DFT, FT-Raman, FT-IR and FT-NMR studies of 4-phenylimidazole

Benzimidazole derivatives as a new scaffold of anticancer agents: Synthesis, optical properties, crystal structure and DFT calculations

The absolute necessity to fight some class of tumour is perceived as serious health concerns, and the discovery and development of effective anticancer agents are urgently needed. So, the novel benzimidazole derivatives (2a-b) were designed, synthesized, with their structures rigorously characterized using single X-ray crystallography, FT-IR, UV, and NMR spectroscopy, alongside elemental analysis. The geometric structures were optimized using density functional theory (DFT) calculations performed at the ωB97X-D/cc-pVDZ level, yielding good agreement with experimental XRD data. The studied salt complexes exhibited the ability to absorb UV light at 275 nm. Furthermore, anticancer activity of the compounds was screened against (MDA-MB-231, MCF-7, HT-29 and healthy cell line (HF)) and revealed the remarkable efficacy of select newly synthesized Benzimidazole derivatives (2a-b). Compound 2a showed relative significant higher cytotoxicity (165.02) in MDA-MB-231 cancer cell line. This underscores their promising potential in therapeutic applications, affirming their role as valuable contenders in the pursuit of novel anticancer agents.

Investigation on the molecular, electronic and spectroscopic properties of rosmarinic acid: an intuition from an experimental and computational perspective

Various drugs such as corticosteroids, salbutamol, and β2 agonist are available for the treatment of asthma an inflammatory disease and its symptoms, although the ingredient and the mode of action of these drugs are not clearly elucidated. Hence this research aimed at carrying out improved scientific research with respect to the use of natural product rosmarinic acid which poses minima, side effects. Herein, we first carried out extraction, isolation, and spectroscopic (FT-IR, 1H-NMR and 13C-NMR) investigation, followed by molecular modeling analysis on the naturally occurring rosmarinic acid extracted from Rosmarinus officinalis. A detailed comparison of the experimental and theoretical vibrational analysis has been carried out using five DFT functionals: BHANDH, HSEH1PBE, M06-2X, MPW3PBE and THCTHHYB with the basis set 6-311++G (d, p) to investigate into the structural, reactivity, and stability of the isolated compound. Frontier molecular orbital analysis and appropriate quantum descriptors were calculated. Results showed that the compound was more stable at M06-2X and more reactive at HSEH1PBE with an energy gap of 6.43441 eV and 3.8047 eV, respectively, which was later affirmed by the global quantum reactivity parameters. From natural bond orbital analysis, π* → π* is the major contributor to electron transition with the summation perturbation energy of 889.57 kcal/mol, while π → π* had the perturbation energy totaling of 145.3 kcal/mol. Geometry analysis shows BHANDH to have lower bond length values and lesser deviation from 120° in carbon-carbon angle. The potency of the title molecule as an asthma drug was tested via a molecular docking approach and the binding score of -8.2 kcal/mol was observed against -7.0 of salbutamol standard drug, suggesting romarinic acid as a potential natural organic treatment for asthma.Communicated by Ramaswamy H. Sarma.

Heteroatom (B, N, P, and S)-Doped Cyclodextrin as a Hydroxyurea (HU) Drug Nanocarrier: A Computational Approach

