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

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 H 2 O 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 H 2 O 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 H 2 O fragment in most complexes, except in QNOL, CNOL and QNAZ clusters with H 2 O 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 (þve ΔH f ) and non-spontaneous (þve ΔG f ).

Understanding the Electronic Interactions, Vertical Excitation Analysis, and the Photovoltaic Properties of 5-(2-ethylhexyl)-1,3-di(furan-2-yl)-4H-thieno[3,4-c]pyrrole-4,6-dione

“…In the simulated ESP map, the yellowish-red region shows the transition from a low electron density region to a high electron density region (red) [63]. Such distributions are visible around the non-polar ethylhexyl group on the A unit.…”

“…Such distributions are visible around the non-polar ethylhexyl group on the A unit. Reactivity, polar properties, electronic transitions and its accompanied properties are not expected around these regions [63,65].…”

“…To further study this FTPF system, we conducted simulations for the scanning tunneling microscopy (STM) which helps study the structural pattern in a chemical system. STM is directly proportional to electronic distribution in a system and its maps give full information about the flow of tunneling current (I) around atoms in a molecule [63,64]. STM plots for FTPF was done in gas, hexane, DMF and THF, in order to investigate the effect of solvent on the tunneling current around the D-A-D molecule.…”

“…The zones with negative potentials, i.e. high electron densities are transcribed as red with negative values for isosurfaces; while the electron deficient zones are blueish (positive isosurface values are recorded for such surfaces) [63,65]. From the plotted MEP map showing four planar view directions of FTPF in gas visualized in Fig.…”

“…The contributions of atoms of the furanyl donor compound to TDOS is represented with red curve, pyrroledione acceptor with blue, and the ethylhexyl group with pink curve. The position of HOMO of the molecule under study is represented by the vertical dashed line on the graph, while the polarity of OPDOS of FTPF D-A-D system at any position on the graph indicates its bonding behaviour at that position[63].…”