Experimental and theoretical studies on o-, m- and p-chlorobenzylideneaminoantipyrines

Spectroscopic properties (FT-IR, NMR and UV) and DFT studies of amodiaquine

Amodiaquine (AQ) was synthesized by a condensation reaction and characterized by experimental FT-IR, 1H and 13C nuclear magnetic resonance (NMR) and UV spectroscopies. In the present work, Density Functional Theory (DFT) calculations. The structural and spectroscopic (FT-IR, 1H and 13C NMR and UV) data of amodiaquine molecule in ground state have been investigated by using Density Functional Theory (DFT). The calculations have been performed at the using B3LYP method with 6-311++G(d,p) and 6-311++G(2d, p) basis sets theory level were performed, first, to confirm its structure, then to explain its reactive nature through its molecular properties such as natural charges, local and global reactivity descriptors or natural bond orbital (NBO). Afterwards, the calculated properties were compared with experimental results. The 1H and 13C NMR chemical shifts were calculated by using the gauge-independent atomic orbital (GIAO) method, while the electronic UV-Vis spectrum is predicted using the time-dependent density functional theory (TD-DFT). Globally, the computerized results showed good agreement close similarity with the experimental values. The molecular properties such as natural charges, local and global reactivity descriptors, molecular electrostatic potential (MEP), natural bond orbital (NBO) of title molecule were calculated insights into the stability, reactivity and reactive sites on the molecule. The calculated energy band gap (ELUMO-EHOMO) value of AQ was found to be 4.09 eV suggesting that it could be considered as a hard molecule with high stability, supported by global reactivity descriptors. Molecular electrostatic potential (MEP) analysis revealed heteroatoms (oxygen and nitrogen) as the most putative nucleophilic sites when hydrogen atoms to which they are linked appear as electrophilic sites. The potential use of amodiaquine as non-linear optical (NLO) material and its thermodynamic indicators have also been assessed.

Molecular Structure, Spectral Analysis, Molecular Docking and Physicochemical Studies of 3-Bromo-2-hydroxypyridine Monomer and Dimer as Bromodomain Inhibitors

In this paper, both methods (DFT and HF) were used in a theoretical investigation of 3-bromo-2-Hydroxypyridine (3-Br-2HyP) molecules where the molecular structures of the title compound have been optimized. Molecular electrostatic potential (MEP) was computed using the B3LYP/6-311++G(d,p) level of theory. The time-dependent density functional theory (TD-DFT) approach was used to simulate the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) on the one hand to achieve the frontier orbital gap and on the other hand to calculate the UV–visible spectrum of the compound in gas phase and for different solvents. In addition, electronic localization function and Fukui functions were carried out. Intermolecular interactions were discussed by the topological AIM (atoms in molecules) approach. The thermodynamic functions have been reported with the help of spectroscopic data using statistical methods revealing the correlations between these functions and temperature. To describe the non-covalent interactions, the reduced density gradient (RDG) analysis is performed. To study the biological activity of the compound of the molecule, molecular docking studies were executed on the active sites of BRD2 inhibitors and to explore the hydrogen bond interaction, minimum binding energies with targeted receptors such as PDB ID: 5IBN, 3U5K, 6CD5 were calculated.

Quantum Computational, Spectroscopic (FT-IR, FT-Raman, NMR, and UV-Vis) Hirshfeld Surface and Molecular Docking-Dynamics Studies on 5-Hydroxymethyluracil (Monomer and Trimer)

For many decades, uracil has been an antineoplastic agent used in combination with tegafur to treat various human cancers, including breast, prostate, and liver cancer. Therefore, it is necessary to explore the molecular features of uracil and its derivatives. Herein, the molecule's 5-hydroxymethyluracil has been thoroughly characterized by NMR, UV-Vis, and FT-IR spectroscopy by means of experimental and theoretical analysis. Density functional theory (DFT) using the B3LYP method at 6-311++G(d,p) was computed to achieve the optimized geometric parameters of the molecule in the ground state. For further investigation and computation of the NLO, NBO, NHO analysis, and FMO, the improved geometrical parameters were utilized. The potential energy distribution was used to allocate the vibrational frequencies using the VEDA 4 program. The NBO study determined the relationship between the donor and acceptor. The molecule's charge distribution and reactive regions were highlighted using the MEP and Fukui functions. Maps of the hole and electron density distribution in the excited state were generated using the TD-DFT method and PCM solvent model in order to reveal electronic characteristics. The energies and diagrams for the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) were also provided. The HOMO-LUMO band gap estimated the charge transport within the molecule. When examining the intermolecular interactions in 5-HMU, Hirshfeld surface analysis was used, and fingerprint plots were also produced. The molecular docking investigation involved docking 5-HMU with six different protein receptors. Molecular dynamic simulation has given a better idea of the binding of the ligand with protein.

