Figure 1. Crystal structure of TnbU. D, D′, and D′′ denote TnbU molecules. Stereoview of crystal packing (a), complementary H-bonding
of dimer (b). The closest C4dO‚‚‚H-N3 contacts are shown by dotted lines. The overlap mode of π-stacking dimer (c).
electron systems.6 The recent theoretical studies for the model
polymers containing DNA base pairs and a successful
synthesis of the TTF derivative with a uracil moiety, TU,
have encouraged us to explore the CT complexes of TU-
based molecules with electron acceptors.7 In this Letter, we
deal with the synthesis of n-butyl-substituted TU, TnbU, and
its CT complexes with 2,5-dicyano-3,6-dihydroxy-1,4-ben-
zoquinone (cyananilic acid, H2CNAL)6e-h and TCNQ. The
H-bonding architecture constructed by uracil moieties and
HCNAL- as well as the electronic properties of the CT
complexes are demonstrated in terms of X-ray crystal
structure analysis, IR, and electronic spectra.
(3) (a) Blanchard, P.; Boubekeur, K.; Salle´, M.; Duguay, G.; Jubault,
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D.; Batail, P. AdV. Mater. 1992, 4, 579-581. (b) Dolbecq, A.; Fourmigue´,
M.; Batail, P. Chem. Mater. 1994, 6, 1413-1418. (c) Dolbecq, A.;
Fourmigue´, M.; Batail, P. Bull. Soc. Chim. Fr. 1996, 133, 83-88. (d) Kepert,
C. J.; Hesek, D.; Beer, P. D.; Rosseinsky, M. J. Angew. Chem., Int. Ed.
1998, 37, 3158-3160. (e) Batsanov, A. S.; Bryce, M. R.; Cooke, G.;
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Metzger, R. M. J. Am. Chem. Soc. 1988, 110, 7903-7904. (j) Zong, K.
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A. J. Chem. Soc., Chem. Commun. 1995, 325-326. (c) Neilands, O.; Tilika,
V.; Sudmale, I.; Grigorjeva, I.; Edzina, A.; Fonavs, E.; Muzikante, I. AdV.
Mater. Opt. Electron. 1997, 7, 93-97. (d) Neilands, O.; Liepinsh, V.;
Turovska, B. Org. Lett. 1999, 1, 2065-2067.
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H.; Okaniwa, K.; Mitani, T.; Yamamoto, H.; Murata, I.; Kawamoto, A.;
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T.; Itoh, T.; Nakasuji, K. Synth. Met. 1997, 86, 2105-2106. (d) Tamaki,
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TnbU was prepared by the Stille cross-coupling reaction
of the tributylstannyl-substituted TTF derivative7c with 1-n-
butyl-5-iodouracil8 in the presence of Pd(PPh3)4 in toluene.9
The cyclic voltammogram of TnbU in DMF shows two-
stage, one-electron reversible oxidation waves.10 Interest-
ingly, the slightly negative shift of two oxidation potentials
of TnbU compared with those of TTF was observed
(TnbU: E1, -0.102; E2, +0.095. TTF: E1, -0.080; E2,
+0.116), indicating that TnbU has a good electron donating
ability as well as a high stability of the oxidation states. A
single crystal of TnbU suitable for X-ray structure analysis
was obtained by the vapor diffusion method using hexane-
THF.11 TnbU crystallizes in the monoclinic space group P21/c
and forms the π-stacking dimers which are connected by
the complementary double hydrogen bonds between uracil
moieties to make a one-dimensional arrangement along the
c-axis (Figure 1). The closest O‚‚‚N contacts within an
(7) (a) Shigeta, Y.; Nagao, H.; Toyoda, J.; Morita, Y.; Nakasuji, K.;
Yoshioka, Y.; Yamaguchi, K. Int. J. Quantum Chem. 2000, 80, 882-891.
(b) Shigeta, Y.; Nagao, H.; Yoshioka, Y.; Toyoda, J.; Morita, Y.; Nakasuji,
K.; Yamaguchi, K. Synth. Met. 2001, 119, 259-260. (c) Maki, S.; Morita,
Y.; Kitagawa, S.; Mitani, T.; Nakasuji, K. Synth. Met. 2001, 120, 741-
742.
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