title: Hydrogen-bonded networks in organic conductors: crystal structures and electronic properties of charge-transfer salts of tetracyanoquinodimethane with 4,4'-biimidazolium having multiprotonated States.
abstract: [structure: see text] Novel hydrogen-bonded charge-transfer salts of TCNQ with mono- and diprotonated 4,4'-biimidazolium were synthesized in order to demonstrate the high potential of the 4,4'-biimidazole system in a molecular conductor from the viewpoint of crystal engineering and electronic modulation. Crystal structure analyses of neutral 4,4'-biimidazole and TCNQ salts revealed the formation of two types of hydrogen-bonding modes of the 4,4'-biimidazole moiety depending on the protonated states. Neutral 4,4'-biimidazole possessed a linear chain mode of hydrogen-bonding to construct two-dimensional network. In the TCNQ salt of monoprotonated 4,4'-biimidazolium, the 4,4'-biimidazole moiety formed a dimer by a complementary mode of hydrogen-bonding. In contrast, the salt of diprotonated 4,4'-biimidazolium showed a double linear chain mode of hydrogen-bonding to construct a three-dimensional network. The formation of two types of hydrogen-bonding modes made the difference in the stacking patterns of TCNQ columns and in their transport properties. The TCNQ salt of diprotonated 4,4'-biimidazolium exhibited high electrical conductivity (sigma(rt) = 1.1 x 10(-1) S cm(-1)).
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. morita@chem.sci.osaka-u.ac.jp
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Morita
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Murata
authors.forename: Kozo
authors.initials: K
authors.lastname: Fukui
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamada
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Sato
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shiomi
authors.forename: Takeji
authors.initials: T
authors.lastname: Takui
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamochi
authors.forename: Gunzi
authors.initials: G
authors.lastname: Saito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakasuji