Spin-lattice (T-1) and spin-spin (T-2) 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 tau from the ratio of the (1/T-1)/2(1/ T-2) using relaxation formulas pertaining to dipolar interactions. The correlation time was calculated from the equation for each peak using experimental data for (1/T-1)/2(1/T-2) ratio. The estimated tau values ranged from 0.7 ns to 2 ns. The similarity of T 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. (c) 2006 Elsevier B.V. All rights reserved.