J O U R N A L O F C H E M I S T R Y Materials Crystal engineering using polyphenols. Host–guest behaviour of planar ribbons in C-methylcalix[4]resorcinarene–4,4¾-trimethylenedipyridine –methanol (1/2/0.5), and capture of 2,2¾-bipyridyl molecules by paired calixarene bowls in C-methylcalix[4]- resorcinarene-2,2¾-bipyridyl–methanol–water (1/1/1/1.16) George Ferguson,a Christopher Glidewell,b* Alan J.Lough,c Gordon D. McManusb and Paul R. Meehana aDepartment of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1 bSchool of Chemistry, University of St Andrews, St Andrews, Fife, UK KY16 9ST cLash Miller Chemical Laboratories, University of Toronto, Toronto, Ontario, Canada M5S 1A1 Received 4th June 1998, Accepted 13th August 1998 Co-crystallisation of the rccc isomer of C-methylcalix[4]resorcinarene 1 with 4,4¾-trimethylenedipyridine from methanol yields a solvated 152 adduct 2 in which the resorcinarene acts as a quadruple donor and the dipyridines both act as double acceptors, in O–H,N hydrogen bonds.The supramolecular structure consists of linear and nearly planar ribbons with the bowls of the resorcinarene units in one ribbon acting as hosts towards the -(CH2)3- spacer units of a neighbouring ribbon, acting as guests.Co-crystallisation of the same resorcinarene 1 with 2,2¾- bipyridyl yields a doubly solvated 151 adduct resorcinarene–2,2¾-bipyridyl–methanol–water (1/1/1/1.16) 3. The resorcinarene, methanol and water molecules combine by means of multiple O–H,O hydrogen bonds to form paired, essentially-planar two-dimensional nets in which centrosymmetric pairs of resorcinarene bowls act as selfassembled carcerands to form large cavities in which pairs of 2,2¾-bipyridyl molecules are held by a combination of O–H,N and C–H,O hydrogen bonds.The design and construction of self-assembled microporous NC5H4C5H4N to continuous {2, 2, 1} interweaving in molecular solids is an attractive target in crystal engineering.[Fe(C5H4COC6H4OH)2]. Such interweaving arises because One approach which has proved successful for the formation the reticulations in the nets are large compared with the of structures containing isolated linear channels formed by the eVective diameters of the molecular strands forming the nets. self-assembly of small molecular building blocks, via hydrogen- To prevent interweaving in supramolecular systems containing bond formation, is the construction of cyclic fragments which large rings, it is necessary to increase the thickness of the can then be induced to stack, in register, to form the channels.strands relative to the hole size; this principle has been demon- Thus 4,4¾-sulfonyldiphenol, O2S(C6H4OH)2, and piperazine strated in 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) form such a channel structure when co-crystallised from butane/(CH2)6N4 (1/1), where the nets contain alternating either methanol or acetonitrile: pairs of phenolate anions R6 6(40) and R6 6(60) rings, but are not interwoven because of [HOC6H4SO2C6H4O]- form hydrogen-bonded R2 2(24) the presence of the tert-butyl groups in the tris-phenol.9 rings1,2† which are bound into parallel linear stacks by piperaz- Seeking to develop further the use of large and stericallyinium dications [C4H12N2]2+.Within each stack there is a demanding molecular building blocks, we have turned our channel of cross-sectional area ca. 14 A° 2, too small to accom- attention to polyhydroxylated calixarenes, specifically those modate methanol molecules but large enough to hold derived from resorcinol, 1.In general, two isomeric forms of acetonitrile molecules.3 The use of this approach for the for- C-alkylcalix[4]resorcinarenes can be obtained, a C4v (rccc or mation of wider channels requires the