Sürdürülebilir Kalkınma Amaçları

Yazarlar

  • MakaleAçık Erişim2026Scopus SJRQ1
    Exergy and DFT-Based Thermodynamic Analysis of a Rankine–VCR Marine Waste Heat Recovery System

    Keven, Arzu; Akçay, Enes; Gümüş, Hacer

    This study investigates the performance of a diesel engine exhaust gas-driven Rankine Cycle-supported vapor compression refrigeration system using quantum chemical approaches beyond conventional thermodynamic analyses. The study focuses on R448A and its components, namely R32, R125, R134a, R1234yf, and R1234ze(E), evaluated at both the system level and the molecular level. At the system level, the Rankine–VCR system was analyzed using a Fortran-based macroscopic thermodynamic model, in which the thermophysical properties of the working fluids were obtained from the NIST Chemistry WebBook. At the molecular level, Density Functional Theory (DFT) calculations were performed to determine molecular structure parameters, including entropy, heat capacity, chemical hardness, and thermal enthalpy correction. The main objective is to investigate the possible relationships between these molecular descriptors and system-level performance indicators, while considering that mass flow rate is primarily governed by cycle thermodynamic properties. The results show that molecular stability and structural order are strongly associated with system performance. Among the R448A components, R32, with the highest chemical hardness (8.19 eV) and lowest molecular entropy (58.9 cal/mol K), exhibits the most favorable exergetic behavior and achieves the highest plant exergy efficiency of 44.92%. In contrast, R1234ze(E), chemically softer (η = 4.42 Ev) and higher in entropy, exhibits the lowest performance. Additionally, R32’s lower thermal enthalpy correction is associated with higher latent heat of vaporization under the selected operating conditions, reducing the required mass flow by approximately 60–70% compared to the other components. This study demonstrates that, in refrigerant selection, not only the global warming potential (GWP) but also quantum parameters such as chemical hardness, molecular entropy, heat capacity, and thermal enthalpy correction can serve as important complementary performance indicators when interpreted together with macroscopic thermodynamic and exergetic results.

    • SDG 7 · Erişilebilir ve Temiz Enerji
    • SDG 13 · İklim Eylemi
  • MakaleAçık Erişim2026Scopus SJRQ3
    Molecular structure, spectral characteristics, and nonlinear optical properties of labetalol: an experimental and computational investigation

    Çınar, Mehmet; Can, Sümeyra

    Labetalol is an antihypertensive agent that possesses both α- and β-adrenergic blocking properties. This characteristic allows for its clinical use in both chronic hypertension and hypertensive emergencies. In this study, the FT-IR, FT-Raman, 1 H, 13 C, and DEPT-135 NMR spectra of labetalol hydrochloride (Labetalol HCl) were recorded and examined. Furthermore, the pharmacologically active (R, R) stereoisomer of labetalol was theoretically investigated using the B3LYP functional and the 6-311++G(d, p) basis set. The theoretically determined ground-state geometry of the molecule showed excellent agreement with experimental data reported in the literature. Using the obtained optimized structure, the vibrational spectra of the molecule were simulated, and the vibrational modes were assigned by evaluating them together with the experimental data. Nuclear Magnetic Resonance (NMR) analysis of the molecule was performed considering experimentally recorded values and calculations for gas phase, DMSO, and chloroform solvent environments, and the chemical shift values for each H and C atom were determined. Using Time-Dependent Density Functional Theory (TD-DFT) and Solvation Model based on Density (SMD) approaches, the UV-Vis spectra of the molecule were obtained in the gas phase and in four different solvent environments (ethanol, methanol, DMSO, and water). To better understand the electronic properties of the molecule, Frontier Molecular Orbitals (FMO), Molecular Electrostatic Potential Surface (MEPS), Hirshfeld surface analysis, Mulliken and Hirshfeld charge distributions, and Density States (DoS) analyses were performed. In addition, the non-linear optical (NLO) properties of the molecule were theoretically calculated, and the results showed that the molecule could be a promising NLO candidate.

