Paraquat Substituent Effect on Complexation with a Dibenzo-24-crown-8-Based Cryptand Jinqiang Zhang, ² Feihe Huang,* ,² Ning Li, ² Hong Wang, ‡ Harry W. Gibson,* ,‡ Peter Gantzel, § and Arnold L. Rheingold § Department of Chemistry, Zhejiang UniVersity, Hangzhou 310027, People’s Republic of China, Department of Chemistry, Virginia Polytechnic Institute and State UniVersity, Blacksburg, Virginia 24061-0212, and Department of Chemistry and Biochemistry, UniVersity of California, San Diego, La Jolla, California 92093-0358 fhuang@zju.edu.cn; hwgibson@Vt.edu ReceiVed August 2, 2007 Dibenzo-24-crown-8-based cryptand 4 forms 1:1 inclusion complexes with three paraquat derivatives, P1, P2, and P3, as demonstrated by proton NMR spectroscopy and X-ray analysis. However, it was found that methyl-substituted paraquat derivatives, P2 and P3, can bind cryptand 4 more strongly than non-methyl-substituted paraquat derivative P1. The association constants (K a ) were determined in acetone by using a UV-vis titration method to be 5.0 × 10 3 M -1 for 4‚P1, 1.0 × 10 5 M -1 for 4‚P2, and 1.2 × 10 5 M -1 for 4‚P3, respectively. In the solid state, 4‚P2 and 4‚P3 have similar T-type inclusion complexation conformations, which are very different from the pseudorotaxane-type complexation conformation of 4‚P1. Theoretical calculations were done to explain these experimental results. In supramolecular chemistry, the control of the direction of incorporation of a guest into a host (or threading of a host onto a guest) and the relative positional changes that take place within the complexes is very important for the construction of molecular machines and preparation of information storage materials. 1 Fujita et al. observed that the guest rotation can be significantly restricted by the distortion of a cyclodextrin cavity. 1a Schalley et al. found that small structural changes such as the simple exchange of a CH group by an isoelectronic N atom can cause unexpectedly large effects on the deslipping reaction of rotaxanes. 1d Harada et al. revealed that the direction of threading cyclodextrins onto alkyl pyridinium derivatives can be kinetically controlled. 1j Paraquat derivatives (N,N′-dialkyl-4,4′-bipyridinium salts) have been widely used as both hosts and guests in supramo- lecular chemistry. 2 The pursuit of high binding ability with paraquat derivatives and the facile synthesis of the precursors have led us to synthesize dibenzo-24-crown-8-based cryptands. Previously, we found that cis- and trans-dibenzo-24-crown-8- based cryptands form pseudorotaxane-type inclusion complexes with a bis(-hydroxyethyl)-substituted paraquat salt P1. 3 Here we report complexation studies between a cis-dibenzo- 24-crown-8-based cryptand (4) and two methyl-substituted paraquat derivatives (P2 and P3) and the comparison of these two complexes with the complex of cryptand 4 with P1. We found that methyl substitution can affect not only host-guest binding strength but also how the guest is incorporated into the host-guest inclusion complex in the solid state. The cis-dibenzo-24-crown-8-based cryptand 4 3 and paraquat derivatives P1, 4 P2, 5 and P3 6 with different N-substitutents were * Address correspondence to these authors. F.H.: fax +86-571-8795-1895, phone +86-571-8795-3189. H.W.G.: fax +01-540-231-8517, phone +01-540- 231-5902. ² Zhejiang University. ‡ Virginia Polytechnic Institute and State University. § University of California, San Diego. (1) (a) Chen, W. H.; Fukudome, M.; Yuan, D. Q.; Fujioka, T.; Mihashi, K.; Fujita, K. Chem. Commun. 