Synthesis and solid state structural analysis of conformers of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene

Article abstract of DOI:10.1016/S0040-4039(99)00143-4

The role of alkaline metal cations in the synthesis and in determining the conformer distribution of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene obtained by treatment of tetrahiacalix[4]arene 1 in acetone by ethyl bromoacetate in the presence of M₂C0₃ was systematically investigated. Among the four possible conformers, the cone, partial cone and 1,3-alternate conformers were obtained, purified and structurally characterised by X-ray analysis in the solid state. Although for Li⁺ no tetra substituted derivative was observed, for Na⁺ the cone conformer was exclusively formed while for both K⁺ and Cs⁺ a mixture of partial cone and 1,3-alternate conformers was obtained.