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.

Department of Organic Chemistry University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Czech Republic

Institute of Physics AS CR v v i Na Slovance 2 182 21 Prague 8 Czech Republic

Laboratory of NMR Spectroscopy UCTP 166 28 Prague 6 Czech Republic

Solid State Department UCTP 166 28 Prague 6 Czech Republic

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Synthesis of Monothiacalix[4]arene Using the Fragment Condensation Approach

Breaking thiacalix[4]arene into pieces - a novel synthetic approach to higher calixarenes bearing mixed (-S-, -CH2-) bridges