Potential Energy Distribution Research Articles

Structural, Quantum Chemical, Spectroscopic (UV, FT-IR, FT-Raman and NMR) and Molecular Docking Studies of Diphenylpyraline Hydrochloride as Antihistaminic Drug

Diphenylpyraline hydrochloride, chemically known as 4-benzhydryloxy-1-methypiperidine hydrochloride is a first-generation antihistaminic drug that produces therapeutic antiallergic effects by binding to histamine H1 -receptors. The molecular structural and electronic properties of title compound have been computed at DFT/TD-DFT method with B3LYP/6-311++G(d,p) level. The theoretical spectral data has been compared with experimental ones, showing good agreement. The atomic charges, molecular electrostaitc potential (MEP), the natural bond orbitals (NBOs), the natural hybrid orbital (NHOs), the non-lilear optical (NLO) properties, the vibrational (IR and Raman) frequencies, UV-vis absorption wavelenghts and nuclear magnetic resonance (NMR) chemical shifts of diphenylpyraline hydrochloride have been investigated. The potential energy distribution (PED) of title compound was performed using the VEDA program and these values were compared with the experimental FT-IR and FT-Raman vibrational frequencies. Moreover, molecular docking studies have been performed between the 3RZE and 7DFL target proteins and the title compound. Docking results revealed that the title compound can be designed as potential antihistaminic agent.

Spectroscopic, Computational, Molecular Docking and Dynamics Simulations Studies of 4-Amino-3-hydroxyNaphthalene-1-Sulfonic Acid (ANSA)

Experimental investigation and computational analysis with the DFT approach were done on 4-amino-3-hydroxy naphthalene-1-sulfonic acid (ANSA). Different spectroscopic analyses like NMR, FT-IR, and UV-Visible were performed. The molecular structure was optimized, and the wavenumbers of typical vibrational modes were calculated using the B3LYP method and the 6-311++G (d, p) basis set. After optimization, the calculated bond lengths and bond angles were compared with experimental ones and found well matched, described by RMSD values. Potential energy distribution (PED) obtained by VEDA. 13C and 1H NMR were calculated with the GIAO method which showed great resemblance with the experimental spectra. UV–Vis in different phases were calculated by the TD-DFT method and the CPCM solvent model and compared with the experimental. The HOMO-LUMO energy gap showed a great opportunity for charge transfer inside the molecule. The MEP surface analysis revealed the molecule’s charge distribution. To investigate the degree of relative localization of electrons, the FLF diagram was used. Eight distinct receptors were used in biological investigations for molecular docking analysis and a molecular dynamic simulation of 15 ns was performed to determine the best ligand-protein interactions. The drug-likeness was also investigated to see the drug-like properties.

Unraveling the structure–property relationship of a chalcone-based push–pull molecule for optical limiting application in high-powered laser

In this work, the optical limiting response of a highly π-conjugated push–pull chalcone derivative (2E)-3-(2,3-dimethoxyphenyl)-1-(3-nitrophenyl)prop-2-en-1-one (abbreviated as 3DPNP) has been investigated. The structure–property relationship of 3DPNP was explored through spectroscopic investigation and quantum chemical computations. The existence of weak-non-covalent interactions and charge transfer species that responsible for the chemical stability of 3DPNP were studied by AIM and NBO analyses. The quantitative and qualitative analysis of vibrational and electronic contribution to non-linear optical (NLO) response of 3DPNP were discussed in detail. The normal vibrational modes associated with a change in the dipole moment, polarizability, first- and second-order hyperpolarizabilities of 3DPNP were identified using DFT calculations followed by potential energy distribution (PED) analysis using Gaussian 09 W software and Gar2ped program, respectively. The changes in the NLO parameters with respect to the varying frequencies and electric dipole fields were studied. The abrupt changes in the NLO properties were noticed when the frequency doubled, confirming the second harmonic generation (SHG) efficiency of 3DPNP. From the non-linear absorption and refraction studies through the z-scan experiment, the optical limiting threshold value of 3DPNP is determined to be 3.26 kJ/cm2, which shows the suitability of the material for optical limiting applications in the continuous wave (CW) laser regime.

