Molecular structure, HOMO, LUMO, MEP, natural bond orbital analysis of benzo and anthraquinodimethane derivatives

Abstract

Objective: Optimized molecular structures have been investigated by DFT/B3LYP method with 6-31G (d,p) basis set. Stability of Benzo and anthraquinodimethane derivatives 1-4, hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond has been analyzed by using natural bond orbital (NBO) analysis. Electronic structures were discussed and the relocation of the electron density was determined. Molecular electrostatic potential (MEP), local density functional descriptors has been studied. Nonlinear optical (NLO) properties were also investigated. In addition, frontier molecular orbitals analyses have been performed from the optimized geometries. An ionization potential (I), electron affinity (A), electrophilicity index (ω), chemical potential (µ), electronegativity (χ), hardness (η), and softness (S), have been investigated. All the above calculations are made by the method mentioned above.Methods: The most stable optimized geometries obtained from DFT/B3LYP method with 6-31G(d,p) basis set were investigated for the study of molecular structures, nonlinear properties, natural bond orbital (NBO), molecular electrostatic potential (MEP) and frontier molecular orbital of Benzo and anthraquinodimethane derivatives.Results: Reactive sites of electrophilic and nucleophilic attacks for the investigated molecule were predicted using MEP at the B3LYP/6-31G(d,p). Compound 4 possesses higher electronegativity value than all compounds so; it is the best electron acceptor; the more reactive sites for electrophilic attacks are shown in compounds 1 and 4, for nucleophilic attacks are indicated in compounds 2 and 3 and the more reactive sites in radical attacks are detected in compounds 2 and 4.Conclusions: Compound 1 is softest, best electron donor and more reactive than all compounds. The calculated first order hyperpolarizability was found much lesser than reported in literature for urea.

Investigation of the Effects of Solvents on the Structural, Electronic and Thermodynamic Properties of Rosiglitazone Based on Density Functional Theory

“…The lowest LUMO energy of -1.44795eV was found to be in ethanol which shows that the molecule will be the best electron acceptor in ethanol compared to the gas phase and other solvents. The largest HOMO-LUMO gap of 4.28507eV was found in water which implies a higher kinetic stability and less chemical reactivity [20] followed by 4.28344eV found in the gas phase both in the 6-31+G(d,p) basis set and a gradual increase in the frontier molecular orbital energy gap as the dielectric constants of the solvents increased was observed, this can be observed across all the basis sets used [21][22].…”

Molecular structure, electronic properties, vibrational analysis and reactivity parameters Of (Z)-N-(4-methoxyphenyl)-2-(4-oxothiazolidin-2-ylidene)acetamide: a theoretical study

“…The global softness = ( /η) is in erse of the hardness [19]. Further the global electro hilicit inde (ω), introduced b Parr et al [20] is calculated in terms of chemical potential and the hardness by the relation ω = µ 2 / η and give the lowering of energy due to maximal electron flow between donor and acceptor. Here the ionization potential (IP) and electron affinity (EA) are defined as the difference in the ground state energy between the cationic and neutral system and difference in the ground state energy between neutral and anionic system i.e.…”

“…Considering the chemical hardness, if one molecule has a large HOMO-LUMO gap, it is a hard molecule or small HOMO-LUMO gap it is a soft molecule. One can also relate the stability of molecule to hardness, which means that the molecule with least HOMO-LUMO gap means it is more reactive [20]. The local reactivity descriptor like Fukui function indicates the preferred regions where a chemical species (molecule) will amend its density when the number of electrons ismodified or it indicates the tendency of the electronic density to deform at a given position upon accepting or donating electrons [21,22].…”

“…The condensed or atomic Fukui functions on the k th atom site, for electrophilic ( ), nucleophilic ( ) and free radical ( ) attacks are defined as = [q(N+1) -q(N)] , =[q(N) -q(N-1)and = 1/2[(q(N+1) -q(N-1)] respectively, where q k is the atomic charge ( NBO) at the k th atomic site in the anionic (N + 1), cationic (N -1) or neutral molecule. Parr and Yang [19,20]showed that sites in chemical species with the largest values of Fukui function (f k ) show high reactivity for corresponding attacks. The Fukui functions calculated from the NBO charges have been reported to be in good acceptation [23,24].…”

Comparative Study of CBS-Q Calculated and Experimental pKa Values for Fluoro-Acetoxy Derivative

“…Calculated pka on antiperiplanar-position orbitals of the 7 molecules were obtained from the quantum chemical calculation by the DFT using cbs-q bases sets as shown in Fig. 1 Nucleofugality is defined as the propensity of an atom or group of them to depart bearing the bonding electron pair in a heterolytic cleavage process [17,18], the highest nucleofugality of the 7 molecules were: 1.562925, 1.549973, 1.541977, 1.532505, 1.341454, 1.248216 and 1.157782. these results for molecules: 7, 4, 6, 5, 3, 2 and 1. According to these values, those molecules have the activation activity to PON1.…”