Potential Nonlinear Optical Material Research Articles

Enhanced non-linear optical properties of porphyrin-based polymers covalently functionalized with graphite phase carbon nitride.

In our work, a flurry of original porphyrin-based polymers covalently functionalized g-C3N4 nanohybrids were constructed and nominated as PPorx-g-C3N4 (x = 1, 2 and 3) through click chemistry between porphyrin-based polymers with alkyne end-groups [(PPorx-C≡CH (x = 1, 2 and 3)] and azide-functionalized graphitic carbon nitride (g-C3N4-N3). Due to the photoinduced electron transfer (PET) between porphyrin-based polymers [PPorx (x = 1, 2 and 3)] group and graphite phase carbon nitride (g-C3N4) group in PPorx-g-C3N4 nanohybrids, the PPorx-g-C3N4 nanohybrids exhibited better non-linear optical (NLO) performance than the corresponding PPorx-C≡CH and g-C3N4-N3. It found that the imaginary third-order susceptibility (Im [χ(3)]) value of the nanohybrids with different molecular weight (MW) of the pPorx group in the nanohybrids ranged from 2.5×103 to 7.0 × 103gmol-1 was disparate. Quite interestingly, the Im [χ(3)] value of the nanohybrid with a pPorx group'sMW of 4.2 × 103gmol-1 (PPor2-g-C3N4) was 1.47 × 10-10 esu, which exhibited the best NLO performance in methyl methacrylate (MMA) of all nanohybrids. The PPorx-g-C3N4 was dispersed in polymethyl methacrylate (PMMA) to prepare the composites PPorx-g-C3N4/PMMA since PMMA was widely used as an alternative to glass. PPor2-g-C3N4/PMMA showed the excellent NLO performance of all nanohybrids with the Im [χ(3)] value of 2.36 × 10-10 esu, limiting threshold of 1.71J/cm2, minimum transmittance of 8% and dynamic range of 1.09 in PMMA, respectively. It suggested that PPorx-g-C3N4 nanohybrids were potential outstanding NLO materials.

Mid-infrared nonlinear optical heptachlorodigallate AGa2Cl7 (A = Ga+, In+) with a unique second harmonic generation mechanism induced by monovalent cations

Nonlinear optical (NLO) anionic group theory holds that the anionic group mainly determines the NLO effect of the materials. The same anionic group basically has similar NLO properties even in different systems, so it is regarded as the “gene” of NLO materials. Isolated monovalent Ga+/In+ cations in the existing AGa2Cl7 (A = Ga+, In+) system carry lone-pair-electronic nonbonding orbitals, which are free between the energy bands near the gap and are not substantially hybridized with the orbitals of anionic [Ga2Cl7]– dimer. Surprisingly, this kind of band structure can significantly enhance the NLO polarizability of both Ga+/In+ cations and [Ga2Cl7]– anionic groups, differing from conventional mechanism of the anionic group theory. First-principles calculations demonstrate that AGa2Cl7 (A = Ga+, In+) indeed exhibits greatly enhanced second harmonic generation (SHG) responses over the analogous KGa2Cl7. The underlying contribution to this unusual enhancement stems not only from the anisotropic distribution of photo-responsive nonbonding electron pairs on Ga+/In+, but also from the synergistic charge transfer effect between cations and anionic groups. Due to the anisotropic induction of Ga+/In+, the same [Ga2Cl7]– anionic group exhibits significantly different SHG effects in different AGa2Cl7 (A = K, Ga, In) systems. This phenomenon is rare and satisfies a unique SHG mechanism, providing insights into NLO crystal physics and novel structural design. Importantly, except for enhanced SHG effects, monovalent Ga+/In+ cations can induce enlarged birefringence, larger than regular tetrahedra-based halides and more conducive to the phase matching. Furthermore, given wide optical transparency and better thermal properties as compared with the infrared NLO benchmark material AgGaS2, the unique AGa2Cl7 (A = Ga+, In+) are predicted as potential mid-infrared NLO materials.

BaSb(H2PO2)3Cl2: An excellent UV nonlinear optical hypophosphite exhibiting strong second-harmonic generation response

Non π-conjugated tetrahedral groups have emerged as potential basic modules for developing ultraviolet (UV) nonlinear optical materials. However, their intrinsic weak hyperpolarizability and small polarizability anisotropy severely restrict the performance of the designed material. Herein, the first antimony hypophosphite, BaSb(H2PO2)3Cl2, was successfully synthesized via rational design, which exhibits superior nonlinear optical properties including strong second harmonic generation response, appropriate birefringence and wide transmittance, indicating it is a potential UV nonlinear optical material. Remarkably, the title compound exhibits the largest nonlinear optical coefficient (5 × KDP) among all reported antimony-based oxyacid compounds. Detailed theoretical calculations confirmed that its excellent nonlinear optical properties are primarily derived from the ordered [Sb(H2PO2)3Cl2]2- anionic clusters composed of [H2PO2]- pseudo-tetrahedra and [SbO3Cl2]5- distorted polyhedra. This work would extend UV nonlinear optical material system to hypophosphites and lead the further inquiry of new structure-driven functional materials.

