Experimental FT-IR Research Articles

Origin of thiocyanate spectral shifts in water and organic solvents.

Vibrational spectroscopy is a useful technique for probing chemical environments. The development of models that can reproduce the spectra of nitriles and azides is valuable because these probes are uniquely suited for investigating complex systems. Empirical vibrational spectroscopic maps are commonly employed to obtain the instantaneous vibrational frequencies during molecular dynamics simulations but often fail to adequately describe the behavior of these probes, especially in its transferability to a diverse range of environments. In this paper, we demonstrate several reasons for the difficulty in constructing a general-purpose vibrational map for methyl thiocyanate (MeSCN), a model for cyanylated biological probes. In particular, we found that electrostatics alone are not a sufficient metric to categorize the environments of different solvents, and the dominant features in intermolecular interactions in the energy landscape vary from solvent to solvent. Consequently, common vibrational mapping schemes do not cover all essential interaction terms adequately, especially in the treatment of van der Waals interactions. Quantum vibrational perturbation (QVP) theory, along with a combined quantum mechanical and molecular mechanical potential for solute-solvent interactions, is an alternative and efficient modeling technique, which is compared in this paper, to yield spectroscopic results in good agreement with experimental FTIR. QVP has been used to analyze the computational data, revealing the shortcomings of the vibrational maps for MeSCN in different solvents. The results indicate that insights from QVP analysis can be used to enhance the transferability of vibrational maps in future studies.

Synthesis, thermal behavior in oxidative and pyrolysis conditions, spectroscopic and DFT studies of some alkaline earth metals p-aminobenzoate complexes using TG-DTA, DSC, PXRD and EGA (TG-FTIR) techniques

p-aminobenzoic acid is a substance widely used in several areas, such as catalysis, biomarkers, magnetic materials, luminescent materials and biological applications. p-aminobenzoate complexes with alkaline earth metal were synthesized and the thermal and pyrolysis behavior was studied using thermoanalytical and spectroscopic techniques. Based on TG/DTG-DTA and EGA results, the thermal decomposition mechanisms of the compounds were proposed under both atmospheres studied. The main gaseous products identified by EGA in both study conditions were H2O, Aniline, CO and CO2. From DSC analysis, it was possible to measure the enthalpies of dehydration and evaluate the phase transitions of the magnesium complex. FTIR data suggest that metal-ligand coordination occurs through carboxylate group by different ways. The coordination modes suggested by experimental FTIR data were supported by DFT study. The X-ray diffraction powder patterns show that the barium compound was obtained in amorphous state, while the other compounds have a crystalline structure.

Synthesis of Novel Tritopic Hydrazone Ligands: Spectroscopy, Biological Activity, DFT, and Molecular Docking Studies.

Polytopic organic ligands with hydrazone moiety are at the forefront of new drug research among many others due to their unique and versatile functionality and ease of strategic ligand design. Quantum chemical calculations of these polyfunctional ligands can be carried out in silico to determine the thermodynamic parameters. In this study two new tritopic dihydrazide ligands, N’2, N’6-bis[(1E)-1-(thiophen-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L1) and N’2, N’6-bis[(1E)-1-(1H-pyrrol-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L2) were successfully prepared by the condensation reaction of pyridine-2,6-dicarboxylic hydrazide with 2-acetylthiophene and 2-acetylpyrrole. The FT-IR, 1H, and 13C NMR, as well as mass spectra of both L1 and L2, were recorded and analyzed. Quantum chemical calculations were performed at the DFT/B3LYP/cc-pvdz/6-311G+(d,p) level of theory to study the molecular geometry, vibrational frequencies, and thermodynamic properties including changes of ∆H, ∆S, and ∆G for both the ligands. The optimized vibrational frequency and (1H and 13C) NMR obtained by B3LYP/cc-pvdz/6-311G+(d,p) showed good agreement with experimental FT-IR and NMR data. Frontier molecular orbital (FMO) calculations were also conducted to find the HOMO, LUMO, and HOMO–LUMO gaps of the two synthesized compounds. To investigate the biological activities of the ligands, L1 and L2 were tested using in vitro bioassays against some Gram-negative and Gram-positive bacteria and fungus strains. In addition, molecular docking was used to study the molecular behavior of L1 and L2 against tyrosinase from Bacillus megaterium. The outcomes revealed that both L1 and L2 can suppress microbial growth of bacteria and fungi with variable potency. The antibacterial activity results demonstrated the compound L2 to be potentially effective against Bacillus megaterium with inhibition zones of 12 mm while the molecular docking study showed the binding energies for L1 and L2 to be −7.7 and −8.8 kcal mol−1, respectively, with tyrosinase from Bacillus megaterium.

