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Synlett 2008(3): 371-376  
DOI: 10.1055/s-2008-1032040
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis and Electronic Properties of a Conjugated TTFAQ Trimer and Donor-Acceptor Ensembles of TTFAQ and Anthraquinone

Min Shao, Guang Chen, Yuming Zhao*
Department of Chemistry, Memorial University of Newfoundland, St. John’s, NF, A1B 3X7, Canada
e-Mail: yuming@mun.ca;
Further Information

Publication History

Received 8 November 2007
Publication Date:
16 January 2008 (online)

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Abstract

We report the first synthesis of a conjugated TTFAQ trimer as well as two TTFAQ-anthraquinone based donor-acceptor ensembles using Sonogashira and Horner-Wadsworth-Emmons reactions. Electronic absorption and electrochemical redox properties of these compounds are described.

Key words

extended-tetrathiafulvalene - donor-acceptor - cross-coupling - olefination, heterocycles

10

Synthesis of 13: To a 100 mL round-bottom flask were added 11b (0.50 g, 0.82 mmol), 8 (0.70 g, 2.1 mmol), anhyd THF (20 mL) and Et3N (10 mL). The mixture was subjected to rigorous degassing through three freeze-pump-thaw cycles. Under N2 protection, PdCl2(PPh3)2 (0.040g, 0.057 mmol) and CuI (0.020g, 0.11 mol) were added. The solution was stirred at r.t. overnight. The solvent was removed in vacuo, and the residue was dissolved in CH2Cl2, then washed with HCl (1 M) and brine. The organic layer was dried with MgSO4 and concentrated in vacuo, affording crude product of 13. The crude compound was purified by flash column chromatography over silica gel (CH2Cl2-hexanes, 2:1) to give pure 13 (0.42 g, 0.41 mmol, 50%) as a dark brown solid; mp >300 °C (dec.). 1H NMR (500 MHz, CDCl3): δ = 8.48 (s, 2 H), 8.36 (m, 6 H), 7.96 (d, J = 8.0 Hz, 2 H), 7.84 (m, 4 H), 7.75 (s, 2 H), 7.62 (d, J = 8.5 Hz, 2 H), 7.55 (d, J = 8.0 Hz, 2 H), 2.442 (s, 6 H), 2.435 (s, 6 H). 13C NMR (125 MHz, CDCl3): δ = 182.8, 182.6, 136.8, 135.4, 134.9, 134.5, 134.4, 134.3, 133.8, 133.7, 133.6, 132.6, 130.5, 130.2, 129.7, 128.6, 127.6, 127.54, 127.50, 126.9, 126.1, 125.8, 122.1, 120.4, 94.5, 89.1, 19.5, 19.3. MALDI-TOF MS: m/z [M + H]+ calcd for C56H33O4S8: 1025.01; found: 1025.37. IR (neat): 3065, 2919, 2850, 2205, 1723, 1674, 1591 cm-1.

11

Synthesis of 14: To a 50 mL round-bottom flask were added anhyd THF (10 mL), 10 (0.076 g, 0.25 mmol), and n-BuLi (1.38 M in hexane, 0.18 mL, 0.25 mmol) at -78 °C, and the solution was stirred for 30 min. Compound 13 (0.050 g, 0.049 mmol) was then added slowly at -78 °C. The solution was allowed to warm up to r.t. and then stirred overnight. The solvent was removed in vacuo, and the residue was dissolved in CH2Cl2, then washed with HCl (1 M) and sat. brine. The organic layer was dried with MgSO4 and concentrated in vacuo, affording crude product of 14. The crude compound was purified by flash column chromatography over silica gel (CHCl3) to give pure 14 (0.076 g, 0.044 mmol, 90%) as an orange solid; mp >300 °C (dec). 1H NMR (500 MHz, CDCl3): δ = 7.73 (s, 4 H), 7.57 (m, 8 H), 7.51 (m, 4 H), 7.33 (m, 4 H), 2.44 (m, 36 H). Meaningful 13C NMR spectrum could not be obtained due to low solubility. MALDI-TOF MS: m/z [M + H]+ calcd for C76H57S24: 1736.77; found: 1736.56. IR (neat): 3052, 2917, 2849, 1670, 1528, 1493 cm-1.

12

Synthesis of 15: To a 100 mL round-bottom flask were added 12b (0.078 g, 0.13 mmol), 5 (0.015 g, 0.033 mmol), THF (15 mL), and Et3N (15 mL). The mixture was subjected to rigorous degassing through three freeze-pump-thaw cycles. Under N2 protection, Pd(PPh3)4 (0.040 g, 0.035 mmol) and CuI (0.020 g, 0.11 mol) were added. The solution was stirred at r.t. overnight. The solvent was removed in vacuo, and the residue was dissolved in CH2Cl2, then washed with HCl (1 M) and sat. brine. The organic layer was dried with MgSO4 and concentrated in vacuo, affording crude product of 15. The crude compound was purified by flash column chromatography over silica gel (CH2Cl2-hexanes, 1:1) to give pure 15 (0.035 g, 0.025 mmol, 76%) as a dark brown solid; mp >250 °C (dec). 1H NMR (500 MHz, CDCl3): δ = 8.48 (s, 2 H), 8.34 (d, J = 8.0 Hz, 2 H), 7.96 (d, J = 8.0 Hz, 2 H), 7.74 (s, 2 H), 7.59 (m, 6 H), 7.52 (d, J = 8.0 Hz, 2 H), 7.34 (m, 4 H), 2.43 (s, 6 H), 2.42 (s, 6 H), 2.412 (s, 6 H), 2.406 (s, 6 H). Meaningful 13C NMR spectrum could not be obtained due to low solubility. MALDI-TOF MS: m/z [M + H]+ calcd for C66H45O2S16: 1380.90; found: 1382.63. IR (neat): 3059, 2918, 2850, 2206, 1724, 1674, 1591 cm-1.

16

The exact origins of the irreversible peaks are not clear and await further investigations. At this juncture, they are tentatively attributed to complex electrode reactions subsequent to the oxidation of 14.