Volume 45, Issue 32 pp. 2899-2911
RESEARCH ARTICLE

Ab initio electronic absorption spectra of para-nitroaniline in different solvents: Intramolecular charge transfer effects

Matheus Máximo-Canadas

Matheus Máximo-Canadas

Departamento de Química, Instituto Militar de Engenharia (IME), Rio de Janeiro, Rio de Janeiro, Brazil

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Lucas Modesto-Costa

Lucas Modesto-Costa

Department of Physics, Federal Rural University of Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil

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Itamar Borges Jr

Corresponding Author

Itamar Borges Jr

Departamento de Química, Instituto Militar de Engenharia (IME), Rio de Janeiro, Rio de Janeiro, Brazil

Correspondence

Itamar Borges Jr, Departamento de Química, Instituto Militar de Engenharia (IME), Praça General Tibúrcio, 80, Rio de Janeiro, Rio de Janeiro 22290-270, Brazil.

Email: [email protected]

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First published: 30 August 2024
Citations: 1

Abstract

Intramolecular charge transfer (ICT) effects of para-nitroaniline (pNA) in eight solvents (cyclohexane, toluene, acetic acid, dichloroethane, acetone, acetonitrile, dimethylsulfoxide, and water) are investigated extensively. The second-order algebraic diagrammatic construction, ADC(2), ab initio wave function is employed with the COSMO implicit and discrete multiscale solvation methods. We found a decreasing amine group torsion angle with increased solvent polarity and a linear correlation between the polarity and ADC(2) transition energies. The first absorption band involves π → π* transitions with ICT from the amine and the benzene ring to the nitro group, increased by 4%–11% for different solvation models of water compared to the vacuum. A second band of pNA is characterized for the first time. This band is primarily a local excitation on the nitro group, including some ICT from the amine group to the benzene ring that decreases with the solvent polarity. For cyclohexane, the COSMO implicit solvent model shows the best agreement with the experiment, while the explicit model has the best agreement for water.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available in the supplementary material of this article. Additional data are available in GitHub and Zenodo90 and can be accessed via https://doi.org/10.5281/zenodo.10524944.

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