Polycatenated Two-Dimensional Polyrotaxane Net Dongmok Whang and Kimoon Kim* Department of Chemistry and Center for Biofunctional Molecules Pohang UniVersity of Science and Technology (POSTECH) San 31 Hyojadong, Pohang 790-784, South Korea ReceiVed September 3, 1996 One of the fascinating developments in supramolecular chemistry during the last decade is the construction of inter- locked molecular structures such as catenanes, rotaxanes, and knots. 1 Pioneering work by Sauvage and Stoddart demonstrated that such elegant structures can be achieved relatively easily by use of metal templating and/or employment of noncovalent interactions. Concurrent with this has been development of 2D or 3D networks composed of linking metal centers and rigid organic bridging components. 2-9 These metal-organic frame- work materials often exhibit interesting electronic 8 and magnetic properties 9 as well as zeolite-like properties. 4b,5c We have recently reported 10 a simple one-step approach to construct 1D polyrotaxane coordination polymers containing a cyclic “bead” in every structural unit of the polymer chain. It involves the formation of a pseudorotaxane by threading a molecular “bead” with a “string” having suitable functional groups at both ends followed by the formation of a 1D polyrotaxane coordination polymer by allowing the end func- tional groups of the pseudorotaxane to coordinate to the metal centers. Extending this approach, we now constructed an unprecedented polyrotaxane containing cyclic beads threaded on 2D coordination polymer networks. Moreover, the 2D polyrotaxane networks are fully interlocked; therefore, it represents the first example of polycatenated polyrotaxane nets. Herein, we report the self-assembly and X-ray crystal structure of the novel supramolecular species. The formation of the pseudorotaxane 3, by threading cucur- bituril (1) 11 with N,N'-bis(4-pyridylmethyl)-1,4-diaminobutane dihydronitrate (2), 12 followed by the reaction of 3 with AgNO 3 yielded 4 (Scheme 1). 13 The X-ray crystal structure 14 of 4 reveals an unprecedented polyrotaxane in which cucurbituril beads are threaded on a 2D coordination polymer network (Figure 1). The 2D network consists of large edge-sharing chair-shaped hexagons with a Ag(I) ion at each corner and a molecule of 2 at each edge connecting two Ag(I) ions. The mean length of the edge is 20.9 Å, and the mean separation of the opposite corners is 38.0 Å. Each silver ion, sitting on a mirror plane, is coordinated by three “supermolecules” (3) and a nitrate ion in a distorted tetrahedral geometry. 15 A cucurbituril bead is held tightly at the middle of each edge of the hexagon by strong hydrogen bonds between the protonated amine nitrogen atoms of the string (2) and the oxygen atoms of cucurbituril. The 2D polyrotaxane network forms layers stacked on each other along the [011] direction with a mean interplane separation of 9.87 Å (Figure 2). There is another 2D polyro- taxane network (denoted B) almost perpendicular to the first one (denoted A). The dihedral angle between the mean planes of the two networks A and B is 69.34°. These networks interpenetrate with full interlocking of the hexagons, as il- (1) For recent review articles, see: (a) Sauvage, J.-P. Acc. Chem. Res. 1990, 23, 319. (b) Amabilino, D. B.; Stoddart, J. F. Chem. ReV. 1995, 95, 2725. (c) Philp, D.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1996, 35, 1154. 