construction of larger crown10,11) isomer, 1a, and a C2h (rctt or chair) isomer, 1b, but rings, and we have reported the formation of nets of despite this structural versatility and the ease of synthesis, R4 4(32) rings in pure O2S(C6H4OH)2,4 of R4 4(40) rings rather little use of such compounds has hitherto been made in [Fe(C5H4COC6H4OH)2],5 and of R6 6(48) rings in in crystal engineering.C-Methylcalix[4]resorcinarene, 1a CH3C(C6H4OH)3/(CH2)6N4 (1/1),6 while nets of R12 12(126) with R=Me (2,8,14,20-tetramethylpentacyclo[19.3.1.13,7.19,13 rings are formed in CH3C(C6H4OH)3/NC5H4C5H4N (2/3).7 .115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23- However, in all these examples the nets are interwoven, with dodecaen-4,6,10,12,16,18,22,24-octol, C32H32O8), has been the interweaving characterised by diVering degrees of shown12 to form a 152 hydrogen-bonded adduct with 4,4¾- complexity, ranging from pairwise {4, 2, 1}8 interweaving of bipyridyl which entraps acetonitrile, but the gross suprathe nets in O2S(C6H4OH)2 and CH3C(C6H4OH)3/ molecular structure in this product does not exploit the (CH2)6N4 via {10,10,9} interweaving in CH3C(C6H4OH)3/ hydrophobic nature of the calixarene bowl.We have now studied the solid-state adducts, 2 and 3 respectively, of this same C-methylcalix[4]resorcinarene with †Pattern designators1,2 for graph sets are of the general type Ga d(r); the descriptor G may be C (chain), D (dimer, or other finite set), R both an extended-reach bipyridyl, 4,4¾-trimethylenedipyridine (ring), or S (self ) (i.e. an intramolecular hydrogen bond).The degree and with 2,2¾-bipyridyl.We reasoned that addition of an r represents the total number of atoms in a ring or in the repeating aliphatic spacer group between the pyridine units in 4,4¾- unit of a chain, the superscript a indicates the number of hydrogenbipyridyl would lead to chain-formation in 2 of a type similar bond acceptors and the subscript d indicates the number of hydrogento that formed by 4,4¾-bipyridyl itself,12 but that additionally bond donors.Thus, for example, the hydrogen-bond pattern in the familiar carboxylic acid dimer is represented as R2 2(8). the C–H,p(arene) interactions between the trimethylene J. Mater. Chem., 1998, 8(11), 2339–2345 2339two half-occupied equivalent sites related by a two-fold rotation axis parallel to [010]. Within one of the molecules of the dipyridine, the heterocyclic ring containing atom N71 was found to be disordered.The diVraction data were most satisfactorily fitted by a model which assigned to this ring two equallypopulated sets of atom-sites, generated by rotation of the ring about the N71,C74 vector, such that the two ring-orientations are inclined at 35.7(4)o to one another. The orthorhombic space group Pbca was uniquely assigned for compound 3 from the systematic absences: 0kl absent when k=2n+1, h0l absent when l=2n+1, hk0 absent when h=2n+1.The asymmetric unit contains one molecule each of the resorcinarene, 2,2¾- bipyridyl and water, all in general positions and fully ordered, together with a disordered molecule of methanol. The water and the methanol molecules in 3 both participate in the spacer units in one chain and the calixarene bowls of neighhydrogen- bonding scheme: there is also a partially-occupied bouring chains could be suYcient to control the mutual water site, with s.o.f.of 0.159(7), which is not involved in any arrangement of the chains of 2 in the solid state. Similarly, close contacts with the rest of the structure. For both 2 and with 2,2¾-bipyridyl in compound 3, we reasoned that the 3, all the hydrogen atoms of the resorcinarene and the bipyri- location of the hydrogen-bond acceptor sites in the bipyridyl dine components, as well as those of the water molecule and would preclude the formation of a simple chain motif, possibly the hydroxy hydrogen in the methanol in 3, were located from leading to a two- or three-dimensional system instead, resulting diVerence maps.All hydrogen atoms located in this way were from some alternative mode of linkage of neighbouring included in the final refinements as riding atoms with O–H resorcinarene units by the bipyridyl molecules. 