Novel crown-ether–methylenediphosphonotetrathioate hybrids as Zn(ii) chelators

Abstract

Hybrids of methylenediphosphonotetrathioate and crown-ether (MDPT–CE) were synthesized forming 7-,8-,9-,10- and 13-membered rings. Both 7- and 13-membered ring-containing compounds were found to be highly stable to air-oxidation for at least four weeks. These hybrids bind Zn(II) by both MDPT and CE moieties, forming a 2 : 1 L : Zn(II) complex. Interestingly, the 13-membered ring MDPT–CE showing a high affinity to Zn(II) (K_a 3 ± 0.5 × 10⁶ mol⁻² L²) does not bind Li(I) or Na(I). The 13-Membered MDPT–CE hybrid is a promising water-soluble, air-stable, high-affinity Zn(II)-chelator, exhibiting selectivity to Zn(II) vs. Mg(II), Na(I), and Li(I).