The Structural Characterisation and DFT-Aided Interpretation of Vibrational Spectra for Cyclo(l-Cys-d-Cys) Cyclic Dipeptide in a Solid State.

Cyclic dipeptides with two intramolecular peptide bonds forming a six-membered 2,5-diketopiperazine ring are gaining significant attention due to their biological and chemical properties. Small changes in the local geometry of such molecules (from cis to trans) can lead to significant structural differences. This work presents the results of a study of cyclo(l-Cys-d-Cys), a dipeptide comprising two cysteine molecules in opposite chiral configurations, with the functional groups situated at both sides of the diketopiperazine ring. X-ray diffraction (XRD) experiment revealed that the molecule crystallises in the P-1 space group, which includes the centre of inversion. The IR and Raman vibrational spectra of the molecule were acquired and interpreted in terms of the potential energy distribution (PED) according to the results of density functional theory (DFT) calculations. The DFT-assisted analysis of energy frameworks for the hydrogen bond network within molecular crystals was performed to support the interpretation of X-ray structural data. The optimisation of the computational model based on three-molecule geometry sections from the crystallographic structure, selected to appropriately reflect the intermolecular interactions responsible for the formation of 1D molecular tapes in cyclo(l-Cys-d-Cys) crystal, allowed for better correspondence between theoretical and experimental vibrational spectra. This work can be considered the first complete structural characterisation of cyclo(l-Cys-d-Cys), complemented via vibrational spectroscopy results with full band assignment aided with the use of the DFT method.

Shedding light into the biological activity of aminopterin, via molecular structural, docking, and molecular dynamics analyses

In this study, the structural and anticancer properties of aminopterin, as well as its antiviral characteristics, were elucidated. The preferred conformations of the title molecule were investigated with semiempirical AM1 method, and the obtained the lowest energy conformer was then optimized by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational frequencies of the optimized structure were calculated by the same level of theory and were compared with the experimental values. The vibrational assignments were performed based on the computed potential energy distribution (PED) of the vibrational modes. The molecular electrostatic potential (MEP) and frontier molecular orbitals (HOMO, LUMO) analyses were carried out for the optimized structure and the chemical reactivity has been scrutinized. To enlighten the biological activity of aminopterin as anticancer and anti-COVID-19 agents, aminopterin was docked into DNA, αIIBβ3 and α5β1integrins, human dihydrofolate reductase, main protease (Mpro) of SARS-CoV-2 and SARS-CoV-2/ACE2 complex receptor. The binding mechanisms of aminopterin with the receptors were clarified. The molecular docking results revealed the strong interaction of the aminopterin with DNA (−8.2 kcal/mol), αIIBβ3 and α5β1 integrins (−9.0 and −10.8 kcal/mol, respectively), human dihydrofolate reductase (−9.7 kcal/mol), Mpro of SARS-CoV-2 (−6.7 kcal/mol), and SARS-CoV-2/ACE2 complex receptor (−8.1 kcal/mol). Moreover, after molecular docking calculations, top-scoring ligand-receptor complexes of the aminopterin with SARS-CoV-2 enzymes (6M03 and 6M0J) were subjected to 50 ns all-atom MD simulations to investigate the ligand-receptor interactions in more detail, and to determine the binding free energies accurately. The predicted results indicate that the aminopterin may significantly inhibit SARS-CoV-2 infection. Thus, in this study, as both anticancer and anti-COVID-19 agents, the versatility of the biological activity of aminopterin was shown. Communicated by Ramaswamy H. Sarma

Synthesis, functional group analysis (experimental and theoretical), solvent –Solute interactions, structural insights of (E)-3-(4-chloro-3-(trifluoromethyl) phenyl) imino) indolin-2-one–In-vitro Antimicrobial activity

