Gaussian Program Research Articles

A spectroscopic approach to compare the quantum chemical calculations and experimental characteristics of some organic molecules; Benzene, Toluene, P-Xylene, P-Toluidine

In this study, first, Benzene molecule pretends as the starting point, and then methyl and amine groups were added to construct Benzene like molecules. After that, the change of the mentioned physical properties above was investigated. In addition, HOMO-LUMO, MEP, and character tables of these organic molecules were obtained, and the effect of group symmetry was investigated. Density functional theory calculations were used in this study to obtain vibrational and electronic spectra for the four ring molecules (Benzene, Toluene, p-Xylene, p-Toluidine) and optimized geometries of molecules were performed in these programs. It was concluded that the molecules belong to D6h, C2v, D2h and C2v symmetry point groups for Benzene, Toluene, p-Xylene, and p-Toluidine respectively. It is concluded that lowest C1-C2 bond was in Benzene and p-Xylene, and the highest C1-C2 bond was in Toluene. On the other hand, it was found out that many vibrational frequencies changed with the addition of subgroups. It was aimed to determine the interaction sites of each molecule. For this purpose, mulliken atomic charges, molecular electrostatic potential (MEP) surface map and quantum chemical properties such as hardness, softness, electronegativity, chemical potential, ionization potential, electrophilic index, dipole moment, electron affinity were calculated via Gaussian program.

Hydrogen bonding guest-water interactions in pinacolone, tert-butyl amine, and tert-butylmethyl ether: a theoretical study on energetics, structure, and topological +

In guest-host interactions, guest molecules used for hydrogen bonding potential of clathrate hydrate cages are involved as "promoters" for hydrogen or methane storage. Among the promoter molecules, there are pinacolone and tert-butylmethyl ether containing oxygen atom, and tert-butyl amine among those containing nitrogen atom. The dimer and trimer interactions of these molecules with the water clusters were investigated. The cooperativity effect, which is a measure of the hydrogen bonding of these oxygen and nitrogen-containing complexes, was calculated and these complexes were analyzed. Moreover, molecular electrostatic potential (MEP) analysis was performed to determine intermolecular interactions. Clusters of several molecules may seem like a non-significant state of matter; however, in systematic studies with small clusters, important results can be obtained. Therefore, it is very useful to work with clusters to understand the properties of the dense phase, and this study aimed to examine the properties of structures, energies, infrared vibration frequencies, and topological parameters, which develop as a result of the interaction of structures in different clusters with water molecules. The MP2 level was performed using aug-cc-pVDZ basis set calculations for this study. Tight converting criteria were used in the optimization step. Harmonic vibrational modes were calculated at the MP2/aug-cc-pVDZ level. Each minima obtained from the MP2 level was subjected to single-point energy calculations using CCSD(T) levels with the aug-cc-pVDZ basis set by the Gaussian16 package program suite. Thetopological analyseswere performed withnon-covalent interaction (NCI). MEP surface of the complex was also composed by Gaussian program using the optimized geometry at a MP2/aug-cc-pvdz level.

Removal of Toxic Basic Fuchsin Dye from Liquids by Antibiotic Azithromycin Using Adsorption, TD-DFT Calculations, Kinetic, and Equilibrium Studies

