The host–guest complex between cone-25,26:27,28-bis­(methyl­ene­dioxy)­calix­[4]­arene and di­chloro­methane

The title compound, 25,26:27,28-bis­(methyl­ene­dioxy)­penta­cyclo­[19.3.1.1^3,7.1^9,13.1^15,19]­octacosa-1(25)3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene di­chloro­methane solvate, C₃₀H₂₄O₄·CH₂Cl₂, possesses crystallographic twofold sym­metry in both components. The calixarene shows a pinched cone conformation with an elliptical cavity, in which the guest di­chloro­methane solvent mol­ecule is accommodated. The contact distance between guest and host (H...ring centroid = 2.44 Å) is extremely short.

S1. Comment

An important property of calix[4]arenes is that they possess cavities that can accommodate neutral guest molecules (see, for example, Vicens & Böhner, 1991; Mandolini & Ungaro, 2000). This behaviour requires the calixarene to be maintained in the cone conformation, although some inclusion complexes have been reported with partial cone conformers (Arduini et al., 2001). The most frequently employed method of locking the cone conformation is to tether large substituents on the narrow rim, thus hindering the transannular rotation of the individual phenol rings. Another method, employed in the present study, consists in linking two pairs of proximal O atoms with short bridging units. The latter method offers the advantage of making the whole calixarene more rigid, a property that is expected to enhance the efficiency of guest complexation. We describe here the synthesis (see Experimental and Scheme) and structure of the title compound, (I), a calix[4]arene locked in the cone conformation, which crystallizes with a well ordered guest molecule of dichloromethane.

The structure of the closely related 5,11,17,23-tetra-tert-butyl-substituted analogue, which crystallized without any guest molecule, was published by Neri et al. (1992), but no coordinates were deposited; we redetermined the structure and deposited it in the Cambridge Structural Database (Allen, 2002) under refcode YAHVOS01. It consists of two independent molecules of similar conformation (the r.m.s. deviation of all atoms except the tert-butyl groups is 0.20 Å). The additional bridging reduces the approximate mm2 symmetry of a standard calixarene (with cone conformation) to approximate twofold symmetry (with a distorted or `pinched' cone conformation and an elliptical cavity).

The title compound, lacking tert-butyl substituents, displays exact twofold symmetry [symmetry code: (i) −x, y, −z + 1/2], but the conformation is similar to that reported by Neri et al. (1992), with an r.m.s. deviation of 0.24 Å from molecule 1 of that structure. The methylene bridges cause the O···O distances across the cavity to differ appreciably: O1···O1ⁱ = 2.854 (2) Å and O2···O2ⁱ = 4.590 (2) Å. The interplanar angles to the calixarene reference plane of atoms C17, C27 and their symmetry equivalents (exactly planar by symmetry) are 148.16 (3) and 109.44 (4)° for C11–C16 and C21–C26, respectively. The centroids of the symmetry-equivalent rings lie 7.54 Å apart for ring C11–C16 and 6.03 Å for ring C21–C26. The latter ring is not eclipsed with its symmetry-generated counterpart (as shown, for example, by the torsion angle C24—Cg—Cgⁱ—C24ⁱ of 19°, where Cg is the centroid of ring C21–C26).

The title compound crystallizes with a guest molecule of dichloromethane, which also shows exact twofold symmetry. Host–guest geometry involving calixarenes as hosts has been discussed extensively by Arduini et al. (2001), and the same nomenclature for angles and distances is used here. The dichloromethane molecule forms extremely short C99—H99···π contacts to the ring C21–26 (Fig. 1), with an H···π distance of 2.44 Å. If the C99—H99 bond length is normalized to 1.08 Å, then the `true' value for the contact is even shorter, at 2.35 Å. The favourable directionality of the interaction is shown by the angles α [8.5°; between the vector C99—Cg and the normal to the ring plane] and σ [166°; between the vectors C99—H99 and H99—Cg). A search of the Cambridge Structural Database (Allen, 2002; version of 2003) for short contacts from dichloromethane hydrogen to a calixarene ring centroid revealed 43 hits with a contact distance < 3.1 Å; the five shortest (2.42–2.46 Å) were the refcodes KOCQEY (Parlevliet et al., 2000), NOVNOB (Giannini et al., 1997), PAYHOM (Giusti et al., 1997), TARXOZ (Beer, Drew, Grieve et al., 1996) and ZUVNAF (Beer, Drew, Kan et al., 1996). It is noteworthy that all these structures are calixarenes modified either by internal bridging or, equivalently, by metal complex formation.