0.820 A° and C–H in the range 0.93–0.98 A° . Supramolecular analysis of the refined structures was made with the aid of Experimental PLATON;20 the figures were prepared with the aid of ORTEPII19 and PLATON.20 Details of the hydrogen-bonding schemes The C4v isomer of C-methylcalix[4]resorcinarene 1a was are in Table 2 and 3.Fig. 1 and 3 show the asymmetric units prepared by the literature method.13 Repeated attempts to of compounds 2 and 3 respectively, and Fig. 2, 4 and 5 recrystallise this compound from methanol or from aqueous illustrate aspects of the supramolecular architectures.methanol invariably provided microcrystalline or powdery Full crystallographic details, excluding structure factors, material for which microanalysis and 1H NMR consistently have been deposited at the Cambridge Crystallographic Data indicated 6–8 molecules of water per calixarene unit.Co- Centre (CCDC). See Information for Authors, J. Mater. crystallisation of this resorcinarene with either 4,4¾-trimethyl- Chem., 1998, Issue 1. Any request to the CCDC for this enedipyridine or 2,2¾-bipyridyl from methanol solutions yielded material should quote the full literature citation and the 2 and 3 respectively, regardless of the molar ratio of resorcinarreference number 1145/115.ene to dipyridine originally taken, within the range of 151 to 154. Analysis for 2, resorcinarene·4,4¾-trimethylenedipyridine ·MeOH (1/2/0.5): found C, 73.5; H, 6.6; N, 5.6%; C58.5H62N4O8.5 requires C, 73.4; H 6.5; N, 5.8%; for 3, Results and discussion resorcinarene·2,2¾-bipyridyl·MeOH·H2O (1/1/1/1.16): found Co-crystallisations C, 68.6; H, 6.3; N, 3.7%; C43H46.32N2O10.16 requires C, 68.5; H, 6.2; N, 3.7%.Crystallisation of the resorcinarene from neat The C4v isomer of C-methylcalix[4]resorcinarene, when copyridine at room temperature yielded the 154 adduct 4 (Found: crystallised with 4,4¾-trimethylenedipyridine from solutions in C, 72.0; H, 6.2; N, 6.4%; C52H52N4O8 requires C, 72.5; H, methanol, provided the expected 152 adduct 2, although 6.1; N, 6.5%), while co-crystallisation with 4,4¾-bipyridyl from solvated with one half a molecule of methanol per resorcinarsolutions in either methanol or ethanol, with input molar ene.The 152 stoichiometry was expected on the grounds that ratios of resorcinarene to bipyridyl in the range 151 to 154, this isomer of the resorcinarene generally exhibits four intraconsistently yielded a microcrystalline material 5 of composi- molecular O–H,O hydrogen bonds,12,21–23 and hence acts as tion resorcinarene5bipyridyl5water (1/2/3) (Found C, 68.3; H, a donor of only four intermolecular hydrogen bonds, while 5.8; N, 6.0%: C52H54N4O11 requires C, 68.5; H, 6.0; N, 6.2%).the 4,4¾-trimethylenedipyridine acts as a double acceptor. However, 2,2¾-bipyridyl was not expected to act as a simple X-Ray crystallography bridging unit between pairs of resorcinarene molecules in the manner of 4,4¾-bipyridyl12 or 4,4¾-trimethylenedipyridine, com- Crystals of compounds 2 and 3 suitable for single-crystal Xpound 2, because of the closeness of the two nitrogen atoms ray diVraction were selected directly from the analytical and the likely orientation of the resulting O–H,N hydrogen samples. Details of the X-ray experimental conditions, cell bonds, regardless of the