Fig. 3. (a) VT ¹H NMR spectra of MC4-S in CD₂Cl₂ (500 MHz); the peaks labelled * indicate residual solvent. The resonance assignment refers to the structure shown in Scheme 1. (b) I × T–T plot of MC4-S in frozen DCM and the red line is the fitted curve. The inset shows the VT ESR spectra in DCM solution.