Negative Electrostatic Potential Regions Research Articles

Study on the compounding optimization of surfactants and synergistic effects on the wettability of bituminous coal

To improve the wettability of surfactants on bituminous coal and to explore its wettability and wettability mechanism on bituminous coal, taking the Sandaogou bituminous coal as an example, a single factor experiment was carried out first. Through contact angle and surface tension experiments, three surfactants with good wettability were selected from among the nine surfactants and mixed in equal proportions two by two to determine the optimal compounding method and compounding concentration. The experimental results show that the compounding of nonionic and anionic, nonionic and zwitterionic, anionic and zwitterionic surfactants can have synergistic effects and significantly improve the wettability of bituminous coal. Among them, the 0.5 wt% SDS + 0.5 wt% CAB-50 (R2) compound surfactant had the best wettability on bituminous coal, and the contact angle and surface tension were only 15.24° and 23.62 mN/m, respectively. The surface electrostatic potential values of each material molecule were calculated by Materials Studio software based on the quantum chemistry method, and correlation analysis was carried out with wettability. The results show that the surface electrostatic potentials of CDEA, SDS and CAB-50 were greater than those of water and bituminous coal, and the region of maximum negative electrostatic potential corresponded to oxygen atoms, which are easier to adsorb on bituminous coal and water molecules. Then, through molecular dynamics simulation, the interaction energy and the distribution of contributions along the Z-axis of the water/compound surfactant/bituminous coal system at equilibrium were investigated, and finally, a spray dust reduction test was carried out in the Sandaogou Coal Mine. The results showed that the 0.5 wt% SDS + 0.5 wt% CAB-50 compound solution can be used as a water molecule adsorption carrier, prompting more water molecules to be embedded into coal molecules, increasing the relative concentration of water molecules on the surface of bituminous coal, restricting the diffusion of water molecules, and greatly improving the wettability. After the addition of 0.5 wt% SDS + 0.5 wt% CAB-50 as a spray agent, the concentration of total dust at the driver's position decreased from 65.14 to 9.11 mg/m3, the concentration of exhaled dust decreased from 30.07 to 3.35 mg/m3, and the efficiency of total and exhaled dust reduction compared with that of pure water was 86.01% and 89.35%, respectively.

Theoretical investigation of asphaltene molecules in crude oil viscoelasticity enhancement

Understanding the mechanisms of viscosity enhancement in crude oil phases is crucial for optimizing extraction and transportation processes. The enhanced viscosity mechanism of crude oil phase can be attributed to the intricate intermolecular interactions between asphaltene molecules. However, the molecular mechanism of the viscosification of asphaltene molecules in crude oil is not yet to be fully understood. In this work, molecular dynamics simulations were employed to investigate the dynamic behavior and viscosification mechanism of asphaltene molecules in complex oil phases. Research suggests that the neutral surface of asphaltenes features abundant positive and negative electrostatic potential regions, facilitating complementary pairing between these areas. This significantly augments electrostatic interactions among asphaltene molecules. Besides, the expansive nonpolar expanse on the normal asphaltene surface facilitates interactions between asphaltenes and crude oil molecules. This leads the crude oil viscosity of the system containing normal asphaltene is higher than that of the system containing acidic asphaltene under the same mass fraction (382 μ Pa·s for AAsp and 416 μ Pa·s for NAsp). This work provides insight into the viscosity enhancement mechanisms in crude oil phases and is helpful in improving the efficiency of crude oil extraction and transportation.

Single crystal XRD and DFT investigation of 1,5-dimethyl-4-[(2-oxo-1,2-diphenylethylidene) amino]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

The single crystal 1,5-dimethyl-4-[(2-oxo-1,2-diphenylethylidene) amine]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one [DDAPDP] was designed to enhance luminescence property using benzil and 4-aminoantipyrine. DFT calculations of DDAPDP were done with Gaussian 16 W program employing hybrid functional B3LYP with 6–311++G (d,p) basis set for geometry optimization without symmetry constraints. The single crystal was studied based on theoretical aspects such as Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), Mullikan atomic charge and Molecular Electrostatic Potential (MEP) using density functional method. The experimental and theoretical spectral analysis of the single crystal system was investigated using FTIR, Raman, UV –visible, 1H NMR and 13C NMR techniques. Positive electrostatic potential regions dispersed throughout the rings and represent possible nucleophilic attack sites, whereas negative electrostatic potential regions are typically grouped around the CO group. Energy gap −3.776391 eV, confirmed by the estimated HOMO and LUMO energies. Natural bond orbital analysis (NBO) was used to assess the molecule's stability as a result of charge delocalization and hyper conjugation. Electron population of each atom was calculated by Mulliken atomic charge distribution analysis. The bacterium E. coli (Gram negative) and the organism S. aureus, together with a standard medication, were used to study and assess the compounds' antimicrobial activity in vitro, which reveals the antibacterial and antifungal activities of DDAPDP.

