5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetramethoxycalix[4]arene tetrahydrofuran solvate

Abstract

Key indicators: single-crystal X-ray study; T = 153 K; mean (C-C) = 0.005 Å; disorder in main residue; R factor = 0.067; wR factor = 0.215; data-to-parameter ratio = 17.4.The asymmetric unit of the title compound, C 44 H 64 O 4 ÁC 4 H 8 O, comprises two crystallographically independent calixarene molecules, which display a partial cone conformation, and two tetrahydrofuran molecules. The crystal packing is stabilized by C-HÁ Á Á contacts involving the methoxy groups, while the solvent molecules are located in voids between the calixarene molecules. Two of the tert-butyl residues of each calixarene Related literatureThe solvent-free title compound has been described as adopting the paco-conformation (Grootenhuis et al., 1990). A corresponding sodium complex including toluene in the crystal structure shows a cone conformation (Bott et al., 1986). A complex containing an aluminium alkyl species (Bott et al., 1987)

Comparative X-ray structural study of laterally mono-ethyl substituted 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-methoxycalix[4]arene and its non-substituted parent compound including guest free and solvated forms. Chemical straightening of guest channels

“…In a more detailed examination, similar to the laterally unsubstituted calix [4]arene 2a [12], due to the absence of any intramolecular hydrogen bonding at the lower rim, the framework of the ethyl derivative 1 adopts a partial cone conformation, which has already been calculated to be the lowest energy conformer [10]. The calice exhibits a nearly coplanar arrangement of the aromatic units A and C, whereas the rings B and D enclose an angle of 49.7° ( Table 3).…”

“…2) crystallise in the same orthorhombic space group Pca2 1 . The THF solvated laterally non-substituted tetra-tert-butyltetramethoxycalix [4]arene 2a [12] has the same space group as the laterally substituted calixarene 1 in unsolvated form. The calixarene inclusion structure 2a differs from all the other presented structures involving 1 in Z 0 .…”

“…Even studies of the inclusion properties of simple laterally monosubstituted calix [4]arenes in the solid state are rather rare [7][8][9] although we recently reported the conformational behaviour of such monoalkyl substituted calix [4]arenes [10] and of a carboxy functionalized analogue [11] both in crystalline state and in solution. Here, we describe crystal structures of the unsolvated laterally ethyl substituted tetratert-butyltetramethoxycalix [4]arene 1 and its solvated inclusion compounds with tetrahydrofuran (THF) (1a) and dichloromethane (1c), and comparatively discuss these structures including also the known structures of the inclusion complexes of 1 with chloroform (1b) [10] and of the basic laterally non-substituted parent calixarene 2 with THF (2a) [12] (Fig. 1).…”

2-(4-Bromobenzyl)-5,11,17,23-tetra-tert-butyl-25,26,27,28-tetramethoxycalix[4]arene

“…The title calixarene ( Fig. 1) adopts a partial cone conformation, similar to the laterally unsubstituted tetramethoxycalix[4]arene (Fischer et al, 2007(Fischer et al, , 2008. The opposite arene rings, A (C1-C6) and C (C15-C20), are almost coplanar Considering the geometric parameters (Table 1), a C-H•••π type contact (Nishio, 2004)…”

“…For the solid-state structures of laterally monosubstituted calixarenes, see: Biali et al (1996); Bergamaschi et al (1997). For laterally unsubstituted calixarenes, see: Fischer et al (2007Fischer et al ( , 2008. For the synthesis of the title compound, see: Scully et al (2001).…”