Synthesis of poly(2,5-thienyleneethynylene)s by alkyne metathesis

Macromolecules

Volumn 37, Issue 11, 2004, Pages 3973-3975

  Zhang, Wei ^a   Moore, Jeffrey S ^a  

^a UNIVERSITY OF ILLINOIS AT URBANA CHAMPAIGN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKYNE; CHEMICAL SHIFT; METATHESIS; POLYDISPERSITIES;

CATALYSIS; CATALYST ACTIVITY; MOLECULAR WEIGHT; PHENOLS; POLYMERIZATION; SOLVENTS; SYNTHESIS (CHEMICAL); THERMAL EFFECTS; TUNGSTEN;

ORGANIC POLYMERS;

EID: 2942527303     PISSN: 00249297     EISSN: None     Source Type: Journal    
DOI: 10.1021/ma049371g     Document Type: Article

References (53)

1. Zhang, W.; Kraft, S.; Moore, J. S. Chem. Commun. 2003, 832-833.
2. (b) Zhang, W.; Kraft, S.; Moore, J. S. J. Am. Chem. Soc. 2004, 126, 329-335.
3. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
4. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
5. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
6. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
7. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
8. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
9. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
10. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
11. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
12. For PAEs, see: (a) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605-1644. For PTEs, see: (b) McCullough, R. D.; Tristran-Nale, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. J. Am. Chem. Soc. 1993, 115, 4910-4911. (c) Chen, T.-A.; Wu, X.; Rieke, R. D. J. Am. Chem. Soc. 1995, 117, 233-244. (d) Anderson, M. R.; Selse, D.; Berggeren, M.; Järvinen, H.; Hiertberg, T.; Inganäs, O.; Wennersröm, O.; Österholm, J.-E. Macromolecules 1994, 27, 6503-6506. (e) Arroyo-Villian, M. I.; Diaz-Quijada, G. A.; Abdou, M. S. A.; Holdcroft, S. Macromolecules 1995, 28, 975-984. (f) Hayashi, H.; Yamamoto, T. Macromolecules 1997, 30, 330-332. For PPEs, see: (g) Yang, J.-S.; Swager, T. J. J. Am. Chem. Soc. 1998, 120, 11864-11873. (h) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 12593-12602. (i) Bumm, L. A.; Arnold, J. J.; Cygan, M. T.; Dunbar, T. D.; Burgin, T. P.; Jones, L.; Allara, D. L.; Tour, J. M. Weiss, P. S. Science 1996, 271, 1705-1707. (j) Wilson, J. N.; Wang, Y.-Q.; Lavigne, J. J.; Bunz, U. H. F. Chem. Commun. 2003, 1626-1627.
13. Cassar, I. J. Organomet. Chem. 1975, 93, 253-257.
14. (b) Dieck, H. A.; Heck, R. F. J. Organomet. Chem. 1975, 93, 259-263.
15. (c) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975, 4467-4470.
16. (d) Bunz, U. H. F.; Enkelmann, V. Organometallics 1994, 13, 3823-3833.
17. (e) Fiesel, R.; Scherf, U. Macromol. Rapid Commun. 1998, 19, 427-431.
18. (f) Tour, J. M. Chem. Rev. 1996, 96, 537-554.
19. (g) Ziener, U.; Godt, A. J. Org. Chem. 1997, 62, 6137-6143.
20. (h) Francke, V.; Mangel, T.; Müllen, K. Macromolecules 1998, 31, 2447-2453.
21. Wautelet, P.; Moroni, M.; Oswald, L.; LeMoigne, J.; Pham, A.; Bigot, J.-Y.; Luzatti, S. Macromolecules 1996, 29, 446-455.
22. (b) Zhou, Q.; Swager, T. J. Am. Chem. Soc. 1995, 117, 12593-12602.
23. Goodson, F. E.; Wallow, T. I.; Novak, B. M. J. Am. Chem. Soc. 1997, 119, 12441-12453.
24. (b) Ghosez, L.; Franc, C.; Denonne, F.; Cuisinier, C.; Touillaux, R. Can. J. Chem. 2001, 79, 1827-1839.
25. Bunz, U. H. F. Acc. Chem. Res. 2001, 34, 998-1010.
26. Schrock, R. R.; Clark, D. N.; Sancho, J.; Wengrovius, J. H.; Rocklage, S. M.; Pedersen, S. F. Organometallics 1982, 1, 1645-1651.
27. (b) Listemann, M. L.; Schrock, R. R. Organometallics 1985, 4, 74-83.
28. Krouse, S. A.; Schrock, R. R. Macromolecules 1989, 22, 2569-2576.
29. (b) Zhang, X. P.; Bazan, G. C. Macromolecules 1994, 27, 4627-4628.
30. Fürstner, A.; Guth, O.; Rumbo, A.; Seidel, G. J. Am. Chem. Soc. 1999, 121, 11108-11113.
31. (b) Fürstner, A.; Mathes, C.; Lehmann, C. W. Chem.-Eur. J. 2001, 7, 5299-5317.
32. (c) Fürstner, A.; Mathes, C.; Lehmann, C. W. J. Am. Chem. Soc. 1999, 121, 9453-9454.
