Proton NMR Spin ? Lattice Relaxation Time in Some Bismaleimides

In this present work we have carried out proton NMR spin-lattice relaxation time 1H T1 measurements of some bismaleimides at 400MHz in DMSO using pulse sequences, and inversion-recovery experiment. This experiment uses two pulses, 180 and 90, separated by a delay time which is varied. The present study, as a part of studying the effect of ring and side chain substitutions on the amides proton spin-lattice relaxation.1H T1 values of imide protons for model system of studied compounds appeared systematically correlation with the differences in type (direct, aromatic and aliphatic) and aliphatic chain length spacer link between two maleimide rings in the each studied compounds.1H T1 value for imide protons of hydrazine bismaleimide BMI1 is 8.0790 sec (which have direct linking between two maleimides rings), were increase up to ethylene bismaleimide BMI2 is 8.2233 sec and propylene bismaleimide BMI3 is 9.5217 sec (which have ethylene and propylene chain spacer respectively), then decrease 1H T1 values in hexamethylene bismaleimide BMI4 and octamethylene bismaleimide BMI5 become 7.7905 and 7.5020 sec respectively. The comparison between the aromatic linking, the values of 1H T1 for imide protons in phenyl bismaleimide BMI6 and diphenylsulphon bismaleimide BMI7 (which have aromatic link spacer) are 7.2134 and 5.7707 sec respectively. It is less than the values in the event that the aliphatic chain link or directly linked. The effect of temperature on the relaxation time T1 has been study.