  • MakaleAçık Erişim2026Scopus SJRQ3
    DFT-based structural and energetic characterisation of nitrogen-rich tetrazine/triazine derivatives with Kamlet-Jacobs performance predictions

    Ekincioğlu, Yavuz; Kepceoğlu, Abdullah; Çakir, Zehra; Şentürk, Şükrü

    Nitrogen-rich heterocycles are attractive candidates for next-generation energetic materials because they can deliver high heats of formation while producing relatively benign, N2-rich decomposition products. In this work, three nitrogen-rich frameworks 3,6-bis(tetrazol-5-yl)−1,2,4,5-tetrazine (H2BTTz), 2,4,6-tris(tetrazol-5-yl)−1,3,5-triazine (H3TTT), and 2,3,5,6-tetra(tetrazol-5-yl)pyrazine (H4TTP) were investigated using a combined conformational sampling and density functional theory (DFT) approach. Initial conformational searches were carried out with the MMFF method, and the lowest-energy structures were optimised at the DFT/B3LYP/6-311++G(d,p) level a widely used compromise between accuracy and computational cost for nitrogen-rich energetic molecules. Electronic structure analyses included frontier molecular orbitals, Mulliken and natural population charges, and molecular electrostatic potential maps. Energetic performance was evaluated through heats of formation, detonation velocity and pressure, and impact sensitivity estimates. Topological descriptors such as ELF, LOL, and NCI were analyzed using Multiwfn program. The calculated HOMO–LUMO gaps (3.54-4.90 eV) indicate electronically stable molecular frameworks. Gas-phase formation enthalpies were converted to condensed-phase values using a sublimation correction, and detonation properties were estimated via the Kamlet–Jacobs equations. The predicted performance follows the order H4TTP > H2BTTz > H3TTT. Although their detonation performance is lower than that of FOX-7 and CL-20, these nitrogen-rich systems remain promising candidates for reduced-sensitivity energetic materials and merit further experimental investigation.

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  • MakaleAçık Erişim2025Scopus SJRQ4
    DFT Calculations, ADME Analysis and Molecular Docking Studies of the Compound AHTPO With the Digestive Enzyme Trypsin Found in Cold-Adapted Fish Species

    Tanrıverdi, Erdi Anıl; Tanrıverdi, Aslıhan Aycan; Yıldıko, Ümit

    For the special amine 7-Amino-3-(4-aminophenyl)-5H-thiazolo[3,2-a]pyrimidin-5-one (AHTPO), previously reported experimental biological activities served as the foundation for further studies. Computational chemistry and molecular simulation techniques were subsequently applied to investigate AHTPO. Its interactions with trypsin enzymes derived from cold-adapted fish species were examined. The compound's biological activity and pharmacokinetic properties were assessed using DFT calculations, molecular docking, and ADME analyses. Molecular docking results indicated that AHTPO exhibits strong binding affinities with the 1A0J and 2TBS enzymes, with the binding to 2TBS being energetically more favorable. Additionally, ADME analysis revealed that while the AHTPO shows potential for pharmaceutical applications, its gastrointestinal absorption and blood-brain barrier permeability may present certain limitations. Regarding its electronic and optical properties, AHTPO's high dipole moment and polarizability values enhance its flexibility and adaptability in biological environments. The HOMO-LUMO energy gap suggests that the AHTPO achieves a balance between stability and reactivity, enabling high activity in biomolecular interactions. These findings highlight the promising pharmacological potential of AHTPO in binding with trypsin enzymes, suggesting its viability as a therapeutic agent.

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  • MakaleAçık Erişim2025Scopus SJRQ1
    Anticancer (cytotoxic, anticlonogenic, antimetastatic, immunomodulatory actions) properties of 3,5-dibromosalicylaldehyde against glioblastoma cells and DFT analyses (FT-IR, Raman, NMR, UV) as well as a molecular docking study

    Karakaş Sarıkaya, Ebru; Pehlivanoğlu, Suray; Türkmen, Merve Özcan; Ekincioğlu, Yavuz; Kostak, Feyza; Çelik, Sultan; Dereli, Ömer

