Nitrogen-14 Nuclear Quadrupole Effects

Crystal structures and melting points of saturated triglycerides in the β-2 phase

“…Moreover, both F resonance peaks showed considerable line broadening. When the F atoms are placed ortho to the N atoms, this line broadening can be explained as the result of the incomplete 14N quadrupolar relaxation (Lehn & Kintzinger, 1973). Therefore, we tentatively assigned the structure of the title compound to the obtained product.…”

Effect of magnetic field strength on the linewidth and spin-lattice relaxation time of the thiocyanate carbon of cyanylated β-lactoglobulin B: optimization of the experimental parameters for observing thiocyanate carbons in proteins

“…For "IC nuclei directly bonded to 2H, this leads to increased linewidths as Mr values and magnetic field strengths increase (Malthouse and Finucane, 1991). However, because of the larger quadrupolar coupling constant (Lehn and Kintzinger, 1973) and smaller gyromagnetic ratio of the 14N nucleus, its quadrupolar spin-lattice relaxation rates are about 1600-fold larger than those of 2H nuclei. Therefore as the 13C-'4N coupling constants are less than 10 Hz (Stothers, 1972;Mlynarik, 1986) we estimate that, in the present study, line-broadening of the thiocyanate carbon caused by scalar relaxation of the second kind will not make a significant contribution to linewidths (<0.02 Hz, if J13 14N= 10 Hz) even at 11.74 T. Likewise we estimate that such line-broadening will be negligible (< 0.3 Hz, if J13C-14N = 10 Hz) when we observe a thiocyanate carbon attached to a protein of Mr about 400000 at 14.1 T. Therefore we 13Cjcyanylated-fl-lactoglobulin-B at 1.88, 6.34 and 11.74 T All the spectra were transformed using a 5 Hz exponential weighting factor which was subtracted from the linewidth (measured at half signal height) to give the experimental linewidth (LWobs).…”

Quadrupolar interactions in amines as determined by 1H nuclear magnetic resonance: mono- and dimethylamines

“…However, as with methylamine and dimethylamine, no vicinal coupling could be measured. This H-C-I4N coupling (JHC14,q 5 0.5 HZ) has only been measured in very symmetrical compounds ((cH,),N) where the electric field gradient at the nitrogen nucleus is zero by symmetry or very weak (12).…”