Molecular Electrostatic Potential Maps Research Articles

A detailed density functional theory investigation on physicochemical properties of ciclopirox derivatives: A potential candidate for prevention of age-related macular degeneration

Structural, electronic and spectral data such as intramolecular hydrogen bonding interaction, HOMO, LUMO energies, reactivity indices, molecular electrostatic potential maps, aromaticity indices, 1HNMR and 13CNMR of ciclopirox derivatives 1-7 as antifungal agents and efficient compounds for treatment and prevention of age-related macular degeneration were calculated using B3LYP/6-311+G(d, p) method and interpreted in detail. Their antioxidant properties were also investigated by three mechanisms. The results show that the antioxidant activity of ciclopirox derivatives 1-7 is higher than phenol as the reference molecule. Finally, the interaction of ciclopirox 3 with metals cations Mn+ was investigated by DFT calculations. The calculated cation affinity for 3 increases as Cu+<Fe2+< Cu2+<Fe3+. Cation affinity is strongly dependent on the charge-to-size ratio of the Mn+.

Synthesis, characterisation, biological and theoretical studies of novel pyridine derivatives

Diversely functionalised pyrazolone analogues have been reported to display a wide range of biological activities. In this paper, we report the synthesis of a series of novel analogues based on piperidine fused pyrazolone core and explore its potential as novel antibacterial agents. The synthesised compounds were analysed using spectroscopic techniques such as 1H NMR, LC-MS, and FT-IR. The major highlight involves the cyclisation reaction of tert-butyl-4-methyl 3-oxopiperidine-1,4-dicarboxylate with the hydrazine component to access the privileged piperdine fused pyrazolone scaffold. This scaffold was further treated with HCl to remove the amine protecting group and subsequently reacted with acid chlorides to deliver the final products in excellent yields. Density functional theory (DFT) calculations were performed to determine the various molecular properties of the synthesised compounds. Based on the reactive sites explored by the molecular electrostatic potential maps, the compounds were screened against two gram positive bacterial strains namely S. aureus, and M. luteus, and a gram negative bacterial strain namely E.coli. Highlights A Series of novel pyrazole derivatives were synthesised using bicyclisation strategy. Computational methods were used to determine various quantum chemical properties. All molecules were screened against S. aureus, M. luteus, and E. coli bacterial strains.

New N-Alkylated Heterocyclic Compounds as Prospective NDM1 Inhibitors: Investigation of In Vitro and In Silico Properties.

A new family of pyrazole-based compounds (1–15) was synthesized and characterized using different physicochemical analyses, such as FTIR, UV-Visible, 1H, 13C NMR, and ESI/LC-MS. The compounds were evaluated for their in vitro antifungal and antibacterial activities against several fungal and bacterial strains. The results indicate that some compounds showed excellent antibacterial activity against E. coli, S. aureus, C. freundii, and L. monocytogenes strains. In contrast, none of the compounds had antifungal activity. Molecular electrostatic potential (MEP) map analyses and inductive and mesomeric effect studies were performed to study the relationship between the chemical structure of our compounds and the biological activity. In addition, molecular docking and virtual screening studies were carried out to rationalize the antibacterial findings to characterize the modes of binding of the most active compounds to the active pockets of NDM1 proteins.

Synthesis, crystal structure analysis, DFT calculations, antioxidant and antimicrobial activity of N,N-di-2,4-dimethoxybenzyl-N'-2-nitrobenzoylthiourea