2000, 541-542. (b) Harada, A. Acc. Chem. Res. 2001, 34, 456-464. (c) Tseng, H.-R.; Vignon, S. A.; Stoddart, J. F. Angew. Chem., Int. Ed. 2003, 42, 1491-1495. (d) Felder, T.; Schalley, C. A. Angew. Chem., Int. Ed. 2003, 42, 2258-2260. (e) Onagi, H.; Blake, C. J.; Easton, C. J.; Lincoln, S. F. Chem. Eur. J. 2003, 9, 5978-5988. (f) Badjic, J. D.; Balzani, V.; Credi, A.; Silvi, S.; Stoddart, J. F. Science 2004, 303, 1845-1849. (g) Hernandez, J. V.; Kay, E. R.; Leigh, D. A. Science 2004, 306, 1532-1537. (h) Scarso, A.; Onagi, H.; Rebek, J., Jr. J. Am. Chem. Soc. 2004, 126, 12728-12729. (i) Scarso, A.; Trembleau, L.; Rebek, J., Jr. J. Am. Chem. Soc. 2004, 126, 13512-13518. (j) Oshikiri, T.; Takashima, Y.; Yamaguchi, H.; Harada, A. Chem. Eur. J. 2007, 13, 7091- 7098. (2) Huang, F.; Fronczek, F. R.; Gibson, H. W. J. Am. Chem. Soc. 2003, 125, 9272-9273. Huang, F.; Gibson, H. W.; Bryant, W. S.; Nagvekar, D. S.; Fronczek, F. R. J. Am. Chem. Soc. 2003, 125, 9367-9371. Huang, F.; Jones, J. W.; Slebodnick, C.; Gibson, H. W. J. Am. Chem. Soc. 2003, 125, 14458-14464. Huang, F.; Gibson, H. W. J. Am. Chem. Soc. 2004, 126, 14738-14739. Huang, F.; Nagvekar, D. S.; Slebodnick, C.; Gibson, H. W. J. Am. Chem. Soc. 2005, 127, 484-85. Huang, F.; Switek, K. A.; Zakharov, L. N.; Fronczek, F. R.; Slebodnick, C.; Lam, M.; Golen, J. A.; Bryant, W. S.; Mason, P. E.; Rheingold, A. L.; Ashraf-Khorassani, M.; Gibson, H. W. J. Org. Chem. 2005, 70, 3231-3241. Schmidt-Scha ¨ffer, S.; Grubert, L.; Grummt, U. W.; Buck, K.; Abraham, W. Eur. J. Org. Chem. 2006, 378- 398. Huang, F.; Gantzel, P.; Nagvekar, D. S.; Rheingold, A. L.; Gibson, H. W. Tetrahedron Lett. 2006, 47, 7841-7844. Zong, Q.-S.; Chen, C.-F. Org. Lett. 2006, 8, 211-214. Han, T.; Chen, C.-F. Org. Lett. 2006, 8, 1069- 1072. Huang, F.; Nagvekar, D. S.; Zhou, X.; Gibson, H. W. Macromolecules 2007, 40, 3561-3567. Alcalde, E.; Pe ´rez-Garcı ´a, L.; Ramos, S.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Chem. Eur. J. 2007, 13, 3964-3979. Reviews: Harada, A. Acta Polym. 1998, 49,3-17. Raymo, F. M.; Stoddart, J. F. Chem. ReV. 1999, 99, 1643-1664. Molecular Catenanes and Knots; Sauvage, J.-P., Dietrich-Bucheker, C., Eds.; Wiley: New York, 1999. Mahan, E.; Gibson, H. W. In Cyclic Polymers, 2nd ed.; Semlyen, A. J., Ed.; Kluwer Publishers: Dordrecht, The Netherlands, 2000; pp 415-560. Hubin, T. J.; Busch, D. H. Coord. Chem. ReV. 2000, 200-202,5-52. Panova, I. G.; Topchieva, I. N. Russ. Chem. ReV. 2001, 70, 23-44. Huang, F.; Gibson, H. W. Prog. Polym. Sci. 2005, 30, 982-1018. (3) Gibson, H. W.; Wang, H.; Slebodnick, C.; Merola, J.; Kassel, W. S.; Rheingold, A. L. J. Org. Chem. 2007, 72, 3381-3393. (4) Shen, Y. X.; Engen, P. T.; Berg, M. A. G.; Merola, J. S.; Gibson, H. W. Macromolecules 1992, 25, 2786-2787. (5) Tundo, P.; Kippenberger, D. J.; Politi, M. J.; Klahn, P.; Fendler, J. H. J. Am. Chem. Soc. 1982, 104, 5352-5358. (6) Luong, J. C.; Nadjo, L.; Wrighton, M. S. J. Am. Chem. Soc. 1978, 100, 5790-5795. 10.1021/jo701653q CCC: $37.00 © 2007 American Chemical Society J. Org. Chem. 2007, 72, 8935-8938 8935 Published on Web 10/13/2007