twist about the central C–C bond of data, data collection and refinements, and the computer prothis bipyridyl.Accordingly the observed 151 ratio in 3 was grams employed14–20 are summarised in Table 1. For comnot unexpected. pound 3, a data set collected using a CAD-4 diVractometer at The degree of solvation and guest-inclusion in the calixarene room temperature provided the essential features of the struccavity is unpredictable and varies quite subtly with crystallis- ture, but the ratio of observations to parameters was very low.ation conditions. Thus when C-methylcalix[4]resorcinarene Accordingly a second data set was collected at low temperature was crystallised by dissolution in boiling pyridine, followed by using a Nonius Kappa-CCD diVractometer as described in cooling, a 156 adduct was produced in which four molecules Table 1.of pyridine are hydrogen bonded to the resorcinarene, a fifth For compound 2, the orthorhombic space group Pbcn was is included in the calixarene cavity and the sixth is outside the uniquely assigned from the systematic absences: 0kl absent calixarene·(pyridine)4 complex as solvent of crystallisation.12 when k=2n+1, h0l absent when l=2n+1, hk0 absent when By contrast, crystallisation of the same calixarene from pyri- (h+k)=2n+1.As well as the resorcinarene and two molecules dine wholly at room temperature yielded just a 154 complex of 4,4¾-trimethylenedipyridine in general positions, the structure analysis also revealed methanol molecules disordered over 4; while structure determination for 4 has so far been precluded 2340 J.Mater. Chem., 1998, 8(11), 2339–2345Table 1 Experimental details Compound 2 Compound 3 Crystal data Chemical formula C58.5H62N4O8.5 C43H46.32N2O10.16 Chemical formula weight 957.12 754.35 Cell setting Orthorhombic Orthorhombic Space group Pbcn Pbca a/A° 25.7972(4) 13.9906(4) b/A° 16.5089(3) 17.8679(5) c/A° 23.7612(4) 29.3316(7) V/A° 3 10119.5(3) 7332.4(3) Z 8 8 F (000) 4072 3199.2 Dx/Mg m-3 1.256 1.367 Dm/Mg m-3 not measured not measured Radiation type Molybdenum Ka Molybdenum Ka Wavelength/A° 0.71073 0.71073 No. of reflections for cell parameters 10286 7408 h range (°) 1.70–26.37 1.97–26.37 m/mm-1 0.084 0.098 Temperature/K 150(1) 150(1) Crystal form Block Plate Crystal size/mm 0.42×0.37×0.36 0.25×0.20×0.05 Crystal colour Brownish-yellow Brownish-yellow Data collection DiVractometer Kappa-CCD Kappa-CCD Data collection method 360×1° w scans 360×1° w scans Absorption correction none none No.of measured reflections 69128 42325 No. of independent reflections 10286 7408 No. of observed reflections 4980 4173 Criterion for observed reflections I>2s( I) I>2s(I ) Rint 0.031 0.031 hmax (°) 26.37 26.37 Range of h, k, l -32AhA32 -17AhA17 -19AkA20 -22AkA22 -29AlA29 -36AlA36 Intensity decay (%) no decay no decay Refinement Refinement on F 2 F 2 R[F 2>s(F 2)] 0.0465 0.0505 wR(F 2) 0.1312 0.1433 S 0.865 0.916 No.of reflections used in refinement 10286 7408 No.of parameters used 671 505 H-atom treatment constr constr k in w=1/[s2(Fo2)+(kP )2] 0.0712 0.0815 [P=(Fo2+2Fc2)/3] (D/s)max 0.001 0.000 Drmax/e A° -3 0.312 0.649 Drmin/e A° -3 -0.347 -0.368 Extinction method SHELXL None Extinction coeYcient 0.00073(12) — Source of atomic scattering factors International Tables for Crystallography (Vol. C) Computer programs Data collection Kappa-CCDa Cell refinement DENZOb Data reduction DENZO Structure solution SHELXS97c Structure refinement NRCVAX96d and SHELXL97e Molecular graphics NRCVAX96, ORTEPf and PLATONg Preparation of material for publication NRCVAX96 and SHELXL97 aRef. 14.bRef. 15. cRef. 16. dRef. 17. eRef. 18. fRef. 19. gRef. 20. by a lack of suitable crystals, the most plausible interpretation during crystallisation.The