The novel low-dimensional nanostructural self-alignment of molecular nanowire composed of a C60 anion radical moiety (fulleride) formed by electrocrystallization was revealed by single crystal structure analysis of C60 fulleride salts stabilized by triphenylmethane dye cations. The structure should be noted as molecular nanowire and anticipated to be an organic novel semiconductor from the preliminary four-probe conductance measurement. C60 fulleride has drawn much attention because of its interesting physical properties, such as superconducting of alkali-metal doped C60(A3C60) and unique ferromagnetic behavior of tetrakis(dimethylamino)ethane salts of C60 fulleride, (TDAE)C60.. These intriguing solid-state properties of C60 fulleride should arise from electronic cooperative interactions, mainly due to electron-accepting ability of C60 and the ball-to-ball van der Waals interaction. However, there have been rather a limited number of well-characterized C60 anion radical salts, in particular, molecular discrete fulleride, predominantly because of their sensitivity to air.
We have succeeded in obtaining highly ordered single crystals of C60 anion radical salts stabilized by cationic triphenylmethane dyes, some of which were found to give rise to an intriguing nanostructural columnar alignment like molecular nanowire of C60 fullerides. The single-crystal structure of [Crystal Violet]+C60−. C6H5Cl, reveals that the C60 fulleride aligns like molecular nanowire with the columnar structure along the a axis (crystal growth direction), as well as a zigzag structure along the b axis, with contacts of almost van der Waals magnitude (ca. 10 Å, distance of the C60–C60 center of mass), stabilized by mutual interactions of C60−. and dye, due to such as CH-π, π-π, and face-to-face mutual interactions.
Magnetic susceptibility measurements for crystal violet salts demonstrate antiferromagnetic behavior, which can be fitted fairly by one-dimensional Heisenberg model (uniform chain), associated with the one-dimensional columnar crystal structure of the C60 fulleride molecular nanowire. These results also account for the semiconducting properties of the corresponding salts.