scholarly journals Structural and quantum chemical studies on aryl sulfonyl piperazine derivatives

2019 ◽  
Vol 9 (1-s) ◽  
pp. 88-97 ◽  
Author(s):  
Tahar Abbaz ◽  
Amel Bendjeddou ◽  
Didier Villemin
Keyword(s):  
Electrostatic Potential ◽  
Quantum Chemical ◽  
Density Functional ◽  
Energy Gap ◽  
Nbo Analysis ◽  
Basis Set ◽  
Linear Optics ◽  
Hydrogen Atoms ◽  
Charge Delocalization ◽  
Piperazine Derivatives

The optimized molecular structure and electronic features of aryl sulfonyl piperazine derivatives 1-4 have been investigated theoretically using Gaussian 09 software package and DFT/B3LYP method with 6-31G (d,p) basis set. The reactivity of the title molecules was investigated and both the positive and negative centers of the molecules were identified using molecular electrostatic potential (MEP) analysis which the results illustrate that the regions reveal the negative electrostatic potential are localized in sulfamide function while the regions presenting the positive potential are localized in the hydrogen atoms. The energies of the frontier molecular orbitals and LUMO-HOMO energy gap are measured to explain the electronic transitions. Global reactivity parameters of the aryl sulfonyl piperazine derivatives molecules were predicted to find that the more reactive and softest compound is the compound 3. Mulliken’s net charges have been calculated and results show that 3N is the more negative and 33S is the more positive charge, which Indicates extensive charge delocalization in the entire molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization (π→π transitions) has been analyzed using NBO analysis. Fist hyperpolarizability is calculated in order to find its importance in non-linear optics and the results show that the studied molecules have not the NLO applications. Keywords: sulfamide; density functional theory; computational chemistry; electronic structure; quantum chemical calculations.

scholarly journals Structural and Vibrational Studies (FT-IR, FT-Raman) of Voglibose Using DFT Calculation

2016 ◽  
Vol 64 ◽  
pp. 45-62 ◽  
Author(s):  
R. Solaichamy ◽  
J. Karpagam
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Shifts ◽  
Nbo Analysis ◽  
Biological Properties ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Charge Delocalization ◽  
Ft Raman

In the present study, we report on the Molecular structure and infrared (IR) and FT-Raman studies of Voglibose (VGB) as well as by calculations based on the density functional theory (DFT) approach; utilizing B3LYP/6-31G(d,p) basis set. The targeted interpretation of the vibrational spectra intended to the basis of calculated potential energy distribution matrix (PED) utilizing VEDA4 program. Stability of the molecule arising from hyperconjugative interactions and charge delocalization was studied using natural bond orbital (NBO) analysis. The results show that change in electron density in the σ∗and π∗antibonding orbitals and E2energies confirm the occurrence of intramolecular charge transfer within the molecule. The UV-Visible and NMR spectral analysis were reported by using TD-DFT and gauge GIAO approach respectively and their chemical shifts related to TMS were compared. The lowering of HOMO and LUMO energy gap appears to be the cause for its enhanced charge transfer interactions. Besides, molecular electrostatic potential (MEP) analysis was reported. Due to different potent biological properties, the molecular docking results are also reported.

Theoretical investigation on tautomerism and NLO properties of Salicylideneaniline derivatives

2021 ◽  
Author(s):  
N. Daho ◽  
N. Benhalima ◽  
F. KHELFAOUI ◽  
O. SADOUKI ◽  
M. Elkeurti ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Intramolecular Proton Transfer ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Visible Absorption ◽  
Charge Delocalization ◽  
Intramolecular Hydrogen

In this work, a comprehensive investigation of the salicylideneaniline derivatives is carried out using density functional theory to determine their linear and non-linear optical properties. Geometry optimizations, for gas and solvent phases, of the tautomers (enol and keto forms) are calculated using B3LYP levels with 6–31G (d,p) basis set . An intramolecular proton transfer, for 1SA-E and 2SA-E, is performed by a PES scan process at the B3LYP/6-31G (d,p) level. The optical properties are determined and show that they have extremely high nonlinear optical properties. In addition, the RDG analysis, MEP, and gap energy are calculated. The low energy gap value indicates the possibility of intramolecular charge transfer. The frontier molecular orbital calculations clearly show the inverse relationship of HOMO–LUMO gap with the first-order hyperpolarizability (β = 59.6471 × 10-30 esu), confirming that the salicylideneaniline derivatives can be used as attractive future NLO materials. Therefore, the reactive sites are predicted using MEP and the visible absorption maxima are analyzed using a theoretical UV–Vis spectrum. Natural bond orbitals are used to investigate the stability, charge delocalization, and intramolecular hydrogen bond.

