Coordination Chemistry and Applications of Phenolic Thiacalixarene–Metal Complexes

Thiacalixarenes are members of the calixarene family in which sulfur has replaced one or more of the methylene bridges between the phenolic moieties of the macrocycles. Oxidation of the thiacalixarenes leads to sulfinyl and sulfonyl homologs. The incorporation of sulfur affects the metal-binding affinities of these calixarenes over their all-carbon analogs through the abilities of the heteroatoms both to bind directly and to influence lower rim phenolic binding. Other binding motifs are possible for the oxidized thiacalixarenes leading to a vast array of complexes with metal cations. This chapter covers the literature concerning thiacalixarenes containing free OH groups at the lower rim since they were first reported. Their coordination chemistry toward alkali, alkaline earth, transition, heavy, lanthanide, and actinide metals is discussed. Examples of crystal structures of these metal complexes are given, as well as brief descriptions of their applications in fields such as catalysis, transition-metal extraction, and cation transport. Keywords: thiacalixarenes; metal phenolates; coordination chemistry; metal complexes; alkali and alkaline earth metals; transition and heavy metals; lanthanide and actinide metals