    Background Information: The primary objectives of this study were to characterize 3,5-dibromosalicylaldehyde (3,5-DBSA) and, investigate its antiproliferative, antimetastatic, cytotoxic, and immunoregulatory properties. NMR, Raman, UV, and FT-IR spectroscopies were used to characterize 3,5-DBSA. Potential conformations of 3,5-DBSA were evaluated using Spartan's MMFF method. Geometry optimization calculations using Gaussian software calculated conformation energy values. Results: Subsequently, Raman, FT-IR, UV (ethanol) and NMR (DMSO) parameters were calculated. The experimental spectrum was compared to theoretical spectroscopic data. The present investigation investigated 3,5-DBSA's anticancer properties; therefore, docking was done once the stable structure had been identified. Conclusion: Identifying stable structure is crucial to molecular docking studies. In order to identify the mechanism by which 3,5-DBSA binds to PI3K as a therapeutic target, molecular docking was utilized. This work is the first to show that 3,5-DBSA is cytotoxic, anticlonogenic, antimetastatic, and immunomodulatory in glioblastoma cell line U87MG compared to healthy fibroblast L929 cells. Cytotoxicity and anti-clonogenicity studies investigated 3,5-DBSA's antiproliferative activities, whereas wound healing assays assessed cell migration. The immunomodulatory effects of 3,5-DBSA in glioblastoma were assessed by measuring Netrin-1 and IL-6 protein levels. According to our findings, 3,5-DBSA may treat glioblastoma. Significance: This work analyzes 3,5-DBSA's conformational search, characterization, molecular docking, and structural and anticancer properties.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
  • MakaleAçık Erişim2025Scopus SJRQ2
    Detailed investigation of the spectroscopic features of nicardipine hydrochloride using experimental and quantum chemical methods

    Can, Sumeyra; Cinar, Mehmet; Baris, Ozlem

    Context: The structural and spectroscopic properties of drug groups can be determined using spectroscopic techniques and quantum chemical calculations. In this study, the structural and spectroscopic properties of nicardipine, a potent calcium channel blocker belonging to the dihydropyridine drug group, were investigated. For this purpose, FT-IR, Raman, NMR, and UV–Vis spectra of nicardipine hydrochloride were recorded. The ground state geometry optimization performed under vacuum conditions showed excellent agreement with X-ray diffraction (XRD) data, with root-mean-square deviations of bond lengths and bond angles calculated as 0.017 Å and 2.2°, respectively. Vibrational spectrum analysis revealed all characteristic modes, and theoretical B3LYP predictions largely agreed with experimental data. NMR spectra recorded in chloroform solvent confirmed the molecular structure of nicardipine. A comparison with previously reported data revealed significant differences in the proton NMR results, while the carbon NMR data showed consistency. The gauge-invariant atomic orbital (GIAO) method, commonly used for NMR spectrum prediction, yielded results within an acceptable error range despite minor inconsistencies arising from differences between experimental and computational conditions. In the UV–Vis spectrum of nicardipine HCl, an absorption peak corresponding to π-π* excitation was observed at 238 nm. Method: The geometric optimizations and vibration spectra of the nicardipine drug molecule were performed using the Gaussian 09 program with the B3LYP functional and the 6–311 + + G(d,p) basis set. Visualizations were performed using the GaussView 5.0 interface program. NMR spectra were recorded in chloroform solvent using the GIAO method. Molecular electrostatic potential (MEP) maps and Mulliken atomic charges were analyzed to gain deeper insight into the electronic properties.

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  • MakaleYalnız künye2024Scopus SJRQ2
    Diltiazem and Verapamil: Combined experimental and computational approaches to structural and spectroscopic characterization

