Estimation of τ value in proton NMR relaxation times of dibenzo diaza 18-crown-6 ether derivative in solution

Spin–lattice (T1) and spin–spin (T2) relaxation times of seven peaks in dibenzo diaza 18-crown-6 ether derivative were measured at 300K with a Bruker 400 MHz NMR spectrometer. An equation was derived for correlation time τ from the ratio of the (1/T1)/2(1/T2) using relaxation formulas pertaining to dipolar interactions. The correlation time was calculated from the equation for each peak using experimental data for (1/T1)/2(1/T2) ratio. The estimated τ values ranged from 0.7 ns to 2 ns. The similarity of τ values of the peaks belonging to the different parts of the molecule suggested that overall molecular tumbling may be responsible for relaxation mechanism of all the groups.