N,N-Di-2,4-dimethoxybenzyl-N'-2-nitrobenzoylthiourea (MBNBT) was synthesized and characterized by 1D and 2D NMR spectroscopy. The molecular structure of MBNBT was also confirmed by SCXRD study. The molecular structure of MBNBT was optimized using the theory level of B3LYP/6–311G(d,p). The obtained theoretical results were compared with experimental ones. Molecular parameters such as bond lengths and bond angles were compared with SCXRD data. Molecular characteristics such as the HOMO-LUMO energy, the energy gap between the LUMO and HOMO energies, and surface maps of molecular electrostatic potential were investigated. Hirshfeld surface analysis showed that H···H (42.5%), H···O/O···H (25.5%), H···C/C···H (17.6%), H···S/S···H (7.1%), and C···O/O···C (2.7%) interactions contact is the most significant contributors in crystal packing of compound. The visualization of 3D topology of molecular packing of the crystal packing for MBNBT is elucidated from energy-framework calculations which suggest that the intermolecular contacts formed between participating molecules are principally dispersive in nature. Furthermore, the antimicrobial and antioxidant activity properties of MBNBT were investigated. The in vitro antioxidant activity of MBNBT was tested by DPPH free radical scavenging activity, H2O2 scavenging activity, superoxide radical scavenging activity and ferric reducing antioxidant power methods. According to the results obtained from the experimental studies, it was determined that MBNBT has effective antioxidant and free radical scavenging activity, when compared with reference substances. At the same time, as a result of antimicrobial activity studies, it was determined that it was effective against C. parapsilosis and C. metapsilosis.

Computational analysis of substituent effect on indole derivatives as potential antibacterial agents

In recent years, indole derivatives have gained attention as an important class of antimicrobial drugs. The modification of 1,3,4-oxadiazole and 1,2,4-triazole, which are known bioactive agents, was carried out with indole. The resulting compounds namely 3-(1H-indole-3yl)-5-((2-((5-phenyl-1,3,4-oxadiazole-2-yl)thio)ethyl)thio)-4H-1,2,4-triazole-4-amine (S) and 2-(5-(benzylthio)-4H-1,2,4-triazole-3yl)-1H-indole (B) were further investigated for their chemical reactivity with 14 different substituents at the phenyl ring using the density functional theory (DFT). The quantum chemical data used to investigate the most effective drug was based on the optimized geometries, molecular electrostatic potential maps, frontier molecular orbital distributions, Hirschfeld charges, Mulliken charges and UV absorption parameters obtained from DFT calculations. Reduced density gradient (RDG) scatter plots and non-covalent interaction isosurfaces were obtained to visualize the intramolecular interactions in the molecules. Based on the DFT calculations, S14 (-NO2 substituted S) and B14 (-NO2 substituted B) exhibited a better chemical activity. Further, the pertinency of S14 and B14 was tested as an antibacterial agent against E. coli using molecular docking studies. The binding affinity of S14 and B14 showed significant binding with the active sites of the E. Coli macromolecule (PDB id- 2Y66). The boiled egg model was also analyzed to study the permeability and lead likeness of the molecules under investigation. From the synthetic accessibility score, the synthetic feasibility of S14 and B14 was analyzed.

Phytochemicals as potential inhibitors for COVID-19 revealed by molecular docking, molecular dynamic simulation and DFT studies.

The COVID-19 pandemic outbreak demands the designing of potential drugs as there is no specific treatment available. Thanks to their safety and effectiveness, phytochemicals have been used to treat various diseases, including antiviral therapeutics. Molecular docking is a simple, quick, and effective way to screen a variety of molecules for structure-based drug design. Here, we investigate molecular docking experiments on compounds present in plant species, Cocculus hirsutus and Rhodiola rosea and show their potential for the treatment of COVID-19. Almost all the components showed higher binding affinity than the built-in ligand, and those with significantly higher binding affinity were explored further. Molecular mechanics-based generalized born surface area calculations were used to re-rank the top candidates, rhodionidin and cocsoline, and their stability in association with viral protease was confirmed. Density functional theory was used for detailed investigations of the geometries, and electrical properties of rhodionidin and cocsoline. Using the frontier molecular orbitals method, the charge transfer within the molecule was calculated. Chemical reactivity and intermolecular interactions were studied using molecular electrostatic potential maps. These in silico discoveries will simulate the identification of powerful COVID-19 inhibitors, and similar research is likely to make a significant contribution to antiviral drug discovery.Supplementary informationThe online version contains supplementary material available at 10.1007/s11224-022-01982-4.

Localized Antiaromaticity Hotspot Drives Reductive Dehydrogenative Cyclizations in Bis- and Mono-Helicenes.