    Cinar, Mehmet; Can, Sümeyra; Baris, Özlem; Demirci, Çiğdem Elif

    Diltiazem and Verapamil are two important drug molecules in a separate group of Calcium Channel Blockers. The purpose of this work is to determine and compare the structural and spectroscopic properties of these two molecules using a number of experimental techniques and quantum chemical calculations. Compounds were characterized spectroscopically using FT-IR, Raman, NMR (1H, 13C, and DEPT), and UV–vis methods. Furthermore, the Density Functional Theory (DFT) method, Becke's three-parameter hybrid functional (B3LYP), and the 6–311++G(d,p) basis set were used to determine the ground state geometric structures of molecules, and the spectroscopic properties of the obtained optimum structures were investigated computationally. The optimization studies performed under vacuum circumstances and for the isolated molecules were found to be very close to the experimental results. In fact, r.m.s. values were discovered for Diltiazem and Verapamil with bond lengths of 0.013 and 0.024, and bond angles of 1° and 2°, respectively. The vibration characteristics of the compounds were discovered using the collected FT-IR and Raman spectra, and significant vibrational modes were assigned. After scaling, it was revealed that the quantum chemical data was congruent with the experimental ones, and that the characteristic vibrational modes were appropriately predicted. DFT calculations effectively determine molecules' structures due to internal consistency, despite being slightly distant from experimental data. Theoretical values for carbon and hydrogen atoms are better in agreement with observed values when scaling with 0.92 and 0.90. From the UV–vis spectra, Diltiazem HCl absorbance peaks were found at 207 and 237 nm, whereas Verapamil HCl absorbance peaks were identified at 203, 229, and 278 nm. When the theoretical calculations and experimental findings were compared, the anticipated absorption peaks were found to have shifted nearer the visible area. Furthermore, Hirshfeld surfaces and Molecular Electrostatic Potential surfaces were obtained and analyzed in order to better understand the electronic characteristics. The TDOS and PDOS (total and partial density of state) spectra were also studied. Finally, using the HOMO and LUMO energy values, the critical chemical parameters were evaluated, and it was discovered that both molecules had positive electron affinity and electronegativity values, indicating that they will accept electrons when the electron-nucleus attraction exceeds the electron-electron repulsion.

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  • MakaleAçık Erişim2024
    Analysis of the nonlinear optical properties, vibrational spectra, DFT method and photovoltaic performance of cyanidin-3-rutinoside chloride

    Sarıkaya, Ebru Karakaş; Ekincioğlu, Yavuz; Bahçeli, Semiha; Dereli, Ömer

    This study aims to identify a cyanidin-3-rutinoside chloride that exhibits both photovoltaic performance and nonlinear optical properties, which may be utilized in the field of optoelectronics. Prior to investigating these properties, the stable structure must be determined. For this purpose, its conformational analysis is performed by the Molecular Force Field method with the spartan program. The exact nature of the stable configuration has been ascertained by empirical evidence. The energy of the stable configuration is -1654184.76 kcal/mol, and its dipole moment is 9.94 Debye. Cyanidin-3-rutinoside chloride has been investigated using experimental FT-IR and Raman spectroscopies. Meanwhile, the DFT method at the B3LYP/6-311 + + G(d, p) level was employed in order to study the simulated FT-IR and Raman spectra, the HOMO-LUMO analysis, the molecular electrostatic potentials (MEP), and the non-linear optical (NLO) characteristics of the title molecule. The HOMO and LUMO energies are − 6.45 and − 3.64 electron volts (eV), respectively, with a gap value of 2.81 eV. Additionally, the title compound’s open-circuit voltage, the transition density matrix light-harvesting efficiency, driving force, and binding energy were calculated with by taking photovoltaic cell properties into account. Furthermore, investigations of hole reorganization energy, electron reorganization energy, and total reorganization energy were carried out at the B3LYP/6-31G(d, p) level for the cyanidin-3-rutinoside chloride of interest. In addition, density of state calculations and NBO were made at the B3LYP/6-31G(d, p) level. We calculated the following values for LHE,,,,, and : 0.06, 2.45 eV, 0.20 eV, 0.56 eV, 0.50 eV, 0.57 eV and 1.06 eV, respectively.

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  • MakaleAçık Erişim2023Scopus SJRQ4
    Theoretical Investigation of (E)-1-(2,4-Dichlorophenyl)-3-[4-(morpholin-4-yl)phenyl]prop-2-en-1-one Molecule As a Possible Potential COVID-19 Drug Candidate: Molecular Docking and DFT Calculations

