NLO Activity Research Articles

Study of the nonlinear optical properties of 4-nitroaniline type compounds by density functional theory calculations: Towards new NLO materials

Abstract In the present work, the values of dipolar moment, linear polarizability, first hyperpolarizability, energies of electronic hyperconjugation, and HOMO-LUMO gaps were determined for investigate the nonlinear optical properties of 18 4-nitroaniline type compounds. For this purpose, the finite field approximation and the Natural Bond Orbital method were used, performing the electronic calculations at the DFT level using the chemical model B3LYP/6-311++G(d,p). The NBO analysis revealed the occurrence of multiple interactions by orbital overlap involving strong intramolecular charge transfer, which is believed to contribute to the NLO activity of the nitro-aniline type derivatives. The properties calculated in this work suggest that several of the studied compounds could exhibit better NLO properties than the reference materials (urea, KDP and 2M4NA), which leads to the possibility of considering some of the compounds studied here as candidates to be experimentally tested in applications such as laser devices and materials for optical information processing.

Quantum chemical studies on 4-(2, 6-diphenylpyridin-4-yl) phenol: An electron transport and nonlinear optical molecule

The present article describes a combined experimental and computational study of 4-(2, 6-diphenylpyridin-4-yl) phenol, denoted as TAP. The TAP has been synthesized and characterized using IR, 1H NMR, and single crystal XRD analysis. Single crystal analysis showed that the crystal belongs to monoclinic system and P21/c space group. The existence of three phenyl rings in a plane is expected to show good NLO activity. Ab initio quantum chemical calculations on the title compound have been performed by density functional theory (DFT) using B3LYP method with 6–31G basis set. First order hyperpolarizability has been predicted, the molecule showed good SHG activity, suggesting that the title compound is a suitable organic NLO active material. Molecular Electrostatic Potential (MEP) analysis showed both electronegative and electropositive potential sites in the molecule. Topology of HOMO-LUMO showed a marked energy gap (3.07eV) indicating the possibility of the molecule to be used as electron transport material.

An experimental and computational approach to electronic and optical properties of Diglycine barium chloride monohydrate crystal: Applications to NLO and OLED

Diglycine Barium Chloride Monohydrate have been synthesized and characterized by the 13C and 1H NMR spectroscopy and single crystal X-ray structural studies with a detailed analysis of Hirshfeld surface and fingerprint plots facilitating the interactions within the crystal structure. The Protonated NH⋯O and intermolecular interaction responsible for the NLO activity are studied using DFT studies as well as experimental spectroscopic techniques. The molecular geometry, first & second hyperpolarizability studies and harmonic vibrational wavenumbers were calculated using density functional theory with B3LYP/SDD methods. The detailed interpretation of the vibrational spectra (FTIR and Raman) was carried out with the Normal Coordinate Analysis (NCA) following the scaled quantum mechanical force field methodology. The inter and intra molecular interactions responsible for the stabilization of the molecule were revealed by the NBO and AIM analyses. Photoluminescence spectrum shows that the luminescence is at the blue region. The observed saturable absorption and self-defocusing effect lead to optical limiting action at 532 nm for a CW diode-pumped Nd: YAG laser (50 mW) beam. Optical nonlinearity studies (z-scan) give the nonlinear refractive index, nonlinear absorption coefficient, third order nonlinear susceptibility, second order hyperpolarizability and optical limiting. The obtained results indicate that the synthesised compound is a good candidate for optical limiting and OLED applications.

Growth, characterization, NLO and biological activities of Fe(III) ions doped Mn(II) L-Histidine hydrochloride monohydrate crystals

Powder XRD, EPR, optical,NLO activity and Biological activities of Fe(III)doped Mn(II)L-Histidine Hydrochloride Monohydrate (LHICl) was carried out at room temperature to ascertain the structural properties. In EPR, the angular variation of Fe(III) hyperfine lines indicated a single site, with spin Hamiltonian parameters (g) values g = 2.0292, The calculated results of the Fe(III)doped Mn(II)L-substitutes the Fe(III) ion in the host lattice, and it has orthorhombic symmetry. The EPR evaluated lattice cell parameters, a = 1.5320, b = 0.8450 and c = 0.6834 nm and V = 884.69 Å3 and optical absorption data Dq = 700, B= 610, C= 2360 [α] = 90 cm-1 were corroborated to obtain various bonding parameters, from which the nature of bonding in the complex was discussed. FT-IR and powder XRD studies were used to observe the effect of dopant on structural parameters of the host lattice.