The distance from C99 to the ring centroids is 4.373 Å to C11–C16 and 3.411 Å to C21–C26, leading to a Σ₄ value (sum of the C···π distances) of 15.568 Å; its distance to the reference plane is 2.909 (3) Å. There is no tilting of the guest molecule relative to the reference plane, with interplanar angles γ (between the CCl₂ plane and the reference plane) and η (between CH₂ and the reference plane) both being 90° by symmetry.

The crystal packing is further characterized by a C—H···Cl hydrogen bond (Table 2). The overall effect is to form layers of calixarene and solvent molecules parallel to the xy plane (Fig. 2). Within the layers, only translation symmetry is involved. There are two such layers per cell at z ≈ 1/4, 0.75.

S2. Experimental

To a suspension of NaH (0.565 g, 11.78 mmol) in DMF (30 ml), cooled to 273 K, was added in small portions calix[4]arene (1.000 g, 2.36 mmol). After stirring for 2 h, CH₂BrCl (6.097 g, 47.12 mmol) was added dropwise over a period of 15 min. After 3 h, cooling was stopped and the solution was stirred for a further 12 h at room temperature. Excess NaH was decomposed with MeOH (10 ml) and the solvent was removed in vacuo. The residue was taken up in CH₂Cl₂ (100 ml), washed with 1 M HCl (50 ml), then with water (2 × 50 ml). The organic layer was dried with MgSO₄, then filtered. Evaporation of the solvent afforded a solid that was purified by flash chromatography using CH₂Cl₂/hexane (1:1 v/v) as eluent. After evaporation of the solvent and recrystallization from CH₂Cl₂–MeOH (1:5 v/v), colourless crystals were obtained (SiO₂, R_F = 0.54, CH₂Cl₂/hexane, 1:1 v/v). Yield: 0.600 g, 57%; m.p. > 523 K; FAB mass spectrum: m/z 448 (M⁺, 100%). Analysis found: C 70.02, H 5.09%; calculated for C₃₀H₂₄O₄·CH₂Cl₂ (448.52 + 84.93): C 69.80, H 4.91%.

S3. Refinement

H atoms were included using a riding model with fixed C—H bond lengths of 0.95 (Csp²) or 0.99 Å (methylene). U_iso(H) values were fixed at 1.2U_eq of the parent atom.

Computing details

Data collection: XSCANS (Fait, 1991); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The formula unit of the title compound in the crystal. Ellipsoids represent 30% probability levels. H-atom radii are arbitrary. Only the asymmetric unit is numbered. The C—H···π interactions are indicated by dashed bonds.
	Fig. 2. Packing diagram of the title compound, viewed perpendicular to the xy plane. Hydrogen bonds are indicated by dashed lines. H atoms not involved in hydrogen bonding have been omitted.

cone-25,26:27,28-bis(methylenedioxy)calix[4]arene dichloromethane solvate

Crystal data

C30H24O4·CH2Cl2	F(000) = 1112
Mr = 533.42	Dx = 1.423 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 16.042 (2) Å	Cell parameters from 64 reflections
b = 9.4781 (10) Å	θ = 8–27°
c = 17.599 (2) Å	µ = 0.30 mm^−1
β = 111.49 (1)°	T = 173 K
V = 2489.9 (5) Å^3	Block, colourless
Z = 4	0.7 × 0.6 × 0.5 mm

Data collection

Siemens P4 diffractometer	Rint = 0.014
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 3.1°
Graphite monochromator	h = −18→7
ω scans	k = 0→11
3350 measured reflections	l = −20→19
2173 independent reflections	3 standard reflections every 247 reflections
1894 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0493P)^2 + 1.8139P] where P = (Fo^2 + 2Fc^2)/3
2173 reflections	(Δ/σ)max < 0.001
168 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Operator: $2 − x, y, −z + 1/2