    Ekíncíoğlu, Yavuz

    Abstract: In this study, a potential new drug to fight against the COVID-19 virus, (E)-1-(2,4-dichlorophen-yl)-3-[4-(morpholin-4-yl)phenyl]prop-2-en-1-one molecule has been investigated via computational assessment and molecular docking approach. From the conformer analysis and optimization, the most stable structure is determined. For this structure, geometrical parameters, Frontier molecular orbitals analysis, chemical reactivity descriptors, nonlinear optical properties, natural bond orbital, mulliken population analysis, molecular electrostatic potential map and thermodynamic properties of molecule were calculated with standard functional at the B3LYP/6-311++G(d,p) method. The geometric parameters (bond lengths and bond angles) are in good agreement with the experimental values available in the literature. The stability, structural and electronic properties obtained for the molecule can be a significant contribution to the future experimental and theoretical studies. The molecular docking mechanisms between the molecule and 7ALI protein points out that the protein-ligand systems are hydrogen bonding, π-stacking, and hydrophobic interactions.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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  • MakaleYalnız künye2015Scopus SJRQ3
    Conformational and spectroscopic behaviors of 2,4-xylyl isothiocyanate

    Cinar, Mehmet; Karabacak, Mehmet; Chand, Satish; Shukla, Vikas K.; Sinha, Leena; Prasad, Onkar; Singh, Manoj Pratap; Asiri, Abdullah M.

    This study aims to identify the conformational and spectroscopic characteristics of 2,4-xylyl isothiocyanate (C9H9NS) compound via experimental and computational methods. To accomplish this, density functional theory (DFT), with the B3LYP functional was used to determine ground state conformation, vibrational wavenumbers and also isotropic chemical shifts of the title molecule. Experimentally, vibrational features of the compound were evaluated by FT-IR and FT-Raman spectroscopic analysis in the solid phase. On the basis of these studies, the conformational and spectroscopic behaviors of 2,4-xylyl isothiocyanate were interpreted. The fundamental vibrational wavenumbers as well as their intensities were computed, and a good correlation between experimental and scaled calculated wavenumbers was observed. The polarizability, first hyperpolarizability and dipole moment values of 2,4-xylyl isothiocyanate were calculated at the same level of theory and basis set. The results show that 2,4-xylyl isothiocyanate molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis.

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  • MakaleYalnız künye2015Scopus SJRQ1
    Spectral features, electric properties, NBO analysis and reactivity descriptors of 2-(2-Benzothiazolylthio)-Ethanol: Combined experimental and DFT studies

    Srivastava, Ruchi; Sinha, L.; Karabacak, M.; Prasad, O.; Pathak, S.K.; Asiri, A.M.; Cinar, M.

    (Chemical Equation Presented). Quantum chemical calculations of ground state energy, geometrical structure and vibrational wavenumbers, nuclear magnetic behaviors, electronic absorption spectra along with the nonlinear optical properties of 2-(2-benzothiazolylthio)-ethanol (BTZTE) were carried out using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The FT-IR and FT-Raman spectra were measuredinthe condensed state. The fundamental vibrational wavenumbers as well as their intensities were calculated, and a good correlation between experimental and scaled calculated wavenumbers was accomplished. The electric dipole moment, polarizability and the first hyperpolarizability values of the BTZTE were calculated at the same level of theory and basis set. The results show that the BTZTE molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis. UV spectrum of the studied molecule was recorded in the region 200-500 nm and the electronic properties were predicted by time-dependent DFT approach. The calculated transition energies are in good concurrency with the experimental data. 1H nuclear magnetic resonance (NMR) chemical shifts of the title molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. The thermodynamic properties of the studied compound at different temperatures were calculated. Global and local reactivity descriptors were computed to predict reactivity and reactive sites on the molecule.

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  • MakaleAçık Erişim2014Scopus SJRQ2
    FT-IR, FT-Raman, NMR, UV and quantum chemical studies on monomeric and dimeric conformations of 3,5-dimethyl-4-methoxybenzoic acid

    Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M.; Cinar, Mehmet; Shukla, Vikas K.