Molecular structure on the detoxification of fluorinated liquid crystal monomers with reactive oxidation species in the photocatalytic process

Fluorinated liquid crystal monomers (LCMs) are begun to emerge as new persistent organic pollutants. Herein, the structure-reactivity relationships of fluorinated LCMs 1,2,3-trifluoro-5-[3-(3-propylcyclohexyl)cyclohexyl]benzene (TPrCB), 1,2-difluoro-4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzene (DPrCB), 4-[(trans,trans)-4'-(3-Buten-1-yl)[1,1′-bicyclohexyl]-4-yl]-1,2-difluoro-benzene (BBDB) and 1-[4-(4-ethylcyclohexyl)cyclohexyl]-4(trifluoromethoxy)benzene (ECTB) subject to photocatalysis-generated oxidation species were investigated. The degradation rate constant of BBDB was 3.0, 2.6, and 6.8 times higher than DPrCB, TPrCB and ECTB, respectively. The results reveal that BBDB, DPrCB and TPrCB had mainly negative electrostatic potential (ESP) regions which were vulnerable to electrophilic attack by h+, •OH and •O2−, while ECTB was composed of mainly positive ESP regions which were vulnerable to nucleophilic attack by •OH and •O2−. The detoxification processes of BBDB, DPrCB and TPrCB included carbon bond cleavage and benzene ring opening. However, the methoxy group of ECTB reduced the nucleophilic reactivity on the benzene ring, leading to slower detoxification efficiency. These findings may help to develop LCMs treatment technologies based on structure-reactivity relationships.

Fused ring effect on optical nonlinearity and structure property relationship of anthracenyl chalcone based push-pull chromophores.

The Ultraviolet-visible (UV-Vis) spectra indicate that anthracenyl chalcones (ACs) have high maximum wavelengths and good transparency windows for optical applications and are suitable for optoelectronic applications owing to their HOMO–LUMO energy gaps (2.93 and 2.76 eV). Different donor substituents on the AC affect their dipole moments and nonlinear optical (NLO) responses. The positive, negative, and neutral electrostatic potential regions of the molecules were identified using molecular electrostatic potential (MEP). The stability of the molecule on account of hyperconjugative interactions and accompanying charge delocalization was analyzed using natural bond orbital (NBO) analysis. Open and closed aperture Z-scans were performed using a continuous-wave frequency-doubled diode-pumped solid-state (DPSS) laser to measure the nonlinear absorption and nonlinear refractive index coefficients, respectively. The valley-to-peak profile of AC indicated a negative nonlinear refractive index coefficient. The obtained single crystals possess reverse saturation absorption due to excited-state absorption. The structural and nonlinear optical properties of the molecules have been discussed, along with the role of anthracene substitution for enhancing the nonlinear optical properties. The calculated third-order susceptibility value was 1.10 x10-4 esu at an intensity of 4.1 kW/cm2, higher than the reported values for related chalcone derivatives. The NLO response for both ACs offers excellent potential in optical switching and limiting applications.

Atomistic Details of Charge/Space Competition in the Ca2+ Selectivity of Ryanodine Receptors.

Ryanodine receptors (RyRs) are ion channels responsible for the fast release of Ca2+ from the sarco/endoplasmic reticulum to the cytosol and show a selectivity of Ca2+ over monovalent cations. By utilizing a recently developed multisite Ca2+ model in molecular dynamic simulations, we show that multiple cations accumulate in the upper selectivity filter of RyRs, and the small size and high valence of Ca2+ make it preferable to K+ in competition for space in this confined region of negative electrostatic potential. The presence of Ca2+ in the upper selectivity filter significantly increases the energy barrier of K+ permeation, while the presence of K+ has little impact on the Ca2+ permeation. Our results provide the atomistic details of the charge/space competition mechanism for the ion selectivity of RyRs, which ensures the robustness of their Ca2+ release function. The mechanism could be utilized in protein- and nanoengineering for valence selectivity of ion species.