We describe reductive dehydrogenative cyclizations that form hepta-, nona-, and decacyclic anionic graphene subunits from mono- and bis-helicenes with an embedded five-membered ring. The reaction of bis-helicenes can either proceed to the full double annulation or be interrupted by addition of molecular oxygen at an intermediate stage. The regioselectivity of the interrupted cyclization cascade for bis-helicenes confirms that relief of antiaromaticity is a dominant force for these facile ring closures. Computational analysis reveals the unique role of the preexisting negatively charged cyclopentadienyl moiety in directing the second negative charge at a specific remote location and, thus, creating a localized antiaromatic region. This region is the hotspot that promotes the initial cyclization. Computational studies, including MO analysis, molecular electrostatic potential maps, and NICS(1.7)ZZ calculations, evaluate the interplay of the various effects including charge delocalization, helicene strain release, and antiaromaticity. The role of antiaromaticity relief is further supported by efficient reductive closure of the less strained monohelicenes where the relief of antiaromaticity promotes the cyclization even when the strain is substantially reduced. The latter finding significantly expands the scope of this reductive alternative to the Scholl ring closure.

Synthesis, virtual screening and computational approach of a quinoxaline derivative as potent anti-HIV agent targeting the reverse transcriptase enzyme

Infection by the human immunodeficiency virus still represents a continuous serious concern and a global threat to human health. Due to the appearance of multi-resistant virus strains and the serious adverse side effects of the antiretroviral therapy administered, there is an urgent need for the development of new treatment agents that are more active, less toxic, and with increased tolerability to mutations. Quinoxaline derivatives are a class of heterocyclic compounds with a wide range of organic and remedial applications. In addition, they are known to significantly inhibit HIV reverse transcriptase (RT) and HIV replication in cell cultures. For these reasons, we are investigating the synthesis and computational studies of quinoxaline derivatives with a focus on their effects on the HIV RT enzyme, and we present here the structure of one such molecule, methyl 2-[(2E)-3-oxo-1,2,3,4-tetrahydroquinoalin-2-ylidene] acetate, which was confirmed by X-ray diffraction studies. In the crystal, N—H···O and C—H···O hydrogen bonds form ribbons whose mean planes are inclined to (111) by 25.69(8)°. The ribbons are formed into stacks by C—H···π(ring) interactions and π-stacking interactions between carbonyl groups. The Hirshfeld surface map allows us to understand the nature of interactions in the contribution to crystal packing. A density functional theory (DFT) calculation was performed to optimize the geometrical parameters and then they were compared with the solid-state phase. The molecular electrostatic potential map displays reactive sites on the surface, which are responsible for intermolecular interaction in the chemical species. Computational molecular docking, in addition to molecular dynamics simulations and MMGB/PBSA binding energy techniques, was used to assess the affinity of the molecule for the HIV reverse transcriptase enzyme. The new quinoxaline derivative is more powerful in terms of binding affinity and binding conformation stability with the HIV reverse transcriptase enzyme, which suggests the molecule is a good candidate for further biological optimization. Communicated by Ramaswamy H. Sarma

The Ability of Chlorophyll to Trap Carcinogen Aflatoxin B1: A Theoretical Approach.

The coordination of one and two aflatoxin B1 (AFB1, a potent carcinogen) molecules with chlorophyll a (chl a) was studied at a theoretical level. Calculations were performed using the M06-2X method in conjunction with the 6-311G(d,p) basis set, in both gas and water phases. The molecular electrostatic potential map shows the chemical activity of various sites of the AFB1 and chl a molecules. The energy difference between molecular orbitals of AFB1 and chl a allowed for the establishment of an intermolecular interaction. A charge transfer from AFB1 to the central cation of chl a was shown. The energies of the optimized structures for chl a show two configurations, unfolded and folded, with a difference of 15.41 kcal/mol. Chl a appeared axially coordinated to the plane (α-down or β-up) of the porphyrin moiety, either with the oxygen atom of the ketonic group, or with the oxygen atom of the lactone moiety of AFB1. The complexes of maximum stability were chl a 1-α-E-AFB1 and chl a 2-β-E-AFB1, at −36.4 and −39.2 kcal/mol, respectively. Additionally, with two AFB1 molecules were chl a 1-D-2AFB1 and chl a 2-E-2AFB1, at −60.0 and −64.8 kcal/mol, respectively. Finally, biosorbents containing chlorophyll could improve AFB1 adsorption.

