Electric properties of the 3-methyl-4-nitropyridine-1-oxyde (POM) molecules in solid phase: A theoretical study including environment polarization effect

First-principles evaluation of the second harmonic generation response of reference organic and inorganic crystals

Using the CRYSTAL17 package at the coupled-perturbed Kohn-Sham (CPKS) level, periodic boundary conditions first-principles calculations are enacted to predict the second harmonic generation second-order nonlinear optical (NLO) susceptibility, χ⁽²⁾, values of six historical NLO crystals. This selection allowed the comparison between state-of-the-art calculations and experiment. Several computational aspects are tackled to define conditions where the results are converged with respect to the range of lattice summations, to the number of k-points in the first Brillouin zone, to the order of the multipole expansions for evaluating the long-range part of the electrostatic interactions, as well as to the atomic basis set size. A valence triple zeta basis set supplemented with polarization functions has been selected. Then, χ⁽²⁾ calculations have been performed using a range of exchange-correlation functionals (XCFs). Results show the large impact of the amount of Hartree-Fock (HF) exchange on the amplitude but also on the sign on the χ⁽²⁾ tensor components. To a given extent, these amplitude effects are consistent with results on molecules, but the sign reversal effects and the non-monotonic behavior of the χ⁽²⁾ tensor components as a function of the amount of HF exchange are scarcely found for molecules. Then, using the recommended range-separated hybrid XCFs, the CPKS scheme leads to good agreement with experimental data for potassium dihydrogenophosphate, urea, and χ_ZXX ⁽²⁾ of LiNbO₃. The agreement is more questionable for χ_ZZZ ⁽²⁾ of LiNbO₃ whereas it remains poor for ammonium dihydrogenophosphate and 2-methyl-4-nitroaniline, with large underestimations by about a factor of 3, opening a path to further fine-tuning of the ranges of inclusion of HF exchange.

Hyperpolarizability studies and Hirshfeld surface analysis of two heterocyclic chalcones

In this work, the nonlinear optical (NLO) properties of two heterocyclic chalcones, (E)-1-(5-chlorothiophen-2-yl)-3-(thiophen-2yl)-2-propen-1-one (CLTT) and (E)-1-(5-methylfuran-2-yl)-3-(5-methylthiophen-2-yl)prop-2en-1-one (2MFT), are investigated. Using an iterative electrostatic embedding approach via the Møller-Plesset perturbation (MP2) theory, the chalcone crystals were simulated and the polarization effects on the isolated molecules are investigated. The electrical parameters of CLTT and 2MFT as dipole moment and linear polarizability were calculated via MP2/6-311++G(d) and the second hyperpolarizability was obtained via DFT/CAM-B3-LYP/6-311++G(d) level. A significant influence of the molecular packing on the chalcone electric parameters was observed. The static linear refractive index and the third-order electric susceptibility of the compounds were calculated and compared with experimental results available for other chalcone derivatives, indicating the CLTT crystal as a promising candidate for NLO applications in photonic and optoelectronic devices. The Hirshfeld surface analysis has been used to quantify the intermolecular interactions of the molecular crystals. Additionally, the solvent medium effects on the electrical properties of the heterocyclic chalcones were also studied.

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.