Stereoselective green synthesis and molecular structures of highly functionalized spirooxindole-pyrrolidine hybrids – A combined experimental and theoretical investigation

Highly functionalized spirooxindole-pyrrolidine hybrids have been synthesized stereoselectively through a [3 + 2] cycloaddition strategy in an ionic liquid, 1-butyl-3-methylimidazolium bromide ([bmim]Br). The structure of these spiro heterocyclic hybrids was elucidated using one and two dimensional NMR spectroscopy, single crystal X-ray crystallographic studies and Density Functional Theory (DFT) calculations. The calculated geometric parameters are in good agreement with the experimental data obtained from the X-ray structures. The Natural Bond Orbital (NBO) calculations on these molecules confirm the electron rich carbonyl oxygen and electron deficient NH groups. The 1H and 13C NMR chemical shifts calculated using GIAO method are in good agreement with the experimental data. The DFT computed polarizability values also suggest the possible NLO activity of these molecules.

Studies on Molecular Structure and Vibrational Spectra of NLO Crystal L-Glutamine Oxalate by DFT Method

Objectives: To explicate structural features of L-GLUTAMINE OXALATE (LGO) using vibrational spectroscopic methods and DFT computations. To identify the functional groups and hydrogen bonding interactions of the molecule by recording FTIR and FT-Raman spectra. To confirm NLO activity by performing SHG test. Methods/Statistical Analysis: Crystals were grown by slow evaporation method and characterized by powder X-Ray diffraction method. FTIR, FT-Raman, UV-Vis analysis and second harmonic generation test were predicted. DFT analysis using Gaussian’09 program package were performed to confirm the NLO properties theoretically. Findings: Lowering of HOMO-LUMO energy gap value explains the intramolecular charge-transfer interaction which indicates NLO property. Second Harmonic Generation of the sample shows good nonlinearity of the sample. Application/Improvements: LGO sample shows good NLO Properties and can be used in optical field.

Thermally induced crystallization, hole-transport, NLO and photovoltaic activity of a bis-diarylamine-based push-pull molecule

The synthesis of a molecule constituted of two diarylamine-based push-pull chromophores covalently linked via their nitrogen atom is described. Comparison of the electronic properties with the parent monomer shows that dimerization has negligible influence on the electronic properties of the molecule but exerts a dramatic impact on the capacity of the material to self-reorganize. Application of thermal annealing to thin films induces the crystallization under original morphologies, a process accompanied by a partial bleaching of the absorption in the visible range and by a huge increase of hole-mobility. X-ray diffraction data on single crystals reveal the presence of π-stacked organization with a non-centrosymmetric co-facial arrangement of the dipoles which leads to intrinsic 2nd order bulk NLO properties of thin films as evidenced by second harmonic generation under 800 nm laser light. The implications of this thermally induced crystallization on the photovoltaic properties of the material are discussed on the basis of preliminary results obtained on simple bilayer organic solar cells.

Growth and characterization of dl-Mandelic acid (C6H5CH(OH)CO2H) single crystal for third-order nonlinear optical applications

An organic conjugated chromophore dl-mandelic acid (DLMA) single crystal was synthesized and grown-up by means of slow evaporation technique. Single crystal X-ray diffraction study proclaimed that the DLMA crystal crystallized in monoclinic system with centrosymmetric space group P21/c. The various characteristic fundamental vibration frequencies were identified by FTIR spectroscopic studies. UV–visible spectral analysis concluded that the lower cut-off wavelength and calculated direct optical band gap of DLMA as 257 nm and 5.40 eV respectively. Thermal property of dl-mandelic acid was established through thermogravimetric and differential scanning calorimetric technique. The electric field response of DLMA crystal was investigated from the dielectric studies at a few selected temperatures and frequencies. The quantum chemical assessments such as HOMO-LUMO, molecular electrostatic potential and NLO activity were calculated and presented. In order to determine mechanical strength of DLMA crystal for various loads using Vickers microhardness tester. The real and imaginary parts of the third-order susceptibility (χ3) were evaluated with the Z-scan technique using closed and open signatures respectively and was found to be Re (χ3) = 4.15 × 10−6 esu and Im (χ3) = 0.47 × 10−6 esu.

Investigations on the growth, optical, mechanical, thermal and nonlinear behavior of transition metals doped anthracene crystals

Transition metal doped anthracene single crystals were grown by the slow evaporation method. The increase of crystallinity with metal doping was confirmed from the diffraction analysis. The optical and spectral properties showed some interesting activities and compared with those of as grown crystal to discuss the influence of dopants. The effectiveness of metal doping was confirmed from the photoluminescence intensity around blue emission (λ ≈ 419 nm). Dominant stability with lower melting point was observed for the metal doped crystals than pure as inferred from the micro hardness and thermo gravimetric analysis respectively. Third order nonlinearites of grown crystals were studied as a function of several variables such as refractive index, absorption coefficient, real and imaginary parts of susceptibilities. Evolved NLO activity for the doped single crystals made it as a promising photonics application.

