Rotaxane or pseudorotaxane? That is the question!

Journal of the American Chemical Society

Volumn 120, Issue 10, 1998, Pages 2297-2307

  Ashton, Peter R ^a   Baxter, Ian ^b   Fyfe, Matthew C T ^a   Raymo, Françisco M ^a   Spencer, Neil ^a   Stoddart, J Fraser ^a,c   White, Andrew J P ^b   Williams, David J ^b  

^a UNIVERSITY OF BIRMINGHAM   (United Kingdom)

^b IMPERIAL COLLEGE LONDON   (United Kingdom)

^c UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CROWN ETHER; DB24C8; DIALKYLAMMONIUM ION; MACROCYCLIC COMPOUND; POLYETHER; PSEUDOROTAXANE; ROTAXANE; SOLVENT; UNCLASSIFIED DRUG;

ARTICLE; BINDING KINETICS; CONTROLLED STUDY; DEVICE; NONHUMAN; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; SYNTHESIS;

EID: 0032542743     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9731276     Document Type: Article

References (64)

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9. For examples of rotaxane-based device-like systems, see: (a) Bissell, R. A.; Córdova, E.; Kaifer, A. E.; Stoddart, J. F. Nature (London) 1994, 369, 133-137. (b) Anelli, P.-L.; Asakawa, M.; Ashton, P. R.; Bissell, R. A.; Clavier, G.; Górski, R.; Kaifer, A. E.; Langford, S. J.; Mattersteig, G.; Menzer, S.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. Chem. Eur. J. 1997, 3, 1113-1135. (c) Martínez-Díaz, M.-V.; Spencer, N.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1904-1907. (d) Murakami, H.; Kawabuchi, A.; Kotoo, K.; Kunitake, M.; Nakashima, N. J. Am. Chem. Soc. 1997, 119, 7605-7606.
10. For examples of rotaxane-based device-like systems, see: (a) Bissell, R. A.; Córdova, E.; Kaifer, A. E.; Stoddart, J. F. Nature (London) 1994, 369, 133-137. (b) Anelli, P.-L.; Asakawa, M.; Ashton, P. R.; Bissell, R. A.; Clavier, G.; Górski, R.; Kaifer, A. E.; Langford, S. J.; Mattersteig, G.; Menzer, S.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. Chem. Eur. J. 1997, 3, 1113-1135. (c) Martínez-Díaz, M.-V.; Spencer, N.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1904-1907. (d) Murakami, H.; Kawabuchi, A.; Kotoo, K.; Kunitake, M.; Nakashima, N. J. Am. Chem. Soc. 1997, 119, 7605-7606.
11. For examples of rotaxane-based device-like systems, see: (a) Bissell, R. A.; Córdova, E.; Kaifer, A. E.; Stoddart, J. F. Nature (London) 1994, 369, 133-137. (b) Anelli, P.-L.; Asakawa, M.; Ashton, P. R.; Bissell, R. A.; Clavier, G.; Górski, R.; Kaifer, A. E.; Langford, S. J.; Mattersteig, G.; Menzer, S.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. Chem. Eur. J. 1997, 3, 1113-1135. (c) Martínez-Díaz, M.-V.; Spencer, N.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1904-1907. (d) Murakami, H.; Kawabuchi, A.; Kotoo, K.; Kunitake, M.; Nakashima, N. J. Am. Chem. Soc. 1997, 119, 7605-7606.
12. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
13. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
14. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
15. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
16. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
17. For some recent examples of rotaxanes from other research groups, see: (a) Li, Z.-T.; Stein, P. C.; Becher, J.; Jensen, D.; Mørk, P.; Svenstrup, N. Chem. Eur. J. 1996, 2, 624-633. (b) Solladié, N.; Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Angew. Chem., Int. Ed. Engl. 1996, 35, 906-909. (c) Vögtle, F.; Dünnwald, T.; Händel, M.; Jäger, R.; Meier, S.; Harder, G. Chem. Eur. J. 1996, 2, 640-643. (d) Anderson, S.; Anderson, H. L. Angew. Chem., Int. Ed. Engl. 1996, 35, 1956-1959. (e) Hannak, R. B.; Farber, G.; Konrat, R.; Krautler, B. J. Am. Chem. Soc. 1997, 119, 2313-2314. (f) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew. Chem., Int. Ed. Engl. 1997, 36, 728-732.
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28. (7) Prior to our research, rotaxane-like species had been synthesized statistically (i.e., involving methods in which noncovalent bonding interactions were not employed as a "synthetic aid") with slippage-type approaches. See: (a) Harrison, I. T. J. Chem. Soc., Chem. Commun. 1972, 231-232. (b) Schill, G.; Beckmann, W.; Schweickert, N.; Fritz, H. Chem. Ber. 1986, 119, 2647-2655. However, in recent times, other researchers have also started to apply the slippage methodology using the supramolecular assistance to synthesis furnished by intermolecular interactions. See: (c) Macartney, D. H. J. Chem. Soc., Perkin Trans. 2 1996, 2775-2778. (d) Händel, M.; Plevoets, M.; Gestermann, S.; Vögtle, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1199-1201.