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

− 6.0691 (0.0088) x + 8.0518 (0.0033) y + 8.4601 (0.0092) z = 6.3362 (0.0034)

* 0.0064 (0.0010) C11 * −0.0040 (0.0010) C12 * −0.0010 (0.0010) C13 * 0.0035 (0.0010) C14 * −0.0012 (0.0010) C15 * −0.0037 (0.0010) C16

Rms deviation of fitted atoms = 0.0038

0.0000 (0.0000) x + 9.4781 (0.0017) y + 0.0000 (0.0000) z = 3.3408 (0.0012)

Angle to previous plane (with approximate e.s.d.) = 31.84 (0.03)

* −0.3656 (0.0011) C17 * 0.3656 (0.0011) C27 * −0.3656 (0.0011) C17_$2 * 0.3656 (0.0011) C27_$2 − 2.9093 (0.0027) C99

Rms deviation of fitted atoms = 0.3656

9.4048 (0.0077) x + 3.1552 (0.0053) y + 8.3147 (0.0090) z = 5.5962 (0.0025)

Angle to previous plane (with approximate e.s.d.) = 70.56 (0.04)

* 0.0180 (0.0010) C21 * −0.0082 (0.0010) C22 * −0.0072 (0.0010) C23 * 0.0126 (0.0010) C24 * −0.0028 (0.0010) C25 * −0.0124 (0.0009) C26

Rms deviation of fitted atoms = 0.0113

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	−0.03403 (7)	0.42569 (11)	0.31439 (6)	0.0280 (3)
O2	0.11689 (7)	0.49167 (10)	0.37375 (6)	0.0283 (3)
C1	0.02659 (11)	0.53078 (16)	0.35714 (10)	0.0298 (4)
H1A	0.0185	0.5500	0.4093	0.036*
H1B	0.0132	0.6188	0.3246	0.036*
C11	−0.08144 (10)	0.35402 (15)	0.35435 (9)	0.0237 (3)
C12	−0.17184 (10)	0.33321 (15)	0.30808 (9)	0.0239 (3)
C13	−0.22337 (10)	0.25816 (16)	0.34289 (9)	0.0262 (3)
H13	−0.2853	0.2433	0.3125	0.031*
C14	−0.18526 (11)	0.20460 (16)	0.42173 (9)	0.0285 (4)
H14	−0.2210	0.1539	0.4452	0.034*
C15	−0.09503 (11)	0.22573 (16)	0.46581 (9)	0.0272 (3)
H15	−0.0695	0.1884	0.5195	0.033*
C16	−0.04048 (10)	0.30035 (15)	0.43361 (9)	0.0247 (3)
C17	0.05941 (10)	0.31391 (16)	0.48318 (9)	0.0271 (3)
H17A	0.0734	0.4140	0.4987	0.032*
H17B	0.0739	0.2585	0.5341	0.032*
C21	0.14032 (10)	0.34996 (15)	0.38371 (8)	0.0235 (3)
C22	0.11842 (9)	0.26379 (16)	0.43802 (8)	0.0243 (3)
C23	0.15267 (10)	0.12747 (17)	0.45113 (9)	0.0274 (3)