Experimental and Theoretical Studies on the Molecular Structure, FT-IR, NMR, HOMO, LUMO, MESP, and Reactivity Descriptors of (E)-1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one

2020 ◽  
Vol 17 (SpecialIssue1) ◽  
pp. 54-72
Author(s):  
Rahul Ashok Shinde ◽  
Vishnu A shok Adole ◽  
Bapu Sonu Jagdale ◽  
Thansing Bhavsing Pawar
Keyword(s):  
Molecular Structure ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Dft Method ◽  
Basis Set ◽  
Group Symmetry ◽  
Ir Absorption ◽  
Hydrogen Atoms ◽  
Reactivity Descriptors ◽  
Ft Ir

The present research deals with the synthesis, characterization and density functional theory (DFT) study of (E)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (DTMPP). For the computational investigation, DFT method at B3LYP/6-311++G(d,p) basis set has been used. Herein, structural properties like molecular structure, bond lengths, and bond angles of the DTMPP have been explored. The all-important examination of the electronic properties; HOMO and LUMO energies were studied by the time-dependent DFT (TD-DFT) method. The experimental and theoretical spectroscopic Investigation on FT-IR, 1HNMR, 13C NMR has been unveiled in the present research. To study the chemical behaviour of the DTMPP, Mulliken atomic charges, molecular electrostatic surface potential, and reactivity descriptors have been explored. The dipole moment of the DTMPP is 1.27 Debye with C1 point group symmetry and -1225.77 a.u. E(B3LYP) energy. The most electropositive carbon and hydrogen atoms in the DTMPP are C14 and H27 respectively. The C1-C6 bond is the longest (1.4089 Å) C=C bond in the DTMPP. The oxygen atom O33 is having short contact interaction with the hydrogen atom H44 with a distance of 3.3258 Å. The molecular electrostatic potential plot predicts the positive electrostatic potential is around hydrogen atoms. The FT-IR assignments were made by comparing the experimental FT-IR absorption peaks with the scaled frequencies obtained using DFT method. Furthermore, some valuable insights on thermochemical data are obtained using the harmonic frequencies at same basis set.

Structural and Electronic Properties of Hydrogen-Passivated Silicon Quantum Dots: Density Functional Calculations

2015 ◽  
Vol 1107 ◽  
pp. 571-576 ◽  
Author(s):  
Muhammad Mus-'ab Anas ◽  
Ahmad Puaad Othman ◽  
Geri Gopir
Keyword(s):  
Quantum Dots ◽  
Density Functional ◽  
Energy Gap ◽  
Local Density ◽  
Basis Set ◽  
Face Centered Cubic ◽  
Hydrogen Atoms ◽  
Silicon Quantum Dots ◽  
Theoretical Approaches ◽  
Passivated Silicon

Density functional theory (DFT) by numerical basis-set calculations of silicon quantum dots (Si-QDs) passivated by hydrogen, ranging in size up to 1.9 nm are presented. These DFT computation results are used to examine and deduce the properties of 14 spherical Si-QDs including its density of state (DOS), and energy gap from the HOMO-LUMO results. The atomistic model of each silicon QDs was constructed by repeating crystal unit cell of face-centered cubic (FCC) structure, then the QDs surface was passivated by hydrogen atoms. The model was relaxed and optimized using Quasi-Newton method for each size of Si-QDs to get an ideal structure. Exchange-correlation potential (Vxc) of electrons were approximated in this system using the Local Density Approximation (LDA) functional and Perdew-Zunger (PZ) functional. Finally, all results were compared with previous experimental data and other similar theoretical approaches, and these results augured well

Non Linear Optical, Thermodynamic Analysis and Spectroscopic Investigation of GPA Optical Materials

2017 ◽  
Vol 730 ◽  
pp. 106-111
Author(s):  
Xiao Jing Liu ◽  
Xin Sun ◽  
Jing Hua Guo
Keyword(s):  
Optical Materials ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Nbo Analysis ◽  
Basis Sets ◽  
Nucleophilic Attack ◽  
Charge Delocalization ◽  
Different Temperatures

In this work, density functional theory (DFT) calculations with B3LYP/6-311++G(d,p) basis sets was used to explore the electronic, structural, nonlinear optical and thermal properties aspects of glycine-phthalic acid (GPA) optical materials. Dipole moment, static polarizability and first hyperpolarizability analysis of the molecule have been performed. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. MEP study confirms GPA as an electron rich species and explains its electrophilic nature. MEP shows that this molecule has several possible sites for electrophilic/nucleophilic attack in which V(r) calculations provide insights into the order of preference. The low value of HOMO-LUMO energy gap reflects the high chemical reactivity, low chemical stability and hardness of GPA molecule. Thermodynamic properties of the title compound have been calculated at different temperatures and the results reveal that the standard heat capacities (Cp), standard entropies (S) and standard enthalpy (H) increase with rise in temperature. These results discussed in this study will upsurge the knowledge to design and synthesize new type nonlinear optical materials with exceptional chemical and physical properties.

