摘要:

CrystEngComm, 1999, 1 Solvent provides a trap for the guest-induced formation of 1D host frameworks based upon supramolecular, deep-cavity resorcin[4]arenes Leonard R. MacGillivray,* Jennifer L. Reid and John A. Ripmeester Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6. E-mail: lmacgil@ned1.sims.nrc.ca; Fax: (613) 998-7833; Tel: (613) 993-4406 Received 2nd September 1999, Accepted 16th September 1999, Published 15th October 1999 Co-crystallization of C-methylcalix[4]resorcinarene 1 with 4,4’-bipyridine 2 from ethanol in the presence of either an aromatic or a polycyclic guest yields a wave-like host–guest framework 3·guest {where 3 = 1·2(2), guest = p-chlorotoluene, adamantanone, [2.2]paracyclophane} in which 3 forms by way of guest template effects.Rational design strategies for the construction of crystalline organic solid state materials continue to attract much interest owing, in part, to their promise to deliver functional solids with predictable properties (e.g.recognition, reactivity).1 A major driving force behind the synthesis of these compounds, which typically involve complementary charged and/or neutral molecular components as building blocks, has been the recognition that self-assembly,2 when coupled with the use of supramolecular synthons and geometric considerations,3 can lead to the facile and rapid development of a vast array of chemical networks.Understanding the structural behaviors of these materials, however, through systematic design and analysis, must remain a key issue if the goal of designing solids with desirable functions is to be realized.4 Scheme 1 Our interest in this area partly lies in exploring the properties of such materials. Along these lines, it has recently been shown that co-crystallization of Cmethylcalix[ 4]resorcinarene (1) with 4,4'-bipyridine (2) typically yields a one dimensional (1D), wave-like polymer, 1·2(2) (3), in which the upper rim of 1 is deepened, interacting with four stacking pyridine units of 2, in the form of a resorcinol based supramolecular synthon, by way of four O–H···N hydrogen bonds (Scheme 1).5 This framework, which may be considered a hybrid material since it combines the recognition properties of deep-cavity resorcin[4]arenes along with the degree of structure control offered by a crystal engineering approach, invariably selfincludes in the solid state which, in turn, gives rise to large, polar cavities capable of hosting single5a–b or multiple guest molecules.5c One drawback encountered with this system, however, has been the range of guests which, using the method to prepare these materials, may be included within 3.The low solubility of the octol 1 in, for example, aromatics— molecules that interact favourably with calix[4]arenes6— has limited structural studies involving 3 to guests that solubilize 1 by serving as hydrogen bond acceptors (e.g.acetonitrile, tetrahydrofuran).5 Moreover, it occurred to us that, by selecting a mixture of solvents,1,4 it should be possible to isolate guests selectively within 3 in which one solvent, for example, solubilizes 1 while the other, upon crystallization, induces formation of 3 and is included as the guest.7 If achieved, such a method could allow us to isolate guests within 3 that are solids and/or gases under ambient conditions (e.g.coordination complexes,8 xenon9) and confront separation problems where the inclusion properties of 3 are governed by the recognition properties of the extended cavity of 1. Here, we demonstrate selective guest inclusion using 3. In particular, we reveal that co-crystallization of 1 with 2 from ethanol in the presence of either an aromatic or a polycyclic guest yields 3·guest (where guest = p-chlorotoluene, adamantanone, [2.2]paracyclophane) in which ethanol, a solvent that assembles with 1 and 2 in the absence of these guests to form a skewed-brick framework [1·2(2)·7EtOH·2H2O 10] that is a supramolecular isomer1b of 3, is excluded from the material.Such observationsTable 1 Crystal data, data collection and refinement parameters for 3·(p-chlorotoluene), 3·adamantanone and 3·[2.2]paracyclophanea Property 3·(p-chlorotoluene) 3·adamantanone 3·[2.2]paracyclophane Crystal system Monoclinic Monoclinic Monoclinic Space group P 21/m P 21/m P 21/m a/Å 10.025(1) 9.903(1) 9.846(1) b/Å 23.982(3) 24.813(2) 24.871(2) c/Å 11.375(2) 10.972(1) 11.338(1) b/° 112.707(3) 114.169(2) 105.708(1) U/Å3 2522.9(6) 2459.8(3) 2672.6(4) Dc/g cm–3 1.30 1.36 1.32 Z 2 2 2 No.unique reflections measured 3033 3308 3597 usedb 2276 1694 2260 R 0.045 0.063 0.062 a Mo-Ka radiation ( l = 0.71070 Å). Aromatic, methylene, methine and