Theoretical examination of hydroxyurea adsorption capabilities toward the cyclodextrin surface for proper drug delivery systems was carried out utilizing DFT simulations. The study aims to assess the efficacy of doped cyclodextrin (doped with boron, nitrogen, phosphorus, and sulfur atoms) in increasing its stability and efficiency in intermolecular interactions, hence facilitating optimal drug delivery. The adsorption energies were found to follow a decreasing order of B@ACD-HU>N@ACD-HU>P@ACD-HU>S@ACD-HU with energies of -0.046, -0.0326, -0.015, and 0.944 kcal/mol, respectively. The S@ACD-HU complex, unlike previous systems, had a physical adsorption energy. The N@ACD-HU and B@ACD-HU complexes had the shortest bond lengths of 1.42 Å (N122-C15) and 1.54 Å (B126-C15), respectively. The HOMO and LUMO values were also high in identical systems, -6.367 and -2.918 eV (B@ACD-HU) and -6.278 and -1.736 eV (N@ACD-HU), respectively, confirming no chemical interaction. The N@ACD-HU has the largest energy gap of 4.54 eV. For the QTAIM analysis and plots, the maximum electron density and ellipticity index were detected in B@ACD-HU, 0.600 au (H70-N129) and 0.8685 au (H70-N129), respectively, but N@ACD-HU exhibited a high Laplacian energy of 0.7524 a.u (H133-N122). The fragments' TDOS, OPDOS, and PDOS exhibited a strong bond interaction of greater than 1, and they had different Fermi levels, with the highest value of -8.16 eV in the N@ACD-HU complex. Finally, the NCI analysis revealed that the complexes were noncovalent. According to the literature, the van der Waals form of interactions is used in the intermolecular forces of cyclodextrin cavities. The B@ACD-HU and N@ACD-HU systems were more greenish in color with no spatial interaction. These two systems have outperformed other complexes in intermolecular interactions, resulting in more efficient drug delivery. They had the highest negative adsorption energies, the shortest bond length, the highest HOMO/LUMO energies, the highest energy gap, the highest stabilization energy, the strongest bonding effect, the highest electron density, the highest ellipticity index, and a strong van der Waals interaction that binds the drug and the surface together.

The Corrosion Inhibition of AA6082 Aluminium Alloy by Certain Azoles in Chloride Solution: Electrochemistry and Surface Analysis

The corrosion inhibition effect of five azole compounds on the corrosion of an AA6082 aluminium alloy in 5 wt.% NaCl solution at 25 and 50 °C was investigated using weight loss and electrochemical measurements. Only 2-mercaptobenzothiazole (MBT) showed a corrosion inhibition effect at both temperatures and was further studied in detail, including with the addition of potassium iodide as a possible intensifier. Surface analysis of the MBT surface layer was performed by means of attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry techniques. The hydrophobicity of the MBT surface layer was also investigated.

Linker-Doped Zeolitic Imidazolate Frameworks (ZIFs) and Their Ultrathin Membranes for Tunable Gas Separations

Zeolitic imidazolate frameworks (ZIFs) have gained much interest due to their potentials in gas separations. A hybrid approach by mixing metals and/or linkers has been recently investigated to fine-tune the ZIF framework porosity and surface properties and potentially extending their separation applications for many important gas mixtures. In general, the hybrid approach requires mixing of isostructural ZIFs to maintain their topology, thus limiting the options of linkers and metal centers to obtain hybrid ZIFs. Linker-doping, as reported here, can be a strategy to expand the option of imidazolate linkers to obtain mixed-linker hybrid ZIFs. Two linkers are investigated to be doped into the ZIF-8 framework: 2-ethylimidazole (eIm) and 2-phenylimidazole (phIm). The linker-doping strategy is shown to tune the "stiffness" of Zn-N bonding as characterized by FT-IR, thereby the linker flip-flopping motion of ZIF-8, which is analyzed through gas adsorption isotherms. Furthermore, well-intergrown ultrathin eIm-doped ZIF-8 membranes are grown on α-Al₂O₃ substrates, in which the incorporation of eIm affects the morphology and thickness of the polycrystalline membranes, improving the permeance of propylene and propane molecules.

Spectroscopic and thermal studies on 2- and 4-phenyl-1H-imidazoles

The polarized IR spectra of isotopically neat and isotopically substituted monocrystalline samples of 2-phenyl-1H-imidazole (2PI) and 4-phenyl-1H-imidazole (4PI) were recorded at two temperatures of 293 K and 77 K. The room-temperature ATR-FTIR and Raman spectra of 2PI and two polymorphic forms of 4PI were also recorded. Theoretical analysis of the vibrational spectra of selected imidazole derivatives reflected similar characteristics of their hydrogen-bond networks and allowed us to obtain the information about the mechanism of the H/D isotopic "self-organization" phenomenon. The distribution of protons and deuterons in the lattices of the isotopically diluted crystalline samples of 2PI and 4PI was found to be non-random. In the crystals of the hydrogen- and deuterium-bonded imidazole derivatives the strongest vibrational exciton interactions favored the intrachain ("tail-to-head")-type exciton coupling widespread at 77 K via the π-electrons. At room temperature a weak interchain ("through-space")-type exciton coupling was also partially responsible for the IR spectra generation. Differential scanning calorimetry (DSC) measurements showed that the two polymorphic forms of 4PI exhibit an extensive supercooling of crystallization process and cold crystallization on reheating. Additionally, both polymorphic modifications of 4PI are monotropically related. 2PI exhibits only the crystallization and melting processes.