Structural, vibrational (FTIR and FT-Raman), NMR, UV–vis spectral analysis, and DFT study of 2-(6-oxo-2-thioxotetrahydropyrimidin-4(1H)-ylidene) hydrazine carboxamide

2017 ◽  
Vol 95 (5) ◽  
pp. 580-589 ◽  
Author(s):  
N. Kalaiarasi ◽  
S. Manivarman
Keyword(s):  
Density Functional ◽  
Nbo Analysis ◽  
Basis Set ◽  
Geometrical Parameters ◽  
Mulliken Population ◽  
Functional Theory ◽  
Charge Delocalization ◽  
Homo Lumo ◽  
Spectral Characterizations ◽  
Ft Raman

Vibrational and spectral characterizations of 2-(6-oxo-2-thioxo tetrahydro pyrimidin-4(1h)-ylidene) hydrazine carboxamide (OTHHPYHC) were experimentally presented for the ground state using FTIR and FT-Raman and theoretically presented by density functional theory (DFT) using B3LYP correlation function with the basis set 6-31G(d,p). The geometrical parameters, energies, and wavenumbers have been obtained. The fundamental assignments were performed on the basis of total energy distribution. The first order hyperpolarizability (β0) and relative properties (β, α0, and Δα) were calculated using B3LYP/6-31G(d, p) method. Solidity of the molecule due to hyperconjugative interactions and charge delocalization has been analysed using natural bond orbital (NBO) analysis. The charge distribution and electron transfer from bonding to antibonding orbitals and electron density in the σ* and π* antibonding orbitals confirms interaction within the molecule. In addition to this, Mulliken population and HOMO–LUMO analysis have been used to support the information of structural properties.

scholarly journals A Combined Experimental (FT-IR) and Computational Studies of 9-Chloroanthracene

2019 ◽  
Vol 31 (6) ◽  
pp. 1332-1342 ◽  
Author(s):  
KATTAESWAR SRIKANTH ◽  
RAMAIAH KONAKANCHI ◽  
JYOTHI PRASHANTH
Keyword(s):  
Density Functional ◽  
Minimum Energy ◽  
Nbo Analysis ◽  
Docking Studies ◽  
Basis Set ◽  
Protein Targets ◽  
Charge Delocalization ◽  
Fukui Functions ◽  
Homo And Lumo ◽  
Ft Ir

The experimental FT-IR spectral analysis of 9-chloroanthracene has worked out by using density functional theory (DFT). The optimized molecular structure and minimum energy of 9-chloroanthracene has analyzed using DFT/B3LYP functional employing 6-311++G(d,p) basis set. The vibrational frequencies along with IR intensities were computed, scaling was used for a better fit between the experimental and computed frequencies, they agreed with rms error 8.48 cm-1 for 9-chloroanthracene. The NLO behaviour of the molecule is investigated from first-order hyperpolarizability. The HOMO and LUMO energies are evaluated to demonstrate the chemical stability, reactivity of molecule. The MESP over the molecules were plotted to evaluate electron density regions and thermodynamic parameters are calculated. Hyper conjugative interactions and charge delocalization of the molecule study from NBO analysis and Fukui functions are evaluated for 9-chloroanthracene. The molecular docking studies were performed against anticancer protein targets Tyrosinase and HER2.

scholarly journals 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)

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Hitler Louis ◽  
Obieze C. Enudi ◽  
Joseph O. Odey ◽  
Izubundu B. Onyebuenyi ◽  
Azuaga T. Igbalagh ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Nbo Analysis ◽  
Basis Set ◽  
Orbital Interactions ◽  
B3lyp Method ◽  
Td Dft ◽  
Donor Acceptor ◽  
Molecular Orbital Analysis

