Electroactive and luminescent polymers: new fluorene-heterocycle-based hybrids

Abstract

The synthesis, characterization, and electrochromic properties of copolymers derived from 9,9-dialkyl-2,7-dibromofluorene (18a, alkyl=C₁₀H₂₁ ; 24, alkyl=Et) and pyrrole, thiophene, 3,4-ethylenedioxythiophene, and furan are described. Two synthetic routes to 9,9-diethyl-2,7-bis(pyrrol-2-yl)fluorene (30) afford product in 30% and 20% yields, respectively. Monomer 30 undergoes electropolymerizationto yield electroactive polymer films. The lowest monomer oxidation potential (E_p,m=0.4 V vs. Ag/Ag⁺) is found in tetraethylammonium tosylate (TEATOS)-CH₃CN, but film formation is slow. Spectroelectrochemical analysis of poly(30) reveals a band gap at 2.4 eV and upon polymer oxidation, two low energy absorptions peaking at 1.2 and 2.2 eV appear. This phenomenon is attributed to formation of bipolaron bands between the valence and conduction bands. Soluble fluorene-heterocycle polymers 34a-d have been synthesized by the Stille coupling reaction of 18a and 2,5-bis(trimethylstannyl)thiophene (21a), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene (21b), 2,5-bis(trimethylstannyl)-3,4-ethylenedioxythiophene (21c), and 2,5-bis(trimethylstannyl)furan (22), respectively, in high yields. The NMR spectra are consistent with the proposed structures of the polymers 34a-d, and no evidence of ring opening of the furyl unit in 34d is seen in the NMR and IR spectra. The molecular weights of 34a-d are in the range of 8000 g mol^–1 with polydispersity indices (PDI) of 2. Polymers 34a-c have band gaps measured at 2.4 eV, while polymer 34d has its gap at 2.6 eV. Polymers 34a-c undergo solution doping with SbCl₅ to form new low energy bipolaron bands at the expense of the absorption in the UV-VIS. However, polymer 34d does not oxidatively dope with SbCl₅.

References

1. (a) Handbook of Conducting Polymers, eds. T. A. Skotheim, R. L. Elsenbaumer and J. R. Reynolds, Marcel Dekker, New York, NY, 1998; (b) J. L. Reddinger and J. R. Reynolds, Adv. Polym. Sci., 1999, 145, 59; (c) T. Yamamoto, Prog. Polym. Sci., 1992, 17, 1153; (d) A. Kraft, A. C. Grimsdale and A. B. Holmes, Angew. Chem., Int. Ed., 1998, 37, 402; (e) J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns and A. B. Holmes, Nature, 1990, 347, 539; (f) J. R. Reynolds, Chemtech, 1988, 440.
2. J. Roncali, Chem. Rev., 1997, 97, 173; J. Roncali, Chem. Rev., 1992, 92, 711.
3. (a) F. Wudl, M. Kobayashi and A. J. Heeger, J. Org. Chem., 1984, 49, 3382; (b) E. E. Havinga, W. ten Hoeve and H. Wynberg, Synth. Met., 1993, 55–57, 299.
4. See for example: M. Rehahn, A. D. Schluter, G. Wegner and W. J. Feast, Polymer, 1989, 30, 1054; A. D. Schluter, M. Loffler and V. Enkelmann, Nature, 1994, 368, 831; B. Karakaya, W. Claussen, K. Gessler, W. Saenger and A. D. Schluter, J. Am. Chem. Soc., 1997, 119, 3296; W. Stocker, B. Karakaya, B. L. Schurmann, J. P. Rabe and A. D. Schluter, J. Am. Chem. Soc., 1998, 120, 7691; J. Grimme, M. Kreyenschmidt, F. Uckert, K. Muellen and U. Scherf, Adv. Mater., 1995, 7, 292; M. Kreyenschmidt, F. Uckert and K. Muellen, Macromolecules, 1995, 28, 4577; R. Fiesel, J. Huber and U. Scherf, Angew. Chem., Int. Ed. Engl., 1996, 35, 2111; G. Grem, C. Paar, J. Stampfl, G. Leising, J. Huber and U. Scherf, Chem. Mater., 1995, 7, 2; J. J. S. Lamba and J. M. Tour, J. Am. Chem. Soc., 1994, 116, 11723; J. M. Tour and J. J. S. Lamba, J. Am. Chem. Soc., 1993, 115, 4935; F. E. Goodson, T. I. Wallow and B. M. Novak, Macromolecules, 1998, 31, 2047; B. M. Novak, E. Hagen, S. Hoff and A. Viswanathan, Macromolecules, 1994, 27, 1985.