Conformational stability, quantum computational, spectroscopic, molecular docking and molecular dynamic simulation study of 2-hydroxy-1-naphthaldehyde

Experimental FTIR, NMR and UV-visible spectrum analyses were used to describe the title compound 2-Hydroxy-1-Naphthaldehyde. The optimized molecular geometry and vibrational wave numbers were determined by using the DFT approach and B3LYP/6-311++G(d, p) basis set. VEDA was used to determine the vibrational assignments. The GIAO technique was used to compute carbon and proton NMR chemical shifts in CDCl3. The most reactive location of the 2H1NA molecule, according to MEP map analysis, is the site containing the oxygen atom. TD-DFT approach was used to produce the theoretical UV-visible spectrum in MeOH and gas phase. HOMO-LUMO and Donor-Acceptor (NBO) interactions were investigated for the title compound. In addition, nonlinear optical characteristics, ELF and Fukui activity were investigated. Temperature-dependent thermodynamic characteristics were also computed. The 3D intermolecular interactions of the crystal surface were characterised using Hirshfeld surface analysis, whereas the 2D interactions were explained using fingerprint plots. 2H1NA was stabilized by the development of H—H/H—C/H—O contacts. The bioactive probability of the title molecule was theoretically demonstrated by computing the electrophilicity index. In a biological study six different receptors, molecular docking was performed to evaluate the best ligand-protein interactions and likeness to the active substance. Biomolecular stability was investigated using a molecular dynamics simulation.

Molecular docking, experimental FT-IR spectra, UV–Vis spectra, vibrational analysis, electronic properties, Fukui function analysis of a potential bioactive agent – Proflavine

Proflavine, having the molecular formula C13H11N3, is a well-known urinary antiseptic and anticancer medication (3,6-diaminoacridine). In this communication, Quantum chemical computations of Proflavine's geometry have been performed and examined in the ground state. The optimized structure and wavenumbers of the molecule's vibrational bands were investigated using the DFT/B3LYP method and 6–311G (d, p) as the basis set. The calculated vibrational frequencies are compared to experimental IR spectra. The link between thermodynamic characteristics and temperature has been studied. The computed IR frequencies correlate well with the experiments, as indicated by the correlation factor (R2 = 0.99). The UV spectra of the title molecule are calculated by using Time Dependent Density Functional Theory (TD-DFT). The molecule's interactions with other species were described using an analysis of a HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital). Natural bond orbitals (NBO) analysis was used to investigate intramolecular and intermolecular hydrogen bonding and their second-order stabilization energies and conjugative and hyperconjugative interactions. By computing the first hyperpolarizability, nonlinear optical (NLO) analysis was utilized to explore the molecule's nonlinear optical properties.

Experimental Raman, FTIR and UV-vis spectra, DFT studies of molecular structures and barrier heights, thermodynamic functions and bioactivity of kaempferol

Molecular structures and vibrational parameters for the all the four possible conformers of kaempferol were investigated using Gaussian 09 and GAR2PED software. Raman and FTIR spectra of kaempferol were recorded in the regions 50–4000 cm−1 and 400–4000 cm−1, respectively and interpreted in the light of the computed quantities. Some of the modes were found to have conformer dependent frequencies, IR and Raman intensities and depolarisation ratios. The complex, broad and intense IR band in the range 2900–3500 cm−1 is explained to arise due to the four OH stretching and an overtone modes. The barrier heights for the OH tops against internal rotations have been determined. The UV–vis absorption spectrum was measured in the range 220–800 nm. MEP and HOMO-LUMO energies were computed for all the four conformers and NBO analysis was carried out. Thermodynamic functions of title compound have been carried out. Different bioactivity scores for this molecule were computed.

