Solvent Media on Nonlinear Optical Properties of Triarylmethane Dye via Facile Z-Scan Method.

Solvent environment on third-order nonlinear optical (TNLO) features of triarylmethane dye namely, basic blue 7 in different solvents is reported herein using 650 nm diode laser with continuous wave mode. The basic blue 7 dye is dissolved in different solvent media including ethanol, methanol, dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). The influence of solvent characteristics such as solvent polarizability and dipole moment on solute molecule is discussed. TNLO characteristics such as nonlinear optical index of refraction, nonlinear optical coefficient of absorption, real and imaginary components of the TNLO susceptibility are measured to be the order of 10‒7 cm2/W, 10‒3 cm/W, 10‒6 esu and 10‒7 esu, respectively. The dye exhibits large TNLO susceptibility by dissolving in DMSO. The TNLO susceptibility of basic blue 7 dye is measured to be the order of 10‒6 esu. The overall results revealed that the basic blue 7 dye is suitable material for optoelectronics applications.

A Critical Review on Therapeutic Potential of Benzimidazole Derivatives: A Privileged Scaffold.

Benzimidazole nucleus is a predominant heterocycle displaying a wide spectrum of pharmacological activities. The privileged nature of the benzimidazole scaffold has been revealed by its presence in most small molecule drugs and in its ability to bind multiple receptors with high affinity. A literature review of the scaffold reveals several instances where structural modifications of the benzimidazole core have resulted in high-affinity lead compounds against a variety of biological targets. Hence, this structural moiety offers opportunities to discover novel, better, safe and highly potent biological agents. The goal of the present review is to compile the medicinal properties of benzimidazole derivatives with a focus on SAR (Structure-Activity Relationships).

Saturable and Reverse Saturable Absorption Features of Lissamine Green Dye in Different Solvent Media.

Organic dyes have shown a remarkable nonlinear optical (NLO) characteristics under low power laser regime because of chemical stability, large nonlinearity and high susceptibility. With this view in mind, herein we report the third-order NLO features of lissamine green dye using 5 mW power laser with operating wavelength of 650 nm. The lissamine green dye is dissolved into various polar solvents such as ethanol, methanol, acetone and DMSO. The closed aperture Z‒scan approach discloses the information about nonlinear refractive index, whereas the open aperture Z‒scan technique provides the information about nonlinear absorption coefficient. The closed aperture curve shows the peak-valley transmittance is the result of self-defocusing nonlinearity and the open aperture transmittance curve switchover from saturable absorption to reverse absorption in high polar solvent due to polarizability and dipole moment. The third-order NLO features such as nonlinear refractive index (n2), nonlinear absorption coefficient (ß), real and imaginary features of third-order NLO susceptibility of the dye is calculated to be the order of, 10-7 cm2/W 10-3 cm/W, and 10-7 esu respectively. The correlation between solvent polarizability and dipole moment on lissamine green dye is discussed. The results are revealed that the lissamine green dye is a good candidate for NLO applications.

DFT studies on vibrational spectra, HOMO-LUMO, NBO and thermodynamic function analysis of cyanuric fluoride.

In this work, the theoretical vibrational spectral characteristics of cyanuric fluoride (C3N3F3) have been investigated and compared with existing experimental results. The density functional theoretical (DFT) computations were performed at the B3LYP level with the basis sets 6-31G(d,p) and 6-311++G(d,p) levels to derive the optimized geometry, vibrational wavenumbers with IR intensities of cyanuric fluoride. In addition, the molecular orbital calculations such as Natural Bond Orbitals (NBOs), HOMO-LUMO energy gap and Mapped molecular Electrostatic Potential (MEP) surfaces were also performed with the same level of DFT. Electronic stability of the compound arising from hyper conjugative interactions and charge delocalization were also investigated based on the natural bond orbital (NBO) analysis. Effective stabilization energy E((2)) connected with the interactions of the π and the lone pair of electrons was determined by the NBO analysis. Mulliken population analysis on atomic charges is also calculated. The thermodynamic properties of the cyanuric fluoride at different temperatures have also been calculated for the range of temperature 50-1000 K.

Density functional theory studies on molecular structure, vibrational spectra and electronic properties of cyanuric acid.

The present work has been carried out a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of cyanuric acid. The FT-IR (100-4000cm(-1)) and FT-Raman spectra (400-4000cm(-1)) of cyanuric acid were recorded. In DFT methods, Becke's three parameter exchange-functional (B3) combined with gradient-corrected correlation functional of Lee, Yang and Parr (LYP) by implementing the split-valence polarized 6-31G(d,p) and 6-31++G(d,p) basis sets have been considered for the computation of the molecular structure optimization, vibrational frequencies, thermodynamic properties and energies of the optimized structures. The density functional theory (DFT) result complements the experimental findings. The electronic properties, such as HOMO-LUMO energies and molecular electrostatic potential (MESP) are also performed. Mulliken population analysis on atomic charges is also calculated. The first order hyperpolarizability (ßtotal) of this molecular system and related properties (ß, µ and Δα) are calculated using DFT/B3LYP/6-31G (d,p) and B3LYP/6-311++G(d,p) methods. The thermodynamic functions (heat capacity, entropy and enthalpy) from spectroscopic data by statistical methods were also obtained for the range of temperature 50-1000K.

Experimental and theoretical spectroscopic analysis, HOMO-LUMO, and NBO studies of cyanuric chloride.

