Vibrational, electronic, spectroscopic properties, and NBO analysis of p-xylene, 3,6-difluoro-p-xylene, 3,6-dichloro-p-xylene and 3,6-dibromo-pxylene: DFT study

Abstract

This study explains the vibration and interaction of p-xylene and effect of three elements (fluorine, chlorine and bromine) of the halogen family substitution on it. Basic chemistry of four, compounds p-xylene (PX); 3,6-diflouro-p-xylene (DFPX); 3,6-dichloro-p-xylene (DCPX) and 3,6-dibromo-p-xylene (DBPX) has been explained extensively using theoretical approach. Vibrational energy distribution analysis (VEDA) software was used to study the potential energy distribution (PED) analysis, bond length, bond angles and dihedral angles of PX, DFPX, DCPX, DBPX after optimization with GAUSSIAN 09 software. The trend in chemical reactivity and stability of the studied compounds was observed to show increasing stability and decreasing reactivity moving from DBPX, DCPX, DFPX to PX and this was obtained from the calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) values. Our results show that PX is the best electron donor (best nucleophile) while DBPX is the best electron acceptor (the best electrophile). We also observed that the substituted halogen increases the value of the bond angles but the effect is reduced as the size of the halogen increases. The maximum intensity and the frequency value for the maximum intensity of the different compounds was determined using the VEDA 04 software . From our natural bond orbital (NBO) 7.0 program analysis, the studied compounds are said to show biological activities as well as the intramolecular hyperconjugative interactions responsible for stabilizing the compounds. The NBO results also revealed that the non-bonding interaction existing between the lone pair electron on the halogen atoms and the aromatic ring increases the stability of the halogen substituted para-xylene molecules. Multiwfn: A Multifunctional Wavefunction Analyzer was used for the spectroscopic plots.

Investigation on electronic structure, vibrational spectra, NBO analysis, and molecular docking studies of aflatoxins and selected emerging mycotoxins against wild-type androgen receptor

“…The natural atomic orbital occupancies of most interacting NBO's of the selected mycotoxins together with their percentage of hybrid atomic orbitals contribution are shown in Table S4. The NBO analysis of these mycotoxins provides information aiding the investigation of the intra and intermolecular bonding as well as accounting for charge transfer [ 31 , 43 , 44 , 45 , 46 ]…”

“…Further, the natural population analysis showed that 170 electrons in the ZEA molecule are distributed on the sub-shells (Table S6 of supporting information). It should be noted that electronegative atoms have the tendency to donate electrons whereas, electropositive atoms tend to accept electrons [ 44 , 45 , 46 , 47 , 48 , 49 , 50 ] Hence, AFM1 molecule has the highest electronegative charge of -0.75723 e accumulated on O 37 and have the tendency to donate electron compared to other investigated mycotoxins. However, ZEA is found to have the highest electropositive charge of 0.83796 e on the C 13 atom (Table S5 of supporting information).…”

Synthesis, characterization, DFT, and TD-DFT studies of (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite)

“…From Fig. 4, Eg is 2.95 eV, which is relatively low [27][28][29][30][31][32], hence excitation from the HOMO to LUMO is easily feasible; this is a basic property of a reactive molecule. Also, the energy gap between HOMO-1 and LUMO + 1 orbitals was determined for a more explicit information about the studied molecule; we obtained Eg to be 4.94 eV.…”

Synthesis, characterization, and theoretical studies of the photovoltaic properties of novel reactive azonitrobenzaldehyde derivatives

“…The energy of the HOMO orbital of the dye must lie below the redox potential of the (I À /I 3 À ) couple (À4.80 eV), which is necessary to enable charge regeneration of the dyes. 26,27 DE LUMO is described as the difference between the energy gap of E LUMO of the dyes and E CB of TiO 2 . It is mathematically represented as:…”