The use and misuse of van der Waals radii

A widely used criterion for the existence of a noncovalent interaction is that the interatomic separation be less than the sum of the van der Waals radii of the respective atoms. However, this criterion should not be applied rigidly, but rather with considerable caution and flexibility, for several reasons. First, there is considerable uncertainty in the values assigned as van der Waals radii. Second, because of the manner in which they are assigned, their sums will necessarily miss a significant number of noncovalent interactions. Finally, not all interactions are between atoms; sometimes, instead of an atom, it is a region of positive or negative electrostatic potential that is involved.

A theoretical study of chemical bonding and topological and electrostatic properties of the anti-leprosy drug dapsone

The theoretical charge density study for the gas phase of anti-leprosy drug Dapsone has been carried out in the light of the theory of atoms in molecules using density functional theory employing B3LYP(6-311G++(d, p) hybrid functional completed with dispersion corrections. The Hirshfeld surface analysis as well as fingerprint plots has been utilized to visualize and quantify the intermolecular contacts present in the molecule. The topological properties such as electron density and its Laplacian, delocalization index have been elucidated to throw light into the chemical bonding and atomic and molecular details. The electron localization function has been used to visualize and deduce information on the lone pair and the subshells of the Cl atom. The electrostatic potential visualizes the positive and negative electrostatic potential regions which are susceptible to nucleophilic and electrophilic attack. On the whole, this study provides an exact mechanism, interaction, and topological and electrostatic properties of the drug through theoretical insights which all will be a platform for our further investigation of the interaction between dapsone and dihydropteroate synthase (DHPS).

Structural, vibrational and electronic spectroscopic study of 6-hydroxycoumarin using experimental and theoretical methods.

Understanding the photochemical behavior of structural isomers of hydroxycoumarin (HC) having different properties of consequence in biological activities demand spectroscopic information of this class of compounds. Barring 6-hydroxycoumarin (6-HC), other isomers of HC's are well studied spectroscopically. To understand and compare the photochemical activity of 6-HC with other isomers, a detailed study of this molecule has been taken up. For this purpose, electronic, vibrational and structural properties of 6-HC have been studied using ultraviolet absorption and Infrared spectroscopy techniques. Quantum chemical calculations have been performed at DFT/B3LYP level of theory to get the optimized geometry and vibrational frequencies of normal modes to support and analyze experimental data. The detailed vibrational assignments were made on the basis of potential energy distributions. Chemical activity, molecular orbital energies, band gap and hyper-polarizability information have been computed from quantum chemical simulations. NBO analysis helped in understanding the stability of the molecule arising from hyper-conjugative interaction and charge delocalization. UV-Visible spectrum of the compound was recorded in the region 300-600nm helped in obtaining band gap data of the compound. Molecular Electrostatic Potentials (MESP) were plotted and the respective centers of electrophilic and nucleophilic attacks were predicted with the help of Fukui functions calculations. Further, it was observed that the negative electrostatic potential regions are mainly localized over the oxygen atoms and the positive regions are localized over the benzene ring. Details of the results and analysis of experimental and theoretical spectroscopy studies are presented in this paper.

Crystal structure and DFT study of a zinc xanthate complex.

In the title compound, bis-(2-meth-oxy-ethyl xanthato-κS)(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')zinc(II) acetone hemisolvate, [Zn(C4H7O2S2)2(C6H16N2)]·0.5C3H6O, the ZnII ion is coordinated by two N atoms of the N,N,N',N'-tetra-methyl-ethylenedi-amine ligand and two S atoms from two 2-meth-oxy-ethyl xanthate ligands. The amine ligand is disordered over two orientations and was modelled with refined occupancies of 0.538 (6) and 0.462 (6). The mol-ecular structure features two C-H⋯O and two C-H⋯S intra-molecular inter-actions. In the crystal, mol-ecules are linked by weak C-H⋯O and C-H⋯S hydrogen bonds, forming a three-dimensional supra-molecular architecture. The mol-ecular structure was optimized using density functional theory (DFT) at the B3LYP/6-311 G(d,p) level. The smallest HOMO-LUMO energy gap (3.19 eV) indicates the suitability of this crystal for optoelectronic applications. The mol-ecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the mol-ecules. Half a mol-ecule of disordered acetone was removed with the solvent-mask procedure in OLEX2 [Dolomanov et al. (2009 ▸). J. Appl. Cryst. 42, 339-341] and this contribition is included in the formula.

