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

In this work, NMR T1 and T2 relaxation times of the protons of the dibenzo diaza 18-crown-6 ether derivative (N,N′-dihexyl-7,16-diaza-1,4,10,13-tetraoxa-2,3,11,12-dibenzo-cyclooctadeca-2,11-diene) were measured at 400 MHz. A 4th order equation was derived for the correlation time, τ from the ratio of (1/T1)/2(1/T2). Then the equation was solved to calculate τ using the experimental data obtained for the (1/T1)/2(1/T2). The τ data suggested that overall molecular tumbling is the source of the relaxation.