Spectroscopic properties, NLO, HOMO-LUMO and NBO analysis of 2,5-Lutidine

Quantum Computational and Spectroscopic Investigation of 3-aminosalicylic Acid

Quantum chemical calculations of 3-aminosalicylic acid (3ASA) (monomer and dimer forms) have been performed using DFT and TD-DFT theories with B3LYP/6-311 G(d,p) functional level in the ground and excited states. Using TD-DFT with IEF-PCM model, the electronic spectra of 3ASA in solvents were computed and correlated with the experimental data. The theoretically calculated absorption and emission maxima of 3ASA (monomer) are observed in the range of 343 - 347 nm (S0 → S1 transition) and 429 - 448 nm (S1 → S0 transition), respectively. The natural bond orbital (NBO) analysis shows that charge transfer interaction contributes significantly to stabilize the molecular system. In the case of dimer, hydrogen bonding plays a dominant role in stabilizing the molecular framework. Additionally, the obtained nonlinear optical (NLO) properties: polarizability (13.86 × 10-24 e.s.u for monomer and 29.46 × 10-24 e.s.u. for dimer), first-order hyperpolarizability (4.21 × 10-30 e.s.u for monomer and 0.18 × 10-30 e.s.u for dimer) and second-order hyperpolarizability (7.44 × 10-36 e.s.u. for monomer and 14.32 × 10-36 e.s.u. for dimer) were found to be larger than those of standard organic compounds suggesting that 3ASA has a significant NLO character for optoelectronic applications. The NLO properties of dimer may differ from monomer due to dimerization. Further, the radiative lifetime, light harvesting efficiency and band gap energy were calculated, and proposed that 3ASA may be useful in photovoltaics and wide bandgap power devices. HIGHLIGHTS: • DFT and TD-DFT theories were employed to calculate structural and molecular properties of 3ASA (monomer and dimer) in ground and excited states. • HOMO-LUMO study shows monomer and dimer of 3ASA are good reactive. • NBO analysis reflects that charge transfer interactions stabilized the 3ASA molecule. • Electronic absorption/emission spectra in solvents calculated by IEF-PCM/TD-DFT method correlate with experimental results. • Calculated NLO parameters suggested that 3ASA is a potential candidate for NLO material.

Unveiling the Influence of Glutathione in Suppressing the Conversion of Aspirin to Salicylic Acid: A Fluorescence and DFT Study

Aspirin is a commonly used nonsteroidal anti-inflammatory drug, associated with many adverse effects. The adverse effects of aspirin such as tinnitus, Reye's syndrome and gastrointestinal bleeding are caused due to conversion of aspirin into its active metabolite salicylic acid after oral intake. Glutathione is a naturally occurring antioxidant produced by the liver and nerve cells in the central nervous system. It helps to metabolize toxins, break down free radicles, and support immune function. This study aims to investigate and explore the possibility of inhibiting aspirin to salicylic acid conversion in presence of glutathione at a molecular level using spectroscopic techniques such as UV-Visible absorption, time-Resolved and time-dependent fluorescence and theoretical DFT/ TD-DFT calculations. The results of steady state fluorescence spectroscopy and time-dependent fluorescence indicated that the aspirin to salicylic acid conversion is considerably inhibited in presence of glutathione. Further, the results presented here might have significant clinical implications for individuals with variations in glutathione level.

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.

In vitro and in silico perspectives on the activation of antioxidant responsive element by citrus-derived flavonoids

Introduction

Oxidative stress plays an essential role in the pathogenesis of chronic diseases. Disrupting the Keap1-Nrf2 pathway by binding Keap1 is identified as a potential strategy to prevent oxidative stress-related chronic diseases. Therefore, of special interest is the utilization of dietary antioxidations from citrus, including narirutin, naringenin, hesperetin, hesperidin, naringin, neohesperidin dihydrochalcone, neohesperidin, and nobiletin, has been exploited as a prospective way to treat or prevent several human pathologies as Keap1-Nrf2 inhibitors for modulation of antioxidant properties.