DNA Conformational Changes Play a Force-Generating Role during Bacteriophage Genome Packaging

Motors that move DNA, or that move along DNA, play essential roles in DNA replication, transcription, recombination, and chromosome segregation. The mechanisms by which these DNA translocases operate remain largely unknown. Some double-stranded DNA (dsDNA) viruses use an ATP-dependent motor to drive DNA into preformed capsids. These include several human pathogens as well as dsDNA bacteriophages—viruses that infect bacteria. We previously proposed that DNA is not a passive substrate of bacteriophage packaging motors but is instead an active component of the machinery. We carried out computational studies on dsDNA in the channels of viral portal proteins, and they reveal DNA conformational changes consistent with that hypothesis. dsDNA becomes longer (“stretched”) in regions of high negative electrostatic potential and shorter (“scrunched”) in regions of high positive potential. These results suggest a mechanism that electrostatically couples the energy released by ATP hydrolysis to DNA translocation: The chemical cycle of ATP binding, hydrolysis, and product release drives a cycle of protein conformational changes. This produces changes in the electrostatic potential in the channel through the portal, and these drive cyclic changes in the length of dsDNA as the phosphate groups respond to the protein’s electrostatic potential. The DNA motions are captured by a coordinated protein-DNA grip-and-release cycle to produce DNA translocation. In short, the ATPase, portal, and dsDNA work synergistically to promote genome packaging.

Structure, spectroscopic study and DFT calculations of 2,6 bis (tri fluro methyl) benzoic acid

The work involves the vibrational spectral analysis of 2.6 bis (tri fluro methyl) benzoic acid using FT-IR and FT-Raman spectroscopy. The computations were performed at DFT level of theory to get the optimized geometry and vibrational wave numbers of the normal modes of the title compound using Gaussian software. The detailed vibrational assignments were proposed on the basis of potential energy distribution. The calculated HOMO and LUMO energies show chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The hyperpolarizability values are also reported. From the MEP plot, the negative electrostatic potential regions are mainly localized over the oxygen atoms and the positive regions are localized over all the hydrogen atoms. Fukui functions are calculated to find the possible sites for electrophilic and nucleophilic attack.

Structural and vibrational characteristics and vibronic coupling of tetramethyltetraselenafulvalene

The molecular, electronic and crystal structures of tetramethyltetraselenafulvalene (TMTSF) have been investigated. The experimental IR and Raman spectra and single crystal XRD for TMTSF have been interpreted. In order to facilitate this, computations have been carried out for the molecular structures and vibrational characteristics of the TMTSF molecule. Study of Molecular electrostatic potential surface of the TMTSF and its cation is also done. Normal mode assignments have been made on the basis of the computed potential energy distributions (PEDs). In addition, a comprehensive study of molecular geometries, atomic charges and vibrational fundamentals of TMTSF and its cationic molecule has been carried out. Vibronic coupling constants in TMTSF and TMTSF+ have been computed using the DFT/B3LYP results. The TMTSF molecule belongs to C2v point group symmetry. All the studied molecules exhibit partial double bond character as all the bond lengths are changed from their usual bond lengths. The partial double bond character has been found to be indicate that the conducting behaviour of these molecules. In the unit cell of TMTSF, some H atoms and all the Se atoms are interacting with the molecules of neighboring and its own cell. The major changes in frequencies from neutral to the cationic state for í (ring) and í(CC) are found for the both molecules. The vibronic coupling corresponding to a vibrational mode helps to transport charge along the stacks of a conducting organic molecules from a neutral molecule to an adjacent charged ion. The magnitude of the VCC is noticed to be maximum for the í (CC). The geometry of the neutral molecule under this mode resembles to that of the ion and vice-versa. The large VCC of this mode shows that removal of an electron is much easier during the vibrational modes. Thus from the present study i.e. the molecular, electronic and crystal structures and vibronic investigations confirm the conducting behaviour of the TMTSF molecule. From the MEP surface it is clear that the sites close to selenium atoms in TMTSF show region of most negative electrostatic potential.

Mol-ecular structure, DFT studies and Hirshfeld analysis of anthracenyl chalcone derivatives.