Photo-induced reversible structural transition of cationic diphenylalanine peptide self-assembly

The photo-induced self-assembly of a cationic diphenylalanine peptide (CDP) is investigated using a photoswitchable sulfonic azobenzene as the manipulating unit. A reversible structural transition between a branched structure and a vesicle-like structure is observed by alternating between UV and visible light irradiation.

QM/MM methodology, docking and spectroscopic (FT-IR/FT-Raman, NMR, UV) and Fukui function analysis on adrenergic agonist

The Fourier transform infrared, FT-Raman, UV and NMR spectra of Ternelin have been recorded and analyzed. Harmonic vibrational frequencies have been investigated with the help of HF with 6-31G (d,p) and B3LYP with 6-31G (d,p) and LANL2DZ basis sets. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. The polarizability (α) and the first hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. Stability of the molecule arising from hyper conjugative interactions, and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in Ternelin. Finally the calculated results were compared to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Molecular docking studies have been carried out in the active site of Ternelin and reactivity with ONIOM was also investigated.

Synthesis, characterization and theoretical studies of 5-(benzylthio)-1-cylopentyl-1H-tetrazole

In this study, 5-(benzylthio)-1-cylopentyl-1H-tetrazole (5B1C1HT) have been synthesized. Boiling points of the obtained compound have been determined and it has been characterized by FT-IR, (1)H NMR, (13)C-APT and LC-MS spectroscopy techniques. The FT-IR, (1)H NMR and (13)C-APT spectral measurements of the 5B1C1HT compound and complete assignment of the vibrational bands observed in spectra has been discussed. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimization and force field calculations based on Density Functional Theory (DFT) at 6-311++G(**), cc-pVDZ and cc-pVTZ basis sets. The optimized geometry with 6-311++G(**) basis sets were used to determine the total energy distribution, harmonic vibrational frequencies, IR intensities.

Quantum chemical and spectroscopic (FT-IR and FT-Raman) investigations of 3-methyl-3h-imidazole-4-carbaldehyde

FT-IR and FT-Raman spectra of 3-methyl-3h-imidazole-4-carbaldehyde (3M3HI4C) were recorded in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. Optimized geometric parameters, conformational equilibria, normal mode frequencies, and corresponding vibrational assignments of 3M3HI4C were theoretically examined by quantum chemical methods for the first time. All vibrational frequencies were assigned in detail with the help of total energy distribution (TEDs). The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT/B3LYP method. The results showed that the B3LYP/6-311++G(d,p) method predicts vibrational frequencies and the structural parameters effectively. The most stable conformer of the title compound was determined. The total electron density and molecular electrostatic potential surfaces of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron+nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. The lower energy band was assigned to the HOMO→LUMO transition. Natural bond orbital analysis of title molecule has been performed to indicate the presence of intramolecular charge transfer. Energies, relative stabilities, and dipole moments of title molecule were also compared and analyzed in the gas phase and in solvents. Furthermore, solvent effects on the geometry and vibrational frequency of 3M3HI4C were studied theoretically at the DFT/B3LYP level in combination with the conductor polarizable continuum model (C-PCM).

