A Straightforward Synthesis to Novel 1,10-Phenanthrolines with Fused Thiophene Structure

Abstract

We report here a straightforward synthesis for a series of new structures with fused 1,10-phenanthroline-thiophene connection. They are synthesized with a modified Hinsberg thiophene procedure, followed by successive modification to yield several 5,7-disubstituted thieno[3,4-f][1,10]phenanthrolines, most notable thiophene-substituted compounds that could be potentially of use for organic electronics ­applications. For some selected examples, crystal structures were ­obtained, showing a nearly coplanar arrangement around the fused connection, also beneficial for an effective electron transfer in organic electronics or solar cells.

Key words

thiophene - 1,10-phenanthroline - fused thiophene - semiconductor - organic solar cells

• References and Notes

• 1a Wu Z.-S. Zheng Y. Zheng S. Wang S. Sun C. Parvez K. Ikeda T. Bao X. Müllen K. Feng X. Adv. Mater. 2017; 29: 1602960
• 1b Zhang W. Han Y. Zhu X. Fei Z. Feng Y. Treat ND. Faber H. Stingelin N. McCulloch I. Anthopoulos TD. Heeney M. Adv. Mater. 2016; 28: 3922
• 2 Yang Y. Zhang Z.-G. Bin H. Chen S. Gao L. Xue L. Yang C. Li Y. J. Am. Chem. Soc. 2016; 138: 15011
• 3 Yu H. Park KH. Song I. Kim M.-J. Kim Y.-H. Oh JH. J. Mater. Chem. C 2015; 3: 11697
• 4a Mitschke U. Bäuerle PJ. Mater. Chem. 2000; 10: 1471
• 4b Barbarella G. Favaretto L. Sotgiu G. Antolini L. Gigli G. Cingolani R. Bongini A. Chem. Mater. 2001; 13: 4112
• 4c Zhao Z. Deng C. Chen S. Lam JW. Y. Qin W. Lu P. Wang Z. Kwok HS. Ma Y. Qiu H. Tang BZ. Chem. Commun. 2011; 47: 8847
• 5 Zhou Y. You X.-Y. Fang Y. Li J.-Y. Liu K. Yao C. Org. Biomol. Chem. 2010; 8: 4819
• 6a Krishnamoorthy T. Kunwu F. Boix PP. Li H. Koh TM. Leong WL. Powar S. Grimsdale A. Grätzel M. Mathews N. Mhaisalkar SG. J. Mater. Chem. A 2014; 2: 6305
• 6b Liu F. Zhou Z. Zhang C. Vergote T. Fan H. Zhu X. J. Am. Chem. Soc. 2016; 138: 15523
• 7a Xu S. Zhu Y. Li R. Su J. Li S. Zhou H. Wu J. Tian Y. New J. Chem. 2016; 40: 8809
• 7b Andrade CD. Yanez CO. Rodriguez L. Belfield KD. J. Org. Chem. 2010; 75: 3975
• 7c Mahapatra AK. Maiti K. Maji R. Manna SK. Mondal S. Ali SS. Manna S. RSC Adv. 2015; 5: 24274
• 8a Roncali J. Blanchard P. Frère PJ. Mater. Chem. 2005; 15: 1589
• 8b Turbiez M. Frère P. Allain M. Videlot C. Ackermann J. Roncali J. Chem. Eur. J. 2005; 11: 3742
• 9 Lee J.-S. US 20150155497, 2015
• 10a Ono N. Hironaga H. Simizu K. Ono K. Kuwano K. Ogawa T. J. Chem. Soc., Chem. Commun. 1994; 1019
• 10b Lash TD. Novak BH. Lin Y. Tetrahedron Lett. 1994; 35: 2493