5. G. Grem, G. Leditzky, B. Ullrich and G. Leising, Adv. Mater., 1992, 4, 36; G. Grem and G. Leising, Synth. Met., 1993, 55–57, 4105.
6. (a) J. L. Musfeldt, J. R. Reynolds, D. B. Tanner, J. P. Ruiz, J. Wang and M. Pomerantz, J. Polym. Sci., Part B: Polym. Phys., 1994, 32, 2395; (b) J. L. Reddinger and J. R. Reynolds, Macromolecules, 1997, 30, 479; (c) S. Kim, J. Jackiw, E. Robinson, K. S. Schanze, J. R. Reynolds, J. Baur, M. F. Rubner and D. Boils, Macromolecules, 1998, 31, 964; (d) A. D. Child and J. R. Reynolds, Macromolecules, 1994, 27, 1975; (e) J. W. Baur, S. Kim, P. B. Balanda, J. R. Reynolds and M. F. Rubner, Adv. Mater., 1998, 10, 1452.
7. N. Miyaura and A. Suzuki, Chem. Rev., 1995, 95, 2457.
8. T. I. Wallow and B. M. Novak, J. Am. Chem. Soc., 1991, 113, 7411; V. Cimrova, W. Schmidt, R. Rulkens, M. Schulze, W. Meyer and D. Neher, Adv. Mater., 1996, 8, 585.
9. T. Vahlenkamp and G. Wegner, Macromol. Chem. Phys., 1994, 195, 1933.
10. Representative papers include: G. Heywang and F. Jonas, Adv. Mater., 1992, 4, 116; Q. Pei, G. Zuccarello, M. Ahlskog and O. Inganas, Polymer, 1994, 35, 1347; M. Dietrich, J. Heinze, G. Heywang and F. Jonas, J. Electroanal. Chem., 1994, 369, 87; E. E. Havinga, C. M. J. Mutsaers and L. W. Jenneskens, Chem. Mater., 1996, 8, 769.
11. Representative papers include: A. Kumar and J. R. Reynolds, Macromolecules, 1996, 29, 7629; J. R. Reynolds, A. Kumar, J. L. Reddinger, B. Sankaran, S. A. Sapp and G. A. Sotzing, Synth. Met., 1997, 85, 1295; G. A. Sotzing, J. R. Reynolds and P. J. Steel, Adv. Mater., 1997, 9, 795; B. Sankaran and J. R. Reynolds, Macromolecules, 1997, 30, 2582; S. A. Sapp, G. A. Sotzing, J. L. Reddinger and J. R. Reynolds, Adv. Mater., 1996, 8, 808; G. A. Sotzing, C. A. Thomas and J. R. Reynolds, Macromolecules, 1998, 31, 3750; G. A. Sotzing and J. R. Reynolds, J. Chem. Soc., Chem. Commun., 1995, 703.
12. See for example: J. Roncali, F. Garnier, R. Garreau and M. Lemaire, J. Chem. Soc., Chem. Commun., 1987, 1500; R. Cloutier and M. Leclerc, J. Chem. Soc., Chem. Commun., 1991, 1194; M. Leclerc and G. Daoust, Synth. Met., 1991, 41–43, 529; M. R. Bryce, A. D. Chissel, N. R. M. Smith, D. Parker and P. Kathirgamanathan, Synth. Met., 1988, 26, 153; T. Hagiwara, M. Yamaura, K. Sato, M. Hirasaka and K. Iwata, Synth. Met., 1989, 32, 367; M. Feldhues, G. Kamf, H. Litterer, T. Mecklenburg and P. Wegener, Synth. Met., 1989, 28, C487; M. Dietrich and J. Heinze, Synth. Met., 1991, 41–43, 503.