Studies on synthesis, structural, luminescent and thermal properties of a new non-linear optical crystal: 4-amino-4H-1,2,4-triazol-1-ium-3-hydroxy-2,4,6-trinitrophenolate

A new organic proton transfer complex having NLO activity, 4-amino-4H-1,2,4-triazol-1-ium-3-hydroxy-2,4,6-trinitrophenolate (ATHTP), was crystallized to investigate the factors which stabilize the structure of the crystal. The compound crystallizes in triclinic system with space group P-1. Elemental analysis, thermal analysis, UV–Vis–NIR, FT-IR and NMR spectral analyses were carried out to characterize the crystal. Optical, spectral and thermal properties of the title crystal were analyzed to recommend the material for optical applications. Z-scan was used to measure the effective third-order nonlinear optical susceptibility and nonlinear refractive index. The crystal structure was determined using single crystal XRD method and the structure was optimized using Gaussian 09 program at B3LYP/6-311++G(d,p) level of basis set. This hydrogen bond interactions led to the increase in first-order hyperpolarizability of ATHTP and was 30 times greater than that of urea. Hirshfeld analyses surface analysis was carried out to explore intermolecular interactions in the crystalline state.

An experimental and theoretical study on a novel donor-π-acceptor bridge type 2, 4, 5-trimethoxy-4′-chlorochalcone for optoelectronic applications: A dual approach

In this article the authors aim is to investigate and analyze the various key parameters of an organic D-π-A type novel nonlinear optical material 2, 4, 5-trimethoxy-4′-chlorochalcone (2,4,5TMCC) through experimental and quantum chemical studies. The Claisen–Schmidt condensation reaction mechanism was applied to synthesize the 2,4,5TMCC compound and its single crystal was grown by a slow evaporation solution growth (low cost) technique. The crystal structure was confirmed by powder X-ray diffraction analysis. The robust vibrational study has been done using FT-IR and FT-Raman spectra and its NLO activity was discussed. The factor group analysis was also performed. The optical absorption spectrum was recorded and the band gap was calculated to be 2.8eV. In photoluminescence spectrum, an intense emission band at ~540nm has been observed which shows that the grown crystals can be used in green organic light emitting diodes and laser applications. To achieve the stable ground state molecular geometry of 2,4,5TMCC, the computational techniques were applied at different levels of theory using 6-31G* basis set. The calculated geometrical parameters and vibrational spectra are found to be in good agreement with the experimental results. To probe the optical properties of the title compound the time dependent density functional theory was applied. The excitation wavelength was observed at ~398.63nm calculated at B3LYP/6-31G* level of theory and found close to experimental value (i.e. 396nm). The static first hyperpolarizability value is found to be 136 times higher than prototype urea molecule. Additionally, the molecular level approach was attained as HOMO–LUMO gap and electrostatic potential maps. The DSC study reveals that the titled material is stable up to 149°C. The photophysical and nonlinear optical properties suggest that the titled material could be a better choice for the fabrication of optoelectronic devices.

Physico-chemical studies of the experimental and theoretical properties of organic nonlinear optical material 4-chloro-4'methoxy benzylideneaniline

The FT-IR, FT-Raman and UV–visible spectral analysis of 4-chloro 4’-methoxy benzylidene aniline were done experimentally and interpreted with the aid of normal coordinate analysis based on density functional theory (DFT) at the B3LYP/6–311++G (d, p) level of theory. Natural Bond orbital analysis was performed to understand the charge transfer interactions and reactive sites within the system. HOMO-LUMO analysis and first static and dynamic hyperpolarizability calculations were carried out in order to confirm the NLO activity of CMOBA. Photophysical characterization was done to understand the fluorescence emission and lifetime of CMOBA leading to application in blue OLEDs. The Molecular Electrostatic Potential Map was simulated to identify the active sites for electrophilic and nucleophilic attack or the active sites of the molecule which can bind to proteins. Molecular docking analysis revealed its potential as an inhibitor for different proteins which are responsible for cancer and many inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, Crohn's disease and psoriasis. Experimental studies of invitro antiproliferative effect by MTT assay verified the anticancer properties of CMOBA.