This work aims to study the removal of new fuchsin dye (NFD) using azithromycin (Az) by a spectrophotometric technique at two different wavelengths (547 and 286 nm), which formed the blend [Az+NFD]. Afterward, the [Az]TF, [NFD]TF, and nanoblend [Az+NFD]NB thin films were fabricated using the spin-coating technique. The models of Langmuir and Freundlich isotherms were applied to examine the experimental data of adsorption equilibrium and activation parameters. At 547 and 286 nm, the sorption capacity (qm) was determined to be 0.0095 and 0.01 mg g–1, correspondingly. The kinetic data showed that the reaction was fitted with a first-order reaction and the maximum adsorption capacity of Az at 547 nm was 0.0198 mg g–1 at 313 and 323 K, whereas at 286 nm, it was 0.0071 mg g–1 at 303 K. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were calculated, and the experimental results showing negative values of ΔH° at 547 and 286 nm (−33.67 and −11.22 kJ mol–1, respectively) indicate the adsorption of NFD using Az is an exothermic reaction. The negative values of ΔG° at 547 and 286 nm (−19.67 and −13.01 kJ mol–1, respectively) indicate a spontaneous reaction. The calculated time-dependent density functional theory (TD-DFT) spectra matched the measured IR spectra precisely and corroborated the molecular structure of the tested materials. The experimental values and TD-DFT/CASTEP predictions for these properties are in great agreement. The optical (TD-DFT/CASTEP) characteristics of the [Az]Iso, [NFD]Iso, and [Az+NFD]NB gaseous phases are in close agreement with the experimental results. The greatest absorption bands for [Az]TF, [NFD]TF, and [Az+NFD]NB correspond to the π → π* electronic transition at 268, 547, and 625 nm, respectively, and the Gaussian program corresponds well with the experimental analysis for synthetic IR and molecular electrostatic potential. Optical illumination studies suggest that the nanoblend device films investigated may be employed in solar cell applications. The quantity of dye removed by Az decreases with an increase in the contact time and optimum adsorption was achieved in 4 min at 547 nm, whereas it increases with time at 286 nm and an optimum adsorption capacity was achieved in 6 min. The isolated molecule of [Az+NFD]Iso has a band gap of 2.415 eV, as determined by TD-DFT/DMol3. Thin films of thickness 100 ± 3 nm of [Az]TF, [NFD]TF, and [Az+NFD]NB via a spin-coating technique at room temperature were fabricated.

TDDFT calculations of the PETN's ultraviolet absorption spectrum under the electric field loading.

The UV(ultraviolet) absorption spectrum of PETN under different electric field loading directions(X, Y, and Z) with the value of strength range from 0.001 a.u. to 0.006 a.u. was calculated with the TDDFT(Time-dependent density functional) in this work. With the increase of electric field strength, the absorbance of PETN in the ultraviolet band decreases. To explain the action mechanism of the electric field on PETN UV(ultraviolet) absorption spectrum, we analyzed and counted the contribution rate, oscillator strength, and vertical excitation energy of the main excitation process whose contribution rate to the UV absorption spectrum is greater than 10%. The contribution of PETN to the UV spectrum in all directions without an electric field was also listed to investigate the anisotropy of PETN in the excitation process under an electric field. The hole-electron analysis showed that the electric field will enhance the charge transfer characteristics in the excitation process of PETN. To investigate the anisotropy of the response under different electric field application directions, the contribution of the UV absorption spectrum in different directions was studied. Optimization and TDDFT calculation were performed at the level of M06-2X/def2-TZVP and PBE0/def2-TZVP respectively, with Gaussian09 program. The hole-electron analysis and UV absorption spectrum plotting were performed with Multiwfn3.8.

