COMPLETE CONFORMATIONAL SWITCHING IN A CALCIUM IONOPHORE

A new, conformationally mobile, ether-amide, calcium ionophore, 1,2-bi s((N,N-dipropylcarbamyl)methoxy)cyclohexane, is described. The changes in the conformation of the ionophore were monitored by H-1 and C-13 N MR spectroscopy at room temperature and at low temperature (-90-degree s-C). Examination of conformational effects on NMR spectra allowed a d irect determination of 2:1 ionophore-to-cation stoichiometry and facil itated the measurement of the association constant. Conformational mon itoring of the difference in complexing ability at room temperature an d at -90-degrees-C demonstrated that complexation was more pronounced at room temperature. Less effective complexation was demonstrated for magnesium and potassium ions.