Non-food bioactive products: Diversified invention of 1,2,4-oxadiazole-containing amide derivatives for novel fungicidal candidate discovery

In an effort for novel fungicidal candidate discovery, a series of diversified 1,2,4-oxadiazole-containing amide derivatives were devised and synthesized. Through an extensive screening of fungicidal activity on four common phytopathogens, all the target compounds exerted satisfactory inhibitory effect on Valsa mali. A detailed and specific discussion on structure and activity relationship (SAR) indicated that the tetrahydro(iso)quinoline substitution was crucial for activity improvement. The EC50 values of compounds 6i, 6p, 6u, 6v, and 6z were far more prominent than the commercial fungicide boscalid. The biochemistry and physiology response of V. mali after treatment with the remarkable compound 6p was examined, and the fruit body production, hyphae morphology, cell membrane permeability, cell wall integrity, and pectinase activity were profoundly affected. In addition, two representative compounds 6p and 6t were picked out for theoretical calculation to assess the most paramount molecular descriptors. The highest and lowest unoccupied molecular orbital (LUMO, HOMO), molecular electrostatic potential (MEP) and electron density (ED) map of compounds were obtained, plotted, and visualized. Based on the integrated analysis of fungicidal activity, biochemistry and physiology response and theoretical calculation, this work would provide some insight for novel fungicide invention and potential mode of action study.

Experimental Spectroscopic, Structural (Monomer and Dimer), Molecular Docking, Molecular Dynamics Simulation and Hirshfeld Surface Analysis of 2-Amino-6-Methylpyridine

2-Amino-6-methylpyridine (2-AMP) was investigated experimentally using FT-IR, 1H, NMR, and UV-Vis spectra, as well as theoretically using DFT calculations. The quantum computational calculations (the optimized structure, FT-IR, NMR and UV-Vis.) to support experimental data were performed by DFT approach at B3LYP functional and 6–311 + +G(d,p) basis set. The optimized molecular geometry and wavenumber calculations were done in the gas phase, while theoretical NMR was performed in Chloroform (CHCL3) solvation. The “Potential Energy Distribution analysis” (PED) of the title compound was performed with VEDA analysis and these assignments were compared with the experimental FT-IR spectrum. Hirshfeld analysis was also performed and analyzed intermolecular interactions on the surface of crystal, However, the most significant contributions to the Hirshfeld surface come from N···H (17.3%), C···H/H···C (23%) and H···H (68.8%). Chemical reactivity studies, Molecular Electrostatic Potential (MEP) maps, and surface area maps were also conducted. To show electron delocalization in the molecule, researchers used the electron localization function (ELF). Other topics included topological and mulliken charge distribution studies. Natural Bond Order Analysis (NBO) was performed to interpret intermolecular charge transfer.The effect of temperature on thermodynamical parameters such as Gibbs free energy, enthalpy, and entropy was examined. TD-DFT analysis was also used to shed more light on how the electronic transitions in the UV–Vis spectra were estimated. For different solvents, the estimated maximum wavelength (λ) absorbance and the band-gap energy of 2-AMP were calculated and compared to experimental results. The molecule's bioactivity is described theoretically using the Electrophilicity index and the interaction between the ligand-protein is depicted using Molecular docking. The proteins 3DQS, 4UX6, 5ADF, 5TUD, and 6E9L were studied via molecular docking. The nature of the molecule was determined by its drug-likeness. A molecular dynamics simulation was used to explore biomolecular stability.