The mol-ecular and crystal structure of two new chalcone derivatives, (E)-1-(anthracen-9-yl)-3-[4-(piperidin-1-yl)phen-yl]prop-2-en-1-one, C28H25NO, (I), and (E)-1-(anthracen-9-yl)-3-[4-(di-phenyl-amino)-phen-yl]prop-2-en-1-one, C35H25NO, (II), with the fused-ring system at the same position are described. In the crystals of (I) and (II), the mol-ecules are linked via C-H⋯O hydrogen bonds into inversion dimers, forming R22(22) and R22(14) ring motifs, respectively. Weak inter-molecular C-H⋯π inter-actions further help to stabilize the crystal structure, forming a two-dimensional architecture. The mol-ecular structures are optimized using density functional theory (DFT) at B3LYP/6-311 G++(d,p) level and compared with the experimental results. The smallest HOMO-LUMO energy gaps of (I) (exp . 2.76 eV and DFT 3.40 eV) and (II) (exp . 2.70 eV and DFT 3.28 eV) indicates the suitability of these crystals in optoelectronic applications. All inter-molecular contacts and weaker contributions involved in the supra-molecular stabilization are investigated using Hirshfeld surface analysis. The mol-ecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the mol-ecules.

Insights into intermolecular interactions, electrostatic properties and the stability of C646 in the binding pocket of p300 histone acetyltransferase enzyme: a combined molecular dynamics and charge density study

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) are enzymes that exhibit an important transcription activity. Dysfunction of these enzymes may lead to different diseases including cancer, cardiovascular, and other diseases. Therefore, these enzymes are the potential target for the generation of new therapeutics. C646 is a synthetic p300 HAT inhibitor; its structural and the electrostatic properties are the paradigm to understand its activity in the active site of p300 HAT enzyme. The docked C646 molecule in the active site forms expected key intermolecular interactions with the amino acid residues Trp1436, Tyr1467, and one water molecule (W1861); and these interactions are important for acetylation reaction. When compare the active site structure of C646 with the gas-phase structure, it is confirmed that the electron density distribution of polar bonds are highly altered, when the molecule present in the active site. In the gas-phase structure of C646, a large negative regions of electrostatic potential is found at the vicinity of O(4), O(5), and O(6) atoms; whereas, the negative region of these atoms are reduced in the active site. The molecular dynamics (MD) simulation also performed, it reveals the conformational stability and the intermolecular interactions of C646 molecule in the active site of p300.

Vibrational spectroscopic investigations and molecular docking studies of biologically active 2-[4-(4-phenylbutanamido)phenyl]-5-ethylsulphonyl-benzoxazole

The optimized molecular structure, vibrational wavenumbers, corresponding vibrational assignments of 2-[4-(4-phenylbutanamido)phenyl]-5-ethylsulphonyl-benzoxazole have been investigated experimentally and theoretically using Gaussian09 software. The wavenumbers were assigned by potential energy distribution and the frontier molecular orbital analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The MEP analysis shows that the negative electrostatic potential regions are mainly localized over the oxygen's of the carbonyl and sulfonyl groups and nitrogen atom of the benzoxazole ring and are possible sites for electrophilic attack and the positive regions are localized over the NH group as possible sites for nucleophilic attack. From the molecular docking study, the ligand binds at the active sites of the protein by weak non-covalent interactions most prominent of which are H-bonding, cation-π and sigma-π interactions.

Step by Step Assembly of Polynuclear Lanthanide Complexes with a Phosphonated Bipyridine Ligand.

The synthesis of the octadentate ligand L (LH8 = ((([2,2'-bipyridine]-6,6'-diylbis(methylene))bis(azanetriyl))tetrakis(methylene))tetrakis(phosphonic acid)) is reported. The coordination of L with various lanthanide cations was monitored by absorption and luminescence spectrophotometric titration experiments (Ln = Tb, Yb), potentiometry (Ln = La, Eu, Lu), and mass spectrometry (Ln = Tb). It was found that L forms very stable mononuclear (LnL) species in aqueous solutions (log K = 19.80(5), 19.5(2), and 19.56(5) for La, Eu, and Lu, respectively) with no particular trend along the series. Spectroscopic data showed the Ln cations to be enclosed in the cavity formed by the octadentate ligand, thereby shielding the metal from interactions with water molecules in the first coordination sphere. When more than one equivalent of cations is added, the formation of polynuclear [(LnL)2Lnx] complexes (x = 1-3) can be observed, the presence of which could be confirmed by electrospray and MALDI mass spectrometry experiments. DFT modeling of the mononuclear (LnL) complexes indicated that the coordination of the cation in the cavity of the ligand results in a very asymmetric charge distribution, with a region of small negative electrostatic potential on the hemisphere composed of the chromophoric bipyridyl moiety and an electron-rich domain at the opposite hemisphere around the four phosphonate functions. DFT further showed that this polarization is most likely at the origin of the strong interactions between the (LnL) complexes and the incoming additional cations, leading to the formation of the polynuclear species. 1H and 31P NMR were used to probe the possible exchange of the lanthanide complexed in the cavity of the ligand in D2O, revealing no detectable exchange after 4 weeks at 80 °C and neutral pD, therefore pointing out an excellent kinetic inertness.

