Theoretical investigations of nonlinear optical properties of two crystalline acetamides structures including polarization effects of their environment

In silico screening of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate and some of its derivatives for their NLO activities using DFT

The nonlinear optical (NLO) properties of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate (EMAB) and some of its derivatives are investigated herein using the density functional theory (DFT) and time-dependent (TD)-DFT methods. The density functionals B3LYP, CAM-B3LYP, M06-2X and ωB97XD, and basis sets 6-31 + G**, 6-311 + + G** and Def2-TZVPP have been used. From the results, EMAB and its substituted derivatives studied are promising candidates for NLO materials. In all cases, the static first and second hyperpolarizabilities (31.7-86.5 × 10^-30 and 84.4-273 × 10^-36 electrostatic units (esu), respectively) and the frequency-dependent NLO properties are found to be significantly larger (about 43-103 and 28-76 times greater) than those of the NLO prototypical molecule, para-nitroaniline. Furthermore, the maximum absorption wavelengths of the molecules fall within the UV region of the electromagnetic spectrum. Relative to EMAB, the derivatives have shown improved transparency-nonlinearity trade-offs. Natural bond orbital (NBO) and density of states (DOS) analyses herein revealed effective charge transfer within the molecules studied, especially those with stronger electron donors than that in EMAB (methoxy group). Among the molecules studied, the derivative obtained by substituting EMAB's methoxy group with the pyrrolyl group was found to exhibit the best NLO properties. Conclusively, the NLO activities of EMAB can be significantly improved through the substitution of its methoxy group with stronger electron donors.

Remarkable Nonlinear Properties of a Novel Quinolidone Derivative: Joint Synthesis and Molecular Modeling

A novel 4(1H) quinolinone derivative (QBCP) was synthesized and characterized with single crystal X-ray diffraction. Hirshfeld surfaces (HS) analyses were employed as a complementary tool to evaluate the crystal intermolecular interactions. The molecular global reactivity parameters of QBCP were studied using HOMO and LUMO energies. In addition, the molecular electrostatic potential (MEP) and the UV-Vis absorption and emission spectra were obtained and analyzed. The supermolecule (SM) approach was employed to build a bulk with 474,552 atoms to simulate the crystalline environment polarization effect on the asymmetric unit of the compound. The nonlinear optical properties were investigated using the density functional method (DFT/CAM-B3LYP) with the Pople's 6-311++G(d,p) basis set. The quantum DFT results of the linear polarizability, the average second-order hyperpolarizability and the third-order nonlinear susceptibility values were computed and analyzed. The results showed that the organic compound (QBCP) has great potential for application as a third-order nonlinear optical material.

Assessment of the proposed pseudo-potential theoretical model for the static and dynamic Raman scattering intensities: Multivariate statistical approach to quantum-chemistry protocols

Accurate calculation of molecular polarizabilities and Raman intensities required high-level correlated wave functions (CCSD) and large basis set with the inclusion of electronic correlation within experimental precision. These requirements, in terms of time and computation, are economically costly. Polarized Gaussian basis sets adapted to effective core potentials (ECPs) for the static and frequency dependent Raman intensities is presented. The results of the proposed basis sets at CCSD and DFT levels in comparison with Sadlej-pVTZ, as reference basis set, show quite a good quantitative agreement in the properties with a valuable reduction in the computational time and resources. Multivariate principal component analysis (PCA) was performed to study the assessment of the efficiency of proposed methodology and diagnose the inherent information related to the kind of normal vibrational mode of each molecule, based on the variations in the computed Raman intensities. The results, in the form of score-plots, explored a clear segregation and classification among the Raman intensities data, revealing its dependence on the excitation frequencies of laser and nature of the vibrational mode of each molecule of interest. Moreover, the projection of the loadings-plots of the PCs successfully enabled to classify the most correlated computational methods in to the same groups, and made isolations of the less efficient basis functions at the corresponding theoretical method.

Synthesis and structural studies on (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one: a promising nonlinear optical material

A new fluorinated chalcone (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one was synthesized in 90% yield and crystallized by a slow evaporation technique. Its full structural characterization and purity were determined by scanning electron microscopy, infrared spectroscopy, gas chromatography-mass spectrometry, 1H, 13C and 19F nuclear magnetic resonance, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman microspectroscopy, UV-Vis absorption spectroscopy, single crystal X-ray diffraction (XRD) and Hirshfeld surface (HS) analysis. The fluorinated chalcone crystallized in centrosymmetric space group P21/c stabilized by the C-H⋯O and C-H⋯F interactions and the π⋯π contact. The crystalline environment was simulated through the supermolecule approach where a bulk with 378 000 atoms was built. The electric parameters were calculated at the DFT/CAM-B3LYP/6-311++G(d,p) level as function of the electric field frequency. The macroscopic parameters such as linear refractive index and third-order nonlinear susceptibility (χ (3)) were calculated, and the results were compared with experimental data obtained from the literature. The χ (3)-value for the chalcone crystal is 369.294 × 10-22 m2 V-2, higher than those obtained from a few similar types of molecule, showing that the chalcone crystal can be considered as a nonlinear optical material. Also, molecular theoretical calculations such as infrared spectrum assignments, frontier molecular orbital analysis and MEP were implemented, revealing that the most positive region is around the hydrogen atoms of the aromatic rings, and electrophilic attack occurs on the carbonyl group.