Methods

To probe into the structural foundation of the molecular identification of citrus-derived antioxidations, we calculated the antioxidant responsive element activation ability of citrus-derived flavonoids after binding with Keap1. Also, the quantum chemistry properties and binding mode were performed theoretically with frontier molecular orbitals, molecular electrostatic potential analysis, molecular docking, and absorption, distribution, metabolism, excretion (ADME) calculation.

Results and discussion

Experimental findings combining computational assays revealed that the tested citrus-derived flavonoids can be grouped into strong agonists and weak agonists. The citrus-derived antioxidations were well housed in the bound zone of Keap1 via stable hydrogen bonding and hydrophobic interaction. Eventually, three of eight antioxidations were identified after ADME and physicochemical evaluations. The citrus-derived flavonoids were identified as potential dietary antioxidants of the Keap1-Nrf2 interaction, and can be used to improve oxidative stress-related chronic diseases.

Glucosamine and maltol anchored Zinc(II) complex of COVID-19 health supplement relevance: DFT collaborated spectroscopic formulation with profound biological implications

In association with other antiviral drugs, Zinc is specially administered to the patients suffering from novel coronavirus infectious disease (nCOVID). Zn, maltol, and glucosamine are famous food and drug additives. The supplements made from them are helpful in minimizing malnutrition problems, and in enhancing immune power. Due to the well-pronounced effects of all these three components in the food and medicinal industry, a novel sugar Zn(II) complex of the general composition, [Zn(gls)(mal)], where Hmal is maltol and Hgls is referred to as glucosamine, was synthesized and formulated. The physicochemical methods that were used to establish the molecular structure include elemental analysis, 1HNMR, FT-IR, UV–Vis., thermal and mass spectrometry. Physical properties like decomposition temperature and molar conductance were also examined. The experimental results at each step of characterization were validated/compared with density functionalized spectroscopic/spectrometric data using the LANL2DZ basis set for the metal atom and 6–31 g(d,p) for other atoms under the B3LYP functional. From the study, a suitable square planar geometry is suggested for the complex. Among biological implications, superoxide dismutation (SOD) and antimicrobial actions were studied. Also, virtual screening using SWISS ADME and Autodock 4.0 program (against 6X2B, SARS-CoV-2 u1S2q 2 RBD Up Spike Protein Trimer) were evaluated for the complex. Good interactions were scored by glucosamine and the complex. The results obtained from antimicrobial sensitivity indicate low inhibition zones, but from the SOD data, the complex has shown satisfactory antioxidant behavior. Therefore, the proposed food supplement could act as a good antioxidant agent and could keep the flora of the intestinal tract less disturbed while going through a metabolic pathway.

Synthesis, spectral analysis, quantum studies, NLO, and thermodynamic properties of the novel 5-(6-hydroxy-4-methoxy-1-benzofuran-5-ylcarbonyl)-6-amino-3-methyl-1H-pyrazolo[3,4-b] pyridine (HMBPP)

Ring opening followed by ring closure reactions of 4-methoxy-5-oxo-5H-furo[3,2-g] chromene-6-carbonitrile (1) with 5-amino-3-methyl-1H-pyrazole (2) afforded the novel 5-(6-hydroxy-4-methoxy-1-benzofuran-5-ylcarbonyl)-6-amino-3-methyl-1H-pyrazolo[3,4-b] pyridine (3, HMBPP). The chemical structure of the synthesized compound was established based on elemental analysis and spectral data. The chemical calculations were performed using the Becke3–Lee–Yang–Parr (B3LYP) and Coulomb Attenuating Method (CAM-B3LYP)/6-311++G(d,p) basis sets at the DFT level of theory. The Coulomb-attenuating method (CAM-B3LYP) and Corrected Linear Response Polarizable Continuum Model (CLR) PCM were used to obtain the theoretical electronic absorption spectra in the gas phase, methanol, and cyclohexane, respectively, indicating good agreement with the observed spectra. The local reactivity descriptors supported the high reactivity of C7 for nucleophilic attack. The computed total energy and thermodynamic parameters at the same level of calculations confirmed the high stability of structure 3 (HMBPP) as compared with the other expected structure 4. The ¹H and ¹³C chemical shift values, as well as vibrational wavenumber values, were theoretically determined and exhibited a high correlation with the experimental data. Natural bond orbital analysis (NBO) was used to investigate hyper conjugative interactions. The first static hyperpolarizability, second hyperpolarizability, polarizability, and electric dipole moment have been determined. At different temperatures, the thermodynamic properties of the compounds were calculated.