Spectroscopic investigations and molecular docking study of (2E)-1-(4-Chlorophenyl)-3-[4-(propan-2-yl)phenyl]prop-2-en-1-one using quantum chemical calculations

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy of (2E)-1-(4-Chlorophenyl)-3-[4-(propan-2-yl)phenyl]prop-2-en-1-one. The computations were performed at DFT level of theory to get the optimizedgeometry and vibrational wave numbers of the normal modes of the title compound using Gaussian09 software. The complete vibrational assignments of wave numbers were made on the basis of potential energy distribution. The calculated HOMO and LUMO energies show chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The hyperpolarizability values are reported and the first hyperpolarizability of the title compound is 83.85 times that of standard NLO material urea. From the MEP plot, the negative electrostatic potential regions are mainly localized over the carbonyl group, the phenyl rings and are possible sites for electrophilic attack. The positive regions are localized over all the hydrogen atoms and are possible sites for nucleophilic attack. The molecular docking results suggest that the compound might exhibit inhibitory activity against lymphocyte-specific kinase and may results in design of novel T-cell immunosuppressants.

First Principles Density Functional Theory Investigation on the Structural, Energetic and Electronic Properties of 6–Bromo–4–Oxo–4H–Chromene–3–Carbaldehyde

In this paper, we report the first principles Density Functional Theory (DFT) calculation to study the structural, energetic, and electronics properties of the 6–Bromo–4–Oxo–4H–Chromene–3–Carbaldehyde, C10H5BrO3 molecular framework. Geometry optimization technique was carried out to find the local energy minimum of the title compound using four hybrid DFT functionals with the basis set of 6–311++G**. The optimized molecular structure of C10H5BrO3 cluster was then used to determine the HOMO–LUMO gaps, Molecular Electrostatic Potential (MEP), Mulliken atomic charges, and others. Using the four hybrid DFT techniques, the optimized geometries of C10H5BrO3 molecular cluster is close to that of measurement data. Our calculation results also show that the total energies obtained are close to each other with the four hybrid DFT procedures. The diagram of electrostatic potential surface show that the regions of negative electrostatic potential around the oxygen atoms, O1 and O2. Using the scheme of Mulliken Population Analysis (MPA), the distributions of atomic charges follow the same arguments for the B3LYP/6–311++G**, B3PW91/6–311++G**, M06/6–311++G**, and PBE1PBE/6–311++G** simulation approaches. For example, the atom of C5 has the highest positively charge, whereas the highest negatively charge was found in the C4 atom. For Br atom, the atomic charge values obtained are –0.158, –0.222, –0.277, and –0.224, respectively for the B3LYP/6–311++G**, B3PW91/6–311++G**, M06/6–311++G**, and PBE1PBE/6–311++G** computational methods.

Vibrational and structural observations and molecular docking study on 1-{3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]-4,5-dihydro-1H-pyrazol-1-yl}-ethanone

A combined experimental and theoretical analysis of on molecular structure, vibrational spectra and HOMO-LUMO analysis of 1-{3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]-4,5-dihydro-1H-pyrazol-1-yl}-ethanone is reported. The equilibrium geometry and vibrational wavenumbers have been computed using desnity functional B3LYP method with 6–311++G(d) (5D, 7F) as basis set. The nonlinear optical properties were evaluated by the determination of the first and second hyperpolarizabilities of the title compound. HOMO is localized over the whole molecule except the ring PhIII and the CH3 groups attached to the PhIII while the LUMO is located through out the whole molecule except the CH3 groups attached with the PhIII and this shows that an eventual charge transfer occurs within the molecule. From the molecular electrostatic potential study, the negative electrostatic potential regions are mainly localized over the carbonyl group, phenyl rings and are possible sites for electrophilic attack and the positive regions are localized over the nitrogen atoms as possible sites for nucleophilic attack. The docked ligand title compound forms a stable complex with kinesin spindle protein (KSP) and gives a binding affinity value of −6.7 kcal/mol the results suggest that the compound might exhibit inhibitory activity against KSP.