H23	0.1387	0.0676	0.4881	0.033*
C24	0.20676 (10)	0.07750 (17)	0.41129 (9)	0.0305 (4)
H24	0.2310	−0.0151	0.4219	0.037*
C25	0.22533 (10)	0.16301 (17)	0.35598 (9)	0.0280 (3)
H25	0.2615	0.1277	0.3279	0.034*
C26	0.19200 (9)	0.30025 (16)	0.34045 (8)	0.0242 (3)
C27	0.21231 (10)	0.39104 (17)	0.27827 (9)	0.0275 (3)
H27A	0.2781	0.3982	0.2940	0.033*
H27B	0.1888	0.4873	0.2793	0.033*
C99	0.0000	0.0455 (3)	0.2500	0.0362 (5)
H99	−0.0486	0.1070	0.2146	0.043*
Cl	−0.04111 (4)	−0.05813 (7)	0.31110 (4)	0.0704 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0285 (6)	0.0328 (6)	0.0256 (5)	−0.0035 (5)	0.0132 (4)	0.0018 (4)
O2	0.0294 (6)	0.0220 (5)	0.0357 (6)	−0.0041 (4)	0.0147 (5)	−0.0064 (4)
C1	0.0345 (8)	0.0218 (7)	0.0381 (8)	0.0005 (6)	0.0193 (7)	−0.0013 (6)
C11	0.0290 (8)	0.0214 (7)	0.0253 (7)	0.0014 (6)	0.0155 (6)	−0.0012 (6)
C12	0.0280 (8)	0.0209 (7)	0.0253 (7)	0.0050 (6)	0.0127 (6)	−0.0006 (6)
C13	0.0262 (8)	0.0245 (7)	0.0296 (8)	0.0006 (6)	0.0121 (6)	−0.0025 (6)
C14	0.0352 (9)	0.0245 (8)	0.0307 (8)	−0.0031 (6)	0.0181 (7)	0.0002 (6)
C15	0.0354 (8)	0.0264 (8)	0.0217 (7)	0.0009 (7)	0.0126 (6)	0.0000 (6)
C16	0.0304 (8)	0.0224 (7)	0.0233 (7)	0.0006 (6)	0.0122 (6)	−0.0041 (6)
C17	0.0309 (8)	0.0302 (8)	0.0209 (7)	−0.0020 (6)	0.0104 (6)	−0.0031 (6)
C21	0.0226 (7)	0.0232 (7)	0.0214 (7)	−0.0031 (6)	0.0044 (6)	−0.0063 (6)
C22	0.0228 (7)	0.0286 (8)	0.0180 (7)	−0.0030 (6)	0.0033 (6)	−0.0055 (6)
C23	0.0284 (8)	0.0303 (8)	0.0193 (7)	−0.0014 (6)	0.0038 (6)	−0.0003 (6)
C24	0.0304 (8)	0.0301 (8)	0.0244 (7)	0.0058 (7)	0.0024 (6)	−0.0016 (6)
C25	0.0243 (8)	0.0349 (8)	0.0220 (7)	0.0029 (6)	0.0051 (6)	−0.0067 (6)
C26	0.0196 (7)	0.0290 (8)	0.0204 (7)	−0.0051 (6)	0.0033 (6)	−0.0068 (6)
C27	0.0241 (7)	0.0304 (8)	0.0295 (8)	−0.0071 (6)	0.0114 (6)	−0.0066 (6)
C99	0.0312 (12)	0.0349 (12)	0.0345 (12)	0.000	0.0026 (10)	0.000
Cl	0.0486 (3)	0.0926 (5)	0.0648 (4)	−0.0202 (3)	0.0147 (3)	0.0214 (3)

