Molecular structure, vibrational spectra and nonlinear optical properties of 2,5-dimethylanilinium chloride monohydrate: a density functional theory approach

Detection of paracetamol by a montmorillonite-modified carbon paste sensor: A study combining MC simulation, DFT computation and electrochemical investigations

This study aims to develop a suitable electrochemical electrode through the incorporation of potassium montmorillonite (MMTK10)clay into the carbon matrix for the direct and sensitive determination of paracetamol (PAR) in pharmaceutical formulations. Electrochemical characterization of the electrodes involves the use of techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The results reveal that the voltammetric response of PAR is linear over a wide concentration range (1.0-15 μM), with a low detection limit of 0.46 μM. Analytically, PAR recovery results were around 94%, indicating that the developed electrode is highly suitable for PAR detection in pharmaceutical formulation. Additionally, density functional theory (DFT) is employed to investigate the reactivity of PAR and explain the interaction process of PAR on the electrode surface at different pH values. A Monte Carlo simulations model is developed to provide a deeper understanding of the adsorption mechanism, particularly to comprehend molecular interactions and preferential orientations of PAR with MMT fractions at the electrode surface. Reduced Density Gradient is calculated and discussed using techniques such as Multiwfn and Visualization of Molecular Dynamics. The developed CPE-MMTK10 sensor provided a simple preparation method, rapid response, high sensitivity, reproducibility, strong selectivity, and extended stability. Moreover, there is a good correlation between most parameters calculated by DFT and experimental results, thereby reinforcing the validity of the theoretical approach in this study.

Application of Novel Ruthenium (II) Polypyridyl Complexes as Robust DNA Probes, Optical Material and Antimicrobials-An Experimental and DFT Approach

The nature of the interaction of DNA with heteroleptic Ruthenium (II) Polypyridyl complexes of the type [Ru (A)2TPIP]2+, where TPIP = 2-(1-p-tolyl-1H pyrazol-4 -yl)-1H-imidazo [4, 5-f[1. 10] phenanthroline and A = 1,10 phenanthroline (1),4,4'-dimethyl-1,10-ortho Phenanthroline (2), 2,2' - bipyridine (3) and 4, 4' dimethyl 2, 2'- bipyridine (4), has been investigated by experimentaland molecular docking approaches. The order of the DNA binding affinities of the synthesised complexes is 1 > 2 > 3 > 4. The findings imply that the unsubstituted complex has a better affinity to bind with DNA than the substituted (dmp and dmb) emphasizing the significance of the auxiliary ligand. Additionally, as the medium's ionic strength drops, the DNA/Ru ratio rises, or when water is displaced by glycerol, the intercalation of complexes into DNA increases. DFT calculations at the B3LYP/LANL2MB level was used for molecular geometry (Ground State) and electronic characteristic calculations. The HOMO-LUMO gap of the Ru [II] complex is less than the intercalator and hence kinetically labile. Among the complexes, the bpy complex has shown utmost non-linear optical properties (α = -153.9099 10-24esu and β = 3.8498 10-30esu). The docking study shows the significance of the Metal-intercalator's shorter length may increase DNA binding affinity. This study divulges that the Ruthenium (II) polypyridyl complexes bind to DNA preponderantly by intercalation supporting Viscosity studies. All the complexes have a considerable attraction for guanine. The standard disk diffusion method reveals that complexes (1, 2, 3 and 4) have good antibacterial activity.

Molecular Investigations of the Newly Synthesized Azomethines as Antioxidants: Theoretical and Experimental Studies

BACKGROUND

In this study, the antioxidant property of new synthesized azomethins has been investigated as theoretical and experimental.

METHODS AND RESULTS

Density functional theory (DFT) was employed to investigate the Bond Dissociation Enthalpy (BDE), Mulliken Charges, NBO analysis, Ionization Potential (IP), Electron Affinities (EA), HOMO and LUMO energies, Hardness (η), Softness (S), Electronegativity (µ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) in order to deduce scavenging action of the two new synthesized azomethines (FD-1 and FD-2). Spin density calculations and NBO analysis were also carried out to understand the antioxidant activity mechanism. Comparison of BDE of FD-1 and FD-2 indicate the weal antioxidant potential of these structures.

CONCLUSION

FD-1 and FD-2 have very high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds.

Anisotropy (optical, electrical and thermal conductivity) in thin polarizing films for UV/Vis regions of spectrum: Experimental and theoretical investigations

In the present work, the quantum theoretical calculations of the molecular structures of the three newly synthesized azomethine dyes: have been predicted using Density Functional Theory (DFT) in solvent dimethylformamide (DMF). The geometries of the azomethine dyes were optimized using the PBE1PBE/6-31+G level of the theory. In addition, the electronic spectra of these compounds in solvent DMF were carried out using the TDPBE1PBE, TDPBEPBE, TDB3LYP methods with 6-31G, 6-31+G, 6-31+G*, 6-31++G* basis sets. After quantum-chemical calculations three new azomethine dyes for optoelectronic applications were synthesized. Based on polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for UV/Vis regions of the spectrum were developed. The main optical parameters of polarizing PVA-films (Transmittance and Polarization Efficiency) have been measured and discussed. Anisotropy of electrical and thermal conductivity of the PVA-films has been investigated.