In English

The hexagon-shape graphene nanoflakes (GNFs) limited by zigzag edges only (with doubly and triply coordinated atoms) have unique increased reactivity. Despite the high systems symmetry (D6h) the Carbon atoms in GNFs occupy non-equivalent positions. Can such physical and chemical characteristics of GNFs, which depend of the atom position in the cluster, definition? This characteristic together with the simplicity of its calculation makes it possible to predict the properties of nanoflakes obtained from GNFs by introducing single and multiatomic vacancies into them or by replacing Carbon atoms with electron withdrawing and electron donating atoms. This characteristic includes the C1s core-level binding energy shifts, the maxima of which characterize the C atoms of a certain type. The proposed work is devoted to quantum chemical calculations of the electronic density of states (DOS) of pristine hexagon-shape GNF C96 (multiplicity, M=5), their saturated counterpart –polycyclic aromatic hydrocarbon(PAH) C96H24 (M=1) and their derivatives with one and two single vacancies in the ground electronic state (GES). All calculations were performed using the density functional theory (DFT) method with the involvement of the valence-split basis set 6-31G (d,p). Systems with open shells were considered using the UB3LYP exchange-correlation functional. The obtained spectra were fitted using Gaussian curve fitting program to determine the binding energy for each peak. The Gaussian function distribution of the theoretically calculated C1s core-level binding energy shifts of GNFs testified the presence of six peaks, each of which refers to a certain type of Carbon atoms. The C1s peak with the highest binding energy (-285.57 eV) is caused by contributions from the doubly coordinated edge cyclic chain (ECC) Carbon atoms. The C1s orbitals of the central hexagon (CHex) atoms and the first cyclic chain (FCC) atoms form delocalized molecular orbitals (MOs) in different parts of the cluster. The analogous spectrum of PAH C96H24 is slightly shifted to the region of lower binding energies and contains only two well-defined peaks. The peak with a higher binding energy (-284.36 eV) is generated by the 1s states of the CHex atoms and the atoms of the FCC, which are bounded to the CHex atoms. The electronic DOS difference in C1s core-level spectra of GNF C96 (M=5) and their saturated counterpart PAH C96H24 is established due to the presence of two weakly bounded π-systems in GNF and common conjugated system in PAH. The electronic DOS of defect-containing cluster C96-1(1) (M=3) (one CHex atom has been removed from the C96nanoflake) is generated by the C1s core-level atoms of the second cyclic chain (SCC), which are located at the different distances from the center of the nanoflake. The peak of the lowest intensity (-284.63 eV) appears in the spectrum as a reflection of the appearance of doubly coordinated Carbon atoms surrounding the single vacancy in the C96-1(1) nanoflake. The analysis of the electronic DOS of the C1s core-level spectrum of the C96-2(1) nanoflakeis shown, that doubly coordinated Carbon atoms, concentrated around two single vacancies, are essentially non-equivalent. If the MO with the lowest binding energy is localized on two of them – the MO with the highest binding energy is localized on the third atoms (one around each single vacancy). The electronic C1s core-level DOS spectrum of defect-containing molecular systems with one C96-1(1)H24 and two C96‑2(1)H24 single vacancies are similar to the analogous spectrum of PAH C96H24. In the first of them – one additional maximum appears due to C1s atoms surrounding the single vacancy. In the second – there are two additional maxima, each of which is generated by C1s core-level atoms adjacent to individual vacancies.

Investigation on Molecular Structure and Electronic Properties of Zinc (II) Complex with 2-acetylpyridinenicotinichydrazone Ligand

In the present study, the structural parameter, the electronic and nonlinear optical properties of three Zn (II) halido complexes of the type [Zn (Hal)2HL] (Hal = Cl, 1; Br, 2; I, 3; HL = 2-acetylpyridine nicotinic hydrazone) have been theoretically investigated in detail. Two of the studied complexes [ZnCl2(HL), [ZnBr2(HL)] have been synthesized before, and some molecular properties have been determined, however, the new complex [ZnI2(HL)] is theoretically modeled for the first time. The polarizability (α), dipole moment (µ) and the first-order hyperpolarizability (β) of the compounds have been investigated using the Density Functional Theory (DFT) based on the B3LYP density functional with basis set combinations. In calculations, LANL2DZ and a mixed basis set of LANL2DZ (for Zn and I) and 6-311G (for other atoms) are used in the gas-phase geometry optimization. In addition, the highest occupied molecular orbital energy (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the compounds in the ground state were calculated by using the same method and the energy band gap (Eg = ELUMO-EHOMO) was obtained from frontier molecular orbitals. The equilibrium state (ground state) dipole moment value of the studied complex was calculated as 12.61 and 12.74 Debye by B3LYP/GENECP/LANL2DZ-6-311G and B3LYP/LANL2DZ method, respectively. The energy gap values of complexes 1-3 are calculated as 1.73/1.38/1.15 eV at the B3LYP/LANL2DZ and are calculated as 3.61/2.28/2.18 eV at the B3LYP/MIX respectively. The energy gap values of complexes 1-3 decrease in the order complex 1>complex 2>complex 3. The approximate geometry of the molecules in three dimensions was drawn in the Gauss View 5.0 molecular imaging program, and all theoretical calculations were used with the Gaussian 09W package program.