The assessment of physicochemical properties of Cisplatin complexes with purines and vitamins B group

The positively charged products of Cisplatin hydrolysis can form bonds with Guanine and Adenine, showing the ability to crosslink with nucleobases within the double helical DNA, and leading to apoptosis of the neoplastic cell. It has been proved that the presence of chemicals other than nucleobases, compound of aromatic rings with a nitrogen lone pair on the ring, such as B vitamins, may have a competitive character in relation to a chemotherapeutic drug. A theoretical study confirms the stability of bonds formed not only between Cisplatin and Guanine/Adenine but also Cisplatin and B vitamins, namely Thiamine (vit.B1), Niacin (vit.B3), Riboflavin (vit.B2) and Pyridoxal phosphate (vit.B6). That is why it seems to be justified to conduct the research on the physicochemical, thermochemical and optical properties of mono and diaqua complexes of Cisplatin with nucleobases and B vitamins. Equally important is carrying out such research as spectroscopic measurements, bond order analysis and vibrational analysis of the studied complexes. The complexation reaction is spontaneous and thermodynamically favored with the high electronegativity value, a shift of the electron density from the metal zone towards organic compounds, a reduction the value of gap parameter and a shift of the maximum absorbance ΔλABS towards longer wavelengths. Moreover, the performed density variation upon photoexcitation showed the contributions from HOMO→LUMO transition, where the maximum of the absorption band shifts towards shorter wavelengths compared to the cisPt derivatives, thereby lowering the photoexcitation energy. The formation of complexes causes the reduction of energy gap (ΔEgap) values and show higher kinetic stability with high values of gap. The bonding energies between Cisplatin and the target molecules were performed. Cisplatin forms the strongest bonds with Guanine and Pyridoxal phosphate (vit.B6). The vibrations of Pt–N7 bond in complexes occur in the low range of frequencies with low intensities. Only in case of nucleobases appeared vibrations of Pt–N7 in high frequencies. The highest intensity is shown by symmetry and asymmetry stretching vibrations of H–O(H2O) bonds in the high range of frequencies. The vibrations related with ammonium groups (NH3) of great importance appear in the medium and high range of frequencies. The complexes with Guanine show the highest intensities. A theoretical IR spectra were studied. The obtained calculated IR spectra for native nucleobases and vitamins from B group were compared with their experimental FT-IR. So the conducted research provides theoretical knowledge in practical terms regarding the physicochemical and spectral properties of the formed Cisplatin complexes with both nucleobases and B vitamins. Theoretical and partially experimental studies of the molecular and electronic structure or prediction of spectroscopic characteristics are quite useful for better understanding of the reactivity of this drug with physiological target molecules.

Theoretical, Experimental Studies on Molecular Structure and Vibrational Spectra of 2,6-Dibromo-4-Nitrophenol

Phenol derivatives are interesting molecules for theoretical studies due to their relatively small size and similarity to organic species. 2,6-dibromo-4-nitrophenol was investigated by using density functional theory (DFT). XRD data and optimized DFT studies are found to be in good correspondence with each other. Analysis of title compound was obtained by B3LYP/6-31 + G(d,p) level of theory to explain the vertical transactions. Calculated FT-IR and FT-Raman results are found to be in good agreement with experimental FT-IR and FT-Raman findings. Natural bond theory (NBO) study was also performed using B3LYP/6-31 + G(d,p) method. Correlations between the proton and carbon-13 experimental chemical shifts and the GIAO NMR calculations are in good agreement and these values have been used for the definitive signal assignments to the corresponding structures. Electronic absorption spectra of DBNP has been calculated by using CIS-DFT method based on the B3LYP/6-311++G (d,p) level of the optimized structure in gas phase.

