OH Group Effect in the Stator of β-Diketones Arylhydrazone Rotary Switches

Hristova, Silvia; Kamounah, Fadhil S.; Crochet, Aurélien; Vassilev, Nikolay G.; Fromm, Katharina M.; Antonov, L.

doi:10.3390/chemistry2020024

Cited by 6 publications

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References 45 publications

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“…They were further improved by Aprahamian et al [6][7][8] who modified the rotor part by introducing a pyridyl group, which leads to substantial (but not full) stabilization of one of the isomers in solution. One of the major difficulties in the investigation of this class of compounds is the large number of possible tautomers and isomers/rotamers, often coexisting in mobile equilibria [9,10]. This is especially important in light of the fact that the interconversion between the rotamers is accompanied by proton transfer [8].…”

Section: Introductionmentioning

confidence: 99%

Unusual Para-Substituent Effects on the Intramolecular Hydrogen Bond in Hydrazone-Based Switches: Insights from Chemical Landscape Analysis and DFT Calculations

et al. 2021

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Тhe adequacy of chemical property predictions strongly depends on the structure representation, including the proper treatment of the tautomeric and isomeric forms. A combination of an in-house developed open-source tool for automatic generation of tautomers, Ambit-Tautomer, based on H-atom shift rules and standard quantum chemical (DFT) calculations is used for a detailed investigation of the possible geometric isomers, conformers and tautomers of unsubstituted and para-substituted phenylhydrazones, systems with experimentally observed unusual para-substituent effects on the intramolecular hydrogen bond (IMHB) for E-isomers of the compounds. The computational results show that the energetically preferred E-isomers are characterized by stronger IMHBs than the corresponding Z-isomers. The HN–N=C–C=N molecular fragment in the E-configurations is less sensitive to the substitution effect than the HN–N=C–C=O fragment in the isomers with Z-configuration. A probable reason for this decreased sensitivity of E-isomers to phenyl ring substitution is the more efficient conjugation and charge distribution in the HN–N=C–C=N fragment.

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