title: p-benzoquinone-benzene clusters as potential nanomechanical devices: a theoretical study.
abstract: The equilibrium structures and binding energies of the benzene complexes of p-benzoquinones (PBQ) and its negatively charged anionic species (PBQ- and PBQ2-) have been investigated theoretically using second-order Møller-Plesset calculations. While neutral p-benzoquinone-benzene clusters (PBQ-Bz) prefer to have a parallel displaced geometry (P-c), CH...pi interactions (T-shaped geometries) prevail in the di-anionic PBQ-benzene (PBQ2- -Bz) complexes (T-e2-). Studies on dianionic p-benzoquinone-benzene clusters showed that two nonbonded intermolecular interactions compete in the most stable conformation. One is H-bonding interaction (C-H...O type) between carbonyl oxygen of p-benzoquinone and one of the hydrogen atoms of benzene, and the other is a pi-H interaction between pi-electron cloud of PBQ2- and another hydrogen atom of benzene. Blueshifted H-bonds were observed in T-shaped clusters. The changes in the geometrical preference of PBQ-Bz complex upon addition of electrons would be useful in designing optimized molecular mechanical devices based on the edge-to-face and face-to-face aromatic interactions.
authors.affiliation: National Creative Research Initiative Center for Superfunctional Materials, Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Hyoja-Dong, Namgu, Pohang 790-784, South Korea.
authors.forename: T K
authors.initials: TK
authors.lastname: Manojkumar
authors.forename: H S
authors.initials: HS
authors.lastname: Choi
authors.forename: B H
authors.initials: BH
authors.lastname: Hong
authors.forename: P
authors.initials: P
authors.lastname: Tarakeshwar
authors.forename: K S
authors.initials: KS
authors.lastname: Kim