Infrared, Raman and NMR spectra, conformational stability and vibrational assignment of 7,8-Dihydroxy-4-Methylcoumarin

We report a combined some (infrared, Raman and NMR) spectroscopic and quantum chemistry study on 7,8-Dihydroxy-4-Methylcoumarin molecule (78D4MC). The Raman and IR spectra of 78D4MC molecule were recorded and analyzed in the region 3500-50 cm(-1) and 4000-400 cm(-1), respectively. Potential energy scans were performed at the MMFF level of theory. All possible conformers, which are results at the MMFF level theory, were re-computed at the B3LYP functional with cc-pVDZ basis set. The optimized geometrical parameters, harmonic vibrational wavenumbers and NMR chemical shifts of the most stable conformer were calculated at the B3LYP/6-311G(d,p), cc-pVTZ and cc-pVQZ level in the proximity of the isolated molecule. DFT calculations were combined with Pulay's scaled quantum mechanics force field (SQMFF) methodology in order to fit the theoretical wavenumbers to the experimental ones.

Novel CO2-capture derived from the basic ionic liquids orientated on mesoporous materials

Two new basic ionic liquids (ILs) are designed and synthesized in order to conquer the challenge arising from the capture of CO2 in flue gas whose temperature is over 373 K, and they possess a suitable basic strength to adsorb CO2 at 393 K with the capacity of 22-49 mg g(-1). After these ILs are immobilized on mesoporous alumina or silica, equimolar CO2 capture is realized at 393 K for the first time. Besides, these adsorbents can be regenerated at 443 K to form a feasible cycle for controlling CO2 emission in flue gas. Theoretical calculations indicated the key role played by the mesoporous support in promoting CO2 adsorption via electrostatic interactions between support and ILs. An unwonted promotion of the support's ζ-potential on the performance of ILs is revealed, which induces the immobilized ILs to be oriented in a favorable dispersion, enhancing the efficiency of ILs in the CO2 adsorption at elevated temperature. This study proposes a new strategy for the sustainable development of novel adsorbent.

Synthesis, characterization, optical properties and theoretical calculations of 6-fluoro coumarin

6-Fluoro coumarin is synthesized and characterized by (1)H NMR and (13)C NMR. The optical properties of the title compound are investigated by UV-vis absorption and fluorescence emission spectra, the results show the title compound can absorb UV-vis light at 319, 269 and 215nm, moreover it exhibits blue-purple fluorescence emission at 416nm. Theoretical studies on molecular structure, infrared spectra (IR), nuclear magnetic resonance ((1)H NMR, (13)C NMR) chemical shifts, UV-vis absorption and fluorescence emission of the synthesized compound have been worked out. Most chemical calculations were performed by density functional theory (DFT) method at the B3LYP/6-311G(d,p) level (NMR at B3LYP/Aug-CC-Pvdz level) using Gaussian 09 program. The compared results reveal that the scaled theoretical vibrational frequencies are in good accordance with the observed spectra; computational chemical shifts are consistent with the experimental values in most parts, except for some minor deviations; the UV-vis absorption calculated matches the experimental one very well, and the fluorescence emission spectrum is in good agreement with the experimental one when the solute-solvent hydrogen-bonding interaction is considered. These good coincidences prove that the computational methods selected can be used to predict these properties of other similar materials where it is difficult to arrive at experimental results.

Investigation of solvent polarity effect on molecular structure and vibrational spectrum of xanthine with the aid of quantum chemical computations

The main scope of this study is to determine the effects of 8 solvents on the geometric structure and vibrational spectra of the title compound, xanthine, by means of the DFT/B3LYP level of theory in the combination with the polarizable conductor continuum model (CPCM) for the first time. After determination of the most-steady state (favored structure) of the xanthine molecule, the role of the solvent polarity on the SCF energy (for the molecule stability), atomic charges (for charge distribution) and dipole moments (for molecular charge transfer) belonging to tautomer is discussed in detail. The results obtained indicate not only the presence of the hydrogen bonding and strong intra-molecular charge transfer (ICT) in the compound but the increment of the molecule stability with the solvent polarity, as well. Moreover, it is noted that the optimized geometric parameters and the theoretical vibrational frequencies are in good agreement with the available experimental results found in the literature. In fact, the correlations between the experimental and theoretical findings for the molecular structures improve with the enhancement of the solvent polarity. At the same time, the dimer forms of the xanthine compound are simulated to describe the effect of intermolecular hydrogen bonding on the molecular geometry and vibrational frequencies. It is found that the CO and NH stretching vibrations shift regularly to lower frequency value with higher IR intensity as the dielectric medium enhances systematically due to the intermolecular NH⋯O hydrogen bonds. Theoretical vibrational spectra are also assigned based on the potential energy distribution (PED) using the VEDA 4 program.