Quantum Mechanical Study of Three Aromatic Bioactive Fatty Alcohol Compounds with Nonlinear Optical and Potential Light Harvesting Properties

In the present work, Quantum mechanical properties of three different organic compounds [(2S)-1-(4-nitrophenyl) pyrrolidin-2-yl] methanol (NPPM), 2-(Methyl(4-nitrophenyl) nitro) ethanol (MNAE), and N, N-Bis (2-hydroxyethyl)-4-nitroaniline (HENA) were investigated by computational approach. The geometries were optimized to ground state using the density functional theory (DFT) with level B3LYP/6311-G (++d, p) basis set. The Mulliken charge distribution and molecular electrostatic potential (MEP) map of the title molecules shows the existence of huge charge distribution and the charge transfer within the molecules due to the presence of nucleophilic and electrophilic moieties. The vibrational spectra of the title molecules seem to have high intensity Raman modes. The UV–Vis spectra for the three molecules were found to indicate the presence of π-π* and n-π* electronic transitions between wavelength 300–500 nm. The computed value of first-order hyperpolarizability for the molecules were found to be higher than the reference materials. This validates the nonlinear optical responses of the title molecules. The light harvesting efficiency of the molecules were also determined. For the NPPM molecule, light harvesting efficiency of 64% was obtained. This validates the potential applications of NPPM in designing new photosensitizer solar cells.

X-ray and DFT calculations of novel spiroisoxazolines derivatives

The present study describes a DFT and X-ray diffraction of spiroisoxazolines derivatives. The title compounds 3b-c have been characterized using single-crystal X-ray diffraction; Both compounds crystallize in orthorhombic system with space group P212121. The organic molecule is built up from fused five- and ten membered rings, with an additional epoxy ring system and a 3-(4-chlorophenyl)-4,5-dihydroisoxazole or 3-(4-methoxyphenyl)-4,5-dihydroisoxazole groups as a substituent. In the crystal, intermolecular O—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π interactions lead to the formation of a three-dimensional framework. Hirshfeld surface analysis and 2D fingerprint revealed the nature of intermolecular contacts. In all compounds, H⋯H interactions are major interactions followed by H⋯O/O⋯H and H⋯C/C⋯H. Energy frameworks were constructed through different intermolecular interaction energies to investigate the stability of the compounds. Additionally, DFT study at B3LYP level of theory and 6-311G(d, p) basis set to investigate the optimized geometry in the gas phase, molecular electrostatic potential (MEP) map analysis and Mulliken charges were produced by using the optimized structures. The natural bond orbital (NBO) analysis is conducted to explore the interactions among different orbital and lone pairs taking place within the compounds.

Synthesis of new thiazine and thiazole derivatives via cyclization reactions; investigating their electronic properties and determination of antioxidant properties

Abstract(4‐[2,4‐dimethoxyphenyl]‐6‐phenyl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidin‐5‐yl)(phenyl) methanone (1) have been prepared by Biginelli three‐component cyclocondensation reaction of catalyzed with p‐toluene sulfonic acid in ethanol. Pyrimido[2,1‐b]thiazine (2) and thiazolo[3,2‐a]pyrimidine (3) derivatives were obtained by a simple one‐pot condensation reaction of starting compound 1 and 3‐bromopropionic acid, bromoacetic acid and, respectively. By performing the reactions of compound 3 with heteroaromatic and aromatic aldehydes, arylidine‐bicyclic thiazolo pyrimidine compounds (4–9) were synthesized. Theoretical calculations and molecular electrostatic potential maps of all synthesized compounds were performed using the Gaussian software package Density Functional Theory (DFT/6‐31G: B3LYP). In addition, studies were carried out to determine the antioxidant properties of all the compounds obtained by the DPPH method, and compound 1 was found to be the most effective compound. The structures of the newly synthesized compounds were analyzed using spectroscopic methods such as IR, 1H, and 13C.