• 10c Villegas JM. Stoyanov SR. Rillema DP. Inorg. Chem. 2002; 41: 6688
• 10d Swavey S. DeBeer M. Li K. Inorg. Chem. 2015; 54: 3139
• 10e Yao H. Zhang L. Peng Y. Carroll PJ. Gong L. Meggers E. Inorg. Chim. Acta 2014; 421: 489
• 11 Wynberg H. Kooreman HJ. J. Am. Chem. Soc. 1965; 87: 1739
• 12 The reaction was conducted under inert atmosphere. Potassium (3.51 g, 89.8 mmol, 4 equiv) was dissolved in dry MeOH (15 mL). 1,10-Phenanthroline-5,6-dione (5.01 g, 23.8 mmol, 1 equiv) and diethyl-2,2′-thiodiacetate (4.99 g, 24.2 mmol, 1 equiv) were mixed in dry MeOH (40 mL) at 0 °C in a second flask, and the potassium methanolate solution was added slowly. During this process, the color changed from yellow to black. The solution was stirred for 3 h at ambient temperature. After this time a solid was formed. Water (500 mL) was added to the mixture, and the reaction solution was concentrated to 250 mL. The suspension was filtered, and concentrated HCl (65 mL) was added. The obtained solid 1 was filtered, washed with diethyl ether, and dried under vacuum; yield 7.42 g (96 %) ¹H NMR (500 MHz, DMSO-d ₆): δ = 8.18 (dd, ³ J _HH = 8.5, 4.9 Hz, 2 H), 9.15 (dd, ³ J _HH = 4.9 Hz, ⁴ J _HH = 1.4 Hz, 2 H), 10.00 (dd, ³ J _HH = 8.5 Hz, ⁴ J _HH = 1.4 Hz, 2 H) ppm. ¹³C NMR (125 MHz, DMSO-d ₆): δ = 125.7 (CH or Cq), 126.5 (Cq), 132.9 (Cq), 134.0 (Cq), 139.2 (Cq), 141.5 (CH), 147.3 (CH), 163.3 (Cq) ppm. ¹⁵N NMR (70.9 MHz, DMSO-d ₆): δ = 245.83 (s) ppm. MS-ESI (pos): m/z = 325.03 [M + H]⁺.
• 13 The reaction was carried out under Ar atmosphere. Compd 5 (0.16 g, 0.4 mmol, 1 equiv), 2-thienylboronic acid (0.12 g, 1.0 mmol, 2.5 equiv) and K₃PO₄ (0.28 g, 1.3 mmol, 3.5 equiv) were added to a Schlenk flask. Afterwards, Pd(PPh₃)₄ (0.06 g, 51.9 μmol, 0.1 equiv) was added to the flask with dry, oxygen-free DMF (5 mL) and heated to 100 °C. After the reaction time of 142.5 h the mixture was allowed to cool down to r.t., extracted with CHCl₃, and washed with EDTA solution to remove palladium residuals. The crude product of 6 was purified by column chromatography over SiO₂ with THF; yield 0.08 g (54 %) ¹H NMR (500 MHz, CDCl₃): δ = 7.23 (dd, ³ J _HH = 5.2, 3.5 Hz, 2 H), 7.27 (dd, ³ J _HH = 8.4, 4.4 Hz, 2 H), 7.31 (dd, ³ J _HH = 3.5 Hz, ⁴ J _HH = 1.2 Hz, 2 H), 7.59 (dd, ³ J _HH = 5.2 Hz, ⁴ J _HH = 1.2 Hz, 2 H), 8.15 (dd, ³ J _HH = 8.4 Hz, ⁴ J _HH = 1.7 Hz, 2 H), 8.95 (dd, ³ J _HH = 4.4 Hz, ⁴ J _HH = 1.7 Hz, 2 H) ppm. ¹³C NMR (125 MHz, CDCl₃): δ = 123.0 (CH), 125.8 (Cq), 128.2 (CH), 128.9 (CH), 129.6 (CH), 130.3 (Cq), 130.9 (Cq), 132.6 (CH), 134.7 (Cq), 147.0 (Cq), 149.6 (CH) ppm. ¹⁵N NMR (50.7 MHz, CDCl3): δ = 305.59 (s) ppm. MS-ESI (pos): m/z = 823.02 [2M + Na]⁺, 401.02 [M + H]⁺. Anal. Calcd for C₂₂H₁₂S₃N₂: C, 65.97; H, 3.02; N, 6.99; S, 24.01. Found: C, 65.15; H, 3.59; N, 6.78; S, 22.19.
