Publisher Summary This chapter presents a summary that discusses the coordination chemistry of homoleptic thioether macrocycles critically, with emphasis on likely future developments and uses. Some unpublished results, mainly crystallographic data from laboratories, are discussed in this chapter. The coordination chemistry of thioether ligands has undergone a renaissance over the past five years. This has been because of the observation that cyclic thioethers can bind to a range of transition metal ions to form stable metal complexes. The properties of the M-S(thioether) bond can now be studied with a variety of metal centers, oxidation states, and coordination geometries. Another impetus for the study of the coordination chemistry of crown thioethers stems from the role of thioether binding in biological systems, such as d-biotin (involving tetrahydrothiophene), and blue copper proteins, such as plastocyanin and azurin (involving methionine). The high-yield syntheses of macrocyclic polyoxoethers are characterized by the strong template effects that arise from oxygen coordination by alkali metal ions during cyclization of polyoxo units. The parallel between the binding of soft transition metal ions by soft cyclic thioether ligands and the binding of hard main-group metal ions (Group IA and IIA) by hard cyclic oxyether ligands is presented.

Chemistry of Thioether Macrocyclic Complexes

The synthetic, structural, and coordination chemistry of crown thioethers with both transition and p-block metal ions is reviewed comprehensively through December 1988. Emphasis falls upon the electronic structures and redox properties induced in metal ions by coordination to crown thioethers. Examples include stabilization of mononuclear Rh(II), Pt(III), and low-spin octahedral Co(II). A subsidiary theme concerns the influence of ligand conformation in determining both the binding efficacy and the qualitative coordination chemistry associated with a given crown thioether. The review concludes with a view toward potential future applications of crown thioethers in catalysis, in sequestration or biological delivery of heavy metal ions, and in fundamental studies directed toward rational design of ligands.

Crown thioether chemistry

Preparation of a novel graphene oxide/Fe-Mn composite and its application for aqueous Hg(II) removal.

Soft and hard templates assisted synthesis mesoporous CuO/g-C3N4 heterostructures for highly enhanced and accelerated Hg(II) photoreduction under visible light.

Natural macrocvclic compounds, such as valinomycin, are attractive to analysts who have interest in the high selectivity of potassium ion as compared to sodium ion. This selectivity in alkali metal ions was not found in other ligands. Pedersen synthesized many crown ethers [1] and published his result that dibenzo-18-crown-6 (DB18C6) had a larger affinity to potassium than other alkali metals. Since then, these ligands and related compounds have held great interest for physical, inorganic and biochemists.

D. Sevdić

Papers

Macrocyclic polythiaethers as solvent extraction reagents—III