Geometric parameters (Å, º)

O1—C11	1.3879 (17)	C17—H17A	0.9900
O1—C1	1.4028 (18)	C17—H17B	0.9900
O2—C21	1.3884 (18)	C21—C22	1.396 (2)
O2—C1	1.4181 (19)	C21—C26	1.397 (2)
C1—H1A	0.9900	C22—C23	1.390 (2)
C1—H1B	0.9900	C23—C24	1.384 (2)
C11—C12	1.393 (2)	C23—H23	0.9500
C11—C16	1.402 (2)	C24—C25	1.380 (2)
C12—C13	1.391 (2)	C24—H24	0.9500
C12—C27^i	1.519 (2)	C25—C26	1.395 (2)
C13—C14	1.391 (2)	C25—H25	0.9500
C13—H13	0.9500	C26—C27	1.518 (2)
C14—C15	1.384 (2)	C27—H27A	0.9900
C14—H14	0.9500	C27—H27B	0.9900
C15—C16	1.396 (2)	C99—Cl^i	1.7539 (15)
C15—H15	0.9500	C99—Cl	1.7539 (15)
C16—C17	1.524 (2)	C99—H99	0.9900
C17—C22	1.518 (2)
C11—O1—C1	118.47 (11)	C16—C17—H17B	108.8
C21—O2—C1	119.19 (11)	H17A—C17—H17B	107.7
O1—C1—O2	112.33 (12)	O2—C21—C22	121.86 (13)
O1—C1—H1A	109.1	O2—C21—C26	116.40 (13)
O2—C1—H1A	109.1	C22—C21—C26	121.61 (14)
O1—C1—H1B	109.1	C23—C22—C21	118.30 (13)
O2—C1—H1B	109.1	C23—C22—C17	119.23 (13)
H1A—C1—H1B	107.9	C21—C22—C17	122.47 (13)
O1—C11—C12	114.81 (12)	C24—C23—C22	121.15 (14)
O1—C11—C16	122.53 (13)	C24—C23—H23	119.4
C12—C11—C16	122.58 (13)	C22—C23—H23	119.4
C13—C12—C11	118.31 (13)	C25—C24—C23	119.58 (14)
C13—C12—C27^i	121.31 (13)	C25—C24—H24	120.2
C11—C12—C27^i	120.37 (13)	C23—C24—H24	120.2
C14—C13—C12	120.72 (14)	C24—C25—C26	121.30 (14)
C14—C13—H13	119.6	C24—C25—H25	119.4
C12—C13—H13	119.6	C26—C25—H25	119.4
C15—C14—C13	119.57 (14)	C25—C26—C21	117.98 (14)
C15—C14—H14	120.2	C25—C26—C27	120.11 (13)
C13—C14—H14	120.2	C21—C26—C27	121.91 (13)
C14—C15—C16	121.88 (14)	C26—C27—C12^i	112.98 (12)
C14—C15—H15	119.1	C26—C27—H27A	109.0
C16—C15—H15	119.1	C12^i—C27—H27A	109.0
C15—C16—C11	116.91 (14)	C26—C27—H27B	109.0
C15—C16—C17	119.63 (13)	C12^i—C27—H27B	109.0
C11—C16—C17	123.40 (13)	H27A—C27—H27B	107.8
C22—C17—C16	113.62 (12)	Cl^i—C99—Cl	111.87 (14)
C22—C17—H17A	108.8	Cl^i—C99—H99	109.2
C16—C17—H17A	108.8	Cl—C99—H99	109.2
C22—C17—H17B	108.8
C11—O1—C1—O2	111.24 (14)	C1—O2—C21—C22	−51.89 (19)
C21—O2—C1—O1	−29.61 (18)	C1—O2—C21—C26	132.11 (14)
C1—O1—C11—C12	136.93 (13)	O2—C21—C22—C23	−173.03 (12)
C1—O1—C11—C16	−46.25 (19)	C26—C21—C22—C23	2.8 (2)
O1—C11—C12—C13	177.96 (12)	O2—C21—C22—C17	6.6 (2)
C16—C11—C12—C13	1.1 (2)	C26—C21—C22—C17	−177.60 (13)
O1—C11—C12—C27^i	−1.83 (19)	C16—C17—C22—C23	−96.46 (16)
C16—C11—C12—C27^i	−178.65 (13)	C16—C17—C22—C21	83.90 (17)
C11—C12—C13—C14	−0.4 (2)	C21—C22—C23—C24	−0.3 (2)
C27^i—C12—C13—C14	179.37 (14)	C17—C22—C23—C24	−179.97 (13)
C12—C13—C14—C15	−0.3 (2)	C22—C23—C24—C25	−1.6 (2)
C13—C14—C15—C16	0.3 (2)	C23—C24—C25—C26	1.2 (2)
C14—C15—C16—C11	0.4 (2)	C24—C25—C26—C21	1.1 (2)
C14—C15—C16—C17	−176.86 (13)	C24—C25—C26—C27	−179.01 (13)
O1—C11—C16—C15	−177.67 (12)	O2—C21—C26—C25	172.86 (12)
C12—C11—C16—C15	−1.1 (2)	C22—C21—C26—C25	−3.1 (2)
O1—C11—C16—C17	−0.6 (2)	O2—C21—C26—C27	−7.00 (19)
C12—C11—C16—C17	175.99 (13)	C22—C21—C26—C27	176.99 (13)
C15—C16—C17—C22	125.23 (15)	C25—C26—C27—C12^i	64.44 (18)
C11—C16—C17—C22	−51.79 (19)	C21—C26—C27—C12^i	−115.70 (15)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C27—H27A···Cl^ii	0.99	2.83	3.8128 (17)	170

Symmetry code: (ii) x+1/2, y+1/2, z.