Synthesis, structural and optical properties, ferromagnetic behaviour, cytotoxicity and NLO activity of lithium sulphate doped l-threonine

Lithium Sulphate doped l-threonine (Li2SO4-LT), a semi-organic crystal, has been synthesised and grown by slow evaporation technique at room temperature. The grown crystal was subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Li2SO4-LT crystal belongs to the orthorhombic crystal system (a=7.66Å, b=5.11Å, c=13.60Å) with space group P212121. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) study was carried out to quantify the concentration of lithium element in the grown crystal. The results show that 0.07mol of lithium sulphate has been incorporated into the parent system. The grown material has been found to possess wide transparency in the range 240–1100nm with lower cut-off wavelength at 240nm. The optical band gap was calculated as 4.92eV using optical absorption spectrum and Tauc's relation. Fourier transform infrared (FTIR) spectroscopic study was performed to identify the functional groups present in the grown crystal. The surface features of the grown crystal were analyzed using Scanning Electron Microscope (SEM) analysis. The magnetic property was studied with the help of Vibrating Sample Magnetometer (VSM). The coercivity and retentivity of the material were measured from the hysteresis curve as 550.06G and 79.50×10−6emu respectively. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay method was performed to understand the cytotoxicity or anticancer activity of the sample. The cell viability and cytotoxicity of the sample against MCF-7 cells were estimated as 49.41% and 50.59% respectively at a concentration of 250μg. The second harmonic generation (SHG) efficiency was measured by the Kurtz powder technique using Nd:YAG laser and was found to be 1.46 times that of standard potassium dihydrogen phosphate (KDP).

Vibrational and structural observations upon 3-((1H-benzo[d]imidazol-1-yl)methyl)naphthalen-2-ol from spectral and DFT computing approaches

An aggregate of experimental and computational study on synthesis, molecular structure, vibrational, electronic, nuclear magnetic resonance spectra, electronic structure, NLO activity and thermochemical characterization has been investigated for 3-((1H-benzo[d]imidazol-1-yl)methyl) naphthalen-2-ol (BDMN). The perspective on structural analysis includes the examination of equilibrium geometry, Natural Bond Orbital analysis (NBO), molecular electrostatic potential (MEP) analysis and frontier molecular orbital calculation. Similarly the following spectral analysis such as vibrational (FT-IR and FT-Raman), electronic (UV–Vis) and NMR (1H and 13C) has been interpreted. The FT-IR, FT-Raman spectrum were recorded in the frequency range of 4000–400 cm−1 and 4000–50 cm−1 respectively. A complete potential energy distribution (PED) was achieved to interpret the normal modes by comparing the experimental and theoretical spectral data. The simulation of NMR spectrum was performed using GIAO strategy. The NLO activity of BDMN has been calibrated using hyperpolarizability. In addition, various thermodynamic entities were predicted against different temperatures. The entire computation was executed using appropriate model chemistries such as B3LYP/Sadlej pVTZ, B3LYP/6-311G(d,p) and PBEPBE (TDDFT)/6-311G(d,p) for the respective properties. The overall hand-in-hand analysis by using both theoretical and experimental calculation on BDMN provides interesting observations and inferences.

Vibrational, NMR and UV–Visible spectroscopic investigation, VCD and NLO studies on Benzophenone thiosemicarbazone using computational calculations

In order to explore the unbelievable NLO property of prepared Benzophenone thiosemicarbazone (BPTSC), the experimental and theoretical investigation has been made. The theoretical calculations were made using RHF and CAM-B3LYP methods at 6-311++G(d,p) basis set. The title compound contains CS ligand which helps to improve the second harmonic generation (SHG) efficiency. The molecule has been examined in terms of the vibrational, electronic and optical properties. The entire molecular behavior was studied by their fundamental IR and Raman wavenumbers and was compared with the theoretical aspect. The molecular chirality has been studied by performing vibrational circular dichroism (circularly polarized infrared radiation). The Mulliken charge levels of the compound ensure the perturbation of atomic charges according to the ligand. The molecular interaction of frontier orbitals emphasizes the modification of chemical properties of the compound through the reaction path. The enormous amount of NLO activity was induced by the Benzophenone in thiosemicarbazone. The Gibbs free energy was evaluated at different temperature and from which the enhancement of chemical stability was stressed. The VCD spectrum was simulated and the optical dichroism of the compound has been analyzed.