Y-shaped potential third-order nonlinear optical material – 3-(2-amino-2-oxoethyl)-5-methyl hexanoic acid: an analysis of structural, spectroscopic and docking studies

The merit of this work is that it has clearly established the structure and the nonlinear optical properties relationship of the title molecule and it could be helpful for developing new nonlinear optical materials.

Theoretical study of solvent effects on the hyperpolarizabilities of two chalcone derivatives

The use of organic as nonlinear optical materials has been intensively explored in the recent years due to the ease of manipulation of the molecular structure and the synthetic flexibility regarding the change of substituent groups. In the present work, the linear and nonlinear properties of two chalcones derivatives (E)-1-(4-methylphenyl)-3-phenylprop-2-en-1-one (4MP3P) and (E)-1-(4-Nitrophenyl)-3-phenylprop-2-en-1-one (4NP3P), that differ by the substituent position at the phenyl ring, were studied in the presence of protic and aprotic solvents simulated by the Polarizable Continuum Model (PCM) at DFT/B3LYP/6-311+G(d) level. The static and dynamic (1064 nm) molecular parameters as the dipole moment, linear polarizability, first and second hyperpolarizabilities were studied as function of the solvent dielectric constant value. The geometrical behavior as the chemical bond angles, torsion angles, and partial charges distribution of the compounds were studied, including calculations of gap energies in various solvents. The obtained results revealed that the substituent change of CH3 (4MP3P) to NO2 (4NP3P) benefits the nonlinear optical properties of the compounds in the presence of the solvent media, the absolute values of the parallel first hyperpolarizability were the ones that present the greater variation.

Chalcone as Potential Nonlinear Optical Material: A Combined Theoretical, Structural and Spectroscopic Study

In this work, we propose the synthesis of a novel bromine chalcone (E)-3-(2-bromophenyl)-1-(2phenylsulfonylamine)-phenyl)prop-2-en-1-one (BRC) that has been crystallized by slow evaporation technique. The second order molecular optical scattering and two-photon absorption(2PA) spectrumof the BRC molecule dissolved in Dimethyl Sulfoxide (DMSO) were evaluated by using Hyper Rayleigh Scattering and femtosecond tunable Z-Scan techniques. The first order hyperpolarizability of BRC dissolved in DMSO was estimated by using a simplified two-level model, in which one- and two-photon absorption parameters were used as input information to the model. The BRC crystal was characterized from single crystal X-ray diffraction (DRX) and spectroscopy analyzes. Also, the thermogravimetric analyses and the fluorescence spectra were obtained. In addition, an ab-initio calculation method, which includes the Møller-Plesset Perturbation Theory (MP2) and the Density Functional Theory (DFT) at CAM-B3LYP level,was used to estimate the crystal linear refractive index and the third-order electric susceptibility. Also, the average first hyperpolarizability of BRC molecules dissolved in DMSO was calculated and compared with the experimental results. The obtained values are good and qualify BRC crystal as a potential candidate for application in nonlinear optical devices.

Using the Supermolecule Approach To Predict the Nonlinear Optics Potential of a Novel Asymmetric Azine

Organic molecules with electron acceptors or withdrawal substituents terminal at π-conjugated system are promising candidates to be explored as materials with high linear and nonlinear optical properties. On the basis of these features, a novel asymmetric azine ( 7E, 8E)-2-(3-methoxy-4-hydroxy-benzylidene)-1-(4-nitrobenzylidene)hydrazineC₁₅H₁₃N₃O₄ (NMZ) was synthesized. The molecular structure of NMZ was elucidated by X-ray crystallography and the supramolecular arrangement was analyzed from Hirshfeld surface methodology. An iterative electrostatic scheme using a super molecule approach, where neighboring molecules are represented by charge points, was employed to investigate optical dipole moment (μ), the linear polarization (α) and the first (β) and second (γ) hyperpolarizabilities. The NMZ crystallized in the centrosymetric space group P2₁/n and packs via combined O-H···O, C-H···O, and N···π interactions. The macroscopic property of third order χ⁽³⁾ found for the NMZ is 298.62 times greater than values reported for chalcone derivative (2 E)-1-(3-bromophenyl)-3-[4 (methylsulfanyl)phenyl]prop-2-en-1-one. The results for NMZ indicate a good nonlinear optical effect.