(E)-3-(4-chloro-3-(trifluoromethyl) phenyl) imino) indolin-2-one (4CTFI) has been synthesised and its structural features have been investigated by spectroscopic (FT-IR, FT-Raman, NMR and UV–vis) techniques. 4CTFI was optimized in gas phase, PA (polar aprotic), PP (polar protic) and NP (nonpolar) solvent phases using WB97XD/6-311++G(d,p) method. Vibrational assignments pertaining to different modes of vibration with potential energy distribution (PED) have been augmented by normal coordinate analysis (NCA). Using natural bond orbital (NBO) analysis, the compound's electronic stability as a consequence of hyper conjugative couplings and charge delocalization has been assessed. The Fukui functions and Molecular Electrostatic Potential (MEP) surface have been utilized to provide information about the nucleophilic and electrophilic locations for the aforesaid phases. The frontier molecular orbital (FMO) energy gap probably indicates a compound's strong chemical reactivity and enables eventual charge transfer inside the molecule. Furthermore, electron-hole distributions for four excited states and topological studies have been discussed. Moreover, this chemical adheres to Lipinski's decree, which implies that, in concept, consuming an oral intake will not be troublesome. ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) attributes have been investigated to evaluate drug discovery initiatives of our synthetic molecule. Docking of 4CTFI with antimicrobial proteins have been performed and the minimum binding energy of -6.52 kcal/mol was obtained for 4WAS protein. Macromolecule flexibility and stability on protein-ligand interactions have been effectively studied using the molecular dynamics simulation. Tests of in-vitro antimicrobial efficacy have been performed on microbial strains.

Insights into synthesis, structural, energetic, vibrational, anticancer activity and molecular characteristics of 2-((2-aminopyridin-3-yl)methylene)-N-phenylhydrazinecarbothioamide as evaluated using spectroscopic and DFT investigations

Synthesis of 2-((2-aminopyridin-3-yl)methylene)-N-phenylhydrazinecarbothioamide (APHB) was attempted. Elemental analysis and NMR spectra were used to ascertain its formation. Torsional potential energy scans, for all the rotating bonds were made to get approximate initial values of dihedral angles. FT-IR, FT Raman, and UV–Vis spectra were measured for APHB. Their anticancer activity was determined experimentally, for human carcinoma cell lines pertaining to liver, Colorectal, and lung. Barrier heights, around six rotating bonds in APHB were computed. Optimized structure parameters, general valence force field, harmonic vibrational fundamentals, potential energy distribution, infrared and Raman intensities, frontier molecular orbital (FMO) parameters, NLO behaviour, NBO characteristics and molecular electrostatic surface potential (MESP) were determined using DFT/B3LYP/6-311++G(d,p) level of theory. TD-DFT was used to compute absorption maxima (λmax) of electronic transitions for the molecule in DMSO‑d6 solvent. Frontier molecular orbitals were used to understand origin of UV–Vis spectrum and chemical reactivity of the molecule. Good agreement was found between measured and computed structure parameters, IR, Raman and UV–Vis spectra. The rms error between experimental and theoretical vibrational frequencies was 9.5 cm−1, for APHB. All vibrational fundamentals were assigned unambiguously. The computations demonstrated that the molecule was good for NLO applications, which was substantiated by NBO analysis. Existence of bifurcated intramolecular hydrogen bond was predicted for APHB.

Geomagnetic Data Analysis to Identify Subsurface Condition of Gondang Area, Bojonegoro

The presence of manifestation in the Gondang indicates a specific geological condition. Those manifestations are Banyu Kuning Hot Spring, Selo Gajah Hot Spring, and Jari Mud Burst. The purpose of this study, which was carried out near Mount Pandan, was to identify the distribution of magnetic fields and magnetic anomalies, including the patterns of potential geothermal energy distribution in the region based on its magnetism. It also aimed to explain the rock structure in the manifestation area based on susceptibility values. The survey was conducted using 94 measuring points that were randomly distributed throughout the manifestation area. The data was corrected using IGRF and diurnal correction, and it was examined using Surfer 11 to construct a contour map and Oasis Montaj to visualize 3D models. According to the processed data, the residual anomaly’s value ranges from -232.1 nT until 159.4 nT. For the anomaly of residual, 2D and 3D models demonstrated low susceptibility dissemination values ranging from -0.029 until -0.0135 cgs on the manifestation zone. The high susceptibility value, which is considered an intrusion rock, has a value range of 0.011 to 0.046 cgs.