• 14 The reaction was conducted under inert atmosphere. Compd 5 (0.04 g, 0.1 mmol, 1 equiv) and 13 (0.10 g, 0.2 mmol, 2 equiv) were added to a Schlenk flask with dry and oxygen-free toluene (2 mL) and DMF (0.5 mL). Pd(PPh₃)₄ (0.01 g, 8.7 μmol, 0.1 equiv) was added in counterflow to the mixture, and the reaction was stirred at 105 °C for 72 h. The mixture was allowed to cool down to ambient temperature while a white solid precipitated. The solvent was filtered off, and the solid was washed with toluene. The powder was dried under vacuum and identified as the desired product 15; yield 0.04 g (69 %). ¹H NMR (500 MHz, CDCl₃): δ = 2.62 (s, 6 H), 2.78 (s, 6 H), 7.10 (d, ³ J _HH = 7.72 Hz, 2 H), 7.22 (d, ³ J _HH = 3.65 Hz, 2 H), 7.33 (d, ³ J _HH = 3.65 Hz, 2 H), 7.34 (d, ³ J _HH = 4.43 Hz, 2 H), 7.70 (d, ³ J _HH = 7.85 Hz, 2 H), 8.37 (dd, ³ J _HH = 8.35 Hz, ⁴ J _HH = 1.60 Hz, 2 H), 9.00 (dd, ³ J _HH = 4.43 Hz, ⁴ J _HH = 1.60 Hz, 2 H) ppm. ¹³C NMR (125 MHz, CDCl3): δ = 24.1 (CH₃), 24.3 (CH₃), 121.1 (CH), 123.1 (CH), 125.7 (Cq), 127.9 (CH), 130.0 (CH), 130.0 (Cq), 131.0 (Cq), 132.6 (CH), 135.0 (Cq), 138.3 (CH), 144.7 (Cq), 147.1 (Cq), 149.8 (CH), 155.3 (Cq), 157.7 (Cq). ¹⁵N NMR (50.7 MHz, CDCl₃): δ = 305.9 (s), 313.1 (s) ppm. MS-ESI (pos): m/z = 633.12 [M + Na]⁺, 611.14 [M + H]⁺, 306.07 [M + 2H]²⁺. Anal. Calcd for CHN₄S₃: N, 9.17; C, 70.79; H, 4.29; S, 15.75. Found: N, 8.76; C, 69.69; H, 4.67; S, 14.5.
• 15 We have prepared bimetallic systems with these ligands that show high activities as hydrogen-evolving devices in photocatalytic proton reduction. The results will be published in the near future.
• 16a Ozawa H. Haga M.-a. Sakai K. J. Am. Chem. Soc. 2006; 128: 4926
• 16b Rau S. Schäfer B. Gleich D. Anders E. Rudolph M. Friedrich M. Görls H. Henry W. Vos JG. Angew. Chem. Int. Ed. 2006; 45: 6215
• 16c Pan X. Liu A. Yao L. Wang L. Zhang J. Wu J. Zhao X. Lin C.-C. Inorg. Chem. Commun. 2011; 14: 763
• 16d Mori K. Kawashima M. Yamashita H. Chem. Commun. 2014; 50: 14501
• 16e Holbrook RJ. Weinberg DJ. Peterson MD. Weiss EA. Meade TJ. J. Am. Chem. Soc. 2015; 137: 3379
• 17a Liang C. Newton MD. J. Phys. Chem. 1992; 96: 2855
• 17b Venkataraman L. Klare JE. Nuckolls C. Hybertsen MS. Steigerwald ML. Nature 2006; 442: 904
• 17c Benniston AC. Harriman A. Coord. Chem. Rev. 2008; 252: 2528
• 17d Woitellier S. Launay JP. Joachim C. Chem. Phys. 1989; 131: 481