Synthesis and Spectroscopic Studies of Various Arylene Ethynylene Fluorophores

Abstract

A series of arylene cores substituted by phenylene ethynylenes were synthesized by Sonogashira coupling of diethynyl ­aromatic compounds with an iododiphenylethyne which had been prepared conveniently by making use of a one-shot double-elimination reaction. Photoluminescence properties of the arylene ethynylenes thus prepared were recorded both in solution and in the solid state.

alkynes - sulfones - sldehydes - eliminations - spectro­scopy

References and Notes

1a Acetylene Chemistry: Chemistry, Biology, and Material Science   Diederich F. Stang PJ. Tykwinski RR. VCH; Weinheim: 2005. 

1b Modern Acetylene Chemistry   Stang PJ. Diederich F. VCH; Weinheim: 1995. 

For reviews of phenylene ethynylenes, see:

1c James DK. Tour JM. In Topics in Current Chemistry   Vol. 257:  Springer; Berlin: 2005.  p.33-62  

1d Stone MT. Heemstra JM. Moore JS. Acc. Chem. Res.  2006,  39:  11 

1e Ray CR. Moore JS. Adv. Polym. Sci.  2005,  177:  91 

2 Shirai Y. Osgood AJ. Zhao Y. Kelly KF. Tour JM. Nano Lett.  2005,  5:  2330 

3a Wackerly JW. Moore JS. Macromolecules  2006,  39:  7269 

3b Elliott EL. Ray CR. Kraft S. Atkins JR. Moore JS. J. Org. Chem.  2006,  71:  5282 

3c Balakrishnan K. Datar A. Zhang W. Yang X. Naddo T. Huang J. Zuo J. Yen M. Moore JS. Zang L. J. Am. Chem. Soc.  2006,  128:  6576 ; and references therein

4 Orita A. Jiang L. Tsuruta M. Otera J. Chem. Lett.  2002,  136 

5 Orita A. An D.-L. Nakano T. Yaruva J. Ma N. Otera J. Chem. Eur. J.  2002,  8:  2005 

6 Orita A. Nakano T. An D.-L. Tanikawa K. Wakamatsu K. Otera J. J. Am. Chem. Soc.  2004,  126:  10389 

7 Oyamada T. Shao G. Uchiuzou H. Nakanotani H. Orita A. Otera J. Yahiro M. Adachi C. Jpn. J. Appl. Phys.  2006,  45:  1331 

8 A part of optical property of 4-(4-methoxyphenyl-ethynyl)phenylethyne has been reported. See: Shao G. Orita A. Nishijima K. Ishimaru K. Takezaki M. Wakamatsu K. Otera J. Chem. Lett.  2006,  35:  1284 