AbstractIn this study, (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite), a cyanurated H-acid (CHA) azo dye, was synthesized and characterized using FT-IR spectrophotometer and GC-MS spectroscopy. A density functional theory (DFT) based B3LYP and CAM-B3LYP method with 6–311 + G (d,p) basis set analysis was computed for HOMO-LUMO, natural bonding orbitals (NBO), UV-Vis absorptions and excitation interactions, in order to understand its molecular orbital excitation properties. A low Energy gap (Eg) of 2.947 eV was obtained from the molecular orbital analysis, which showed that HOMO to LUMO transition is highly feasible; hence CHA is adequate for diverse electronic and optic applications. Studies of the first five excitations (S0 → S1/S2/S3/S4/S5) of CHA revealed that S0 → S1 and S0 → S3 are π → π* type local excitations distributed around the –N=N– group; S0 → S2, a Rydberg type local excitation; S0 → S4, a highly localized π → π* excitation; while S0 → S5 is an n → π* charge transfer from a benzene ring to –N=N– group. From NBO analysis, we obtained the various donor–acceptor orbital interactions contributing to the stabilization of the studied compound. Most significantly, some strong hyper-conjugations (n → n*) within fragments, and non-bondingand anti-bonding intermolecular (n → n*/π* and π → n*/π*) interactions were observed to contribute appreciable energies. This study is valuable for understanding the molecular properties of the azo dyes compounds and for synthesizing new ones in the future.

scholarly journals Comprehensive spectroscopic (FT-IR, FT-Raman, 1H and 13C NMR) identification and computational studies on 1-acetyl-1H-indole-2,3-dione

2017 ◽  
Vol 15 (1) ◽  
pp. 225-237 ◽  
Author(s):  
Maha S. Almutairi ◽  
S. Muthu ◽  
Johanan C. Prasana ◽  
B. Chandralekha ◽  
Alwah R. Al-Ghamdi ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Density Functional ◽  
Energy Gap ◽  
Solid Phase ◽  
Atomic Orbital ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Charge Delocalization ◽  
Ft Ir ◽  
Ft Raman

AbstractFourier transform infrared (FT-IR) and FT-Raman spectra of 1-acetyl-1H-indole-2,3-dione (N-acetylisatin) were recorded in the solid phase and analyzed. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges were calculated using density functional theory (DFT/B3LYP) calculations with a standard 6-311++G(d,p) basis set. The fundamental vibrational modes of N-acetylisatin were analyzed and fully assigned with the aid of the recorded FT-IR and FT-Raman spectra. The simulated FT-IR and FT-Raman spectra showed good agreement with the experimental spectra. The stability of the molecule, arising from hyper-conjugative interactions and charge delocalization, was analyzed using natural bond orbital (NBO) analysis. The dipole moment (µ), polarization (α) and hyperpolarization (β) values of N-acetylisatin were also computed. The potential energy distribution (PED) was computed for the assignment of unambiguous vibrational fundamental modes. The HOMO and LUMO energy gap illustrated the chemical activity of N-acetylisatin. The energy and oscillator strength were calculated by DFT. Gauge–including atomic orbital NMR (1H and 13C) chemical shift calculations were performed and compared with the experimental values. Thermodynamic properties (heat capacity, entropy and enthalpy) of the compound at different temperatures were also calculated.

scholarly journals Quantum chemical studies of interactions between Au6 cluster and DNA bases

2020 ◽  
Vol 4 (2) ◽  
pp. First
Author(s):  
Nhat Vu Pham ◽  
Nguyen Thanh Si ◽  
Mai Mac Son ◽  
Pham Thi Bich Thao ◽  
Nguyen Van Hong ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Energy Gap ◽  
Gold Cluster ◽  
Water Environment ◽  
Gold Surface ◽  
Electrical Signal ◽  
Binding Energies ◽  
Basis Set ◽  
Dna Bases

Density functional theory (DFT) is employed to examine the adsorption mechanism of DNA bases (adenine, guanine, cytosine, and thymine) on the gold surface using Au6 cluster as model reactant. Geometries of resulting complexes are optimized using the PBE functional in conjunction with the cc-pVTZ-PP consistent-correlation pseudopotential basis set for gold and the cc-pVTZ basis set for the non-metals. The binding sites and energies, along with several quantum chemical indicators are also investigated at the same level of theory. The binding energies between Au6 cluster and DNA bases are computed to be around 14–25 kcal/mol in gas-phase and slightly reduced to 10 – 20 kcal/mol in the water environment. Cytosine has the highest affinity with gold cluster, decreasing as follows cytosine > adenine  guanine > thymine. If a visible light with a frequency of Hz (500 nm) is applied, the time for the recovery of Au6 from the complexes will be in the range of   (for thymine) to 10 (for cytosine) seconds at 298 K in water. In addition, the geometric structures of both the gold cluster and DNA bases are almost unchanged during the complexation. The gold cluster is found to benefit from a larger change of energy gap that could be converted to an electrical signal for the detection of these molecules. Current results could provide us with fundamentals for understanding the DNA bases absorption on gold nanoparticle surfaces at the atomic and molecular levels.

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