Density Functional Theory and Ab Initio Hartree-Fock Computational Study of 2-[1-Acetyl-3-Methyl-4,5-Dihydro-1H-1,2,4-Triazol-5-One-4-Yl]-Phenoxyacetic Acide

In the present theoretical study, the 2-[1-acetyl-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl]-phenoxyacetic acide was optimized by B3PW91 and HF methods 6-311+G (d.p) basis set using the Gaussian G09W program. The molecular structure, HOMO and LUMO energy analysis, electronic transitions, total static dipole moment, the mean polarizability, the anisotropy of the polarizability, the mean first-order hyperpolarizability, electronegativity, chemical hardness, molecular electrostatic potential maps (MEP) and Mulliken charges of 2-[1-acetyl-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl]-phenoxyacetic acide molecule have been investigated by using B3PW91 and HF methods with the 6-311+G (d, p) basis set. The calculated IR data of titled compound were calculated in gas phase by using of 6311+G (d, p) basis sets of B3PW91 and HF methods and are multiplied with appropriate adjustment factors. Theoretical infrared spectrums are formed from the data obtained according to B3PW91 method. In the identification of calculated IR data was used the veda4f program. 1H-NMR and 13C-NMR spectral data values were calculated according to the method of GIAO using the program package Gaussian G09W Software. Experimental data were obtained from the literature. Experimental and theoretical values were inserted into the graphic according to equitation of δ exp=a+b. δ calc. The standard error values were found via SigmaPlot program with regression coefficient of a and b constants. In addition, in vitro antioxidant properties of this compound was investigated.

Investigation of Conformational Analysis of (m-Carbamoylphenyl) Boronic Acid Molecules by Theoretical Methods

In this study, the structural parameters, the electronic energy, the dipole moment (μ), the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy, the polarizability (α), hyperpolarizability (β) and vibrational frequency of (3-Carbamoylphenyl) boronic acid were calculated at Density Functional Theory (DFT) with B3LYP (Becke 3 Parameter Lee-Yang-Parr) model using the 6-311+(2d,p) basis set in gas phase. Also, using the EHOMO and ELUMO energy values of the molecule, the energy gap (Eg = ELUMO -EHOMO), electronegativity (χ), chemical potential (Pi), chemical hardness (η), softness (σ), ionization energy (I), electron affinity (A), electronic chemical potential (µ), global softness (S) values were calculated according to the literature. Equilibrium state (ground state) energy gap value of the molecule were calculated as 5.59 eV. The dipole moment value of the molecule was calculated as 3.41 Debye by the DFT/B3LYP/6-311+G(2d,p) method. The obtained vibrational wave numbers were scaled with appropriate scale factors and the assigning of these vibrational wavenumbers was made according to the potential energy distribution (PED) using the VEDA 4f program. The approximate geometry of the molecules in three dimensions was drawn in the Gauss View 5.0 molecular imaging program, and all theoretical calculations were used with the Gaussian 09W package program.

Theoretical Investigation of Vibration and Electronic Properties of (E)-3-(Benzylideneamino)-4H-1,2,4-Triazol-4-Amine

In this study, the important application areas of triazoles have increased the interest in studies related to them. In this study, the structural parameters, vibrational frequency, the electronic energy, the dipole moment (μ), the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy, the polarizability (α), hyper polarizability (β) and the potential energy curves (PEC) of (E)-3-(benzylideneamino)-4H-1,2,4-triazol-4-amine molecule were calculated at Hartree-Fock (HF) and Density Functional Theory (DFT) with B3LYP (Becke 3 Parameter Lee-Yang-Parr) model using the different basis set in gas phase. The potential energy curves of the studied molecule were performed as a function the θ[C3-N5-C2-N3] torsion angle varying from -180º to 180º at 10º intervals using both B3LYP/6-31+G(d) and HF/6-31+G(d) level of theory. The dipole moment value of the molecule was calculated as 5.43 Debye by the B3LYP/6-311++G(2d,2p) method and as 5.73 Debye by the HF/6-311++G(2d,2p) method, respectively. The obtained vibrational wave numbers were scaled with appropriate scale factors and the assigning of these vibrational wavenumbers was made according to the potential energy distribution (PED) using the VEDA 4f program. Also, by using HOMO-LUMO energies, energy gap values, ionization energy, electron affinity, chemical potential, electronegativity, hardness and softness indices were obtained. The approximate geometry of the molecules in three dimensions was drawn in the Gauss View 5.0 molecular imaging program, and all theoretical calculations were used with the Gaussian 09W package program.