extreme sensitivity of structure in these systems to the solvent employed for crystallisation is of the 154 stoichiometry is in terms of the hydrogen-bonded adduct previously observed,12 but without the cavity-included further illustrated by the resorcinarene itself, for which both aquated cubic (space group I432, Z=12)24 and butanone- and the solvating pyridine units.Similarly, co-crystallisation of C-methylcalix[4]resorcinarene with 4,4¾-bipyridyl from solvated monoclinic (space group P21/m, Z=2)22 forms have been reported. acetonitrile solution yielded a 152 adduct, with acetonitrile trapped in the calixarene cavity;12 use of methanol or ethanol as solvent, as here, produced again the 152 adduct, but now The supramolecular structure of 2 solvated not by either alcohol, but by three molecules of water per calixarene, compound 5; the water in 5 has presumably In compound 2, the resorcinarene component forms four asymmetric intramolecular O–H,O hydrogen bonds (Fig. 1 been captured either from the solvent, or from the atmosphere J. Mater. Chem., 1998, 8(11), 2339–2345 2341Table 2 Hydrogen-bond dimensions in compound 2 and Table 2): the orientation of these hydrogen bonds is such as to reduce the overall symmetry of this component from C4v Bond D H A D,A/A° H,A/A° D–H,A (°) to C2v.There are thus four hydroxy groups available on each resorcinarene molecule in compound 2 for the formation of a O23 H23 O15 2.749(2) 1.94 171 intermolecular O–H,N hydrogen bonds to the 4,4¾-trimethyl- b O25 H25 O33 2.721(2) 1.92 165 c O43 H43 O35 2.753(2) 1.94 169 enedipyridine component: four of the eight oxygen atoms in d O45 H45 O13 2.838(2) 2.04 166 the resorcinarene component thus act as both donor and e O13 H13 N51 2.738(2) 1.93 169 acceptor of hard hydrogen bonds,25 and the other four as f O15 H15 N71 2.614(2) 1.82 162 donor only.The disordered methanol molecules, however, do g O33 H33 N81a 2.639(2) 1.85 160 not play any part in the hydrogen bonding in 2: the oxygen h O35 H35 N61a 2.734(2) 1.93 167 atom forms no non-bonded contacts significantly shorter than i C53 H53 O43b 3.397(3) 2.59 146 j C65 H65 O45b 3.399(3) 2.51 159 the sum of the van der Waals radii with any of the other atoms in the structure.Oxygen atoms O13 and O15 form Symmetry codes: ax, y, -1+z; b0.5-x, 1.5-y, 0.5+z.O–H,N hydrogen bonds with N51 and N71 respectively, within the asymmetric unit (Fig. 1 and Table 2), while atoms O33 and O35 at (x, y, z) form hydrogen bonds with N81 and N61 respectively in the neighbouring unit at (x, y, -1 +z). Table 3 Hydrogen-bond dimensions in compound 3 The basic supramolecular structure thus comprises a ribbon running parallel to the [001] direction and generated by Bond D H A D,A/A° H,A/A° D–H,A (°) translation: eight such ribbons run through the unit cell.This essentially flat ribbon propagated by translation may be com- a O13 H13 O45 2.741(2) 1.94 166 pared with the highly-puckered zig-zag ribbon in the analogous b O15 H15 O23 2.808(2) 2.04 155 c O25 H25 O33 2.749(2) 1.94 169 adduct formed by the same resorcinarene with 4,4¾-bipyridyl,12 da O35 H35 O43 3.191(3) 2.56 134 where the ribbon is propagated by the action of a two-fold e O43 H43 O8 2.705(3) 1.90 166 screw axis.f O45 H45 O7 2.759(3) 1.97 162 The eight identical ribbons in the structure of compound 2 g O7 H7 N51 2.727(3) 1.64 167 are connected together in pairs. The aliphatic spacer unit h O23 H23 O7b 2.685(3) 1.89 164 C57–C59 (Fig. 1 and 2) of the dipyridine at (x, y, z) fits across i O33 H33 N61c 2.680(2) 1.88 165 ja O35 H35 O25d 2.794(2) 2.22 128 the rim of the resorcinarene bowl in the neighbouring ribbon, k O8 H81 O35e 2.972(3) 2.05 144 at (0.5-x, 1.5-y, 0.5+z), while the aliphatic spacer C57–C59 l O8 H82 O33d 