Synthesis, crystal structure, ATR-FTIR, FT-Raman and UV spectra, structural and spectroscopic analysis of (3E)‐4‐[4‐(dimethylamine)phenyl]but‐3‐en‐2‐one

Chalcones are a large and promising source of molecules that can be used for drug development, as they have a wide variety of pharmacological activities associated with their structural diversity. In this work, the chalcone named (3E)‐4‐[4‐(dimethylamine)phenyl]but‐3‐en‐2‐one (DMAP) was synthesized, crystallized, and characterized by single-crystal X-Ray Diffraction (XRD), Fourier Transform Raman (FT-Raman), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), and Ultraviolet-visible (UV–Vis) spectroscopy. Theoretical calculations of quantum chemistry were performed to obtain data regarding normal vibration modes, dipole moment, frontier molecular orbitals, quantum chemical parameters, molecular electrostatic potential map, Hirshfeld surfaces, and theoretical UV–vis spectrum. In contrast to most chalcones which are formed by two aromatic rings, the DMAP is formed by only one aromatic ring. The crystal of DMAP at 300 K has orthorhombic symmetry with space group P212121 with four molecules per unit cell. The crystalline structure is stabilized by two intermolecular short contacts, both involving the dimethylamine group. In the direction of the crystallographic a-axis, the molecules are arranged to form layers.

Computer Aided Drug Design of 1,2,3-Triazole Fused Bioactive Derivative Targeting Glucosamine-6-Phosphate Synthase (GlmS) – XRD, Computational Crystallography, and Molecular Simulation Approach

The crystal structure of a 1,2,3-triazole fused heterocyclic derivative 2-(1-Benzyl-5-methyl-1H-1,2,3-triazol-4-yl)-4-(2,4-dichlorophenyl)-6-phenyl pyridine (DICLPY; 4h) is reported. The structural characterization is done by single crystal X-ray technique. The Hirshfeld surfaces (HS) and 2D fingerprint graphs are generated to investigate the inter atomic contacts contribution for structure by CrystalExplorer 17.5 program. The pairwise interaction energies between neighboring molecules are computed at the B3LYP/6-31G(d,p) method. This interaction energy analysis showed that the total stability of the DICLPY structure is mainly contributed by the dispersion force factor followed by the coulomb potential force factor. The DFT-based HOMO, LUMO orbitals and molecular electrostatic potential map are studied to identify the reactivity of our molecule. In-silico molecular docking technique is used to inspect the DICLPY compound as a possible antibacterial agent by docking with Glucosamine-6-phosphate synthase protein (PDB ID: 2VF5) using PyRx and AutoDock Vina programs. The molecular dynamics simulation is performed to examine the physical movement of our molecule DICLPY with Glucosamine-6-phosphate synthase protein for 100 ns time period. MD simulation revealed the greater stability of DICLPY and Glucosamine-6-phosphate synthase protein complex during the simulation period.

Synthesis, Crystal structure, photoluminescence properties and quantum mechanics studies of two schiff bases of 2-amino-p-cresol

The compounds, (E)-2-((2,5-dimethoxybenzilidene) amino)-4-methylphenol (DMB–APC) and 2-((E)-((E)-3-(4-methoxyphenyl)allylidene)amino)-4-methylphenol (TPPC) were synthesized and characterized using FTIR, 1H and 13C NMR, MS and single crystal X-ray crystallographic techniques. The molecular geometry and vibrational frequencies of the compounds in the ground state were calculated using the density functional theory in conjunction with Becke 3-Lee–Yang Parr functional and 6–31 G (d,p) basis set. The electronic structure calculation (energy gap) and molecular electrostatic potential map of the compounds were performed at the B3LYP level of theory and the 6 -31 G (d,p) basis set.. The nonlinear optical properties [dipole moment(μ), average polarizability(α), anisotropy of polarizability (Δα) and first hyperpolarizability(β)] of the compounds were determined from fluorescence spectra and quantum mechanical calculation. The excitation spectra of the compounds showed bands in the UV region of 306, 345 nm for DMB–APC and 311, 410 nm for TPPC, while the emission spectra of the compounds showed bands in the visible region centred at 462, 486 nm for DMB–APC and 492, 533 nm for TPPC. The energy gap of the first electron excitation from HOMO to LUMO are 3.89 and 3.69 eV, while the first hyperpolarizability is 100.55 and 154.22 eV for DMB–APC and TPPC respectively. The calculated parameters of the compound are in good agreement with the experimental data. Based on the emission bands, low energy gap, and the high first hyperpolarizability values, DMB –APC and TPPC show promise for the development of non-linear optical materials.