9 Orita A. Taniguchi H. Otera J. Chem. Asian J.  2006,  1:  430 

10

Double Elimination Method for 1 and 7: 1-(3,7-Di-methyloctyloxy)-4-(4-ethynylphenylethynyl)benzene ( 1). To a THF solution (15 mL) of 4-(3,7-dimethyloctyl-oxy)phenylmethyl phenyl sulfone (3, 466 mg, 1.2 mmol), 4-(trimethylsilylethynyl)benzaldehyde (4, 202 mg, 1.0 mmol) and diethylchlorophosphate (0.17 mL, 1.2 mmol) was added a THF solution of LiHMDS (1.0 M, 5.0 mL, 5.0 mmol) at 0 °C, and the mixture was stirred at r.t. for 16 h under argon. After usual work-up, the organic layer was evaporated and the residue was subjected to a column chromatography on silica gel (10% EtOAc-hexane) to give 1-(3,7-dimethyl-octyloxy)-4-[4-(trimethylsilylethynyl)phenyl-ethynyl]benzene in a pure form (358 mg, 83%). To a solution of 1-(3,7-dimethyloctyloxy)-4-[4-(trimethylsilyl-ethynyl)phenylethynyl]benzene (2.15 g, 5.0 mmol) in THF (25 mL) and MeOH (25 mL) was added 6.91 g of K₂CO₃. The reaction mixture was stirred for 1.5 at r.t. After H₂O had been added, the aqueous layer was extracted with EtOAc. The combined organic layer was washed with brine, dried over MgSO₄ and filtered. The solvents were evaporated, and the residue was subjected to column chromatography on silica gel (20% CH₂Cl₂-hexane) to afford 1 in a pure form (1.63 g, 91%).
Compound 1: ¹H NMR (300 MHz, CDCl₃): δ = 0.87 (d, J = 6.5 Hz, 6 H), 0.94 (d, J = 6.3 Hz, 3 H), 1.14-1.32 (m, 6 H), 1.48-1.64 (m, 3 H), 1.78-1.84 (m, 1 H), 3.16 (s, 1 H), 3.98-4.03 (m, 2 H), 6.87 (d, J = 8.9 Hz, 2 H), 7.43-7.46 (m, 6 H). ¹³C NMR (125 MHz, CDCl₃): δ = 19.6, 22.5, 22.6, 24.6, 27.9, 29.8, 36.0, 37.2, 39.2, 66.3, 78.6, 83.3, 87.5, 91.6, 114.5, 114.6, 121.3, 124.1, 131.2, 132.0, 133.0, 159.4.
According to the same procedure, compound 7 was prepared from 3 and 4-iodobenzaldehyde.
Compound 7: 68%. ¹H NMR (500 MHz, CDC1₃): δ = 0.88 (d, J = 6.7 Hz, 6 H), 0.95 (d, J = 6.7 Hz, 3 H), 1.15-1.34 (m, 6 H), 1.52-1.68 (m, 3 H), 1.80-1.85 (m, 1 H), 3.99-4.03 (m, 2 H), 6.88 (d, J = 7.9 Hz, 2 H), 7.24 (d, J = 8.2 Hz, 2 H), 7.45 (d, J = 8.6 Hz, 2 H), 7.68 (d, J = 8.6 Hz, 2 H). ¹³C NMR (125 HMz CDC1₃): δ = 19.6, 22.6, 22.7, 24.6, 28.0, 29.8, 36.1, 37.3, 39.2, 66.4, 87.1, 91.0, 93.6, 114.6, 114.6, 123.2, 132.9, 133.0, 137.4, 159.4.

