Synthesis, Structure, and Properties of Unsaturated Thiacrown Ethers Possessing Sulfonium Groups.

Thiacrown ethers have attracted much attention in host-guest chemistry. Herein, we present the polymethylation reactions of unsaturated thiacrown ethers. Unsaturated thiacrown ethers having sulfonium groups were synthesized by the reaction of corresponding unsaturated thiacrown ethers with methyl triflate. The obtained methylated unsaturated thiacrown ethers were characterized by single-crystal X-ray diffraction analysis, UV absorption measurement, and cyclic voltammetry. The occupied and unoccupied molecular orbitals of the obtained methylated unsaturated thiacrown ethers are essentially localized respectively around the sulfide groups and the sulfonium groups. Furthermore, the results of electrostatic potential maps indicated that positive charges were distributed throughout the entire unsaturated thiacrown ether moieties.