Interpretation of the spectral wave forecast model results using the phase-resolving model

The paper presents an interpretation of the results of spectral wave-forecast model using the phase-resolving model. Spectral models provide the information on the evolution of the potential energy distribution in terms of angle and frequency though the information about the geometry and statistical wave characteristics in such models are not available. This information has to be extracted through the additional, often unsubstantiated, hypotheses. The proposed computational procedure transforms spectral information into a two-dimensional wave field which consists of a set of linear modes with randomly distributed phases is proposed. The wave field is not realistic since it does not have non-linear properties, for example, various asymmetry properties such as increased kurtosis. Afterwards the linear wave field reproduced on the basis of the wave spectrum is set as the initial condition for the exact phase-resolving model. The exact models formally suitable for such calculations are cumbersome and inefficient and that practically restricts their broad and regular application. This restriction can be overcome by using a new type of 3D wave simulation based on 2D equations. The 2D model reproduces the statistical characteristics of the wave field similar to the results of the 3D exact model and runs several times faster. The examples of using the developed method of interpretation of the spectral wave forecast in the Baltic Sea are demonstrated.

Molecular Dynamics and Quantum Chemical Studies on Piperine, a Naturally Occurring Alkaloid

Piperine (a naturally occurring alkaloid), is a biologically active natural product belonging to the alkaloid series of compounds. In this study, the spectral characterization of piperine isolated from black pepper has been performed using FT-IR, 1H-NMR, and 13C-NMR. To explain spectral features, we have calculated the vibrational frequencies of the optimized structure of piperine using the B3LYP/6-311 + G(d,p) level of theory and NMR spectra using the GIAO method. All vibrational modes of the title molecule have been assigned based on potential energy distribution. The calculated scaled wavenumbers and NMR chemical shifts show good agreement with the experimental FT-IR and NMR data, respectively. To assess the bioactivity of piperine, we have first performed molecular docking using the ITK receptor and subsequently, the molecular dynamics simulation of the resulting complex for 100 ns. The results suggest the potential of piperine for possible anti-inflammatory action.

Spectroscopic characterization, DFT study, topological, molecular docking and pharmacological analysis of Iminodiacetic acid Hydrochloride

Iminodiacetic Acid Hydrochloride (IAH) optimum geometries and vibration spectra have been determined by density functional theory computations at B3LYP with 6-311++G(d, p) level basis functions. Finding the most stable structure of IAH is done through conformational analysis. In order to interpret IR and Raman spectra both quantitatively and qualitatively, vibrational spectra have been examined based on the potential energy distribution (PED) within each vibrational mode. By means of calculations both theoretical and experimental, UV–Visible and NMR spectral studies of IAH have been performed. Utilising NBO analysis, stabilisation resulting from inter- and intramolecular interaction has been studied. For predicting the reactivity and stability of the molecule, chemical reactivity descriptors are computed. Molecule size, shape, electrical potential distribution, and point of chemical reactivity will all be revealed by mapping the charge density isosurface well with electrostatic potential surface (ESP). ELF and LOL maps intended topological aspects of IAH have also been depicted. Additionally, the Natural atomic charge and the hyperconjugative interactions that cause its NLO activity have been predicted. The hyper polarizability values indicate that these compounds could be used in electro-optical applications. IAH is screened for its pharmacological activity. The binding location of the molecule to its target protein has been predicted via a molecular docking study.

Anti Microbial Activity, Vibrational, Electronic and Topology Analysis of 3, 4, 5-Trimethoxybenzaldehyde

The density functional theory (DFT) approach has become one of the most gainful means to scrutinize the molecular structure and vibrational spectra are finding well-known use in the applications related to biological systems. The experimental and theoretical on the molecular structure, electronic, and characteristics of 3, 4, 5-Trimethoxybenzaldehyde (TMB) are reported. The structure of the molecule was optimized and structural characteristics were determined by DFT using the wb97xd method with 6-311 G++ (d, p) basis sets. The vibrational assignments were made on the basis of potential energy distribution. A good consistency between the observed and calculated spectra was achieved. The intramolecular charge transfer and second-order perturbation theory of Fock Matrix in Natural bond orbital analysis by means NBO analysis. It shows the electronic stability of the compound arising from hyper conjugative interactions and charge delocalization of that molecule. Besides, the HOMO-LUMO, MEP, and Fukui were performed. In this review, the present benzaldehyde derivatives for skirmishing against bacteria strain Escherichia coli and fungi strain Candida Sp. Spectral and quantum chemical calculations are also discussed.