Evans hole and non linear optical activity in Bis(melaminium) sulphate dihydrate: A vibrational spectral study

Bis(melaminium) sulphate dihydrate (BMSD), an interesting melaminium derivative for nonlinear optical activity, has been subjected to vibrational spectral analysis using FT IR and FT Raman spectra. The analysis has been aided by the Potential Energy Distribution (PED) of vibrational spectral bands, derived using density functional theory (DFT) at B3LYP/6-31G(d) level. The geometry is found to correlate well with the XRD structure and the band profiles for certain vibrations in the finger print region have been theoretically explained using Evans hole. The detailed Natural Bond Orbital (NBO) analysis of the hydrogen bonding in BMSD has also been carried out to understand the correlation between the stabilization energy of hyperconjugation of the lone pair of donor with the σ∗ orbital of hydrogen-acceptor bond and the strength of hydrogen bond. The theoretical calculation shows that BMSD has NLO efficiency, 2.66times that of urea. The frontier molecular orbital analysis points to a charge transfer, which contributes to NLO activity, through N–H…O intermolecular hydrogen bonding between the melaminium ring and the sulphate. The molecular electrostatic potential (MEP) mapping has also been performed for the detailed analysis of the mutual interactions between melaminium ring and sulphate ion.

Assessment of long-range corrected and conventional DFT functional for the prediction of second – Order NLO properties and other molecular properties of N-(2-cyanoethyl)-N-butylaniline – A vibrational spectroscopy study

Vibrational spectral analysis and quantum chemical computations based on density functional theory have been performed on the N-(2-cyanoethyl)-N-butylaniline. The geometry, structural properties, intermolecular hydrogen bond, and harmonic vibrational frequencies of the title molecule have been investigated with the help of DFT (B3LYP) and LC-DFT (CAM-B3LYP) method. Molecular electrostatic potential (MEP) have been performed. The various intramolecular interactions have been exposed by natural bond orbital analysis. The distribution of atomic charges and bending of natural hybrid orbitals also reflect the presence of intramolecular hydrogen bonding. Global reactivity and local reactivity descriptors of the title molecule have been calculated. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicated the electron transport in the molecule and thereby NLO activity. The effect of solvent on second-order NLO properties has been studied using polarized continuum model (PCM) in the tetrahydrofuran (THF) solution. The solvent leads to a slight enhancement of the NLO responses for the studied complexes relevant to their NLO responses in gas phase. The electronic absorption spectra were investigated by the TDDFT methods. The frequency-dependent first hyperpolarizabilities of the N-(2-cyanoethyl)-N-butylaniline were also evaluated. The 1H and 13C NMR chemical shifts have been calculated by gauge-indepedent atomic orbital (GIAO) method with B3LYP/6-311++G(d, p) approach.

Synthesis and spectroscopical study of rhodanine derivative using DFT approaches

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of (E)-5-benzylidene-2-thioxothiazolidine-4-one (E5BTTO) have been investigated experimentally and theoretically based on Density Functional Theory (DFT) approach. The FT-Raman and FT-IR spectra of E5BTTO were recorded in solid phase. Theoretical calculations were performed at the DFT level using the Gaussian 03 program. The experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumber by their Total Energy Distribution (TED). The results of the calculation were applied to simulate infrared and raman spectra of the title compound which showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. Stability arising from hyperconjugative interactions leading to its NLO activity and charge delocalization were analyzed using Natural Bond Orbital (NBO) analysis.

Spectroscopic Investigation of the Stimulus of NLO Property on Acetone Thiosemicarbazone Using Computational [HF and DFT] Confinement

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.

Synthesis, characterization and DFT studies of two new silver(I) complexes with 3,4-lutidine

The synthesis, characterization and molecular structure of two new Ag(I) complexes with 3,4-lutidine (34lut) have been reported. The [Ag(34lut)3(OAC)]; 1 and [Ag(34lut)2(TFA)]; 2 complexes, where OAC and TFA are acetate and trifluoroacetate respectively, have been characterized using elemental analysis, FTIR, NMR and mass spectra. Their molecular structures were calculated using DFT quantum chemical calculations. Both 1 and 2 were found to have distorted tetrahedral geometry around the Ag(I). The spectroscopic properties of the studied complexes have been calculated using the same level of theory. The Infrared vibrational frequencies of the COO stretches confirmed that the OAC is monodentate in 1 while the TFA is bidentate in 2. The calculated polarizability (α0) and HOMO–LUMO energy gap (ΔE) values indicated that 1 has higher NLO activity than 2. The electronic spectra of these complexes are calculated using the TD-DFT calculations. The calculated 1H NMR chemical shift values using GIAO approach showed good correlations with the experimental data. The interaction energies using the second order perturbation theory have been used to study the different intramolecular charge transfer interactions in the studied complexes. The NBO calculations indicated that both the AgO bonds are almost identical in 2 but not in 1.