29. Prior to our research, rotaxane-like species had been synthesized statistically (i.e., involving methods in which noncovalent bonding interactions were not employed as a "synthetic aid") with slippage-type approaches. See: (a) Harrison, I. T. J. Chem. Soc., Chem. Commun. 1972, 231-232. (b) Schill, G.; Beckmann, W.; Schweickert, N.; Fritz, H. Chem. Ber. 1986, 119, 2647-2655. However, in recent times, other researchers have also started to apply the slippage methodology using the supramolecular assistance to synthesis furnished by intermolecular interactions. See: (c) Macartney, D. H. J. Chem. Soc., Perkin Trans. 2 1996, 2775-2778. (d) Händel, M.; Plevoets, M.; Gestermann, S.; Vögtle, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1199-1201.
30. Prior to our research, rotaxane-like species had been synthesized statistically (i.e., involving methods in which noncovalent bonding interactions were not employed as a "synthetic aid") with slippage-type approaches. See: (a) Harrison, I. T. J. Chem. Soc., Chem. Commun. 1972, 231-232. (b) Schill, G.; Beckmann, W.; Schweickert, N.; Fritz, H. Chem. Ber. 1986, 119, 2647-2655. However, in recent times, other researchers have also started to apply the slippage methodology using the supramolecular assistance to synthesis furnished by intermolecular interactions. See: (c) Macartney, D. H. J. Chem. Soc., Perkin Trans. 2 1996, 2775-2778. (d) Händel, M.; Plevoets, M.; Gestermann, S.; Vögtle, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1199-1201.
31. Prior to our research, rotaxane-like species had been synthesized statistically (i.e., involving methods in which noncovalent bonding interactions were not employed as a "synthetic aid") with slippage-type approaches. See: (a) Harrison, I. T. J. Chem. Soc., Chem. Commun. 1972, 231-232. (b) Schill, G.; Beckmann, W.; Schweickert, N.; Fritz, H. Chem. Ber. 1986, 119, 2647-2655. However, in recent times, other researchers have also started to apply the slippage methodology using the supramolecular assistance to synthesis furnished by intermolecular interactions. See: (c) Macartney, D. H. J. Chem. Soc., Perkin Trans. 2 1996, 2775-2778. (d) Händel, M.; Plevoets, M.; Gestermann, S.; Vögtle, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 1199-1201.
32. Fyfe, M. C. T.; Stoddart, J. F. Acc. Chem. Res. 1997, 30, 393-401.
33. Philp, D.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1996, 35, 1154-1196.
34. (10) Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
35. Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
36. Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
37. Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
38. Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
39. Pseudorotaxanes have been defined (Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J. F. J. Chem. Soc., Chem. Commun. 1991, 1677-1679) as the noninterlocked counterparts of rotaxanes, in which one or more linear "filaments" interpenetrate the cavities of one or more macrocyclic species to form inclusion complexes. Notably, as distinct from rotaxanes, these supramolecular complexes are free to dissociate into their separate components since they do not possess bulky stopper groups. For some recent examples, see: (a) Amabilino, D. B.; Anelli, P.-L.; Ashton, P. R.; Brown, G. R.; Córdova, E.; Godínez, L. A.; Hayes, W.; Kaifer, A. E.; Philp, D.; Slawin, A. M. Z.; Spencer, N.; Stoddart, J. F.; Tolley, M. S.; Williams, D. J. J. Am. Chem. Soc. 1995, 117, 11142-11170. (b) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 1996, 1387-1388. (c) Baxter, P. N. W.; Sleiman, H.; Lehn, J.-M.; Rissanen, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1294-1296. (d) Mirzoian, A.; Kaifer, A. E. Chem. Eur. J. 1997, 3, 1052-1058. (e) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068-2070.
40. (a) Ashton, P. R.; Campbell, P. J.; Chrystal, E. J. T.; Glink, P. T.; Menzer, S.; Philp, D.; Spencer, N.; Stoddart, J. F.; Tasker, P. A.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1995, 34, 1865-1869.
41. (b) Ashton, P. R.; Chrystal, E. J. T.; Glink, P. T.; Menzer, S.; Schiavo, C.; Spencer, N.; Stoddart, J. F.; Tasker, P. A.; White, A. J. P.; Williams, D. J. Chem. Eur. J. 1996, 2, 709-728.