13. J. R. Reynolds, A. R. Katritzky, J. Soloducho, S. Belyakov, G. A. Sotzing and P. Myoungho, Macromolecules, 1994, 27, 7225; G. A. Sotzing, J. R. Reynolds, A. R. Katritzky, J. Soloducho, S. Belyakov and R. Musgrave, Macromolecules, 1996, 29, 1679.
14. (a) J. P. Ruiz, J. R. Dharia, J. R. Reynolds and L. J. Buckley, Macromolecules, 1992, 25, 849; (b) J. R. Reynolds, J. P. Ruiz, A. D. Child, K. Nayak and D. S. Marynick, Macromolecules, 1991, 24, 678; (c) A. D. Child, B. Sankaran, F. Larmat and J. R. Reynolds, Macromolecules, 1995, 28, 6571; (d) G. A. Sotzing, J. R. Reynolds and P. J. Steel, Chem. Mater., 1996, 8, 882; (e) J. A. Irvin and J. R. Reynolds, Polymer, 1998, 39, 2339.
15. J. L. Reddinger, G. A. Sotzing and J. R. Reynolds, Chem. Commun., 1996, 1777; G. A. Sotzing, J. L. Reddinger, A. R. Katritzky, J. Soloducho, R. Musgrave and J. R. Reynolds, Chem. Mater., 1997, 9, 1578.
16. J. Rault-Berthelot and J. Simonet, J. Electroanal. Chem., 1985, 182, 187; J. Rault-Berthelot and J. Simonet, New J. Chem., 1986, 10, 169; J. Rault-Berthelot and M. M. Granger, J. Electroanal. Chem., 1993, 353, 341; J. Rault-Berthelot, M. A. Orliac and J. Simonet, Electrochim. Acta, 1988, 33, 811; J. Rault-Berthelot, M. Cariou and J. Tahri-Hassani, J. Electroanal. Chem., 1996, 402, 203.
17. M. Fukuda, K. Sawada and K. Yoshino, J. Polym. Sci., Part A: Polym. Chem., 1993, 31, 2465; M. Fukuda, K. Sawada and K. Yoshino, Jpn. J. Appl. Phys., 1989, 28, L1433.
18. Q. Pei and Y. Yang, J. Am. Chem. Soc., 1996, 118, 7416.
19. M. Ranger and M. Leclerc, Macromolecules, 1999, 32, 3306; M. Ranger, D. Rondeau and M. Leclerc, Macromolecules, 1997, 30, 7686; M. Ranger and M. Leclerc, Chem. Commun., 1997, 1597.
20. X. Long, A. Malinowski, D. D. C. Bradley, M. Inbasekaran and E. P. Woo, Chem. Phys. Lett., 1997, 272, 6.
21. V. N. Bliznyuk, S. A. Carter, J. C. Scott, G. Klarner, R. D. Miller and D. C. Miller, Macromolecules, 1999, 32, 361; J. I. Lee, G. Klaerner and R. D. Miller, Chem. Mater., 1999, 11, 1083; G. Klaerner and R. D. Miller, Macromolecules, 1998, 31, 2007.
22. R. D. Scurlock, B. Warg, P. R. Ogilby, J. R. Sheats and R. L. Clough, J. Am. Chem. Soc., 1995, 117, 10194; Photodegradation, Photo-oxidation and Photostabilization of Polymers, eds. B. Ranby and J. F. Rabek, John Wiley and Sons, New York, 1975, ch. 3.
23. G. Klarner, M. H. Davey, W. D. Chen, J. C. Scott and R. D. Miller, Adv. Mater., 1998, 10, 993; M. Kreyenschmidt, G. Klaerner, T. Fuhrer, J. Ashenhurst, S. Karg, W. D. Chen, V. Y. Lee, J. C. Scott and R. D. Miller, Macromolecules, 1998, 31, 1099; G. Klarner, J. I. Lee, M. H. Davey and R. D. Miller, Adv. Mater., 1999, 11, 115.