hydroxy hydrogen atoms were placed as rigid groups with idealized geometry, maximizing the sum of the electron density at calculated hydrogen positions.Structure solutions: SHELXS-86; refinement: SHELXL93 on a Pentium PC. b Inet > 2.0 s(Inet). Click here for full crystallographic data (CCDC no. 1350/1). provide insight into guest template effects that lead to the formation of isomeric host frameworks, which is of much current interest.1b,11 In doing so, we also present details concerning the interaction of 1 with bulky guests (e.g. adamantanone) which, thus far, are unknown and have been determined to template the formation and effect the binding properties of molecular capsules8 and extended-cavity cavitands12 and carcerands.13 When 1 (0.020 g) was co-crystallized with 2 equiv.of 2 (0.011 g) from a boiling aliquot of ethanol (5 mL) in the presence of an approximate 2-fold excess of either guest outlined above, single crystals suitable for X-ray analysis grew, upon cooling, within approximately 1 d. The formulation of each compound was confirmed by single crystal X-ray diffraction (Table 1) and thermogravimetric analysis.A space filling view of the X-ray crystal structure of 3·(p-chlorotoluene) is shown in Fig. 1(a) and a 3D model generated from the structure coordinates is displayed in Fig. 2(a). In a similar manner to 3·acetonitrile,5a the assembly process has yielded a 1D hydrogen bonded wave-like polymer [O···N separations (Å): O(1)···N(1) 2.670(3), O(2)···N(2) 2.754(3)], in which the aromatic guest, which lies across a crystallographic mirror plane, has assembled within 3, interacting with the interior of 1 by way of C– H···p interactions.14 In this orientation, the chloro substituent of the aromatic is positioned above the cavity of 1 such that the guest, in a similar manner to p-tertbutylcalix[ 4]arene·nitrobenzene,15 lies approximately 39° off-axis to the principal rotation axis of the host. In contrast to 1·4(pyridine)·pyridine,5a the aromatic ring of the guest interacts with the walls of 1 such that the benzene moiety lies effectively sandwiched between the extender units of 1, interacting with 2 by way of edge-to-face p–p interactions. 3·(p-chlorotoluene) represents the first example in which a substituted aromatic has been isolated within 3. Further evidence which demonstrates the ability of the components of 3 to entrap guests from ethanol is provided by a complex involving adamantanone. As shown in Fig. 1b, co-crystallization of 1 with 2 from ethanol in the presence of adamantanone has yielded 3·adamantanone (a) (b) (c) Fig. 1 Space filling views of the X-ray crystal structures of 3·guest (inset: structural formula for each guest): (a) 3·(p-chlorotoluene), (b) 3·adamantanone, (c) 3·[2.2]paracyclophane. Color scheme: gray: carbon; red: oxygen; blue: nitrogen; green: chlorine; light gray: hydrogen.(a) (b) (c) Fig. 2 3D models of the X-ray crystal structures of 3·guest: (a) 3·(pchlorotoluene), (b) 3·adamantanone, (c) 3·[2.2]paracyclophane. The crystal structures of 3·adamantanone and 3·[2.2]paracyclophane show a degree of disorder for the guest molecules.This has been eliminated here for the sake of clarity. Color scheme: as for Fig. 1. [O···N separations (Å): O(1)···N(1) 2.739(5), O(2)···N(2) 2.670(5)] in which the bulky12 guest, which lies disordered across a mirror plane, interacts with 1 by way of C–H···p interactions.14 Such observations confirm recent solution phase NOESY experiments involving a series of selffolding cavitands in which a number of adamantane derivatives were determined to interact with a deepened cavity of 1—extended, in contrast to 3, using covalent bonds—by directing alkane functional groups within the cavity of the macrocycle.12 The carbonyl group of the guest, in a similar manner to the chloro substituent of pchlorotoluene, lies completely above the upper rim of 1. To our knowledge, 3·adamantanone represents the first example in which a polycyclic alkane has been isolated within 1 in the solid state.