42. (c) Glink, P. T.; Schiavo, C.; Stoddart, J. F.; Williams, D. J. Chem. Commun. 1996, 1483-1490.
43. (12) Utilizing this recognition motif, rotaxanes have been synthesized previously by a "threading followed by stoppering" approach. See: (a) Kolchinski, A. G.; Busch, D. H.; Alcock, N. W. J. Chem. Soc., Chem. Commun. 1995, 1289-1291. (b) Ashton, P. R.; Glink, P. T.; Stoddart, J. F.; Tasker, P. A.; White, A. J. P.; Williams, D. J. Chem. Eur. J. 1996, 2, 729-736. (c) Reference 3c.
44. Utilizing this recognition motif, rotaxanes have been synthesized previously by a "threading followed by stoppering" approach. See: (a) Kolchinski, A. G.; Busch, D. H.; Alcock, N. W. J. Chem. Soc., Chem. Commun. 1995, 1289-1291. (b) Ashton, P. R.; Glink, P. T.; Stoddart, J. F.; Tasker, P. A.; White, A. J. P.; Williams, D. J. Chem. Eur. J. 1996, 2, 729-736. (c) Reference 3c.
45. Utilizing this recognition motif, rotaxanes have been synthesized previously by a "threading followed by stoppering" approach. See: (a) Kolchinski, A. G.; Busch, D. H.; Alcock, N. W. J. Chem. Soc., Chem. Commun. 1995, 1289-1291. (b) Ashton, P. R.; Glink, P. T.; Stoddart, J. F.; Tasker, P. A.; White, A. J. P.; Williams, D. J. Chem. Eur. J. 1996, 2, 729-736. (c) Reference 3c.
46. 11 we have noted that secondary dialkylammonium ions form the strongest complexes with DB24C8 in solvents possessing the lowest DNs, i.e., those lacking the ability to donate their electrons into noncovalent bonds.
47. (14) For excellent overviews describing the utility of fuzzy logic in chemistry, see: (a) Rouvray, D. H. Chem. Br. 1995, 31, 544-546. (b) Rouvray, D. H. Chem. Ind. (London) 1997, 60-62.
48. For excellent overviews describing the utility of fuzzy logic in chemistry, see: (a) Rouvray, D. H. Chem. Br. 1995, 31, 544-546. (b) Rouvray, D. H. Chem. Ind. (London) 1997, 60-62.
49. Katritzky, A. R.; Zhao, X.; Hitchings, G. J. Synthesis 1991, 703-708.
50. See the Supporting Information for details.
51. 6a,f-g slippage systems that are much less susceptible to steric effects. For instance, a much broader range of stopper groups can be used for slippage processes involving the larger and more flexible crown ether bis-p-phenylene[34]crown-10.
52. 2 protons appears as a second-order multiplet presumably as a result of vicinal coupling between the two sets of protons.
53. 2 for 92 days.
54. 2SO at 25 °C.
55. + together is stable in low donicity solvents - however, this "lock" is "released" in high donicity solvents.
56. It should be noted that the demeanor of this transitional phase will vary with solvent and temperature, i.e., the degree of rotaxane-like characteristics that a particular species is endowed with depends strongly upon the external conditions it experiences.
57. Adrian, J. C., Jr.; Wilcox, C. S. J. Am. Chem. Soc. 1991, 113, 678-680 and references therein.
58. 16 from the integrated rate equation for an equilibrating reaction between two reactants - in this instance. DB24C8 and the dialkylammonium ion - and a single product-here, the 1:1 pseudorotaxane complex formed between DB24C8 and the dialkylammonium ion.
59. This feature of the LSIMS arises since the dialkylammonium ions are already charged and do not need to be ionized before they are desorbed into the "gas phase" from the matrix. On the other hand, the neutral crown ether molecules are not desorbed to such a great extent since they must be ionized beforehand.
60. 6 mixtures may be considered to be negligible before desorption. On the other hand, cocrystals of DB24C8 with the salts - isolated after the components had been allowed to equilibrate completely - may be considered to consist of pure pseudorotaxane, as verified by X-ray crystallographic analysis (vide supra).
61. 10e the expression "co-conformation" to designate the three-dimensional spatial arrangement of the atoms in supramolecular systems that can be interconverted by bond rotation.
62. Hanson, I. R.; Hughes, D. L.; Truter, M. R. J. Chem. Soc., Perkin Trans. 2 1976, 972-978.
63. Stronger π-π stacking interactions between the two aromatic systems are probably precluded by the bulky i-Pr substituent.
64. Mahamadi, F.; Richards, N. G. K.; Guida, W. C.; Liskamp, R.; Lipton, M.; Caufield, D.; Chang, G.; Hendrickson, T.; Still, W. C. J. Comput. Chem. 1990, 11, 440-467.