Vibrational Spectroscopies, Global Reactivity, Molecular Docking, Thermodynamic Properties and Linear and Nonlinear Optical Parameters of Monohydrate Arsonate Salt of 4-Aminopyridine

In this work, a structural and electronic properties of a novel organic arsenate template by 4-aminopyridine, with the general formula (C₅H₇N₂)(C₅H₈N₂)[AsO₄]·H₂O ((4-APH)(4-APH₂)[AsO₄]·H₂O) have been presented. The density functional theory (DFT) along with B3LYP hybrid functional is employed. The optimized structure was found to be in well consistent with the X-ray diffraction geometry. The examination of the vibrational spectrum was correlated by DFT calculation using the unit cell parameters obtained from the experiment data. Besides, the thermodynamic functions (heat capacity, entropy, enthalpy) from spectroscopic data by statistical methods were obtained for the range of temperature 100–1000 K. In addition, the molecular orbital calculations such as Natural Bond Orbitals (NBOs), AIM approach, HOMO–LUMO energy gap, NLO characteristic and Hirshfeld surface analysis were also performed with the same level of DFT. Electronic stability of the compound arising from hyper conjugative interactions and charge delocalization were also investigated based on the natural bond orbital (NBO) analysis. Molecular docking studies were also conducted as part of this study. The theoretical results showed an excellent agreement with the experimental values.

Exploring novel fluorine-rich fuberidazole derivatives as hypoxic cancer inhibitors: Design, synthesis, pharmacokinetics, molecular docking, and DFT evaluations

Sixteen fuberidazole derivatives as potential new anticancer bioreductive prodrugs were prepared and characterized. The in vitro anticancer potential was examined to explore their cytotoxic properties by employing apoptosis, DNA damage, and proliferation tests on chosen hypoxic cancer cells. Eight substances (Compound 5a, 5c, 5d, 5e, 5g, 5h, 5i, and 5m) showed promising cytotoxicity values compared to the standard control. The potential of compounds was also examined through in silico studies (against human serum albumin), including chem-informatics, to understand the structure-activity relationship (SAR), pharmacochemical strength, and the mode of interactions responsible for their action. The DFT calculations revealed that only the 5b compound showed the lowest ΔET (2.29 eV) while 5i showed relatively highest βtot (69.89 x 10-31 esu), highest αave (3.18 x 10-23 esu), and dipole moment (6.49 Debye). This study presents a novel class of fuberidazole derivatives with selectivity toward hypoxic cancer cells.

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.

Quantum chemical studies on structural, spectroscopic, nonlinear optical, and thermodynamic properties of the 1,2,4-triazole compound

In this study, the structure of 4-[4-(diethylamino)-benzylideneamino]-5-benzyl-2H-1,2,4-triazol-3(4H)-one (DBT) was examined through spectroscopic and theoretical analyses. In this respect, the geometrical, vibrational frequency, 1H and 13C-nuclear magnetic resonance (NMR) chemical shifts, thermodynamic, hyperpolarizability, and electronic properties including the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energies of DBT as a potential non-linear optical (NLO) material were investigated using density functional theory at the B3LYP level with the 6-311G basis set. 1H and 13C-NMR chemical shifts of DBT with the gauge-invariant atomic orbital and continuous set of gauge transformation methods (in the solvents) were estimated, and the computed chemical shift values displayed excellent alignment with observed ones. Time-dependent density-functional theory (TD-DFT) calculations with the integral equation formalism polarizable continuum model within various solvents and gas phases in the ground state were used to evaluate UV-vis absorption and fluorescence emission wavelengths. Thermodynamic parameters including enthalpy, heat capacity, and entropy for DBT were also calculated at various temperatures. Moreover, calculations of the NLO were carried out to obtain the title compound’s electric dipole moment and polarizability properties. To illustrate the effect of the theoretical method on the spectroscopic and structural properties of DBT, experimental data of structural and spectroscopic parameters were used. The correlational analysis results were observed to indicate a strong relationship between the experimental and theoretical results.

