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Prediction of Structural, Vibrational and Nonlinear Optical Properties of Small Organic Conjugated Molecules Derived From Pyridine
摘要： Nonlinear optical (NLO) effects of organic materials are caused by delocalized electrons and large polarization in molecules. In the present work, theoretical study by using the Density Functional Theory (DFT) at B3LYP/6-311G(d,p) level of theory on three types of pyridine derivates 2,6-dimethoxy-3,5-dinitropyridine (M1), 2-methoxy-3-nitropyridine (M2) and 2-methoxy-5-nitropyridine (M3) is reported. The nuclear magnetic resonance (1H- and 13C-NMR) chemical shifts of the title compounds were calculated using the Gauge Independent Atomic Orbital (GIAO) method and compared to the observed results. Both infrared absorption and Raman are complementary to provide characteristic fundamental vibrations that are necessary for the identification of the molecular structures. Electronic properties such as frontier molecular orbital (HOMO, LUMO), ionization potential (IPad) and electronic affinity (EAad) were determined to get better insight into the molecular properties. Using the Time-Dependent Density Functional Theory (TD-DFT), electronic absorption spectra have been predicted and closely matching the experimental findings. The natural bonding orbital (NBO) calculations were performed in order to elucidate various second order interactions in between the filled and vacant orbitals which are a measure of the intermolecular as well as the delocalization within the molecule. In addition, we have demonstrated that these molecular systems have large first static hyperpolarizabilities and may have potential applications in the development of NLO materials.
关键词： NLO properties,Electronic properties,DFT,Optical spectra,NBO
更新于2025-09-23 15:23:52
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Spectroscopic behavior, FMO, NLO and NBO analysis of two novel aryl boronic acid derivatives: Experimental and theoretical insights
摘要： Here we report, experimental and theoretical determination of ground and excited state dipole moments of aryl boronic acid derivatives, 2-Bromophenyl boronic acid (2BPBA) and 2-Isopropylphenyl boronic acid (2IPBA). In both the compounds, Bathochromicshift is observed with increasing solvent polarity indicating π →π* transition due to intermolecular charge transfer interactions. For both the compounds, the ground and excited sate dipole moments are parallel to each other. The excited state dipole moment (μe) is greater than ground state dipole moment (μg) for the compound 2IPBA where as for 2BPBA, excited state dipole moment (μe) is less than ground state dipole moment (μg). Further, experimentally obtained Δμ are compared with those using microscopic empirical solvent polarity (??????). In parallel, the use of Kamlet-Taft parameters to the solvent effect on spectral properties of 2BPBA and 2IPBA are also discussed. The molecular structure, Frontier Molecular Orbitals (FMO), Natural Bond Orbital (NBO) analysis, Non-Linear Optical (NLO) properties of 2BPBA and 2IPBA have been investigated using the (DFT) calculations with B3LYP/6?311++G (d, p) basis set. The chemical reactivity and kinetic stability of the compounds is shown by differences between the energy levels by analyses of Frontier molecular orbitals. The polarizability and hyperpolarizability computations determine the NLO properties, whereas Natural bond orbital (NBO) analysis showed proton transfer within the selected donor-acceptor depicting large energy of stabilization for the compounds under study.
关键词： Kamlet-Taft,FMO,MEP,ground and excited state dipole moments,Solvatochromic shift method,NBO and NLO
更新于2025-09-23 15:23:52
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Exploring the spectral features and quantum chemical computations of a novel biologically active heterocyclic class of compound 2MEFPBA dye: Experimental and theoretical approach
摘要： Here we report, experimental and theoretical determination of ground and excited state dipole moments of the class of heterocyclic compound namely 2-Methoxy-5-fluoro phenyl boronic acid (2MEFPBA) dye. Bathochromic shift with increasing solvent polarity is observed indicating π →π* transition due to intermolecular charge transfer interactions. The ground and excited state dipole moments are found to be parallel to each other. The molecular structure, Frontier molecular orbital (FMO), Natural bond orbital (NBO) analysis and Nonlinear optical (NLO) properties of 2MEFPBA have been investigated using the Density Functional Theory with B3LYP/6?31 ++ g(d, p) basis set. Chemical reactivity and kinetic stability of 2MEFPBA are analyzed using F M O energy. Polarizability and hyperpolarizability computations are used to determine the NLO properties, whereas Natural bond orbital (NBO) analysis showed the proton transfer within the selected donor-acceptor depicting large energy of stabilization for the compound under study.
关键词： MEP,NBO,FMO,Solvatochromic ground and excited state dipole moments,and NLO.
