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. 2021 Jul 10;7(7):e07531.
doi: 10.1016/j.heliyon.2021.e07531. eCollection 2021 Jul.

Understanding the aqueous chemistry of quinoline and the diazanaphthalenes: insight from DFT study

Obieze C Enudi  1 , Hitler Louis  1 , Moses M Edim  1 , John A Agwupuye  1 , Francis O Ekpen  1 , Emmanuel A Bisong  1 , Patrick M Utsu  1
Affiliations

Understanding the aqueous chemistry of quinoline and the diazanaphthalenes: insight from DFT study

Obieze C Enudi et al. Heliyon. .

Abstract

The inter-fragment interactions at various binding sites and the overall cluster stability of quinolone (QNOL), cinnoline (CNOL), quinazoline (QNAZ), and quinoxaline (QNOX) complexes with H2O were studied using the density functional theory (DFT) approach. The adsorption and H-bond binding energies, and the energy decomposition mechanism was considered to determine the relative stabilization status of the studied clusters. Scanning tunneling microscopy (STM), natural bonding orbitals (NBO) and charge decomposition were studied to expose the electronic distribution and interaction between fragments. The feasibility of formations of the various complexes were also studied by considering their thermodynamic properties. Results from adsorption studies confirmed the actual adsorption of H2O molecules on the various binding sites studied, with QNOX clusters exhibiting the best adsorptions. Charge decomposition analysis (CDA) revealed significant charge transfer from substrate to H2O fragment in most complexes, except in QNOL, CNOL and QNAZ clusters with H2O at binding position 4, where much charges are back-donated to substrate. The O---H inter-fragment bonds was discovered to be stronger than counterpart N---H bonds in the complexes, whilst polarity indices confirmed N---H as more polar covalent than O---H bonds. Thermodynamic considerations revealed that the formation process of all studied complexes are endothermic (+ve ΔH f ) and non-spontaneous (+ve ΔG f ).

Keywords: Adsorption; Aqueous; DFT; Diazanaphthalenes; Quinolone.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Plots of Adsorption energies for the various interactions positions in QNOL, CNOL, QNAZ and QNOX studied with DFT/B3LYP method and 631-G (d) basis set.
Figure 2
Figure 2
PDOS, TDOS and OPDOS Plots for (a) QNOL2, (b) CNOL2, (c) QNAZ2 and (d) QNOX2 studied with DFT/B3LYP method and 631-G (d) basis set.
Figure 3
Figure 3
STM images of (a) QNOL2, (b) CNOL2, (c) QNAZ2 and (d) QNOX2 studied with DFT/B3LYP method and 631-G (d) basis set.
Figure 4
Figure 4
Plots of Electron Obtained by Fragment 2 (H2O) from CDA for the various interactions positions in QNOL, CNOL, QNAZ and QNOX studied with DFT/B3LYP method and 631-G (d) basis set.
Figure 5
Figure 5
Orbital interaction diagrams from CDA for the various interactions positions in QNOL, CNOL, QNAZ and QNOX studied with DFT/B3LYP method and 631-G (d) basis set.
Figure 6
Figure 6
ESP Isosurface plots for all Clusters studied with DFT/B3LYP method and 631-G (d) basis set.
See this image and copyright information in PMC

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