimental data are also supported by high-level DFT calculations. The results contribute significantly to our fundamental understanding of the interactions within the TTF radical dimers.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Coskun
authors.forename: Jason M
authors.initials: JM
authors.lastname: Spruell
authors.forename: Gokhan
authors.initials: G
authors.lastname: Barin
authors.forename: Albert C
authors.initials: AC
authors.lastname: Fahrenbach
authors.forename: Ross S
authors.initials: RS
authors.lastname: Forgan
authors.forename: Michael T
authors.initials: MT
authors.lastname: Colvin
authors.forename: Raanan
authors.initials: R
authors.lastname: Carmieli
authors.forename: Diego
authors.initials: D
authors.lastname: Benítez
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Tkatchouk
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Friedman
authors.forename: Amy A
authors.initials: AA
authors.lastname: Sarjeant
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart
mesh_terms: D043863:Catenanes / Q000737:chemistry; D019281:Dimerization; D005609:Free Radicals / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction
chemical_list: D043863:Catenanes; D005609:Free Radicals; D006571:Heterocyclic Compounds; C063887:tetrathiafulvalene