Molecular Structure, Experimental and Theoretical Vibrational Spectroscopy, (HOMO-LUMO, NBO) Investigation, (RDG, AIM) Analysis, (MEP, NLO) Study and Molecular Docking of Ethyl-2-{[4-Ethyl-5-(Quinolin-8-yloxyMethyl)-4H-1,2,4-Triazol-3-yl] Sulfanyl} Acetate

The spectroscopic characterization of the new synthesized heterocyclic aromatic organic compound ethyl −2-{[4-ethyl −5-(quinolin- 8-yloxymethyl) -4H- 1,2,4-triazol −3-yl] sulfanyl} acetate (abbreviated by Q-tsa) was carried out using experimental FTIR, UV–Vis, 1H, and 13C NMR techniques. To support the analytical results, theoretical calculations were performed on Q-tsa using DFT method associated with B3LYP functional with 6-31G(d,p) and 6-311G(d,p) basis sets. Furthermore, the reactivity of the title compound was studied by the investigation of frontier molecular orbitals (FMO) analysis, HOMO-LUMO energies, density of state (DOS), molecular electrostatic potential (MEP), global and local chemical reactivity descriptors. Thermodynamic properties were separately computed and discussed. The attractive, repulsive and van der Waals strong and weak interactions in Q-tsa were performed via RDG analysis followed by the investigation of topological properties via AIM theory. Similarly, the NLO activity of the studied compound was highlighted by computing the first hyperpolarizability in different available solvents. Finally, through molecular docking, the biological activity of Q-tsa was studied and discussed.

Synthesis, spectroscopic investigation and quantum chemical computation of 2-(2-arylamino-4-aminothiazol-5-oyl) naphthalene derivatives

The aim of the work is to synthesis and examines novel 2-(2-arylamino-4-aminothiazol-5-oyl) naphthalene derivatives by experimental and theoretical spectroscopic investigations and to identify its structural and biological properties. The vibrational behavior of the title molecule was extracted by using Fourier transform infrared analysis. The experimental FT-IR (400–4000 cm−1) spectra of 2-(2-arylamino-4-aminothiazol-5-oyl) naphthalene derivatives have been recorded in the solid phase. The UV–visible spectrum recorded and analyzed using ethanol solvent, reveals the electronic transition properties. Hydrogen (1H) nuclear magnetic resonance spectra were also recorded. The geometry optimization has been performed to analyze the 2-(2-arylamino-4-aminothiazol-5-oyl) naphthalene active site with bonding features. Natural bond orbital (NBO) analysis showed proton transfer within the selected donor-acceptor depicting large energy of stabilization for the molecules under study. The chemical stability of the molecule was identified with the help of highest occupied and lowest unoccupied molecular orbital energies. The reactive sites of the title molecule were discussed by Fukui and MEP analysis. The RDG analysis was used to predict the weak interaction of the molecule with the help of electron density. Docking studies have been performed for title molecules using the molecular docking software.

Synthesis, spectroscopic (FT-IR, FT-Raman, NMR), reactivity (ELF, LOL and Fukui) and docking studies on 3-(2‑hydroxy-3‑methoxy-phenyl)-1-(3-nitro-phenyl)-propenone by experimental and DFT methods

The present article encloses synthesis and characterizations of 3-(2‑hydroxy-3‑methoxy-phenyl)-1-(3-nitro-phenyl)-propenoneby several experimental techniques such as FT-IR, FT-Raman, NMR and UV-Vis spectral method. The similar techniques are also investigated by computational method using Gaussian softwarewith DFT/ B3LYP/6–311++G (d,p) basis set. Primarily the geometrical parameters obtained by DFT are compared with the related experimental parameters. The experimental FT-IR and FT-Raman spectra of the title molecule are acquired in the span of 4000–400 cm−1 and 4000–50 cm−1 respectively. The complete vibrational analysis of the title molecule is conducted and the assignments concerned to the observed bands are mentioned with the support of potential energy distribution (PED). The comparison between experimental and theoretical vibrational spectra gives a precise knowledgeof the fundamental vibrational modes and leads to a better interpretation of the experimental Raman and infrared spectra. The theoretical NMR (1H and 13C) analysis is conducted by GIAO method for its structural characterization and compared with experimental chemical shifts. In addition to these studies other analyses such as NLO, FMO, MEP, ELF and LOL have been performed to understand the nature of the molecule. Molecular docking studies carried out to understand more common targeted proteins associated with severe acute respiratory syndrome corona virus (SARS-CoV).