Calculation of Some Theoretical Properties of 3-(p-Methoxybenzyl)-4-(4-Hydroxybenzylidenamino)-4,5-Dihydro-1H-1,2,4-Triazol-5-One with DFT

In this study, the quantum chemical computations of 3-(p-methoxybenzyl)-4-(4-hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-one that is a triazole derivaties were calculated using DFT method in the 6-311++G(d,p) basis set. Firstly, the molecule was optimized for the most stable positions of the atoms. The nuclear magnetic rezonans (13C-NMR and 1H-NMR) data were calculated with the GIAO method in the Gaussian O9W package program and the results were compared with the experimental values in the literature. Furthermore, theoretical infrared (IR) vibration frequencies values which were scaled with certain scala factor were obtained using the Veda 4 program. In this study, compound’s thermodynamic parameters such as (entropy S0, heat capacity CV0 and enthalpy H0), geometric properties (bond angle and length), electronic parameters (global hardness (η), electron affinity (A), electronegativity (χ), softness (σ) and ionization potential (I), ELUMO-EHOMO energy gap, HOMO-LUMO energy), dipole moment, mulliken atomic charges were also studied.

The study of Letrozole adsorption upon CCT nanotube: A DFT/TD-DFT and spectroscopic (excited states and UV/Vis)

In this research, the geometric structure of LTZ and CCT (5,0) was optimized with B3LYP/6-31G* method using the Gaussian 09W program package to investigate the weak interaction of Letrozole (LTZ) and carbon carbon nanotube (CCT). According to the calculation of the release energy, it was found that the drug delivery process is desirable. Also, the structural properties of the title compounds were assessed by thermodynamic and frontier molecular orbital (FMO) parameters. In this study, a series of measures have been performed to detect changes in drug loading properties and non-bonding interactions between the LTZ and CCT (5,0) nanotube. The non-bonding interaction effects of LTZ and CCT over the electronic properties were also evaluated and argued. The research is based on the fact that studies can help to understand the interaction between the LTZ drug and CCT (5,0) nanotube and the development of CCT-based drug release systems. This research aimed to determine variations in electronic properties of anticancer LTZ drug in presences CCT. Then, the reactivity and stability behavior of LTZ drug and on CCT to be examined by density functional theory (DFT). Then, frontier molecular orbital (FMO) and noncovalent interaction (NCI) analyses were performed, which decrease in reactivity described increase in the stability of LTZ drug.

DFT and Molecular Docking Study of 1-(2´-Thiophen)-2-propen-1-one-3-(2,3,5-trichlorophenyl) (TTCP) Molecule as Antiviral to Covid-19 Main Protease.

Thiophene-containing compounds have antiviral properties and may be among the drugs tested for the treatment of COVID-19 diseases. In order to better understand the molecular definition of the 1-(2´-Thiophen)-2-propen-1-one-3-(2,3,5-trichlorophenyl) molecule from thiophene-containing compounds, the physico-chemical (molecular structure analysis, spectroscopic properties, boundary orbital analysis) mechanisms underlying the protein–ligand interaction should be examined in detail. For this reason, geometric parameters, IR and UV–vis spectra, conformational analysis, electronic, NBO and NLO properties, molecular electrostatic potential map and Mulliken charge distributions of the TTCP molecule were investigated theoretically using DFT theory in the Gaussian program. Accordingly, molecular docking calculations with COVID-19 main protease (PDB 5R7Y) were performed to determine the pharmaceutical activities of the TTCP molecule against coronavirus diseases.