Investigations of FT-IR, FT-Raman, FT-NMR spectra and quantum chemical computations of Esculetin molecule

In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra and electronic properties of Esculetin (ESC). The FT-IR, FT-Raman and FT-NMR spectra have been recorded and analyzed. The molecular geometry, harmonic vibrational frequencies, chemical shifts, HOMO, LUMO energies and molecular electrostatic potential map of ESC have been calculated by using Density Functional Theory (B3LYP) with 6-311G++(d,p), cc-pVDZ, cc-pVQZ and cc-pVTZ basis sets.

Vibrational spectroscopic analyses of unique yellow feather pigments (spheniscins) in penguins

Many animals extract, synthesize and refine chemicals for colour display, where a range of compounds and structures can produce a diverse colour palette. Feather colours, for example, span the visible spectrum and mostly result from pigments in five chemical classes (carotenoids, melanins, porphyrins, psittacofulvins and metal oxides). However, the pigment that generates the yellow colour of penguin feathers appears to represent a sixth, poorly characterized class of feather pigments. This pigment class, here termed 'spheniscin', is displayed by half of the living penguin genera; the larger and richer colour displays of the pigment are highly attractive. Using Raman and mid-infrared spectroscopies, we analysed yellow feathers from two penguin species (king penguin, Aptenodytes patagonicus; macaroni penguin, Eudyptes chrysolophus) to further characterize spheniscin pigments. The Raman spectrum of spheniscin is distinct from spectra of other feather pigments and exhibits 17 distinctive spectral bands between 300 and 1700 cm(-1). Spectral bands from the yellow pigment are assigned to aromatically bound carbon atoms, and to skeletal modes in an aromatic, heterocyclic ring. It has been suggested that the penguin pigment is a pterin compound; Raman spectra from yellow penguin feathers are broadly consistent with previously reported pterin spectra, although we have not matched it to any known compound. Raman spectroscopy can provide a rapid and non-destructive method for surveying the distribution of different classes of feather pigments in the avian family tree, and for correlating the chemistry of spheniscin with compounds analysed elsewhere. We suggest that the sixth class of feather pigments may have evolved in a stem-lineage penguin and endowed modern penguins with a costly plumage trait that appears to be chemically unique among birds.

Molecular structure, vibrational, UV, NMR, hyperpolarizability, NBO and HOMO-LUMO analysis of Pteridine2,4-dione

The FTIR and FT-Raman spectra of Pteridine2,4-dione has been recorded in the region 4000-450 and 4000-100 cm(-1), respectively. The tautomeric stability, optimized geometry, frequency and intensity of the vibrational bands of Pteridine2,4-dione were obtained by the density functional theory (DFT) using 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The (1)H and(13)C NMR spectra chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method. The theoretical UV-Vis spectrum of the compound using CIS method and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (β(0)) of these novel molecular system and related properties (β, α(0) and Δα) of Pteridine2,4-dione are calculated using DFT/6-311++G (d,p) method on the finite-field approach. The Mulliken charges, the values of electric dipole moment (μ) of the molecule were computed using DFT calculations. The change in electron density (ED) in the σ(*) antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions.

Molecular structure, vibrational spectroscopic, first-order hyperpolarizability and HOMO, LUMO studies of 2-aminobenzimidazole

In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and HOMO-LUMO analysis of 2-aminobenzimidazole (2-ABD). The FTIR (400-4000 cm(-1)) and FT-Raman spectra (50-3500 cm(-1)) of 2-ABD were recorded. The molecular geometry, harmonic vibrational wavenumbers and bonding features of 2-ABD in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G(d,p) and 6-31G(d) as basis sets. The energy and oscillator strength were calculated by time-dependent density functional theory (TD-DFT) result complements with the experimental findings. The calculated HOMO and LUMO energies showed that charge transfer occurs within the molecule. Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with the observed spectra.