Quantum computational, spectroscopic investigations on N-(2-((2-chloro-4,5-dicyanophenyl)amino)ethyl)-4-methylbenzenesulfonamide by DFT/TD-DFT with different solvents, molecular docking and drug-likeness researches

The experimental (x-ray, FT-IR NMR and UV-Vis. Spectral data) and theoretical researches of N-(2-((2-chloro-4,5-dicyanophenyl)amino)ethyl)-4-methylbenzenesulfonamide molecule were conducted in this study. The theoretical quantum computations (the optimized structure, IR NMR and UV-Vis.) to support experimental data were performed by DFT theory at B3LYP functional and 6–311 + +G(d,p) basis set. The optimized and IR calculations were done in the gas phase, while theoretical NMR was performed in Dimethyl Sulfoxide (DMSO-d6) solvation. A variety of solutions were used to explore the UV-Visible spectrum using the TD-DFT method. The Potential Energy Distribution analysis (PED) of the title compound was performed with VEDA4 analysis and these assignments were compared with the experimental FT-IR spectrum. Hirshfeld surface analysis of the molecule by using crystal information file was carried out with Crystal Explorer the program. Additionally, over the check point file of the molecule HOMO, LUMO, MEP analyses were performed. Finally, the molecular docking calculations and drug-likeness properties were conducted according to the five rules of Lipinski.

Synthesis, structural, vibrational, molecular docking and nonlinear optical studies of (E)-N′-(2,3-dimethoxybenzylidene)-4-fluorobenzohydrazide

Organic nonlinear optical single crystals of (E)-N′-(2,3-dimethoxybenzylidene)-4-fluorobenzohydrazide (DMB-FBH) were synthesized and grown using slow evaporation crystallization from ethanol solution. The single crystal X-ray diffraction scattering revealed that the DMB-FBH crystallised in the tetragonal crystal system with a centro symmetric space group of I 41/a. The crystallographic bond lengths and bond angles were compared with the values generated from optimized molecular geometry based on quantum chemical calculations. The functional group vibrations were identified theoretically by density functional theory with B3LYP 6–311 G (d,p) basis set using Gaussian 09 software package and their vibrations were compared with the experimental FT-IR spectra. The UV-visible and the fluorescence emission spectra of the DMB-FBH in aqueous solutions were recorded. The HOMO-LUMO energy level pictogram addressed the intramolecular charge transfer (ICT) interaction between donor and acceptor moieties and their impact on the energy gap was determined. Different interactions such as O···H, N···H, C···C and C···H in DMB-FBH were quantified via fingerprint plots and these results were compared with that of similar structure. The detailed molecular docking simulation was carried out with M. tuberculosis protein [PDB ID:2 × 22]. The third order nonlinear optical susceptibility (χ3) of DMB-FBH was confirmed experimentally by Z-scan method and their conversion efficiency was higher than the other hydrazones derivatives. In short, this work discusses the crystal structure, identification and quantification of the molecular interactions, thermal, antimycobacterial and optical properties of new hydrazone derivative.

FTIR signal assignment in Chitin using density functional theory calculations – A monomer approximation

Density functional theory (DFT) calculations are performed on Chitin to investigate the geometry and vibrational properties under monomer approximation. Vibrational spectra of chitin have been analysed using the DFT monomer approach, and complete assignments of experimental FTIR signals are being reported in the present work. DFT calculations with the 6-311G basis set produces results for vibrational modes that reasonably agree with the experimental FTIR results.

Computational, Hirshfeld surface, and molecular docking analysis of 2-(((4-methoxyphenyl)imino)methyl)-4-nitrophenol: In-vitro anticancer, antimicrobial, anti-inflammatory, and antioxidant studies