The vibrational spectral analysis of cyanuric chloride was carried out by using FT-Raman and FT-IR spectra in the range 100-4000cm(-1) and 400-4000cm(-1) respectively. The structure optimization was done and structural characteristics were determined by Density Functional Theory (B3LYP) method with 6-31G(d,p) and 6-311++G(d,p) basis sets. The vibrational wavenumbers have been calculated and scaled values are compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED). The Natural bonding orbital (NBO) analysis performed to confirm the stability of the molecule arising from hyper conjugation and delocalization. The Mulliken atomic charges were also calculated. The computed HOMO-LUMO energy gap shows that charge transfer occurs within the molecule. The thermodynamic properties at different temperatures have been calculated from the vibrational analysis.

Molecular structure and vibrational spectroscopic investigation of melamine using DFT theory calculations.

The FT-Raman and FT-IR spectra for melamine have been recorded in the region 4000-100cm(-1) and 4000-400cm(-1), respectively compared with the harmonic vibrational frequencies calculated using density functional theory method (B3LYP) by employing 6-31G(d,p) and 6-311++G(d,p) basis set with appropriate scaling factors. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values. The experimental geometrical parameters prove satisfactory concurrence with the theoretical prediction from DFT. The scaled vibrational frequencies seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms have been constructed and compared with the experimental FT-Raman and FT-IR spectra. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs in the molecule. The first order hyperpolarizability ßtotal of this molecular system and related properties (α, ß, µ and Δα) are calculated using DFT/B3LYP/6-31G(d,p) and 6-311++G(d,p) basis set based on the finite-field approach. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Thermodynamic properties like entropy, heat capacity and zero-point energy have been calculated for the molecule.

Study of vibrational spectra, normal coordinate analysis and molecular structure of 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine using density functional theory.

In the present analysis, the FT-IR, FT-Raman spectra of 6-(2,3-dichlorophenyl)-1,2,4 triazine-3,5-diamine (DCTDA) have been recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The stable structure geometry of the isolated molecule in the gas phase was investigated theoretically using density functional theory (B3LYP) with 6-311G(d,p) basis set. The assignment of the vibrational spectra has been calculated to aid with normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). UV-Vis spectra of the compound was recorded in water solvent and the electronic properties, such as HOMO and LUMO energies were calculated by time-dependent density functional theory (TD-DFT) approach. The various intramolecular interactions which are responsible for the stabilization of the molecule were revealed by the natural bond orbital analysis. The molecule orbital contributions are studied by density of energy states (DOS). The other molecular properties like molecular electrostatic potential (MEP), NLO and thermodynamic properties of the title compound at different temperatures have been calculated. Finally the calculation results were applied to stimulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Normal coordinate analysis, molecular structure, vibrational and electronic spectral investigation of 7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethylpurine-2,6-dione by ab initio HF and DFT method.

In the present work, the characterization of 7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethylpurine-2,6-dione (7DDMP26D) molecule was carried out by quantum chemical method and vibrational spectral techniques. The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectra of 7DDMP26D were recorded in solid phase. The UV-Vis absorption spectrum of the 7DDMP26D was recorded in the range of 200-400 nm. The molecular geometry, harmonic vibrational frequencies and bonding features of 7DDMP26D in the ground state have been calculated by HF and DFT methods using 6-31G(d,p) basis set. The complete vibrational frequency assignments were made by normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The molecular stability and bond strength were investigated by applying the natural bond orbital analysis (NBO). The electronic properties, such as excitation energies, absorption wavelength, HOMO and LUMO energies were performed by time-depended DFT (TD-DFT) approach. The other molecular properties like electrostatic potential (ESP), Fukui function and thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the calculation results were analyzed to simulate infrared, FT-Raman and UV spectra of the title compound which shows better agreement with observed spectra.

Normal coordinate analysis and vibrational spectroscopy (FT-IR and FT-Raman) studies of (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid using ab initio HF and DFT method.

The FT-IR and FT-Raman spectra of (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid (2ADMA) were recorded in the region 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The geometrical structure, harmonic vibrational frequency, infrared intensity, Raman activities and bonding features of this compound was carried out by ab initio HF and DFT methods with 6-31G (d,p) basis set. The complete vibrational frequency assignments were made by normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The electric dipole moment (µ) and the first-order hyperpolarizability (ß(0)) values have been the computed quantum mechanically. The calculated HOMO and LUMO energies show that, the charge transfer occurs within the molecule. The charge delocalizations of these molecules have been analyzed using NBO analysis. The solvent effects have been calculated using TD-DFT in combination with the polarized continuum model (PCM), and the results are in good agreement with experimental measurements. The other molecular properties like Mulliken population analysis, electrostatic potential (ESP) and thermodynamic properties of the title compound at the different temperatures have been calculated. Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which shows good agreement with observed spectra.

Cytomorphological and molecular diversity in backcross-derived inbred lines of sunflower (Helianthus annuus L.).

A set of 250 distinct, stable, and uniform backcross-derived inbred lines were developed in sunflower through 5 interspecific cross combinations involving 4 wild diploid annual species (Helianthus argophyllus, H. petiolaris, H. annuus, and H. debilis). The presence of the wild-species genome in these inbred lines was confirmed through higher chromosome associations (tri- and quadrivalents) at diakinesis. Maximum structural rearrangements of chromosomes were observed in lines derived from H. petiolaris. Forty morphologically diverse inbred lines along with 2 controls were subjected to measurements of phenotypic and genetic distance using 118 simple sequence repeat (SSR) markers of known map location. A total of 204 alleles were identified and the number of alleles per locus varied between 2 and 5. There were 46 unique alleles and the number of unique alleles was highest in the lines derived from the cross involving H. petiolaris. The polymorphism information content (PIC) values ranged from 0.05 to 0.575. The pair-wise comparison values based on genetic dissimilarity estimates computed using molecular marker data varied between 0.143 and 0.486 among the 42 lines. The results indicate that the sunflower gene pool could benefit from introgression of novel alleles from the latent genetic diversity present in the wild species and particularly through exploitation of the diploid annual H. petiolaris.