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Angew. Chem., Int. Ed. Engl. 1995, 34, 207. (b) Yaghi, O. M.; Li, H. J. Am. Chem. Soc. 1995, 117, 10401. (c) Yaghi, O. M.; Li, G.; Li, H. Nature 1995, 378, 703. (d) Yaghi, O. M.; Li, H. J. Am. Chem. Soc. 1996, 118, 295. (6) (a) Fujita, M.; Kwon, Y. J.; Washizu, S.; Ogura, K. J. Am. Chem. Soc. 1994, 116, 1151. (b) Fujita, M.; Kwon, Y. J.; Sasaki, O.; Yamaguchi, K.; Ogura, K. J. Am. Chem. Soc. 1995, 117, 7287. (7) (a) Soma, T.; Yuge, H.; Iwamoto, T. Angew. Chem., Int. Ed. Engl. 1994, 33, 1665. (b) Goodgame, D. M. L.; Menzer. S.; Smith, A. M.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1995, 34, 574. (c) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi, A. Angew. Chem., Int. Ed. Engl. 1996, 35, 1088. (8) Simon, J.; Andre´, J.-J.; Skoulios, A. New J. Chem. 1986, 295. (9) (a) Real, J. A.; Andre´s, E.; Mun˜oz, M. C.; Julve, M.; Granier, T.; Bousseksou, A.; Varret, F. Science 1995, 268, 265. (b) Stumpf, H. O.; Ouahab, L.; Pei, Y.; Grandjean, D.; Kahn, O. Science 1993, 261, 447. (c) Miyasaka, H.; Matsumoto, N.; Oh kawa, H.; Re, N.; Gallo, E.; Floriani, C. Angew. Chem., Int. Ed. Engl. 1995, 34, 1446. (10) Whang, D.; Jeon, Y.-M.; Heo, J.; Kim, K. J. Am. Chem. Soc. 1996, 118, 11333. (11) For reviews on cucurbiturilm, see: (a) Mock, W. L. Top. Curr. Chem. 1995, 175, 1. (b) Cintas, P. J. Inclusion Phenom. Mol. Recognit. Chem. 1994, 17, 205. (12) Colautti, A.; Maurich, V. Boll. Chim. Farm. 1972, 111, 593. (13) Cucurbituril (1) decahydrate (1.00 g; 0.86 mmol) and N,N′-bis(4- pyridylmethyl)-1,4-diaminobutane dihydronitrate 2 (0.207 g; 0.60 mmol) were added to water (20 mL). After overnight stirring, undissolved cucurbituril was filtered. The 1 H NMR spectrum of the filtrate (using D2O) indicates the formation of a 1:1 complex (pseudorotaxane 3) of 1 and 2. Neither free 1 nor free 2 was detected in the filtrate by 1 H NMR spectroscopy. A 0.2 M solution of AgNO3 in methanol was layered over the filtrate in a diffusion tube to produce colorless, plate-like, X-ray quality crystals of 4 in a week (37%). Anal. Calcd for AgC78H90N46O30‚10H2O: C, 38.39; H, 4.54; N, 26.40. Found: C, 38.62; H, 4.51; N, 26.12. The elemental analysis sample was dried under vacuum overnight. When a solution of Ag(C7H7SO3) in methanol was used instead of AgNO3 in the above procedure crystals of 5 were produced (29%). Anal. Calcd for AgC73H81N28O21S3‚9H2O: C, 42.73; H, 4.86; N, 19.11; S, 4.69. Found: C, 43.10; H, 5.32; N, 18.73; S, 5.10. (14) Crystal data of 4: [Ag2(C16H24N4)3‚(C36H36N24O12)3](NO3)8‚40H2O, fw ) 5240.30, orthorhombic, Cmca, a ) 31.408(3) Å, b ) 32.508(4) Å, c ) 22.479(3) Å, V ) 22951(5) Å 3 , Z ) 4, dcalcd ) 1.517 g cm -3 , T ) 293 K, Enraf-Nonius CAD4 diffractometer, Mo KR (λ ) 0.710 73), μ ) 2.88 cm -1 . The structure was solved by direct methods (SHELXS-86). All non- hydrogen atoms were refined anisotropically (SHELXL-93). Final full- matrix least-squares refinement on F 2 with all 6266 reflections and 637 variables converged to R1 (I > 2σ(I)) ) 0.118, wR2 (all data) ) 0.383 and GOF ) 1.08. Crystal data of 5: [Ag(C16H24N4)‚(C36H36N24O12)](C7H7O3S)3‚- 11H2O, fw ) 2100.89, triclinic, P1h,a ) 15.001(2) Å, b ) 15.491(2) Å, c ) 23.580(2) Å, R) 91.896(10)°,  ) 105.538(9)°, γ ) 116.707(13)°, V ) 4641(1) Å 3 , Z ) 2, dcalcd ) 1.504 g cm -3 , T ) 293 K, Mo KR (λ ) 0.71073), μ ) 3.82 cm -1 . Final full-matrix least-squares refinement on F 2 with all 9913 reflections and 987 variables converged to R1 (I > 2σ(I)) ) 0.111, wR2 (all data) ) 0.330 and GOF ) 1.06. (15) A PLUTO diagram of the asymmetric unit of 4 along with atom- labeling scheme is given in Supporting Information. Scheme 1 451 J. Am. Chem. Soc. 1997, 119, 451-452 S0002-7863(96)03096-X CCC: $14.00 © 1997 American Chemical Society