1,721,034 research outputs found
Favipiravir Tautomerism: A Short Theoretical Report
No full textThere is no experimental data about the tautomerism of Favipiravir (T-705). Therefore its tautomeric state was predicted by using density functional theory in gas phase and in solution (toluene, acetonitrile and water). The solvent effect was described by means of the Polarizable Continuum Model. The results have shown that the enol form is strongly dominating in both gas phase and solution. In order to validate the theoretical predictions, 2-hydroxy pyridine and 2-hydroxy pyrazine were also included in the set of studied compounds. The available experimental data for their tautomerism are in very good agreement with the theoretical predictions, which validate the conclusions made for T-705
Absorption UV-Vis Spectroscopy and Chemometrics: From Qualitative Conclusions to Quantitative Analysis
No full text
An alternative for the calculation of derivative spectra in the near-infrared spectroscopy
No full textTautomerism in Azo and Azomethyne Dyes: When and If Theory Meets Experiment
No full textThe performance of 26 hybrid density functionals was tested against a tautomeric dataset (TautData), containing experimental information for the keto-enol tautomeric equilibrium in 16 tautomeric azodyes and Schiff bases in cyclohexane, carbon tetrachloride and acetonitrile. The results have shown that MN12-SX, BHandH and M06-2X can be used to describe the tautomeric state of the core structures in the frame of ~0.5 kcal/mol error and correctly predict the tautomeric state in respect of dominating tautomeric form. Among them MN12-SX is the best performer, although it fails to describe the nonplanarity of some of the enol tautomers. The same experimental dataset was used to develop and test a special DFT functional (TautLYP) aimed at describing the tautomeric state in azo- and azomethyne compounds in solution when nonspecific solvents are used
Comment on “Learning To Read Spectra: Teaching Decomposition with Excel in a Scientific Writing Course”
No full text
The neglected tautomerism in “Study of the electronic effect and quantitative spectra predictions of o-methoxyanilineterminated monoazonaphthols: a combined experimental and DFT study” by Guoxun Zhu, Yan Lin, Wenxian Zhou, Huacan Song and Zhengquan Li, RSC Advances, 2023, 13, 33736
No full textIn the paper of Zhu and co-workers, cited in the title, the authors derived a protocol for the absorption spectra prediction is sulphonated azo naphthols assuming that they exist as single azo tautomers. However, as shown by the available experimental data and the calculations, performed in this note, the studied dyes exist almost solely in hydrazone tautomeric form, which unavoidably affects the conclusions and linear relations made in the original paper
8-(Pyridin-2-yl)quinolin-7-ol as a Platform for Conjugated Proton Cranes: A DFT Structural Design
No full textTheoretical design of conjugated proton cranes, based on 7-hydroxyquinoline as a tautomeric sub-unit, has been attempted by using ground and excited state density functional theory (DFT) calculations in various environments. The proton crane action request existence of a single enol tautomer in ground state, which under excitation goes to the excited keto tautomer through a series of consecutive excited-state intramolecular proton transfer (ESIPT) steps with the participation of the crane sub-unit. A series of substituted pyridines was used as crane sub-units and the corresponding donor-acceptor interactions were evaluated. The results suggest that the introduction of strong electron donor substituents in the pyridine ring creates optimal conditions for 8-(pyridin-2-yl)quinolin-7-ols to act as proton cranes
- …
