Structure and vibrational assignment of tautomerism of 4-hydroxyquinazoline in gaseous and aqueous phases

Vibrational assignments, spectroscopic investigation (FT-IR and FT-Raman), NBO, MEP, HOMO‒LUMO analysis and intermolecular hydrogen bonding interactions of 7-fluoroisatin, 7-bromoisatin and 1-methylisatin ‒ A comparative study

“…Thus, it would be more precise to say that the intra-molecular hydrogen bonding interaction, hydrogen atom transferring and long-range electrostatic interactions can be responsible for the stability order and percentage values of 7-bromoisatin and 7-fluoroisatin due to the existence of the difference between the hydrogen atom positions/orientations in the molecular structures given above. The similar results can be encountered in the literature [33,55].…”

“…Hence, the most stable tautomer is supposed to maximize (minimize) the attractive (the repulsive) intra-molecular interactions. However, it is hard to choose a priority the interactions of which is the most significant [33]. Thus, it would be more precise to say that the intra-molecular hydrogen bonding interaction, hydrogen atom transferring and long-range electrostatic interactions can be responsible for the stability order and percentage values of 7-bromoisatin and 7-fluoroisatin due to the existence of the difference between the hydrogen atom positions/orientations in the molecular structures given above.…”

“…The C=C stretching modes of benzene are normally expected in the change from 1200 to 1650 cm -1 [83,84]. In benzene ring, the strong experimental IR bands observed at 1612 (for 4-hydroxyquinazoline) [33] and at 1681 cm -1 (for 2-hydroxyquinoxaline) [32] were assigned as the C-C stretching vibrations. The mode was also found in quinoxaline at 1623 cm -1 [85,86].…”

Theoretical and experimental study of solvent effects on the structure, vibrational spectra, and tautomerism of 3-amino-1,2,4-triazine

“…PCM model describes the solutesolvent interaction energies by four terms: electrostatic, dispersions, repulsions, and cavitations which are supplemented by a fifth term called thermal motion [31].…”

Synthesis, X-ray Structure, Hirshfeld, DFT and Biological Studies on a Quinazolinone-Nitrate Complex

“…In this regard, 4-hydroxyquinazoline ( 4-HQZ ) could exist as the four possible isomers as shown in Figure 2 . In 2011 Polat et al [ 49 ], reported the properties of structure and energy of the different isomers of 4-HQZ . They reported that the most stable form is tautomer A in both the gaseous and aqueous phases based on DFT calculations, and the sequence of tautomer stability in the gas phase is A > B > C > D .…”