Intra- and Intermolecular Hydrogen Bonding in a Tetrahydroxycalix[4]arene

The title calix[4]arene, cis-11,17-di-tert-butyl-2,5,23-trimethyl-14-(4-nitrophenyl)pentacyclo[19.3.1.1^3,7.1^9,13.1^15,19]octacosa-1(25),3,5,7(26),9,11,13(27), 15,17, 19(28), 21,23-dodecaene-25,26,27,28-tetraol–chloroform (1/0.5), C₄₅H₄₉NO₆.0.5CHCl₃, substituted at two opposite methylene bridges by methyl and p-nitrophenyl groups, forms centrosymmetric hydrogen-bonded dimers in the solid state. This results in an eight-membered (O-H...)₈ ring with O...O distances in the range 2.637 (4)–2.828 (4) Å. Pairs of calix[4]arene molecules (related by another inversion centre) each have a p-methyl group of one molecule fitting snugly into the cavity of the other with shortest intermolecular C...C contacts corresponding to normal C...π-arene interactions. The half-occupancy chloroform molecule lies disordered about another independent inversion centre filling what would otherwise have been a void in the crystal lattice.

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