11

Typical Procedure for Sonogashira Coupling.
A 50 mL flask was charged with 7 (318 mg, 0.69 mmol), 1,4-diethyl-2,5-diethynylbenzene (55 mg, 0.30 mmol), Pd(PPh₃)₄ (34 mg, 0.03 mmol), CuI (5.0 mg, 0.03 mmol), i-Pr₂NH (1.0 mL) and toluene (20 mL), and the mixture was heated at 65 °C for 12 h. After filtration, the filtrate was poured into aq NH₄Cl and extracted with CH₂Cl₂. The combined organic layer was washed with brine, dried over MgSO₄ and filtered. After evaporation, the residue was subjected to column chromatography to afford 2a as white powder in a pure form (228 mg, 90%).
Compound 2a: mp 151-153 °C. ¹H NMR (500 MHz, CDCl₃): δ = 0.87 (d, J = 6.7 Hz, 12 H), 0.94 (d, J = 6.4 Hz, 6 H), 1.15-1.20 (m, 6 H), 1.25-1.37 (m, 12 H), 1.50-1.67 (m, 6 H), 1.82-1.85 (m, 2 H), 2.85 (q, J = 7.5 Hz, 4 H), 3.99-4.05 (m, 4 H), 6.88 (d, J = 8.8 Hz, 4 H), 7.39 (s, 2 H), 7.45-7.49 (m, 12 H). ¹³C NMR (125 MHz, CDCl₃): δ = 14.7, 19.6, 22.6, 22.7, 24.6, 27.1, 27.9, 29.8, 36.0, 37.2, 39.2, 66.4, 88.0, 89.8, 91.5, 94.1, 114.5, 114.7, 122.4, 122.7, 123.5, 131.3, 131.4, 131.5, 133.0, 143.4, 159.3. Anal. Calcd for C₆₂H₇₀O₂: C, 87.90; H, 8.33. Found: C, 88.12; H, 8.60.
Compound 2b: mp 178-181 °C. ¹H NMR (500 MHz, CDCl₃): δ = 0.87 (d, J = 6.4 Hz, 12 H), 0.94 (d, J = 6.7 Hz, 6 H), 1.15-1.34 (m, 12 H), 1.50-1.69 (m, 6 H), 1.80-1.86 (m, 2 H), 3.97-4.04 (m, 4 H), 6.87 (d, J = 8.8 Hz, 4 H), 7.17 (s, 2 H), 7.45-7.48 (m, 12 H). ¹³C NMR (125 MHz, CDCl₃): δ = 19.6, 22.6, 22.7, 24.6, 27.9, 29.8, 36.0, 37.2, 39.2, 66.4, 83.9, 87.7, 91.8, 94.0, 114.5, 114.7, 121.8, 123.9, 124.6, 131.3, 131.4, 132.0, 133.0, 159.4. ESI-MS: m/z calcd for C₅₆H₆₀O₂S [M + H⁺]: 797.4; found: 797.3.
Compound 2c: mp 235-238 °C. ¹H NMR (500 MHz, CDCl₃): δ = 0.87 (d, J = 6.7 Hz, 12 H), 0.94 (d, J = 6.7 Hz, 6 H), 1.15-1.37 (m, 12 H), 1.49-1.67 (m, 6 H), 1.80-1.86 (m, 2 H), 3.97-4.05 (m, 4 H), 6.87 (d, J = 8.8 Hz, 4 H), 7.45-7.50 (m, 10 H), 7.56 (d, J = 8.2 Hz, 4 H), 7.69 (t, J = 7.7 Hz, 1 H). ¹³C NMR (125 MHz, CDCl₃): δ = 19.6, 22.5, 22.6, 24.6, 27.9, 29.8, 36.0, 37.2, 39.2, 66.3, 87.6, 89.4, 89.7, 91.9, 114.5, 114.6, 121.3, 124.4, 126.3, 131.3, 132.0, 133.1, 136.4, 143.6, 159.4. ESI-MS: m/z calcd for C₅₇H₆₁NO₂ [M + H⁺]: 792.3; found: 792.5.
Compound 2d: mp 208-212 °C. ¹H NMR (500 MHz, CDCl₃): δ = 0.86 (d, J = 6.7 Hz, 12 H), 0.93 (d, J = 6.7 Hz, 6 H), 1.14-1.33 (m, 12 H), 1.50-1.65 (m, 6 H), 1.80-1.84 (m, 2 H), 3.97-4.01 (m, 4 H), 6.77 (d, J = 7.6 Hz, 2 H), 6.85 (d, J = 8.8 Hz, 4 H), 6.91 (s, 2 H), 7.15 (t, J = 7.4 Hz, 2 H), 7.35-7.43 (m, 14 H), 7.55 (d, J = 7.6 Hz, 2 H), 7.82 (d, J = 7.9 Hz, 2 H), 7.87 (d, J = 7.6 Hz, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 19.6, 22.5, 22.6, 24.6, 27.9, 29.8, 36.0, 37.2, 39.2, 65.5, 66.3, 87.7, 89.9, 91.3, 91.5, 114.5, 114.7, 120.1, 120.2, 122.4, 122.6, 123.4, 124.1, 127.2, 128.0, 128.1, 131.2, 131.3, 131.5, 133.0, 141.2, 141.7, 147.6, 149.2, 159.3. Anal. Calcd for C₇₇H₇₂O₂: C, 89.84; H, 7.05. Found: C, 89.79; H, 7.27.
Compound 2e: mp 263-266 °C. ¹H NMR (500 MHz, CDCl₃): δ = 0.87 (d, J = 6.4 Hz, 12 H), 0.95 (d, J = 6.4 Hz, 6 H), 1.15-1.37 (m, 12 H), 1.49-1.67 (m, 6 H), 1.80-1.87 (m, 2 H), 2.49 (d, J = 13.4 Hz, 2 H), 3.32 (d, J = 13.4 Hz, 2 H), 3.97-4.05 (m, 4 H), 6.88 (d, J = 8.8 Hz, 4 H), 6.99 (s, 2 H), 7.31 (t, J = 7.1 Hz, 2 H), 7.43-7.56 (m, 20 H), 7.73 (d, J = 7.9 Hz, 2 H), 8.07 (d, J = 8.2 Hz, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 19.6, 22.6, 22.7, 24.6, 28.0, 29.8, 36.1, 37.3, 39.2, 42.4, 61.0, 66.4, 87.8, 89.7, 91.5, 91.8, 114.6, 114.8, 120.1, 121.9, 122.7, 123.4, 125.3, 125.8, 127.4, 127.6, 128.0, 128.4, 128.9, 131.3, 131.4, 131.5, 131.9, 133.1, 133.2, 134.5, 135.6, 138.8, 151.4, 159.4. ESI-MS: m/z calcd for C₈₇H₈₀O₂ [M + H⁺]: 1157.5; found: 1157.6.