Molecular docking, QTAIM analysis, UV-Vis spectra, vibrational analysis, and electronic properties of Lantadenes C and D — A complete comparative study

We have done geometry optimization of two conformers of Lantadene series C and D. The fundamental vibrational frequencies with intensity have been done by using B3LYP/6-311G (d, p) method. The complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The nonbonding interactions in Lantadenes C and D are calculated by using the same level theory at the bond critical point (BCP). The calculated topological parameters at BCP are utilized to determine the nature and strength of interactions. We have also computed HOMO–LUMO gap and plotted frontier orbital HOMO–LUMO surfaces, molecular electrostatic potential surfaces to explain the reactive nature of Lantadenes C and D. The electronic transition spectra UV–Vis spectra of Lantadenes C and D are calculated by using TDDFT theory. The values of hyperpolarizability show a probable use of these compounds in electro-optical applications. The natural bonding orbital theory is utilized to calculate transition of electron from donor to acceptor which is very useful to describe nonbonding as well as bonding interactions. The calculated value of Log [Formula: see text] and Log [Formula: see text] for Lantadene C Lantadene D established its pharmaceutical behaviors. The biological activity of Lantadenes C and D is also calculated by using PASS online server for [Formula: see text]. The docking of Lantadene C Lantadene D is also performed by using Auto dock with predicted drug by Swiss dock online server.

Synthesis, Spectroscopic (FT‐IR, FT‐Raman), Electronic Properties and Molecular Docking Studies of 1‐(2, 6‐dibromo‐4‐methyl‐phenoxymethyl)‐benzo[f]chromen‐3‐one

AbstractHerein, 1‐(2,6‐dibromo‐4‐methyl‐phenoxymethyl)‐benzo[f]chromen‐3‐one (DBMPBC) is chosen to be thoroughly investigated in terms of structural, spectroscopic (FT‐IR, FT‐Raman) and molecular electronic properties based on density functional theory (DFT). The title molecule is synthesized by the reaction of 5,6‐benzo‐4‐bromomethylcoumarin with 2,6‐dibromo‐4‐methylphenol in presence of anhydrous potassium carbonate in dry acetone. All the computational studies for the selected structure are carried out at the theoretical level DFT/B3LYP/6‐311++G (d, p). The theoretically determined geometrical parameters from optimized structure and experimental values are compared to each other to confirm the structural properties of the molecule. The vibrational wavenumbers are studied by FT‐IR and FT‐Raman spectral techniques in both experimental and computational methods and compared to each other. The detailed vibrational assignments are assigned through potential energy distribution method by VEDA. The MEP surface analysis is carried out in order to identify the potential sites of electrophilic and nucleophilic attack. The Natural Bond Orbital (NBO) study significantly verified the existence of the intermolecular interactions in the molecule. The stability and reactivity properties of the molecule are estimated in terms of HOMO‐LUMO energies. Molecular docking investigations are carried out to simulate the inhibitory impact of the title molecule against the VEGFR2 (PDB: 2XIR) and PI3K (PDB: 2RDO) receptors for anti‐angiogenic therapy in the treatment of NSCLC. ADMET parameters and toxicity properties of the title molecule is conducted.