A Schiff base, 2-(((4-methoxyphenyl) imino) methyl)-4-nitrophenol (1) was synthesized with high yield. We have focused on its computational investigation using density functional theory (DFT) approach with B3LYP/6-311G+(d,p) level and in-vitro pharmacological, antioxidant activity, and molecular docking studies. The computational results were evaluated with experimental FT-IR, UV-Vis, NMR and crystal diffraction data. Moreover, elucidation of molecular electrostatic potential (MEP), natural bond orbital (NBO), global reactivity parameters, frontier molecular orbitals, and density of state of the compound were done. In addition, 3D energy framework, Hirshfeld surface, and ADMET profiles were also performed. The characteristic peak of the azomethine group was found in FT-IR, NMR, powder XRD spectra, and single crystal data. The experimental n → π* and π → π* electronic transitions were well matched with the computed data. The title compound exhibited more binding affinity with the target (1GTV) in molecular docking study. Besides, the studied compound showed similar activity in experimental and docking results as compared to kanamycin. The O⋯H/ H⋯O, H⋯H/ H⋯H, C⋯H/ H⋯C, and N⋯H/ H⋯N contacts were found in the two-dimensional fingerprint plots with 32.1, 33.3, 14.5, and 4.2% contribution. The dispersion energy framework was prevalent over the electrostatic energy framework. Drug like character of 1 was assessed by Lipinski’s rule of five. The studied compound has potential activity against B. megaterium and E. coli bacteria and moderate activity against A. niger fungus. It has promising anti-inflammatory activity and exhibited protective power to stabilize the human red blood cell (HRBC). The title Schiff base offered highest cytotoxic activity with IC50 value of 82.04 μg/mL against A549 lung cancer cells. The title compound showed potential free radical scavenging activity with IC50 value of 6.24 ppm in DPPH scavenging assay.

Spectroscopic Identification, Structural Features and Molecular Docking Studies on 5-(4-Propoxybenzylidene)-2-[3-(4-chlorophenyl)-5-[4(propan-2-yl) phenyl-4,5-dihydro- 1H-pyrazol-1-yl]-1,3-thiazol-4(5H)-one using Pim-1 Kinase Cancer Protein

A comprehensive investigation of the molecular structure, electronic properties and vibrational spectra of 5-(4-propoxybenzylidene)-2-[3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]-4,5-dihydro-1Hpyrazol- 1-yl]-1,3-thiazol-4(5H)-one have been studied. Many natural and/or synthetic compounds contain, thiazole which are attractive compounds found in the building of numerous natural products and certain pharmaceutical agents. To understand the molecular-orbital interaction and structural investigation of the title compound, the density functional theory (DFT) calculation has been carried out using B3LYP/6-31G and 6-311G basis sets combination. The experimental FT-IR, FT-Raman spectral data along with theoretical quantum chemical calculation were investigated. For potential energy distributions (PED) analysis, the VEDA 4 program is utilized to do comparative frequency assignments. With the optimized structures, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energies, molecular electrostatic potential (MEP) and natural bond orbital (NBO) were applied to describe the chemical reactivity.The electron density interactions distributed in space, which exist within these compounds are analyzed by different topological methods namely, atom in molecule (AIM), localized orbital locator (LOL), electron localization function (ELF) and the reduced density gradient (RDG). Finally, the molecular docking studies of the title compound for potent Pim-1 kinase cancer PDB ID: 3A99, 1GJ8, 1XQZ was investigated using theAuto Dock program

Quantum chemical, spectroscopic, hirshfeld surface and molecular docking studies on 2-aminobenzothiazole

The quantum chemical properties and experimental spectroscopy of 2-aminobenzothiazole (2-ABT) were explored. DFT(Density functional theory) technique used to calculate different properties of 2-ABTcomputationally. Surface analysis carried out by Hirshfeld, and experimental spectrochemical analysis such as-NMR (1H NMR and 13C NMR), FT-IR, and UV-Visible examined experimentally. The B3LYP method with 6–311++G(d,p) basis set was used to obtain the optimal structure that serves as the foundation for all other calculations (vibrational frequency, NBO, NHO, NLO, FMO, and so on). Hirshfeld surface analysis and finger print plots were used to describe the intermolecular interactions on the crystal surface in detail. 2-ABT is stabilized primarily via the creation of H…H/C…H and S…H contacts, according to a Hirshfeld surface analysis of intermolecular interactions. VEDA completed all potential energy distribution assignments. The electron localization function was used to determine binding energy, ellipticity, and isosurface projection using the atom in molecule theory (AIM). The NBO analysis was used to determine the interactions between the donor and the acceptor. The molecule's reactive areas were revealed using Fukui functions and molecular electrostatic potential (MEP). UV–Vis spectrum calculated with different solvents using TD-DFT/IEFPCM techniques. ORCA calculated thermodynamic parameters such as free energy, enthalpy, and entropy at various temperatures. In the excited state, maps of hole and electron density distribution were generated using DMSO and MeOH. The bio-active probability of the chemical was theoretically proven by computing the electrophilicity index. Molecular docking is used to calculate and confirm protein-ligand interactions. The title molecule was also used in medicinal fields and for drug development.