24. (a) M. Redecker, D. D. C. Bradley, M. Inbasekaran, W. W. Wu and E. P. Woo, Adv. Mater., 1999, 11, 241; (b) H. Antoniadis, M. Inbasekaran and E. P. Woo, Appl. Phys. Lett., 1998, 73, 3055.
25. M. Grell, D. D. C. Bradley, M. Inbasekaran and E. P. Woo, Adv. Mater., 1997, 9, 798; E. P. Woo, W. R. Shiang, M. Inbasekaran and G. R. Roof, U. S. Patent 5708130, 1998.
26. An earlier catalyst system was Pd(PPh₃)₄ with excess LiCl, which is essential for catalyst activation. It is proposed that formation of a Pd(II) active species occurs which undergoes transmetalation with the trialkylstannyl hydrocarbyl component. The modern catalyst Cl₂Pd(PPh₃)₂ is air-stable and faster relative to Pd(PPh₃)₄.
27. (a) D. Milstein and J. K. Stille, J. Am. Chem. Soc., 1979, 101, 4992; (b) A. M. Echavarren and J. K. Stille, J. Am. Chem. Soc., 1987, 109, 5478; (c) W. J. Scott and J. K. Stille, J. Am. Chem. Soc., 1986, 108, 3033; (d) W. J. Scott, G. T. Crisp and J. K. Stille, J. Am. Chem. Soc., 1984, 106, 4630; (e) J. K. Stille, Angew. Chem., Int. Ed. Engl., 1986, 25, 508.
28. L. Yu, W. K. Chan, Z. Peng and A. Gharavi, Acc. Chem. Res., 1996, 29, 13; L. Yu, Z. Bao and R. Cai, Angew. Chem., Int. Ed. Engl., 1993, 32, 1345; W. K. Chan, Y. Chen, Z. Peng and L. Yu, J. Am. Chem. Soc., 1993, 115, 11735; T. Maddux, W. Li and L. Yu, J. Am. Chem. Soc., 1997, 119, 844; Z. Peng, A. R. Gharavi and L. Yu, J. Am. Chem. Soc., 1997, 119, 4622; H. Saadeh, T. Goodson and L. Yu, Macromolecules, 1997, 30, 4608; Z. Bao, W. K. Chan and L. Yu, J. Am. Chem. Soc., 1995, 117, 12426.
29. F. Larmat, J. R. Reynolds, B. A. Reinhardt, L. L. Brott and S. J. Clarson, J. Polym. Sci., Part A: Polym. Chem., 1997, 35, 3627.
30. D. E. Seitz, S. H. Lee, R. N. Hanson and J. C. Bottaro, Synth. Commun., 1983, 13, 121.
31. N. Engel and W. Steglich, Angew. Chem., Int. Ed. Engl., 1978, 17, 676.
32. F. Lucchesini, Tetrahedron, 1992, 48, 9951.
33. H. D. Abruna, Coord. Chem. Rev., 1988, 86, 135.
34. Conjugated polymers tend not to undergo combustion analysis consistently. See for example: B. L. Lucht and T. D. Tilley, Chem. Commun., 1998, 1645; B. L. Lucht, S. S. H. Mao and T. D. Tilley, J. Am. Chem. Soc., 1998, 120, 4354.
35. Fernando Larmat, PhD thesis, The University of Florida, 1997, p. 130.
36. Y. Furukawa, Synth. Met., 1995, 69, 629; K. Fesser, A. R. Bishop and D. K. Campbell, Phys. Rev. B, 1983, 27, 4804.
37. (a) R. G. Harvey, P. P. Fu and P. W. Rabideau, J. Org. Chem., 1976, 41, 2706; (b) M. Rehahn, A. Schluter and W. J. Feast, Synthesis, 1988, 386; (c) R. C. Bansal, J. Eisenbraun and R. J. Ryba, Org. Prep. Proced. Int., 1987, 19, 258.