Computational Chemistry by Ponnadurai Ramasami

Author:Ponnadurai Ramasami
Language: eng
Format: epub
Publisher: De Gruyter
Published: 2021-05-08T20:15:23.800000+00:00

8.2.2

Nanocomposites/complexes involving other compounds

First, it is worthwhile to mention the recent study by Liu et al. [78]. This study was devoted to interactions of NGs with electro-active molecules; these interactions result in π-systems of the donor-acceptor (D-A) type, with the electronic-rich NGs generally playing the electron donors role. The research resulted in a series of reversed D-A complexes generated by the reaction of CeN coupling between electron-deficient perchlorinated NGs and electron-rich anilines. The occurrence of the selective amination at the NG vertexes along with the D-A NGs concave geometries was proved by single-crystal X-ray diffraction study. The anilino groups donating ability was demonstrated to assist to finely tune the optical absorption of these complexes as well as intermolecular interactions inside them. The concave electron-deficient D-A NGs were found to produce assemblies with various donor-type guest molecules, such as tetrathiafulvalene, via intermolecular CT. DFT calculations helped to investigate the intramolecular CT in the aminated NGs. All calculations were performed with the Gaussian 09 software. In the search for the suitable DFT method, the comparison of the theoretically calculated HOMO–LUMO gaps (obtained with B3LYP, CAM-B3LYP, M062X, and HSEH1PBE functionals) with the experimental optical gap values was done. The CPCM solvation model was employed to take into account the solvent effects of dichloromethane used in experiments. The structures optimized with different functionals were compared with the crystallographic data. According to the results obtained, the HSEH1PBE functional was more suitable for the calculations on these systems. The NGs frontier orbital analysis showed that the NGs LUMOs were distributed over the whole NG moiety and the NG HOMOs were dominated by the peripheral anilino units. The analysis of the electron density differences between the first excited and the ground states showed an electron density depletion at the anilino groups and electron density accumulation at the NG core. Note: it would be of interest to study complexes of these NGs with electron-rich molecules formed by intermolecular D-A interactions.

Next, it is quite interesting to mention the 2018 computational studies by Vatanparast and Shariatinia [1] which were performed for candidates of drug delivery systems for the isoniazid (Iso) drug. In this study, DFT approach was employed to investigate both pristine and doped GQDs as potential carriers for the Iso. As a GQD model, the HBC (C42H18) was used along with its BN-, BP-, AlN-, and AlP-doped derivatives with general formula C36X3Y3H18 (where X = B, Al and Y = N, P). In the doped models, the three C=C bonds in the central ring were replaced with B=N, B=P, Al=N, and Al=P bonds. The complexes of the HBC-Iso and doped HBC-Iso can be broadly considered as a form of nanocomposites. The numerous properties of these complexes were studied: adsorption energies, thermochemical properties, electronic properties (including molecular ESPs, dipole moments, and DOSs), molecular reactivity descriptors, and IR/UV–vis spectra. All calculations were carried in the implicit solvent (water, ɛ = 78.4) using PCM as implemented in the Gaussian 09. The structural optimizations were carried out without any symmetry constraints with the M06-2X/6-31G(d,p) approach.

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