Computational investigation, comparative approaches, molecular structural, vibrational spectral, non-covalent interaction (NCI), and electron excitations analysis of benzodiazepine derivatives

The present work explores the structural parameters and vibrational frequencies as well as molecular interactions of benzodiazepine derivatives, such as clothiapine (CT), clozapine (CZ), and loxapine (LX). Employing fitting experimental data to theoretical results is used to assess the structural parameters of heading composites. The main assignment is passed out according to the overall distribution of energy of the vibrational modes. From the hyper-conjugative interaction, the permanency of the structure had been predicted through natural bond orbital analysis; it is also used to identify the bonding and antibonding regions of the molecules. Moreover, electrostatic potential (ESP), density of states (DOS), and charge transfer occurring of the molecule among HOMO as well as LUMO energy were calculated and presented; utilizing electron localized field (ELF), localized orbital locator (LOL), and reduced density gradient (RDG), the chemical interactive regions are found. Additionally, mean polarizability (α_tot), the first-order hyperpolarizability (β_tot), and softness and hardness of the entitled compounds were also performed. The interaction between protein-ligand was also predicted by docking studies.

2,4-Dimorpholino-4-yl-6-(4-nitrophenoxy)-[1,3,5]-triazine: Structural and spectroscopic study using experimental and DFT method

2,4-Dimorpholino-4-yl-6-(4-nitrophenoxy)-[1,3,5]-triazine (DMNT) was synthesized and the molecular structure and vibrational frequencies were studied by density functional theory (DFT) method. The functional used was Becke’s three parameter exchange functional combined with the Lee-Yang-Parr correlation (B3LYP) and the standard basis set was 6-31G(d) for all atoms. The Fourier Transform-Infra Red (FT-IR) and FT-Raman spectra of DMNT were recorded and complete assignments of the observed vibrational frequencies are done. The assignments were confirmed by isotopic labelling. The structural parameters, harmonic vibrational frequencies, IR intensities and Raman intensities of DMNT in the ground-state were also computed. Non-linear optical behaviour of DMNT was analysed by examining the properties like electric dipole moment, polarizability and hyperpolarizability. Molecular properties such as ionization potential, electro-negativity, chemical potential and chemical hardness were obtained from molecular orbital analysis. Hyper conjugative interaction and charge delocalization taking place in DMNT was confirmed by Natural bond analysis studies. UV-Vis spectrum of DMNT was also recorded to understand the electronic properties.

Graphical Abstract:

DFT study of structural and electronic properties of 1,4-diarylcyclopenta[d] pyridazines and oxazines for non-linear optical applications

Polymer and molecular-based electronic materials incorporating heterocycles like thiophenes and pyrroles are attractive possibilities as substitutes for semimetal materials. Heterocyclic materials are heavily studied in this regard due to the large variations in possible substrates. Herein we evaluated four different 5,6-fused ring heterocycles to gain a better understanding of any favorable optical and electronic properties that were due to incorporation of certain moieties. The molecules chosen would highlight the effects that the central ring (pyridazine versus oxazine), aromatic substituent, and heterocyclic side group may have on electronic and optical properties. Computational analysis of these four molecules was done using density functional theory (B3LYP and PBEPBE) with 6-31G(d,p), 6-311 ++G(d,p), and cc-pVTZ basis sets. The constituent molecules were optimized, and calculations were done for the dipole moment, polarizability, first-order hyperpolarizability (β), HOMO and LUMO orbitals, and a natural bonding order (NBO) analysis. These calculations allow for the study of charge density via electrostatic potential mapping and bonding orbitals. The results indicated that the pyridazine molecules presented here are more favorable than the oxazines for non-linear optical (NLO) applications. It is also noted that side ring substituents (thienyl and furyl) in the two pyridazines studied showed very little calculated differences. Finally, heterocyclic rings showed more favorable properties when incorporated as substituents for NLO applications over hydrocarbon aromatics. Graphical abstract.