Ring opening followed by ring closure reactions of 4-methoxy-5-oxo-5H-furo[3,2-g] chromene-6-carbonitrile with 5-amino-3-methyl-1H-pyrazole gave the novel 5-(6-hydroxy-4-methoxy-1-benzofuran-5-ylcarbonyl)-6-amino-3-methyl-1H-pyrazolo[3,4-b] pyridine.

Synthesis, Spectroscopic Characterization (FT-IR, NMR, UV), NPA, NBO, NLO, Thermochemical Analysis and Molecular Docking Studies of 2-((4-hydroxyphenyl)(piperidin-1-yl)methyl)phenol

In this study, a new alkylaminophenol compound was synthesized and characterized by spectroscopic techniques (FT-IR, NMR, UV). The optimized molecular geometry and the vibrational wavenumbers were calculated using density functional theory (DFT) B3LYP/WB97XD and HF methods with 6-311++ G([Formula: see text], [Formula: see text]) basis set. Thus, theoretical data were compared within themselves before comparing with experimental data. The detailed interpretation of the vibrational spectra has been carried out by VEDA program. 1H-NMR and [Formula: see text]C-NMR chemical shifts of the compound were calculated using GIAO/IEFPCM method in CDCl3. Using time-dependent (TD-DFT) approach electronic properties such as HOMO and LUMO energies, the electronic spectrum of the title compound has been studied and reported. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Linear polarizability, anisotropic linear polarizability and hyperpolarizability values of the title compound were found to be higher than the values of the pNA compound that are used as a standard substance in the NLO analysis. Molecular electrostatic potential (MEP), the thermodynamic properties (heat capacity, entropy and enthalpy) were calculated. Also, to investigate the biological properties of the title compound, molecular docking was done with DNA(PDB ID: 414D). It has been observed that the effective interaction is hydrogen bonds.

Reinvestigation of the photophysics of 3-aminobenzoic acid in neat and mixed binary solvents

The present study elucidates the reinvestigation of the photophysical behavior of 3-aminobenzoic acid (3ABA) in solvents of different polarities using the steady-state spectroscopic techniques. Kamlet-Taft and Catalan solvatochromic models have been used to analyze the solvatochromic changes in neat solvents. The hydrogen bond donating ability of the solvent was found to be the main parameter affecting the spectral behavior of 3ABA. The solvatochromic characteristics of 3ABA have also been examined in binary solvent mixtures viz. acetonitrile (ACN)-methanol (MeOH) and benzene (BEN)-MeOH using the concept of preferential solvation. The preferential solvation of 3ABA shows unusual behavior for BEN-MeOH binary mixture and described unnoticed sigmoidal behavior in the ground state and synergistic impact in the excited state. Besides, the 3ABA was studied theoretically by quantum chemical calculations using (HF) Hartree-Fock and (DFT/B3LYP) density functional theories and its electronic absorption bands have been assigned by time-dependent density functional theory (TD-DFT). The effect of solvents on 3ABA was considered using a IEF-PCM-TDDFT (integral equation formalism of the polarizable continuum model- TDDFT) method. Thus, the theoretical results were found to be closer to the experimental results.

