Chemistry of 2,14-Dithiacalix[4]arene: Alkylation and Conformational Behavior of Peralkylated Products

2,14-Dithiacalix­[4]­arene,
prepared on a multigram scale, was alkylated
using the reaction conditions well known from the chemistry of classical
calixarenes or thiacalixarenes to study the specific conformational
preferences and dynamic behavior of the corresponding tetraalkylated
derivatives. As proved by the combination of the X-ray crystallography
and dynamic NMR techniques, the presence of mixed bridges (−CH2– and −S– groups) within the basic skeleton
brings about considerable changes in the mutual ratios of the individual
conformers compared to the parent macrocycles. Interestingly, certain
conformers, hardly accessible for common calixarenes/thiacalixarenes
(e.g., 1,2-alternates) are easily prepared in very
good yields in the case of 2,14-dithiacalix[4]­arene, which makes this
mixed-bridge system attractive as molecular scaffold for supramolecular
applications.