2.894(2) 1.94 138 of this latter unit fits across the bowl at (x, y, 1+z) in the first m C48 H48B O13f 3.127(3) 2.52 121 ribbon.Thus pairs of ribbons, in this case related by the action n C66 H66 O25c 3.310(3) 2.56 139 of the 21 screw axis at (0.25, 0.75, z), are held closely together: aHydrogen bonds d and j are part of a three-centre system with O43 aliphatic spacers in one ribbon are guests in the calixarene and O25d as the two acceptors: the angle O43,H35,O25c is 94° and bowls of the neighbouring ribbon.Additional stabilisation of the sum of the three hydrogen-bond angles around H35 is thus 360°. these inter-ribbon interactions arises from the precise align- Symmetry codes: b0.5-x, -0.5+y, z. c-x, -y, -z. d-0.5-x, 0.5+y, z. e0.5+x, 0.5-y, -z. f-0.5+x, y, 0.5-z. ment of a pair of aromatic C–H bonds in the dipyridine of one ribbon, acting as hydrogen-bond donors to a pair of oxygen atoms in the neighbouring ribbon.Thus atoms C53 and C65 in the dipyridine at (x, y, z), i.e. one carbon atom in each heteroaromatic ring of this dipyridine, act as hydrogen- Fig. 1 The asymmetric unit in compound 2, showing the atom- Fig. 2 View of part of the structure of 2, showing the aliphatic spacer unit C57–C59 of one ribbon fitting across the resorcinarene bowl in labelling scheme.Displacement ellipsoids are drawn at the 30% probability level. the neighbouring ribbon. 2342 J. Mater. Chem., 1998, 8(11), 2339–2345Fig. 4 Stereoview of part of the structure of 3, showing one of the two-dimensional nets generated solely by O–H,O hydrogen bonds with the centrosymmetric pairs of resorcinarene bowls.Fig. 3 The asymmetric unit of compound 3, showing the atomlabelling scheme. Displacement ellipsoids are drawn at the 30% probability level. bond donors to two atoms, O43 and O45 respectively, on the same aromatic ring of the resorcinarene at (0.5-x, 1.5-y, 0.5+z). These C–H,O hydrogen bonds to the rim of the resorcinarene represent a form of intermolecular bonding, soft hydrogen bonds with oxygen as acceptor, which has not hitherto been widely recognised or exploited in this area.Supramolecular structure of 3 The asymmetric unit of compound 3 contains one molecule each of the resorcinarene, 2,2¾-bipyridyl, water and methanol (Fig. 3): all four components participate in the formation of hard hydrogen bonds. The resorcinarene forms four intramolecular O–H,O hydrogen bonds, arranged not in the usual C2v configuration, but with only C1 symmetry (Fig. 3 and Table 3). The other four hydroxy groups, associated with O23, O33, O43 and O45, all form hydrogen bonds with other components of the structure: O23 and O45 form O–H,O bonds with methanol molecules, O33 with a bipyridyl molecule, and O43 with a water molecule; in addition, atom O35 by Fig. 5 View of part of the structure of 3, showing the placing of pairs forming a bifurcated (three-centre) hydrogen bond is linked of 2,2¾-bipyridyl molecules within the cavity formed by a pair of also to another resorcinarene molecule. Hence each resorcinarresorcinarene molecules. ene acts as a quintuple donor of hydrogen bonds to, and as a triple acceptor from, other molecules. The methanol molecule acts both as hydrogen-bond donor, to a bipyridyl, and as a pairs, there are no contacts which are significantly shorter double acceptor, from two diVerent resorcinarene molecules.than the sum of the van der Waals radii. The water molecule acts as a single acceptor from one resorcinarene and as donor to two others. Finally, the bipyridyl Hydrogen-bonding motifs molecule acts as a double acceptor in O–H,N hydrogen bonds, where the two donors are methanol and a resorcinarene All of the four independent intramolecular O–H,O hydrogen molecule.Within the asymmetric