title: Dynamic Characterization of Crystalline Supramolecular Rotors Assembled through Halogen Bonding.
abstract: A modular molecular kit for the preparation of crystalline molecular rotors was devised from a set of stators and rotators to gain simple access to a large number of structures with different dynamic performance and physical properties. In this work, we have accomplished this with crystalline molecular rotors self-assembled by halogen bonding of diazabicyclo[2.2.2]octane, acting as a rotator, and a set of five fluorine-substituted iodobenzenes that take the role of the stator. Using variable-temperature (1)H T1 spin-lattice relaxation measurements, we have shown that all structures display ultrafast Brownian rotation with activation energies of 2.4-4.9 kcal/mol and pre-exponential factors of the order of (1-9) × 10(12) s(-1). Line shape analysis of quadrupolar echo (2)H NMR measurements in selected examples indicated rotational trajectories consistent with the 3-fold or 6-fold symmetric potential of the rotator.
authors.affiliation: Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano , via L. Mancinelli 7, 20131 Milano, Italy.|Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095-1569, United States.
authors.forename: Luca
authors.initials: L
authors.lastname: Catalano
authors.affiliation: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095-1569, United States.
authors.forename: Salvador
authors.initials: S
authors.lastname: Pérez-Estrada
authors.affiliation: Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano , via L. Mancinelli 7, 20131 Milano, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Terraneo
authors.affiliation: Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano , via L. Mancinelli 7, 20131 Milano, Italy.
authors.forename: Tullio
authors.initials: T
authors.lastname: Pilati
authors.affiliation: Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano , via L. Mancinelli 7, 20131 Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Resnati
authors.affiliation: Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano , via L. Mancinelli 7, 20131 Milano, Italy.|VTT-Technical Research Centre of Finland , P.O. Box 1000, Espoo FI-02044, Finland.
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Metrangolo
authors.affiliation: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095-1569, United States.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Garcia-Garibay