DFT Study on the Electronic Properties, Spectroscopic Profile, and Biological Activity of 2-Amino-5-trifluoromethyl-1,3,4-thiadiazole with Anticancer Properties

Extensive investigation on the molecular and electronic structure of 2-amino-5-trifluoromethyl-1,3,4-thiadiazole in the ground state and in the first excited state has been performed. The energy barrier corresponding to the conversion between imino and amino tautomers has been calculated, which indicates the existence of amino tautomer in solid state for the title compound. The FT-Raman and FT-IR spectra were recorded and compared with theoretical vibrational wavenumbers, and a good coherence has been observed. The MESP map, dipole moment, polarizability, and hyperpolarizability have been calculated to comprehend the properties of the title molecule. High polarizability value estimation of the title compound may enhance its bioactivity. Natural bonding orbital analysis has been done on monomer and dimer to investigate the charge delocalization and strength of hydrogen bonding, respectively. Strong hydrogen bonding interaction energies of 17.09/17.49 kcal mol^-1 have been calculated at the B3LYP/M06-2X functional. The UV-vis spectrum was recorded and related to the theoretical spectrum. The title compound was biologically examined for anticancer activity by studying the cytotoxic performance against two human cancer cell lines (A549 and HeLa) along with the molecular docking simulation. Both molecular docking and cytotoxic performance against cancer cell lines show positive outcomes, and the title compound appears to be a promising anticancer agent.

A rational design of excellent light-absorbing dyes with different N-substituents at the phenothiazine for high efficiency solar cells

Dye-sensitized solar cells (DSSCs) have attracted great interest due to their simple fabrication process and low cost. However, most organic dyes with D-π-A configuration usually exhibit narrow absorption band, leading to poor light harvesting ability and great loss on photon conversion efficiency. In this research, a series of excellent light-absorbing dyes (CC202-I - CC202-III) with different N-substituents at phenothiazine entities based on the champion dye CC202 were designed and investigated by density functional theory (DFT) and time-dependent DFT (TD- DFT). According to the analysis of absorption property, the results demonstrated that different N-substituents (12-crown-4-substituted phenyl, 4-hexoxyphenyl, and bare phenyl) at phenothiazine entities lead to stronger and broader absorption band as well as red-shifted spectra; moreover, larger electronic injection driving force (ΔG^inject), regeneration driving force (ΔG^reg), capability of light harvested (η_LHE(λ_strong)/η-_LHEλ) and maximal photon generated current (J_ph) in CC202-I - CC202-III are observed compared to that of CC202, which further increase J_SC. Additionally, a larger V_OC can be obtained in CC202-I - CC202-III due to larger dipole moment (u_normal) and slow electron recombination rate. Considering the all calculated characteristics related to J_SC and V_OC, dyes with 12-crown-4-substituted phenyl, 4-hexoxyphenyl, and bare phenyl substituent on phenothiazine can effectively enhance the photoelectric conversion efficiency of DSSCs.

4-(4-Chloro-2-oxo-3(1H-phenanthro[9,10-d]imidazol-2-yl)-2H-chromen-6-yl) benzaldehyde as a fluorescent probe for medical imaging: linear and nonlinear optical properties

This study presents the full theoretical optical and biological characteristics of a new fluorescent probe based on the phenanthroimidazole backbone (PB5). The aldehyde group was selected as the active group to bind to the protein during conjugation. The new fluorescent probe is based on the phenanthroimidazole backbone; however, unlike previously presented works, as the chromophore part, it contains the first introduction of the 4-chloro-2H-chromen-2-one part. In order to achieve the best cognitive aspect, the study included not only the dye itself but also the concanavalin A conjugate. The linear and non-linear optical properties and biological activities described in this study clearly indicate that the presented dye is a promising material as a fluorescent probe in medical imaging.

Spectroscopic and quantum computational study on naproxen sodium

The spectroscopic (FT-IR, FT-Raman, NMR), electronic (UV--Vis.), structural and thermodynamical properties of an anti-inflammatory analgesic called Naproxen Sodium, (s)-6-methoxy-α-methyl-2-naphthaleneacetic acid sodium salt are submitted by using both experimental techniques and theoretical methods as quantum chemical calculations in this work. The equilibrium geometry and vibrational spectra are calculated by using DFT (B3LYP) with 6-311++G (d,p) basis set using GAUSSIAN 09. The vibrational wavenumbers are also corrected with scale factor to take better results for the calculated data. The HOMO-LUMO calculations are carried out on the title compound. The theoretical and experimental NMR peaks were found to be in good agreement. In addition, the detailed study on the Non-Bonding Orbitals, the excitation energies, AIM charges, condensed fukui calculations, thermodynamical properties, Localized Orbital Locator (LOL) and Electron Localization Function (ELF) are also performed. Furthermore, the study is extended to calculate the first order hyperpolarizability and to predict its NLO properties. The docking studies details helped on predicting the binding with different proteins.