Computational analyses of the vibrational spectra of fentanyl, carfentanil and remifentanil

The infrared (IR) spectra of fentanyl, carfentanil and remifentanil, and protonated salts, are computed using quantum chemistry methods. New experimental FTIR spectra are also reported and compared to the calculations. The accuracy of two density functional theory methods, B3LYP and M06-2X, are tested against higher level theories (MP2) and the experimental data. Gas phase IR spectra are calculated for both the neutral and protonated molecules in order to compare with the experimental data measured for various salts of fentanyl and its analogues. Key vibrational modes are selected and studied in detail using a vibrational mode locality calculation. The main contributing atomic movements in these vibrational modes are identified.

Synthesis and Structure Characterization of 1-(4-Bromophenyl)-3-(2-Chloro-6-Fluorophenyl) Prop-2-En-1-One Using Spectroscopic Techniques and Density Functional Theory

Abstract: The structural confirmation of the 1-(4-Bromophenyl)-3-(2-chloro-6-fluorophenyl) prop-2-en-1-one compound is done by experimental techniques. Experimental techniques FTIR, proton NMR, UV-Visible, performed for the compound. The experimentally obtained results are compared with density functional theory obtained results. The decomposition and melting point of the compound is obtained by TGA & DTA. Density functional theory is performed for the 1-(4-Bromophenyl)-3-(2- chloro-6-fluorophenyl) prop-2-en-1-one compound B3LYP/6-311G++(d,p) basis set. Time dependent density functional theory calculated for three different methods B3LYP, Hartree-Fock and CAMB3LYP also employed for the 2C6FBC at 6-311G++(d,p) basis set. Keywords: DFT Study, HOMO-LUMO, FTIR, 1H NMR, TGA/DTA, chalcone

The online coupling of liquid chromatography to Fourier transform infrared spectroscopy using a solute-deposition interface: A proof of concept

Hyphenated techniques combining chromatographic and spectroscopic methods are the gold standard to effectively handle the emerging challenges in the analysis of unknown chemical components in mixtures, and in this regard the coupling of liquid chromatography to Fourier transform infrared spectroscopy (LC-FTIR) is no exception. While earlier attempts to couple LC to IR spectroscopy relied almost entirely on offline techniques, clear motivations for implementing online LC-FTIR instrumentation emerged from the need for shorter analysis time, a higher degree of automation and sample throughput, better reproducibility, and reduced contamination. Most recent designs of LC-FTIR concepts have aimed to combine the advantages of both approaches by means of a solvent-elimination interface. The hyphenated instrumentation and method presented in this research are based on a pneumatically assisted LC-FTIR interface, relying on a small-scale self-regulating spray dryer to attain desolvation of the LC eluent stream while retaining the spatial and temporal resolution of the dissolved substrates. Focused deposition of the dried analytes occurs onto a ZnSe disc for continuous transmission mid-IR analysis at a resolution of 4 cm-1. The optimization of the LC-FTIR technique is discussed in terms of interface parameters, limits of detection, and limits of quantification for a pair of furanocoumarin isomers differing in the position (linear or angular type) of the furan ring fused to coumarin. Finally, confident discrimination between the two closely related molecules was attained by matching the experimental FTIR spectra in a dedicated library. The quality match factors obtained were higher than 99% for both molecules. The limit of identification (LOI) was determined experimentally as the minimum amount of substance yielding a library-searchable IR spectrum (affording a quality match factor higher than 90%). Specifically, LOI of 0.6 μg and 1.25 μg was determined for psoralen and angelicin, respectively.