The structural, spectral, frontier molecular orbital and thermodynamic analysis of 2-hydroxy 2-methyl propiophenone by MP2 and B3LYP methods

In the present work, we have studied the 2-hydroxy 2-methyl propiophenone (2H2MPP) theoretically as well as experimentally. The optimized molecular structure has been obtained by the density functional theory (DFT), second-order Moller–Plesset perturbation theory (MP2) and Hartree Fock (HF) in the gas phase as well as in different media like ethanol, DMSO and heptane. FT-IR and FT-Raman spectra were computed as well as recorded and fundamental vibrational wavenumbers were assigned. The electronic absorption spectra were calculated by employing the time-dependent density functional theory (TD-DFT) to get the information about excitation energies, oscillator strength and excited state geometries in gas phase and in different solvent media. Chemical activity and chemical stability obtained by HOMO-LUMO studies using a HF/6-31[Formula: see text]G and MP2/6-311[Formula: see text]G calculations. The chemical interpretation of hyperconjugation interactions obtained by the Natural Bond Orbital (NBO) analysis. Moreover, electrostatic potential (ESP) calculations performed to get the visual representation of relative polarity of molecule. Thermodynamic parameters like enthalpy, entropy, heat capacity, and Gibbs free energy computed with varying temperature from 10[Formula: see text]K to 500[Formula: see text]K. The aim of the current investigation is to find out the quantum chemical properties of the title compound which show an active role in the pharmaceutical and printing industries.

Synthesis, spectroscopic investigation, molecular docking and DFT studies of novel (2Z,4Z)-2,4-bis(4-chlorobenzylidene)-5-oxo-1-phenylpyrrolidine-3-carboxylic acid (BCOPCA)

The synthesized compound (2Z,4Z)-2,4-bis(4-chlorobenzylidene)-5-oxo-1-phenylpyrrolidine-3-carboxylic acid (BCOPCA) was characterised by Ultraviolet, FT-Infra Red, ¹H, ¹³C Nuclear Magnetic Resonance and mass spectroscopy. The compound was further subjected to quantum chemical calculations at the level of density functional theory (DFT) using 6-31G (d,p) basis sets method with B3LYP and CAM-B3LYP hybrid functionals. The intramolecular interactions, polarizability, hyperpolarizability and nonlinear optical properties of the title compound were also incorporated in the study. The total first static hyperpolarizability (β₀ = 19.477 × 10⁻³⁰ and 16.924 × 10⁻³⁰ esu) value was also computed and indicated the title molecule as an interesting forthcoming NLO material. The other thermodynamic properties (entropy, heat capacity and zero vibrational energy) were also discussed. The study also includes NBO computations, complete vibrational assignments, Mulliken charges, UV–Visible spectral analysis and HOMO–LUMO energies. The regions of low and high electron density were obtained from MESP and ESP maps. The calculated parameters for BCOPCA using aforementioned functions are harmonious with the experimental findings. The in-vitro antimicrobial activity and molecular docking studies of BCOPCA were also done and showed a good correlation.

Ultrasound assisted fabrication of a novel optode base on a triazine based Schiff base immobilized on TEOS for copper detection

This work introduces novel selective and sensitive optical sensor based on a nano sized triazine based Schiff base (H₂L) immbolized on a transparent glass substrate through the sol-gel process to detection of copper (II) ions in aqueous solutions. This sensor can determine the copper (II) in the range of 8.54 × 10^-8-1.0 × 10^-5 mol L^-1 with a low detection limit of 1.53 × 10^-8 mol L^-1. The optimized geometry of H₂L and its copper complex was obtained based on DFT/B3LYP levels of theory with B3LYP/6-311 + G(d,p) and LANL2DZ/6-311 + G(d,p) basis sets respectively. The calculated electronic properties of them including the molecular orbital, Mulliken population analysis, contour of electrostatic potential, and molecular electrostatic potential map confirmed the behavior of the sensor. Some advantage of the fabricated sensor such as high selectivity, sensitivity, short response time, easy production, fast regeneration, low cost, being portable and user friendly can make it a good choice to detection of Cu(II) ion in various application. The suggested sensor was revealed excellent sensitivity in the natural samples that confirmed by Inductively Coupled Plasma-Mass (ICP) spectrometry method.

A novel high performance nano chemosensor for copper (II) ion based on an ultrasound-assisted synthesized diphenylamine-based Schiff base: Design, fabrication and density functional theory calculations

A novel high selective colorimetric chemosensor was introduced based on a nano diphenyl-based Schiff base (H₂L), 2,2'-((1E,1'E)-(((hexylazanediyl)bis(4,1-phenylene))bis(methanylylidene))bis(azanylylidene))bis(4-methylphenol) that synthesized using sonochemical method. H₂L was characterized by FT-IR, MS, TGA, ¹H NMR, ¹³C NMR, SEM and elemental analysis techniques, then fabricated as the portable strips for sensing copper (II) ions in aqueous media. The binding interaction between H₂L and various metal ions was investigated by UV-Vis spectroscopic that showed favorable coordination toward Cu²⁺ ion. H₂L exhibited binding-induced color changes from yellow to pink and practically no interference in the presence of other metal ions, i.e., Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Mg²⁺ and Ca²⁺. The chemsensor showd the color change from yellow to pink in presence of copper (II) ion in aqueous media due to binging of H₂L and Cu (II). This sensor can determine the copper (II) at in the rang of 7.5 × 10^-8-1.8 × 10^-5 mol L^-1 with a correlation equation: Absorbance = 0.0450[Cu²⁺] × 10^-6 + 0.71 and R² = 0.975 and low detection limit of 1.89 × 10^-8 mol L^-1. Density functional theory (DFT) calculations were carried out at the B3LYP levels of theory with B3LYP/6-311+G(d,p) and LANL2DZ/6-311+G(d,p) basis sets for chemosensor and its copper complex respectively. The optimized geometry, harmonic vibrational frequencies, ¹H NMR and ¹³C NMR chemical, Molecular orbital (M.O.), Mulliken population analysis (MPA), contour of Electrostatic Potential (ESP) and Molecular Electrostatic Potential (MEP) map of H₂L were calculated which show good agreement with behavior of sensor for detection of Cu²⁺ ion.

Molecular structure, FT IR, NMR, UV, NBO and HOMO-LUMO of 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile by DFT/B3LYP and PBEPBE methods with LanL2DZ and 6-311++G(d,2p) basis sets

Structural and molecular properties of antidepressants 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile were examined using quantum mechanics of Density Functional Theory (DFT)/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets to study the therapeutic properties of the drug. For this, the structure of desired material was optimized by the computer calculation method and with the use of powerful Gaussian 09 software. Then the lowest energy value and the bond length, bond angle and dihedral angle between its constituent atoms in the crystal structure of the desired material were measured from the optimized values. Then the amount of positive and negative charges, polarizability and dipole moment of its atoms using Mulliken charge and Natural atomic charges, DFT/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets were determined and the results were compared with each other for individual atoms and by mentioned methods. Also the type of stretching vibrations and bending vibrations between the constituent atoms of the molecule were specified using mentioned computational methods and FT IR vibrational spectra. The experimental spectrum of this material was taken to determine the functional groups and the computational and experimental values were compared to each other and Nuclear Magnetic Resonance (NMR) was used to specify the isomer shift between the carbons and protons in the presence of polar and nonpolar solvents. Also Natural Bond Orbital (NBO) was used to determine the type of electron transfers in σ→σ∗ and π→π∗ and LP(1)→σ∗ and LP(2)→σ∗ and the amount of hardness and softness in molecule was determined using the difference between ionization energy and electron affinity energy in constituent atoms of that molecule in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and in the presence of solvents H₂O, CH₃CN and C₆H₁₂. UV-Vis spectrum of the drug was taken using DFT/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets as well as solvents H₂O, CH₃CN and C₆H₁₂ and the associated transmissions were examined.