Substituent effects on the intramolecular hydrogen bond in 1-hydroxyanthraquinone: AIM and NBO analyses

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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Intramolecular hydrogen bond in 3-imino-propenylamine isomers: AIM and NBO studies

International Journal of Quantum Chemistry ◽

10.1002/qua.21955 ◽

2009 ◽

pp. NA-NA

Author(s):

H. Raissi ◽

Abraham F. Jalbout ◽

B. Abbasi ◽

F. Fazli ◽

F. Farzad ◽

...

Keyword(s):

Hydrogen Bond ◽

Intramolecular Hydrogen Bond ◽

Intramolecular Hydrogen ◽

Aim And Nbo

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Dielectric enrichment in binary solvent mixtures. The intramolecular hydrogen bond in N-alkyl-substituted o-nitroanilines. Substituent effects

Canadian Journal of Chemistry ◽

10.1139/v92-337 ◽

1992 ◽

Vol 70 (10) ◽

pp. 2677-2682 ◽

Cited By ~ 19

Author(s):

Rosa Cattana ◽

Juana J. Silber ◽

Jorge Anunziata

Keyword(s):

Hydrogen Bond ◽

Intramolecular Hydrogen Bond ◽

Preferential Solvation ◽

Substituent Effects ◽

Solvent Mixture ◽

Binary Solvent ◽

Solvent Mixtures ◽

Hydrogen Bond Acceptor ◽

Intramolecular Hydrogen ◽

Strong Intramolecular Hydrogen Bond

In this work we report solvatochromism studies on o-nitroaniline and several N-alkyl-o-nitroaniline derivatives used as solutes in solvent mixtures of an "inert" nonpolar cosolvent, cyclohexane, and THF as a solvent with hydrogen bond acceptor ability. These studies allowed us to establish the competition between inter- and intramolecular hydrogen bond in solutes. This was done by comparing the magnitude of the local inhomogeneity induced by the solute-in-solvent mixture, that is, "preferential solvation," using Suppan's dielectric enrichment model as modified by us to be applied to electronic transitions. Since preferential solvation accounts for dielectric as well as specific interactions while dielectric enrichment only for the former, it was shown by comparison that it is possible to separate both effects and even quantify them. It was deduced that N-alkyl-o-nitroanilines form a strong intramolecular hydrogen bond, which remains unbroken even in polar solvents and hydrogen bond acceptors such as dimethyl sulfoxide. This was also confirmed by solvatochromic studies in pure solvents. On the other hand, a symmetrical dependence of the effects of alkyl substituents and solvents on the shifts of the absorption spectra was observed.

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