unit (Fig. 3) atoms O43 and bonds in compound 2, labelled a–d in Table 2, form cyclic O45 act as donors to water and methanol respectively; meth- motifs, whose graph set descriptor is S(8),1,2 while each of anol in turn acts as donor to atom N51 of the bipyridyl, while the O–H,N and C–H,O hydrogen bonds, e–h and i and j the other ring of the bipyridyl (N61 and C62–C66) lies over respectively in Table 2, is of type D.For the hard hydrogen the rim of the calixarene. The hydrogen bonding is thus much bonds, O–H,O and O–H,N, it is necessary to consider more complex in compound 3 than in compound 2.four-fold combinations of independent hydrogen bonds in The overall supramolecular structure of compound 3 order to describe the overall supramolecular structure (Fig. 1 consists of paired two-dimensional rhomboidal nets generated and 2). The combination of the four O–H,O hydrogen solely by intermolecular O–H,O hydrogen bonds. These nets bonds a–d gives N4=R4 4(24), while the combination of the are aligned so that pairs of calixarenes, which lie across centres four independent O–H,N hydrogen bonds e–h gives of inversion with their hydroxylic rims close to one another, N4=R4 4(36).There are also two independent combinations of generate large cavities in which pairs of 2,2¾-bipyridyl molecules O–H,O and O–H,N hydrogen bonds, defining the two are held (Fig. 4 and 5). Such a pair of nets utilises only half edges of the ribbon: each of (a+b+f+g) and (c+d+e+h) the contents of the unit cell and there are two such paired gives N4=C4 4(22). The inter-ribbon soft C–H,O hydrogen nets, one lying in the domain -0.27<z<+0.27 and the other bonds, i and j, combine to give a cyclic motif with N2=R2 2(14). in the domain +0.23<z<+0.77.Between the independent J. Mater. Chem., 1998, 8(11), 2339–2345 2343In compound 3, the water molecule at (x, y, z) acts as of the intra- and inter-molecular hydrogen bonds formed by the hydroxy groups around the rim, in particular those involv- hydrogen-bond donor, via H81 (Table 3), to atom O35 of the ing guest species within the calixarene bowl.The shape of the resorcinarene molecule at (0.5+x, 0.5-y, -z), while the calixarene bowl is most simply described in terms of the angles water molecule at (0.5+x, 0.5-y, -z) in turn acts as donor made by each of the aromatic rings Cnm (n=1–4; m=1–6) via H81 to atom O35 at (1+x, y, z). Propagation of this with a reference plane, conveniently chosen as the plane interaction thus produces a continuous chain running parallel defined by the atoms Cn7 (n=1–4).In both compounds 2 and to [100] and generated by the action of a two-fold screw axis: 3 these angles are alternately ca. 40° and ca. 65°, showing that this chain, built up from hydrogen bonds d, e and k in Table 3, the skeletal conformation is, in each case, much closer to C2v is thus a spiral and has graph-set descriptor N3=C3 3(6).The symmetry than to the idealised C4v. A complementary measure same water molecule at (x, y, z) also acts as hydrogen-bond of the deviation of the bowl from idealised symmetry is donor, this time via H82, to atom O33 of the resorcinarene at provided by the O,O distances in the intramolecular O–H,O (-0.5-x, 0.5+y, z), and the water at (-0.5-x, 0.5+y, z) in hydrogen bonds (Table 2 and 3).turn acts as donor to atom O33 at (x, 1+y, z). Propagation There are two independent molecules of 4,4¾-trimethylenedi- of this hydrogen-bond sequence (hydrogen bonds d, e and l pyridine in compound 2: in both, the central aliphatic spacer of Table 3) produces a zig-zag chain with N3=C3 3(10), generunit is in the fully-extended all-trans conformation. 