更新于2025-09-23 15:22:29
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Enhanced photoelectrochemical performance of plasmonic Ag nanoparticles grafted ternary Ag/PaNi/NaNbO3 nanocomposite photoanode for photoelectrochemical water splitting
摘要： In this work, we have successfully synthesized silver nanoparticles (Ag-NPs) decorated binary PaNi/NBO nanocomposite by facile chemisorption route and demonstrated enhanced photoelectrochemical (PEC) water splitting activity. The ternary Ag/PaNi/NBO nanocomposite photoanode exhibits ~5 fold higher current density than pristine NaNbO3 nanofibers (NBO-NFs). The ternary Ag/PaNi/NBO photoanode exhibits a current density of 5.93 mA/cm2 at 0.9 V with respect to Ag/AgCl, whereas the pristine NBO-NFs photoanode exhibits only 0.85 mA/cm2 at 0.9 V. The improved performance is correlated to the high surface area, formation of the type-II heterojunction among PaNi and NBO-NFs and the introduction of the plasmonic behaviour of Ag-NPs as it expands the absorption of the visible part of the solar spectrum, which together decreases the recombination of charges with strong redox capability. Furthermore, the ternary Ag/PaNi/NBO photoanode showed lower charge transfer resistance (Rct) in the EIS measurements and improved incident photon to current efficiency (IPCE) of ~31.3% which is ~23% higher to the IPCE of bare NBO-NFs photoanode. Thus, these results suggest that the ternary Ag/PaNi/NBO nanocomposite is a promising material for PEC activity and wide practical applications.
关键词： Water Splitting,Silver nanoparticle,PaNi,NaNbO3,Ag/PaNi/NBO
更新于2025-09-23 15:19:57
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Significance of five membered heterocycles in fine tuning of HOMO-LUMO gap of simple donor-acceptor system as organic solar cell material: A DFT approach
摘要： The significance of five membered heterocycles in simple donor-acceptor system was elaboratively studied by density functional theory (DFT) and time dependent density functional theory (TDDFT). By effectively substituting eight different rings the HOMO-LUMO gap can be reduced considerably. The nuclear independent chemical shift (NICS) calculations help to predict the aromaticity of central heterocyclic systems. The natural bond orbital (NBO) analysis reveals the charge contribution. The close observation of frontier molecular orbitals (FMO) gives a detailed explanation of delocalization.
关键词： NICS,DFT,NBO,TDDFT,HOMO-LUMO
更新于2025-09-23 15:19:57
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NBO, nonlinear optical and thermodynamic properties of 10-Acetyl-10H-phenothiazine 5-oxide
摘要： In this paper, natural bond orbital (NBO) analysis, nonlinear optical and the thermodynamic properties of 10-Acetyl-10H-phenothiazine 5-oxide have been analyzed by employing density functional theory level employing 6-311++G(d,p) basis set. NBO analysis reveals that the intra- intermolecular charge transfer occurs within the molecule leading to the stabilization. The predicted nonlinear optical properties (NLO) like; polarizability and first hyperpolarizabiliy support that the molecule could attract the interests for future investigation.
关键词： DFT,Nonlinear optical and thermodynamic properties.,NBO,APTZ
更新于2025-09-10 09:29:36
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Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach
摘要： Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π – bridge, donor group and LUMO are localized on π – bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π – bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π–bridge display an enhanced optoelectronic properties than with less π – bridge.
关键词： Thiophene oligomer,TDDFT,π – bridge,PCM,NBO
更新于2025-09-09 09:28:46
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Molecular properties, crystal structure, Hirshfeld surface analysis and computational calculations of a new third order NLO organic crystal, 2-aminopyridinium benzilate
摘要： A third order nonlinear optically active (NLO) organic proton transfer compound was synthesized by the reaction between 2-aminopyridine and benzilic acid. Single crystals of the product, 2-aminopyridinium benzilate, (2-APB) were grown by slow evaporation technique and the structure of 2-APB was confirmed by single crystal X-ray diffraction. In the structural network, cations and anions are linked through N+-H…O- intermolecular hydrogen bonding interactions. Elemental analysis, thermal analysis, UV-Vis, FT-IR and 1H and 13C NMR spectroscopic analyses were carried out to assess the structure and chemical makeup of the 2-APB crystal. Computational studies that include optimization of molecular geometry, natural bond orbital (NBO), Mulliken atomic charge and HOMO-LUMO analyses were also performed using B3LYP method at 6-311+ G (d,p) level of theory to explore various intermolecular interactions especially hydrogen bonding. Hirshfeld surface analysis indicates that the contacts involving hydrogen such as H…H, C…H and O…H have greater influence on the molecular properties of 2-APB.
关键词： NBO analysis,Hydrogen bonding,DFT,Single crystal XRD,Hirshfeld surface analysis
更新于2025-09-04 15:30:14
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Spectroscopic Investigation of the Stimulus of NLO Property on Acetone Thiosemicarbazone Using Computational [HF and DFT] Confinement
摘要： In this attempt of research work, the inducement of NLO property on the compound Acetone thiosemicarbazone has been analyzed using computational calculations. The FT-IR, FT-Raman, FT-NMR and UV-Visible spectra have been recorded in specified region. The optimized inducement of NLO activity by the molecular structural deformation due to the addition of acetone compound has been investigated. The supportive analyses such as Mulliken charge levels, first order and second order polarization, vibrational confirmation, frontier molecular interactions, thermodynamic function (Gibbs energy) and VCD profile for proving NLO mechanism in the compound have been carried out. The chemical environment of the compound was simultaneously monitored by simulating and recording 1H and 13C NMR spectra. The isotropic and anisotropic chemical shift related to carbons and hydrogens after the formation of target compound have been carefully interpreted. The stabilization of orbitals by interchanging of energy between donor and acceptor was observed by NBO perturbation calculations.
关键词： NLO activity,Acetone thiosemicarbazone,Isotropic,NBO perturbation,VCD
更新于2025-09-04 15:30:14