Silicon surface characteristics in vibration-assisted machining process via molecular dynamics

This study investigates the impacts of vibration amplitude, vibration frequency, and sliding velocity on the characteristics of the machined silicon substrate. The results show that increasing the vibration amplitude increases atomic strain, stress, and kinetic energy distributions while decreasing subsurface damage thickness, potential energy distribution, and especially surface roughness. The surface roughness values are 7.5 Å, 6.4 Å, 6.9 Å, and 6.0 Å corresponding to vibration amplitude of 15 Å, 20 Å, 25 Å, and 30 Å. Moreover, increasing the vibration frequency results in increased atomic strain, stress, and kinetic energy levels. The surface roughness values are 7.1 Å, 7.1 Å, 6.5 Å, 6.4 Å, and 6.0 Å corresponding to the vibration frequencies of 16.7 GHz, 33.3 GHz, 50 GHz, 66.7 GHz, 100 GHz, and 200 GHz. Furthermore, increasing the sliding velocity lowers the surface quality of the silicon sample. The surface roughness values of the silicon substrate are 6.5 Å, 6.7 Å, 6.9 Å, 6.9 Å, and 7.1 Å corresponding to 50 m/s, 100 m/s, 150 m/s, 200 m/s, and 250 m/s. Improving the vibration amplitude and frequency while decreasing the sliding velocity improves surface quality by increasing the collision between the diamond tips and the substrate. Remarkably, the vibration movement of the diamond tips could leave wave marks on the substrate surface. In general, the optimal parameters that generate a good surface are 30 Å, 200 GHz, and 50 m/s.

Exploration of Experimental, Theoretical, Molecular Docking, and Electronic Excitation Studies of Carboxylate-Appended (2-Pyridyl)Alkylamine Ligand †

‘In this study, we employed density functional theory (DFT)/B3LYP method with a 6-311++G(d,p) basis set to analyze the infrared and UV spectra of a carboxylate-appended (2-pyridyl)alkylamine ligand. The FT-IR spectra were recorded within the range of 4000–500 cm-1. Geometrical parameters, energies, and wavenumbers were determined, and the fundamental vibrations were assigned based on the potential energy distribution (PED) of the vibrational modes. The UV spectrum of the compound was measured in various solvents, namely DMSO, CHCl3, and CH3OH. The 1H-NMR shifts were estimated using the GIAO method, and the results were compared to experimental spectra. To further investigate the electronic properties, including excitation energies, absorption wavelengths, and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies, we employed the DFT/B3LYP approach. The degree of electron localization was assessed through analysis of the ELF diagram. Additionally, a molecular electrostatic potential (MEP) was generated, and a 3-D color representation was utilized to visualize reactive sites. Lastly, a biological study involving molecular docking was conducted using six different receptors in order to identify optimal ligand-protein interactions and assess drug similarities.’

Experimental and theoretical vibrational spectral Investigations, structural conformations, DFT estimations and docking studies of antibacterial drug Nitrilotriaceticacid

Nitrilotriaceticacid (NTA) was utilised without additional purification after being bought from Sigma Aldrich Chemical Company in powdered form with 99% purity. Density Functional Theory calculations at B3LYP with a 6-311++G (d,p) level were performed to gain knowledge of molecule geometries, harmonic vibrational spectra, and molecular docking analysis. Vibrational spectral investigations have been carried out with the aid of Normal Coordinate Analysis on the basis of potential energy distribution (PED) of each mode, which helps us to attain a quantitative as well as qualitative analysis of IR and Raman spectra followed by empirical scaled quantum mechanical force field methodology. Natural bond orbital analysis, Fukui analysis, RDG analysis, and Mulliken’s net charges have also been predicted. FMO's energy gap predicts the occurrence of charge transport within molecule. UV–Visible spectral analyses of NTA have been examined by experimental and theoretical calculations. By mapping electron density isosurface with an electrostatic potential surface (ESP), information about the size, shape, charge density distribution, and site of chemical reactivity of the molecules has been acquired. ELF and LOL maps portrayed topological aspects of NTA which also have been depicted. Hyperpolarizability values are in good agreement revealing that these compounds could be employed in electro optical applications. Antibacterial activity reveals that NTA have been found to exhibit antibacterial effects. Docking simulation has been carried out for the optimized ligand molecule to identify binding energy and coupling with protein molecule. NTA molecule underwent a drug likeness test utilising Lipinski's criterion, and using ADMET contour, the molecule is recommended for inclusion in pharmaceuticals.