33. Weiss, K.; Michel, A.; Auth, E.-M.; Bunz, U. H. F.; Mangel, T.; Müllen, L. Angew. Chem., Int. Ed. Engl. 1997, 36, 506-509.
34. (b) Kloppenburg, L.; Song, D.; Bunz, U. H. F. J. Am. Chem. Soc. 1998, 120, 7973-7974.
35. (c) Kloppenburg, L.; Jones, D.; Bunz, U. H. F. Macromolecules 1999, 32, 4194-4203.
36. Acyclic diyne metathesis is similar to acyclic diene metathesis (ADMET) which was pioneered by Wagener and Boncella. See: (a) Lindmarkhamberg, M.; Wagener, K. B. Macromolecules 1987, 20, 2949-2951. (b) Wagener, K. B.; Boncella, J. M.; Nell, J. G.; Duttweiler, R. P.; Hillmyer, M. A. Makromol. Chem. 1990, 191, 365-374.
37. Acyclic diyne metathesis is similar to acyclic diene metathesis (ADMET) which was pioneered by Wagener and Boncella. See: (a) Lindmarkhamberg, M.; Wagener, K. B. Macromolecules 1987, 20, 2949-2951. (b) Wagener, K. B.; Boncella, J. M.; Nell, J. G.; Duttweiler, R. P.; Hillmyer, M. A. Makromol. Chem. 1990, 191, 365-374.
38. Mortreux, A.; Blanchard, M. Chem. Commun. 1974, 786-787.
39. Pschirer, N. G.; Bunz, U. H. F. Tetrahedron Lett. 1999, 40, 2481-2484.
40. (b) Fürstner, A.; Mathes, C. Org. Lett. 2001, 3, 221-223 and ref 9b.
41. Tamao, K.; Sumitani, K.; Kiso, Y.; Zembayashi, M.; Fijioka, A.; Kodama, S. I.; Nakajima, I.; Minato, A.; Kumada, M. Bull. Chem. Soc. Jpn. 1976, 49, 1958.
42. Li, H.; Powell, D. R.; Hayashi, R. K.; West, R. Macromolecules 1998, 31, 52-58.
43. Vidal, P.-L.; Divisia-Blohorn, B.; Bidan, G.; Hazemann, J.-L.; Kern, J.-M.; Sauvage, J.-P. Chem.-Eur. J. 2000, 6, 1663-1673.
44. King, A. O.; Okukado, N.; Negishi, E. J. Chem. Soc., Chem. Commun. 1977, 683-684.
45. (b) King, A. O.; Negishi, E.; Villani, F. J., Jr.; Silveira, A., Jr. J. Org. Chem. 1978, 43, 358-360.
46. 2. Addition of methanol causes the polymeric product to precipitate. The solid is filtered and vacuum-dried, giving yields as summarized in Table 1 and Supporting Information.
47. During the metathesis of 3a,b, it was observed that PPEs precipitated out of the solution. Therefore, the poor solubility of 5a,b in 1,2,4- trichlorobenzene at 30°C likely explains the formation of low molecular weight PPEs in both cases.
48. In small molecule model reactions, the butynyl groups were superior for reasons previously discussed (ref 1b). However, for the polymerizations, the propynyl groups were superior.
49. In alkyne metathesis the only side reaction is alkyne polymerization through the "ring expansion" mechanism (ref 1b). Polymerization of alkynes by a tungsten carbyne catalyst was reported before. See: (a) Weiss, K.; Goller, R.; Lössel, G. J. Mol. Catal. 1988, 46, 267-275. (b) Bunz, U. H. F.; Kloppenburg, L. Angew. Chem., Int. Ed. 1999, 38, 478-481. (c) Katz, T. J.; Ho, T, H.; Shih, N. Y.; Ying, Y. C.; Stuart, V. I. W. J. Am. Chem. Soc. 1984, 106, 2659-2668.
50. In alkyne metathesis the only side reaction is alkyne polymerization through the "ring expansion" mechanism (ref 1b). Polymerization of alkynes by a tungsten carbyne catalyst was reported before. See: (a) Weiss, K.; Goller, R.; Lössel, G. J. Mol. Catal. 1988, 46, 267-275. (b) Bunz, U. H. F.; Kloppenburg, L. Angew. Chem., Int. Ed. 1999, 38, 478-481. (c) Katz, T. J.; Ho, T, H.; Shih, N. Y.; Ying, Y. C.; Stuart, V. I. W. J. Am. Chem. Soc. 1984, 106, 2659-2668.
51. In alkyne metathesis the only side reaction is alkyne polymerization through the "ring expansion" mechanism (ref 1b). Polymerization of alkynes by a tungsten carbyne catalyst was reported before. See: (a) Weiss, K.; Goller, R.; Lössel, G. J. Mol. Catal. 1988, 46, 267-275. (b) Bunz, U. H. F.; Kloppenburg, L. Angew. Chem., Int. Ed. 1999, 38, 478-481. (c) Katz, T. J.; Ho, T, H.; Shih, N. Y.; Ying, Y. C.; Stuart, V. I. W. J. Am. Chem. Soc. 1984, 106, 2659-2668.
52. Sluch, M. I.; Godt, A.; Bunz, U. H. F.; Berg, M. A. J. Am. Chem. Soc. 2001, 123, 6447-6448.
53. (b) Halkyard, C. E.; Rampey, M. E.; Kloppenburg, L.; Studer-Martinez, S. L.; Bunz, U. H. F. Macromolecules 1998, 31, 8655-8659.