Electron density distribution in 2-nitro-5-methylimidazole derivatives studied by NMR-NQR double resonance

Measurement of the 14N nuclear quadrupole resonance frequencies by the solid effect

“…The results are summarized in Table 2. The known 14 N NQR parameters of the imidazole ring [18,19] and of the amines [11,20] are used to assign the spectrum.…”

“…They namely depend on the nitrogen contribution W N to the spin-lattice relaxation rate W, that is for m = m + ± m L given by Eq. (19). The value of W N is for m = m À ± m L and m = m 0 ± m L obtained from Eq.…”

Nuclear Quadrupole Resonance Spectroscopy: Tautomerism and Structure of Functional Azoles

“…Tautomeric transformations, structural peculiarities and distribution of electron in tautomeric and non-tautomeric imidazole derivatives (2-methyl-5-nitroimidazoles, metronidazole) [94,95], 5-substituted tetrazoles [96], 1,3,4-thiadiazole derivatives [97], indazoles [98], benzimidazoles [99], and other nitrogen-containing compounds [100][101][102][103], were investigated by NMR-NQR double resonance and quantum chemical methods. The asymmetry parameter in derivatives of 5-nitroimidazoles is reduced with augmentation of the substituent size.…”

Nuclear Quadrupole Resonance spectroscopy in studies of biologically active molecular systems—a review

“…The most important finding implied by the studies was that in the search for anticancerous drugs from the group of 4N-derivatives of cytosine, the more effective would be those in which the aromatic substituents were strongly separated by the CH 2 CH 2 chain [53]. It was found that the substitution at position 1H of imidazole led to a redistribution of the electron density from the nitrogen atom N onto NR [54]. On the basis of the results obtained for two groups of compounds: 4N-derivatives of cytosine (anticancerous drug) and imidazole derivatives (anticancerous through bacteriostatic activity depending on the substituents), it was found that the substitution with substituents causing redistribution of -electron density led to a change in the biological activity of the compounds [53][54]21].…”