Laser-assisted rapid synthesis of anatase/rutile TiO2 heterojunction with Function-specified micro-zones for the effective photo-oxidation of sulfamethoxazole

A solid-state laser scanning treatment (SLST) was adopted to synthesize anatase/rutile TiO2 heterojunction with effective charge carrier separation and high surface adsorption performances for the photodegradation of sulfamethoxazole (SMX). The 1064 nm pulsed fiber laser could in-situ generate rutile zones on the pristine sheet-like anatase crystal enclosed by (001) facets, which could form the well-defined anatase/rutile interface to promote the formation of dominating active species (h+ and ∙OH) on the anatase zones. X-ray absorption fine structure (XAFS) measurements, low temperature electron paramagnetic resonance (LT-EPR) as well as the density functional theory (DFT) simulation proved that the oxygen vacancies (VO) could both introduce defective energy states to promote the light absorption and enhance the SMX adsorption on anatase zones. Based on the delicately designed micro-zones, the photodegradation efficiency of the optimized catalyst could reach 99.3 %, which demonstrated ∼7 times higher performance than that of pristine TiO2 and exhibited robust stability under environmental conditions. Gaussian and Vienna Ab Initio Package (VASP) programs were used to provide detailed degradation pathways and mechanism for SMX. This SLST could be potentially employed to create function-specified zones on various catalysts for different applicational aims.

Synthesis, spectroscopic characterization, biological application and molecular docking studies of some transition metal complexes of isophthalamide ligand

Various spectrum techniques were used to analyze the newly synthesized isophthalamide ligand, N1,N3-bis(1-hydrazinyl-1-oxopropan-2-yl)isophthalamide (L). The reaction of isophthalamide ligand with Fe(III), Co(II), Ni(II) and Zn(II) ions produced complexes of 1:1 (M:L) stoichiometry. The spectral data, FTIR and NMR disclosed that the isophthalamide ligand chelated the central metal ions in neutral tetradentate manner via the two carbonyl oxygens and two amide nitrogen atoms. The octahedral configuration of the complexes has been elucidated by electronic and magnetic moment measurements. The molar conductivity described the electrolytic nature of the synthesized complexes. The structural features of the title compounds were investigated based on mass spectral analysis which showed good agreement between the calculated and experimental data and in concise with the elemental analyses data. The thermal decomposition characteristics of the ligand and its complexes are measured using thermogravimetric analysis. The DFT quantum chemical simulation validated the suggested structures and was used to calculate HOMO-LUMO energies. To optimize the structural formula for the examined ligand, the Gaussian09 program was used. The existence of Fe(III) and Ni(II) complexes in the nanostructure was confirmed using a scanning electron microscope (SEM). The isophthalamide ligand and its transition metal complexes were studied for their antibacterial characteristics against two Gram-positive bacteria (Bacillissubtilis and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) microorganisms. Title complexes were shown to be more physiologically active than the parent ligand. The title compounds have a positive interaction with the crystal structures of 3t88-E. coli, 3ty7-Staphylococcus aureus, 5h67-Bacillus subtilis, and 5i39-Pseudomonas aeruginosa, according to molecular docking study.

Novel complexes derived from tetra-(2-pyridyl) pyrazine (TPPZ): Spectroscopic, DFT, molecular docking, and biological studies

In continuation of our previous study to synthesize a series of novel complexes isolated from polypyridyl-azine as the main ligand (tetra-(2-pyridyl) pyrazine (TPPZ)) or in the presence of co-ligand, mono and polymetallic chelates such as [Cu(TPPZ)(SCN)Cl] (1), [Ag2(TPPZ)(NO3)2]. H2O (2) and [(OsO2)3(TPPZ)].2·5H2O.C2H4Cl2(3) were synthesized and characterized. In addition, a series of VO2+ complexes, [(VO)2(TPPZ)OH(SO4)0.5][(VO)4(OH)10].H2O (4), [(VO)2(TPPZ)EtOH.SO4][(VO)2(SO4)3dipy].12.H2O (5), and [VO(acac)(HTPPZ)]2Cl.CH3CN (6) was investigated in detail. Crystal data of Cu(II) complex (1) indicates monoclinic, P21/a, a = 10.6983(3) Å, b = 19.9128(9) Å, c = 11.5958(5) Å, α = γ = 90.00° ≠ β = 108.819(3), V = 2338.2 (2) Å3 and Z = 4. The chelates were characterized by elemental analyses and spectral (FTIR, electronic, and EPR) studies. Also, cyclic voltammetry studies were investigated. The modeling study of TPPZ and their complexes were approved with the Gaussian09 program in DFT/B3LYP. Os4+ and VO2+-mono complexes show superiority as promising anticancer agent for the PC-3 cell lines. Molecular modeling is utilized to examine the molecular characteristics and binding propensity of ligands and their complexes with 3s7s and 3IG7 protein and to signify inhibitory strength.

