1H and 13C nuclear magnetic resonance relaxation-time studies of ionophoric calixarene esters

Abstract

¹ H and ¹³C NMR relaxation times (T₁) of ethoxycarbonylmethyl derivatives of p-t-butylcalix[n]arenes have been determined at 90 MHz and 36 °C in [²H₈]THF. It was found that these calixarenes feature a ‘seesaw motion’ around the ArCH₂Ar linkage as a central support and that this molecular motion is largely suppressed through complexation with Na ⁺.