1,2,4-Triazole derivative containing thiophen ring: Comparison of theoretical IR and NMR data with experimental

The molecular structure of 1,2,4-triazole containing thiophene derivative which called as ethyl-2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-triazole-1-yl) acetate (I) was optimized using DFT/B3LYP method with 6–311++G(d,p) basis set and the structural parameters of the compound were obtained. Thus, the molecular structure was compared with that identified by X-ray analysis. IR and NMR parameters were calculated by DFT/B3LYP/6–311++G(d,p) method. Theoretical vibrational frequencies and NMR chemical shift values were obtained. In addition, the molecular electrostatic potential (MEP) map was calculated. The structural and spectral data obtained from the theoretical study strongly confirm the experimental data. The compatibility of the structural parameters reveal that the choice of the method and the basis function is appropriate.

Computational study of heterocyclic anticancer compounds through nbo method

In the present study NBO method contain the HOMO and the LUMO energies are calculated for 10 different heterocycles anticancer drug using B3LYP/6-31G(d,p). Frontier molecular orbitals (HOMO and LUMO) and Molecular Electrostatic Potential map of the compound was produced by using the π stacking of structures and anticancer activity of molecules. The NBO analysis was suggested that the molecular system contains π- π interaction, strong conjugative interactions and the molecule become more polarized owing to the movement of π-electron cloud from donor to acceptor. NBO, HOMO and LUMO energies, were investigated and Anticancer activity of Aromatic Heterocyclic compounds was investigated by NBO study and result was compared with our previous study about NICS and S-NICS of these 10 anticancer drug. the HOMO/LUMO gap of the heterocycle anticancer drug is significantly different from each other. The NBO method is used in both symmetric and asymmetric molecules and provides accurate information on the aromatics of the compound, especially the heterocyclic rings. It also provides accurate information in protected areas. Molecule 8 has the highest amount of HOMO and therefore aromaticity among the studied compounds which confirms the result of molecular orbital examination.

Solvent Effects on the Photophysical Properties of a Donor-acceptor Based Schiff Base.

In this work, a donor-acceptor substituted aromatic system ((E)-N-((E)-3-(4 (dimethylamino)phenyl) allylidene)-4-(trifluoromethyl) benzenamine (DPATB) has been synthesized and its detailed photophysics of intramolecular charge transfer process have been explored on the basis of steady state absorption, fluorescence and time resolved spectroscopy in combination with density functional theory calculations. Large solvent dependency fluorescence spectral shift and the calculated large excited state dipole moment clearly indicate an efficient charge transfer occurring from the donor group to the acceptor moiety in the excited state. Effect on addition of acid and pH on steady state spectral properties further reveals excited state charge transfer character. Quantum chemical calculations were performed in order to study the conformation and polarity of DPATB at their ground as well as excited electronic states. The HOMO and LUMO molecular orbital pictures are obtained at DFT level using B3LYP functional and 6-311 + g(d,p) basis set which clearly support excited state intramolecular charge transfer process. The molecular electrostatic potential maps for the optimized ground state, donor twisted and acceptor twisted geometry shed insight on the electrostatic potential and charge distribution in a system which gives information about the reacting site of the probe and nature of the reaction. In this work, detailed photophysics of excited state intramolecular charge transfer process in donor-acceptor system (DPATB) was evaluated using steady state and time-resolved fluorescence spectroscopy in combination with density functional theory calculations. Large solvent dependency fluorescence spectral shift and the calculated large excited state dipole moment clearly indicate an efficient charge transfer occurring in DPATB. Molecular orbital pictures as obtained from DFT based computational analysis reveals a significant change in the distribution of electron density upon transition from HOMO to LUMO which confirms an ICT process occurring from the donor group to the acceptor moiety in the excited state.