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Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks
journal contribution
posted on 2012-11-07, 00:00 authored by Tsuyoshi Murata, Eigo Miyazaki, Kazuhiro Nakasuji, Yasushi MoritaSynthesis, crystal structures and redox properties of
1,6-dithiapyrene
(DTPY)-type electron-donors functionalized with nucleobases (uracil,
cytosine and adenine) were investigated. The electrochemical measurements
showed that the uracil-substituted derivatives were slightly stronger
electron-donors than DTPY, and the cytosine- and adenine-substitution
caused a slight weakening of the electron-donating ability. In the
crystal structures, DTPY-nucleobases constructed multidimensional
assemblies by complementary hydrogen-bonds on the nucleobase moieties
and π-stacks and S···S interactions on the DTPY
skeleton. The uracil derivative formed two kinds of hydrogen-bonded
pairs with different H-bonding modes (Watson–Crick and reverse
Watson–Crick types), both of which were further linked through
π-stacks on the DTPY skeleton to construct one-dimensional alternating
columns. In the CH2Cl2 solvated crystal, the
uracil derivative built up a two-dimensional π-layer by the
complementary hydrogen-bonds and π-stacks. In the cytosine derivative,
the complementary hydrogen-bonded pair assembled by the π-stacks
and S···S interactions of the DTPY skeleton constructed
a two-dimensional network. The adenine derivative formed a channel
structure by the one-dimensional π-stack of complementary hydrogen-bonded
pairs, where crystalline water molecules with a ladder-like hydrogen-bonded
chain were included. Charge-transfer complexes of DTPY-nucleobases
with tetracyanoquinodimethane possessed a neutral ground state and
exhibited semiconductive behaviors with room temperature conductivities
of 10–6 to 10–7 S cm–1.