4,4¾- ated by the glide plane and running parallel to [010]. The Trimethylenedipyridine itself does not appear in the Cambridge interaction of these two chain motifs generates a two-dimen- Structural Database,29 but the bond lengths and angles found sional, rhomboidal network parallel to the (001) plane. Each here in compound 2 are unexceptional. In compound 3, the chain utilises just one O–H bond of the water molecules, two pyridyl rings are inclined to one another at an angle of O–H81 in the [100] direction and O–H82 in the O–H82 40.4(1)°: the N,N bite distance, 2.806(3) A° , is thus rather direction, so that the intermediate water molecules in each larger than the 2.69 A° expected for a planar 2,2¾-bipyridyl chain still have hydrogen-bonding capacity to be accounted component.for. The intermediate water molecule in the [100] chain, at (0.5+x, 0.5-y, -z) acts as donor via H82 to atom O33 in the resorcinarene at (-x, -y, -z): similarly, an intermediate The Nonius Kappa-CCD diVractometer was purchased with water molecule in the [010] chain, at (0.5-x, -0.5+y, z) acts an equipment grant from NSERC (Canada). as donor via H81 to atom O35 in the same resorcinarene molecule at (-x, -y, -z).Hence the hydrogen-bonding role of the water molecules is two-fold: firstly, they generate the References two sets of chains parallel to [100] and [010] and hence the resulting two-dimensional network; secondly, they link 1 M. C. Etter, Acc. Chem. Res., 1990, 23, 120. 2 J. Bernstein, R. E. Davis, L. Shimoni and N.-L. Chang, Angew.together pairs of such parallel networks related by the action Chem., Int. Ed. Engl., 1995, 34, 1555. of centres of inversion. 3 P. I. Coupar, G. Ferguson and C. Glidewell, Acta Crystallogr., The arrangement of the two linked nets is such that pairs Sect. C, 1996, 52, 3052. of resorcinarenes lie across centres of inversion. The two 4 C. Glidewell and G. Ferguson, Acta Crystallogr., Sect C, 1996, calixarene bowls point towards each other but the local 52, 2528.(approximately four-fold) rotation axes of the resorcinarenes 5 A.C.Be� nyei, C. Glidewell, P. Lightfoot, B. J. L. Royles and D. M. Smith, J. Organomet. Chem., 1997, 539, 177. are oVset by ca. 2.9 A° . Together with the associated water and 6 P. I. Coupar, G. Ferguson, C. Glidewell and P. R.Meehan, Acta methanol molecules, these pairs of resorcinarenes produce a Crystallogr., Sect. C, 1997, 53, 1978. large cavity in which two molecules of 2,2¾-bipyridyl are held 7 A.C.Be� nyei, P. I. Coupar, G. Ferguson, C. Glidewell, A. J. Lough by a combination of O–H,N and C–H,O hydrogen bonds and P. R. Meehan, Acta Crystallogr., Sect. C, 1998, 54, in the (Fig. 5). The combination of the O–H,O hydrogen bonds a, press.b, c and f at the equator of the cavity and the O–H,N 8 G. Ferguson, C. Glidewell, R. M. Gregson and P. R. Meehan, Acta Crystallogr., Sect. B, 1998, 54, 330. hydrogen bonds g and i holding the bipyridyl molecules in the 9 P. R. Meehan, R. M. Gregson, C. Glidewell and G. Ferguson, cavity, generates a cyclic R12 12(46) motif. Acta Crystallogr., Sect. C, 1997, 53, 1637.In eVect, the supramolecular structure of 3 has formed by 10 V. Bo�hmer, Angew. Chem., Int. Ed. Engl., 1995, 34, 713. self-assembly of a network of hydrogen-bonded carcerands, 11 A. Shivanyuk, E. F. Paulus, V. Bo�hmer and W. Vogt, Angew. each cavity in which is constructed from two resorcinarenes, Chem., Int. Ed. Engl., 1997, 36, 1301. 12 L. R. MacGillivray and J.L. Atwood, J. Am. Chem. Soc., 1997, analogous to covalently-linked carcerands.13,26 Calixarene 119, 6931. dimers, having much more open structures with the two 13 L. M. Tunstad, J. A. Tucker, E. Dalcanale, J.Weiser, J. A. Bryant, components linked together by eight molecules of either J. C. Sherman, R. C. Helgeson, C. B. 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