MYOGLOBIN vs. HEMOGLOBIN BLOCKADE MODEL RELATED SMOKE GAS INHALATION - A COMPUTATIONAL ANALYSIS

To identify the pattern of myoglobin compared to hemoglobin blockade by the combustion products contained in the fire smoke using computational chemistry tools. The myoglobin unavailability can be a determining factor of the severity and consequences of smoke poisoning, generating the inability of patients to attempt evacuate themselves, compromising myocardial function, leading to crush syndrome-like effects and increasing of multi-organ failure to the victims of mass burn casualties event. In this study, it was used quantum chemical calculations performed with the Gaussian program suite using DFT/B3LYP/6-311G level of theory to optimize molecular geometries, calculate the molecular electrostatic potential, and obtain the vibrational spectrum. These calculations were applied to the myoglobin and hemoglobin model, thus studying their binding to the essential components of toxic fire smoke. Comparing the structural descriptors – frontier molecular orbitals, energy difference, electric dipole moment (μ), was obtained the highest values as belonging to hydrogen cyanide (2.9), which may explain its increased reactivity, meaning strong interaction with both myoglobin and hemoglobin, followed by hydrochloric acid (1.03) and carbon monoxide (0.122). Within the framework of complex intoxication generated by the inhalation of fire smoke, myoglobin is blocked in a temporal manner and according to a very similar pattern to hemoglobin. It follows that the significant rhabdomyolysis found in these patients is due not only to hypoxemia but also to the primary unavailability of myoglobin, and myocardial damage is also multifactorial. Although slightly discussed, the calculation of different structural and geometric descriptors for hydrochloric acid reveals for hydrochloric acid high values, suggesting binding affinities comparable to those of carbon monoxide. Molecular modeling programs allow for new approaches and can identify parameters or areas of their reference that influence the management of patients intoxicated with fire smoke components.

Photophysical and in vitro photoinactivation of Escherichia coli using cationic 5,10,15,20-tetra(pyridin-3-yl) porphyrin and Zn(II) derivative conjugated to graphene quantum dots

Pathogenic microorganisms may continue causing infection through the transfer of antibiotic resistance genes. As a result, the efficacy of pharmaceuticals in microbial inactivation is deteriorating. The present study was conducted to investigate the antimicrobial activity of neutral and quaternized free base and Zn 5,10,15,20-tetra(pyridin-3-yl) porphyrins on Escherichia coli (E. coli), a gram-negative bacterium that causes cholecystitis, pneumonia and urinary tract infections. Conjugation of the porphyrin to graphene quantum dots (GQDs) was implemented to enhance photocatalysis and reactive oxygen species generation. Density functional theory (DFT) geometry optimizations for free base and Zn porphyrin based on the B3LYP (Becke 3-Parameter (Exchange), Lee, Yang and Parr) functional of the Gaussian09 program package and Time-dependent density-functional theory (TD-DFT) calculations of the associated UV-visible absorption spectra are reported to analyse the electronic structure and optical properties of the porphyrins. The TD-DFT calculations showed that for both porphyrins the value of highest occupied molecular orbital (ΔHOMO) is greater than that of lowest unoccupied molecular orbital (ΔLUMO) which tells that there is no unusual splitting of (LUMO) orbitals which may be caused by systematic error in TD-DFT calculations. Due to the red shift in the spectrum of ZnT(3-Py)P and the ΔLUMO being higher, the HOMO-LUMO gap was expected to be lower than that of H2T(3-Py)P. The photophysical properties and Photodynamic antimicrobial chemotherapy activities of these nanoconjugates were investigated. The highest ΦΔ was that of Q-ZnT(3-Py)P- GDQs at 0.69 with the log reduction of 9.42.