† With the realization that the isolation of p-chlorotoluene and adamantanone within 3 from ethanol could be achieved, we shifted our focus to [2.2]paracyclophane.16 The most strained of the [2.2]cyclophanes,17 this hydrocarbon exhibits a surface with features of both guests described above while crystal structure studies indicate that the molecule is of sufficient size and shape to fit within the deepened cavity of 1 or 3.Being a key compound of the cyclophane family, [2.2]paracyclophane has, notably, been the subject of numerous theoretical and experimental studies which reveal a minimum energy structure in which the two benzene rings of the molecule lie stacked in a faceto- face manner.16 As shown in Fig. 1c, when 1 was co-crystallized with 2 from ethanol in the presence of [2.2]paracyclophane, 3·[2.2]paracyclophane formed [O···N separations (Å): O(1)···N(1) 2.685(4), O(2)···N(2) 2.731(3)] in which the cyclic guest, which lies disordered across a mirror plane, has assembled within 3 such that the hydrocarbon interacts with 1, in a manner similar to 3·adamantanone, by way of C–H···p forces. In this orientation, the aromatic rings of the cyclophane, as in 3·(p-chlorotoluene), lie orthogonal to 2 and approximately 42° off-axis to the principal rotation axis of 1.Notably, the benzene rings of the guest are separated by 3.10 Å which compares favourably to the corresponding separation of the free molecule (3.09 Å).‡18 To our knowledge, 3·[2.2]paracyclophane represents the first example in which a [2.2]cyclophane has been included within a molecular receptor in the solid state.In this report, we have shown that 3 may be induced to form by way of guest template effects, from an appropriate solvent, for the inclusion of guests that are generally too large to fit within the parent receptor 1. We believe that these results widen the scope for studying 3, and related discrete systems,5a since they suggest that 3, owing to the size of the deepened cavity of 1 and the known recognition properties of the receptor,19 may be used as a host for a diverse range of guests which, in turn, could bear relevance in a number of areas including problems of chemical separations and reactivity.20,21 We also note that such observations may be used for screening guests to be included within a hexameric assembly based upon 122 and suggest that the template effects7 reported here may be relevant to the construction of other host frameworks designed by way of a crystal engineering approach and selfassembly. 1,4 Footnotes † To our knowledge, a polycyclic guest has not been observed to assemble within a calix[4]arene in the solid state.‡ The disorder displayed by the [2.2]paracyclophane guest precludes an account of the conformation adopted by the guest within the host lattice. References 1 (a) K. Biradha, D. Dennis, V. A. MacKinnon, C.V. Krishnamohan Sharma and M. J. Zaworotko, J. Am. Chem. Soc., 1998, 120, 11903; (b) T. L. Hennigar, D. C. MacQuarrie, P. Losier, R. D. Rogers and M. J. Zaworotko, Angew. Chem., Int. Ed. Engl., 1997, 36, 972. 2 J.-M. Lehn, Supramolecular Chemistry, VCH, Weinheim, 1995.3 G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311. 4 V. A. Russell, C. C. Evans, W. Li and M. D. Ward, Science, 1997, 276, 575. 5 (a) L. R. MacGillivray and J. L. Atwood, J. Am. Chem. Soc., 1997, 119, 6931; (b) L.R. MacGillivray, K. T. Holman and J. L. Atwood, Cryst. Eng., 1998, 1, 87; (c) L. R. MacGillivray, K. T. Holman and J. L. Atwood, Trans. Am. Crystallogr. Assoc., 1998, 33, 129. 6 C. D. Gutsche, in Calixarenes, ed. J. F. Stoddart, Royal Society of Chemistry, Cambridge, 1989. 7 Y. Tokunaga, D. M. Rudkevich, J. Santamaría, G. Hilmersson and J. Rebek, Jr., Chem. Eur. J., 1998, 4, 1449. 8 R. Meissner, S. Mecozzi and J. Rebek, Jr., J. Am. Chem. Soc., 1997, 119, 77. 9 (a) N. Branda, R. M. Grotzfeld, C. Valdés and J. Rebek, Jr., J. Am. Chem. Soc., 1995, 117, 85; (b) F. Lee, E. Gabe, J. S. Tse and J. A. Ripmeester, J. Am. Chem. Soc., 1988, 110, 6014. 10 L. R. MacGillivray, K. T. Holman and J. L. Atwood, submitted. 11 C. C. Evans, L. Sukarto and M. D. Ward, J. Am. Chem. Soc., 1999, 121, 320. 12 D. M. Rudkevich, G. Hilmersson and J. Rebek, Jr., J. Am. Chem. Soc., 1998, 120, 12216. 13 M. L. C. Quan and D. J. Cram, J. Am. Chem. Soc., 1991, 113, 2754. 14 G. R. Desiraju and T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and Biology, OUP, Oxford, 1999. 15 E. B. Brouwer, G. D. Enright and J. A. Ripmeester, Supramol. Chem., 1996, 7, 7. 16 D. Henseler and G. Hohlneicher, J. Phys. Chem. A, 1998, 102, 10828. 17 D. J. Cram and J. M. Cram, Acc. Chem. Res., 1970, 4, 204. 18 H. Hope, J. Berstein and K. N. Trueblood, Acta Crystallogr., Sect. B, 1972, 28, 1733. 19 D. J. Cram and J. M. Cram, in Container Molecules and Their Guests, ed. J. F. Stoddart, Royal Society of Chemistry, Cambridge, 1994. 20 F. Macásek and J. D. Navratil, Separation Chemistry, Ellis Horwood, New York, 1992. 21 H. Hopf, H. Greiving, P. G. Jones and P. Bubenitschek, Angew. Chem., Int. Ed. Engl., 1995, 34, 685. 22 L. R. MacGillivray and J. L. Atwood, Nature, 1997, 389, 469. Paper 9/07110E CrystEngComm © The Royal Society of Chemistry 1999

ISSN:1466-8033    

DOI:10.1039/a907110e

出版商:RSC    

年代:1999

数据来源: RSC