DFT computations on: Crystal structure, vibrational studies and optical investigations of a luminescent self-assembled material

The current work undertakes the growth and the physicochemical properties of a novel green-yellow luminescence semi-organic material, the 3-picolylammonium bromide abbreviated (Pico-Br). In this paper, we report the X-ray diffraction measurements which show that the crystal lattice consists of distinct 3-picolylammonium cations and free bromide anions connected via NH⋯Br and NH⋯N hydrogen bonds leading to form a two dimensional frameworks. Molecular geometry compared with its optimized counterpart shows that the quantum chemical calculations carried out with density functional method (DFT) well produce the perceived structure by X-ray resolution of the studied material. To provide further insight into the spectroscopic properties, additional characterization of this material have been performed with Raman and infrared studies at room temperature. Theoretical computations have been computed using the (DFT) method at B3LYP/LanL2DZ level of theory implemented within Gaussian 03 program to study the vibrational spectra of the investigated molecule in the ground state. Optical absorption spectrum inspected by UV-visible absorption reveals the appearance of sharp optical gap of 280nm (4.42eV) as well as a strong green photoluminescence emission at 550nm (2.25eV) is detected on the photoluminescence (PL) spectrum at room temperature. Using the TD/DFT method, HOMO-LUMO energy gap and the Mulliken atomic charges were calculated in order to get an insight into the material. Good agreement between the theoretical results and the experimental ones was predicted.

Sonochemical synthesis, in vitro evaluation and DFT study of novel phenothiazine base Schiff bases and their nano copper complexes as the precursors for new shaped CuO-NPs

The current work reports the ultrasound-assisted synthesis of two nano binuclear copper complexes derived from novel tetradentate (N₂O₂) phenothiazine based Schiff bases. The synthesized compounds were characterized using the physicochemical methods, including ¹H NMR, ¹³C NMR, FE-SEM, Mass, FT-IR, UV-Vis, elemental analysis, magnetic moment and molar conductance measurements. It is found that the geometrical structure of Cu^II₂LⁿCl₄ is distorted tetrahedral around the copper atoms using the results of ¹H NMR, UV-Vis and magnetic moment studies. In addition, CuO nano particles were produced in the nano range (14.3-12.1nm) by the thermal decomposition of the copper complexes CuO NPs were characterized using FT-IR, FE-SEM, XRD, UV-Vis and photoluminescence methods and indicated a close accordance with the standard pattern. Also, the antioxidant studies revealed that the copper complexes exhibit comparable scavenging effects (against O₂ and OH) with the standard antioxidants, such as vitamin C, while, they show more antioxidant activity than ligands. Similarly, the complexes show more antibacterial activity against four gram positive and gram negative bacteria in comparison to their Schiff base ligands. furthermore, The optimized structure, Molecular orbital (M.O.), Mulliken population analysis (MPA), contour of Electrostatic Potential (ESP) and Molecular Electrostatic Potential (MEP) map of the titled compounds were calculated base on DFT calculations that were carried out at the B3LYP levels of theory with a double basis set LANL2DZ for copper, and 6-311+G(d,p) basis set for the other atoms.

Quantum chemical studies on structural, vibrational, nonlinear optical properties and chemical reactivity of indigo carmine dye

Structural and vibrational spectroscopic studies were performed on indigo carmine (IC) isomers using FT-IR spectral analysis along with DFT/B3LYP method utilizing Gaussian 09 software. GaussView 5 program has been employed to perform a detailed interpretation of vibrational spectra. Simulation of infrared spectra has led to an excellent overall agreement with the observed spectral patterns. Mulliken population analyses on atomic charges, MEP, HOMO-LUMO, NLO, first order hyperpolarizability and thermodynamic properties have been examined by (DFT/B3LYP) method with the SDD basis set level. Density of state spectra (DOS) were calculated using GaussSum 3 at the same level of theory. Molecular modeling approved that DOS Spectra are the most significant tools for differentiating between two IC isomers so far. Moreover, The IC isomers (cis-isomer) have shown an extended applicability for manufacturing both NLO and photovoltaic devices such as solar cells.

Molecular structure, NLO, MEP, NBO analysis and spectroscopic characterization of 2,5-dimethylanilinium dihydrogen phosphate with experimental (FT-IR and FT-Raman) techniques and DFT calculations

Single crystals of 2,5-dimethylanilinium dihydrogen phosphate were grown by slow evaporation method at room temperature. The synthesized compound was characterized by powder X-ray diffraction analysis to confirm its crystalline nature. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the density functional theory (DFT) method using the B3LYP function with the 6-31G(d,p) basis set. Theoretical simulation of infrared and Raman spectra led to excellent overall agreement with the observed spectral patterns. The complete assignments of the vibrational spectra were carried out with the aid of potential energy distribution (PED). The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using natural bond orbital (NBO) analysis leading to high nonlinear optical (NLO) activity. The lowering in the HOMO and LUMO energy gap explains the eventual charge transfer interactions that take place within the molecules.