Sb(V) Kaempferol and Quercetin Derivative Complexes: Synthesis, Characterization and Antileishmanial Activities.

Recent studies on Leishmaniasis treatment have confirmed the antiparasitic effects of flavonols and organic antimony pentavalent [(Sb(V)] complexes. This study aimed to identify new Sb(V) complexes by combining the benefits of antimonials and flavonols as well as by optimizing their properties. Kaempferol and quercetin peracetate were prepared using acetic anhydride in pyridine. By performing regioselective synthesis, 7-O-paramethylbenzyl as an electron-donating group and 7-O-paranitrobenzyl as an electron-withdrawing group were added to quercetin, and, then, the synthesis of Sb(V) kaempferol and quercetin derivative complexes were performed using SbCl5 solution in glacial acetic acid. The structures were confirmed by UV, ESI mass, IR, 1H-, and 13C-NMR spectral data, and the Stoichiometry of the ligand-metal complex by the mole ratio method. Computational molecular modeling was conducted using the Gaussian program. The structures were confirmed based on the results from UV, nuclear magnetic resonance (NMR), and electrospray ionization (ESI) mass analyses (3-12). Among the produced compounds, 11 and 12 as newly described, and other compounds as pre-defined compounds were identified. According to the results from biological test, kaempferol triacetate with more lipophilicity showed the highest anti-promastigote activity with an IC50 value of 14.93 ± 2.21 µM. As for anti-amastigote activity, despite the differences, all antimony complexes showed anti-amastigote effects in vitro with IC50 values of 0.52 to 14.50 µM. All flavonol Sb(V) complexes showed higher activity compared to meglumine antimonate in anti-amastigote effect. Inside the host macrophages, by breaking down the complex into antimony and quercetin or kaempferol analogs, the observed antiparasitic effects may have been related to both Sb(V)/Sb(III) conversion and flavonoid antileishmanial activities.

SYNTHESIS, CHARACTERIZATION AND THEORETICAL CALCULATION OF 4-(((1H-IMIDAZOL-2-YL)METHYLENE)AMINO)PHENOL

In this study, the Schiff base 4-(((1H-imidazol-2-yl)methylene)amino)phenol (3) has been synthesized and structure of the compound was characterized by elemental analysis, FTIR, 1H NMR, 13C NMR and UV-Vis spectroscopic techniques. Correlation of theoretical and experimental spectroscopy data was examined. The acidity constant was calculated by using PM6 method in MOPAC2012 program at gas and liquid phases at 25 °C. Basically in calculations, it was calculated by the DFT method in Gaussian09 program at B3LYP/6-311+g(d,p) levels. After deciding the stable conformation of the synthesized molecule, HOMO, LUMO, MEP and SAS theory were calculated using the B3LYP / 6-311+g(d, p) level. The low HOMO-LUMO values of the resulting compound indicate that the reaction activity will be easier and can easily bind to metal atoms or a receptor in future studies.

NMR Susceptibility and Magnetization of DNA Bases, Nucleotides and Their Derivatives with C2Fe+, A DFT Study

DNA strands and their bases are in the cells in every creature. They essential for growth, metabolism regulation and carrying genetic information bases to new generations. The bases of DNA are working with 0 and 1 system. In this theoretical research, first, by using Gaussian program, NMR susceptibility of DNA bases and their C2Fe+ attached varieties are determined. In the next step, with effect of magnetic field (H) and NMR susceptibility of these compounds, their resulted Magnetization (M) is calculated. These resulted magnetizations not only can be considered as a method to make a new (0) and (1) system for DNA bases but also can be used as creating certain signals to mark of DNA bases and their compounds which are attached to C2Fe+.