    Extensive spectroscopic investigations along with theoretical quantum chemical studies on 3,5-dimethyl-4-methoxybenzoic acid (DMMBA) have been consummated. The fundamental vibrational transitions were addressed by experimental FT-IR (4000-400 cm-1) and FT-Raman (4000-10 cm -1) techniques and density functional calculations at B3LYP/6-311++G(d,p) and B3LYP/6-311++G(df,pd) levels of theory. The 1H, 13C and DEPT 135 NMR spectra of studied compound were recorded in deuterated dimethylsulfoxide (DMSO-d6), and compared with computed data obtained by using gauge including atomic orbital (GIAO) method. The electronic absorption spectra in methanol and ethanol solution were evaluated in the range of 200-400 nm, and TD-DFT method was chosen for computational study. The spectroscopic and theoretical results were compared to the corresponding properties for monomer and dimer structures for the most stable conformer. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Moreover, the thermodynamic and nonlinear optical (NLO) properties were evaluated.

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  • MakaleAçık Erişim2014Scopus SJRQ2
    Identification of structural and spectral features of synthesized cyano-stilbene dye derivatives: A comparative experimental and DFT study

    Karabacak, M.; Asiri, A.M.; Al-Youbi, A.O.; Qusti, A.H.; Cinar, M.

    The synthesized three dye derivatives of cyano-stilbene monomer were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with the nonlinear optical (NLO) properties of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm-1 and 3600-50 cm-1, respectively. The theoretical ground state equilibrium conformations and vibrational wavenumbers were carried out by using density functional method with 6-311G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The UV absorption spectra of monomers were observed in the range of 200-600 nm in chloroform, acetonitrile and toluene, and time dependent DFT method was used to obtain the electronic properties. The linear polarizability and first hyperpolarizability of the studied molecules indicates that the title compounds can be used as a good nonlinear optical material. A detailed description of spectroscopic behaviors of compounds was given based on the comparison of experimental measurements and theoretical computations.

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  • MakaleYalnız künye2013Scopus SJRQ2
    The infrared, Raman, NMR and UV spectra, ab initio calculations and spectral assignments of 2-amino-4-chloro-6-methoxypyrimidine

    Cinar, Z.; Karabacak, M.; Cinar, M.; Kurt, M.; Chinna Babu, P.; Sundaraganesan, N.

    (Graph Presented) The 2-amino-4-chloro-6-methoxypyrimidine abbreviated as ACMP have been investigated by both the experimental and theoretical methods; through this work we provide the essential fact about the structural and vibrational insights. The optimized molecular structure, atomic charges, vibrational frequencies and ultraviolet spectral interpretation of ACMP have been studied by performing DFT/B3LYP/6-311++G(df,pd) level of theory. The FT-IR, FT-Raman spectra were recorded in the region 4000-400 cm -1 and 4000-50 cm-1 respectively. The UV absorption spectrum of the compound that dissolved in ethanol and water solution were recorded in the range of 200-400 nm. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Based on the UV spectrum and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. The 1H, 13C and DEPT 135 nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated using with the Gauge Including Atomic Orbital (GIAO) method and compared with experimental results. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

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  • MakaleYalnız künye2013Scopus SJRQ2
    Molecular structure, electronic properties, NLO, NBO analysis and spectroscopic characterization of Gabapentin with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations

    Sinha, Leena; Karabacak, Mehmet; Narayan, V.; Cinar, Mehmet; Prasad, Onkar

    Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated.

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  • MakaleYalnız künye2013Scopus SJRQ2
    Experimental and theoretical FTiR and FT-Raman spectroscopic analysis of 1-pyrenecarboxylic acid

    Karabacak, M.; Cinar, M.; Kurt, M.; Chinna Babu, P.; Sundaraganesan, N.

    The title molecule 1-pyrenecarboxylic acid (1PCA) has been characterized by FTiR, FT-Raman, NMR and UV-Vis spectral analyses. The molecular geometry, harmonic vibrational modes, the corresponding wavenumbers and iR intensities of 1PCA were calculated by DFT method with 6-311G(d, p) basis set. The assignments of the fundamentals were proposed on the basis of total energy distribution (TED) calculations. The calculated 13C and 1H NMR chemical shifts using gauge including atomic orbitals (GiAOs) approach are in good agreement with the observed chemical shifts. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. Using TD-DFT method, the electronic transitions have been compared with the experimental wavelengths. The molecular electrostatic potential map was used for prediction of possible hydrogen and oxygen bonding sites 1PCA molecule.

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