Molecular dynamics evaluations of homogeneous condensation and thermophysical properties of (R-1234ze(E)+R-134a) binary blends

Environmental concerns demand prioritizing the development of eco-friendly refrigerants and prompting the replacement of conventional working fluids. The HFCs (hydrofluorocarbon) will be banned soon, and HFOs (hydrofluoroolefin) have been indicated as an alternative. In this study, numerous blends were attained by mixing two refrigerants, R-1234ze(E) and R-134a. Few blends are proposed as substitutes for high Global Warming Potential (GWP) fluids and are employed in refrigeration systems. The homogeneous condensation and thermophysical properties of nine binary blends of R-1234ze(E) + R-134a by varying composition with increment and decrement, respectively of 10% for each in a sequence were investigated using a molecular dynamics simulations scheme. The density, isobaric heat capacity, mean square displacement, internal potential energy and radial distribution function were investigated at constant pressure and different condensation temperatures (273.15 K to 328.15 K). The present study aims to check how the mass ratio of different refrigerants can affect mentioned properties. The current outcomes are compared, analyzed and discussed with earlier available simulation data for pure and mixtures of refrigerants and along with REFPROP data. The computed results show that Blend 4, with a 60.0+40.0% mass ratio composition and R-450A, has similar condensation behavior and thermophysical properties. The properties of Blend 5 with a composition 50.0+50.0% mass ratio are nearly equal to Blend 4 and R-450A. The R-450A has a good inclusive performance as a pure alternative refrigerant. The physical properties of pure R-1234ze(E), R-134a and its nine binary blends were investigated and these results may be helpful for new HFO refrigerants based on these blends.

Spectroscopic investigations, quantum chemical, drug likeness and molecular docking studies of methyl 1-methyl-4-nitro-pyrrole-2-carboxylate: A novel ovarian cancer drug

Density functional theory (DFT) calculation was used to analyse the structural and vibrational properties of Methyl 1-Methyl-4-nitro-pyrrole-2-carboxylate (MMNPC) using the cc-pVTZ basis set. The potential energy surface scan and the most stable molecular structure were optimized using Gaussian 09 program. A potential energy distribution calculation was used to calculate and assign vibrational frequencies using the VEDA 4.0 program package. The Frontier Molecular Orbitals (FMOs) were analysed to determine their related molecular properties. Ab initio density functional theory (B3LYP/cc-pVTZ) method with basis set was used to calculate 13C NMR chemical shift values of MMNPC in the ground state. Fukui function and molecular electrostatic potential (MEP) analysis confirmed the bioactivity of the MMNPC molecule. The charge delocalization and stability of the title compound were studied using natural bond orbital analysis. All experimental spectral values from FT-IR, FT-Raman, UV–VIS, and 13C NMR are in good agreement with the value calculated by the DFT. Molecular docking analysis was carried out to find the MMNPC compound that can be used as a potential drug development candidate for ovarian cancer.

Application of IRI Visualization to Terahertz Vibrational Spectroscopy of Hydroxybenzoic Acid Isomers

The characteristic absorption spectra of three positional isomers of hydroxybenzoic acid are measured using a terahertz time-domain spectroscopy system (THz-TDS) in the 0.6–2.0 THz region at room temperature. Significant differences in their terahertz spectra are discovered, which indicates that THz-TDS is an effective means to identify positional isomers. In order to simulate their spectra, the seven molecular clusters of 2-, 3-, and 4-hydroxybenzoic acid (2-, 3-, and 4-HA) are calculated using the DFT-D3 method. Additionally, the potential energy distribution (PED) method is used to analyze their vibration modes. The analysis indicates that the vibration modes of 2-HA are mainly out-of-plane angle bending and bond angle bend in plane. The vibration modes of 3-HA are mainly bond length stretch and dihedral angle torsion. The vibration modes of 4-HA are mainly bond angle bend in plane and dihedral angle torsion. Interaction region indicator (IRI) analysis is used to visualize the location and type of intermolecular interactions in 2-, 3-, and 4-HA crystals. The results show that the weak interaction type of 2-, 3-, and 4-HA is dominated by van der Waals (vdW) interaction. Therefore, we can confirm that terahertz spectroscopy detection technology can be used as an effective means to identify structural isomers and detect the intermolecular interactions in these crystals. In addition, it can explain the absorption mechanism of terahertz waves interacting with matter.