Tetrahydroxyphthalocyanine as a potential nonlinear optical material

We have synthesized a new zinc(II)-phthalocyanine (ZnPc) incorporating hydroxyl groups at the peripheral positions. This new zinc(II)-tetra-hydroxyphthalocyanine (1) has been characterized by high-resolution MALDI TOF MS, UV-Vis, FT-IR (ATR), and 1H- and 13C-NMR techniques, and further by the electrochemical measurements. DFT and TD-DFT computations were performed to model plausible structure and also analyze the electronic structure and optical properties of 1. The effects of the polarity and hydrogen bonding ability of the hydroxyl substituents on the peripheral positions of 1 on the optical and electrochemical properties are reported in this study. The redox behavior of 1 in dimethyl sulfoxide (DMSO) was determined by voltammetry and colorimetry supported in situ spectroelectrochemistry. The nonlinear absorption and optical limiting (OL) properties of 1 were measured in tetrahydrofuran (THF) by utilizing the open aperture Z-scan technique with nanosecond pulses at 532 nm. The sample demonstrated good reverse saturable absorption and OL behaviors. The ultrafast pump-probe experiments revealed the intersystem crossing (ISC) mechanism (triplet-triplet transition) and the nonlinear absorption mechanism of the compound. The results indicate that this new phthalocyanine (1) can be considered a potential candidate for low-power OL applications.

Eu2P2S6: The First Rare‐Earth Chalcogenophosphate Exhibiting Large Second‐Harmonic Generation Response and High Laser‐Induced Damage Threshold

AbstractMetal chalcogenophosphates are receiving increasing interest, specifically as promising infrared nonlinear optical (NLO) candidates. Here, a rare‐earth chalcogenophosphate Eu2P2S6 crystallizing in the monoclinic noncentrosymmetric space group Pn was synthesized using a high‐temperature solid‐state method. Its structure features isolated [P2S6]4− dimer, and two types of EuS8 bicapped triangular prisms. Eu2P2S6 exhibits a phase‐matchable second‐harmonic generation (SHG) response ≈0.9×AgGaS2@2.1 μm, and high laser‐induced damage threshold of 3.4×AgGaS2, representing the first rare‐earth NLO chalcogenophosphate. The theoretical calculation result suggests that the SHG response is ascribed to the synergetic contribution of [P2S6]4− dimers and EuS8 bicapped triangular prisms. This work provides not only a promising high‐performance infrared NLO material, but also opens the avenue for exploring rare‐earth chalcogenophosphates as potential IR NLO materials.

Eu2 P2 S6 : The First Rare-Earth Chalcogenophosphate Exhibiting Large Second-Harmonic Generation Response and High Laser-Induced Damage Threshold.

Metal chalcogenophosphates are receiving increasing interest, specifically as promising infrared nonlinear optical (NLO) candidates. Here, a rare-earth chalcogenophosphate Eu2 P2 S6 crystallizing in the monoclinic noncentrosymmetric space group Pn was synthesized using a high-temperature solid-state method. Its structure features isolated [P2 S6 ]4- dimer, and two types of EuS8 bicapped triangular prisms. Eu2 P2 S6 exhibits a phase-matchable second-harmonic generation (SHG) response ≈0.9×AgGaS2 @2.1 μm, and high laser-induced damage threshold of 3.4×AgGaS2 , representing the first rare-earth NLO chalcogenophosphate. The theoretical calculation result suggests that the SHG response is ascribed to the synergetic contribution of [P2 S6 ]4- dimers and EuS8 bicapped triangular prisms. This work provides not only a promising high-performance infrared NLO material, but also opens the avenue for exploring rare-earth chalcogenophosphates as potential IR NLO materials.

Chiral {Ni6PW9} Cluster-Organic Framework: Synthesis, Structure, and Properties.

A chiral three-dimensional polyoxometalate cluster-organic framework (POMCOF) H3[(btc)Ni6(μ3-OH)3(H2O)5(B-α-PW9O34)]·17H2O (1, btc = 1,2,4-benzenetricarboxylate) has been made under hydrothermal conditions in the absence of amine or chiral starting reagents. 1 shows high stability in CH3CN/DMF (1:3), acidic, and basic solutions with the pH ranging from 2 to 12 for 5 days. The UV-vis reflectance spectra and Mott-Schottky measurements reveal that 1 could be a suitable catalyst for photocatalysis. Visible-light-driven H2 evolution studies have demonstrated that 1 is an ecofriendly, efficient, and recyclable catalyst with a H2 evolution rate of 1058.24 μmol h-1g-1. Nonlinear optical (NLO) measurement reveals that 1 exhibits a second-harmonic generation (SHG) response of about 1.4 times that of KH2PO4 (KDP), indicating that 1 is a potential NLO material as well.

An investigation on structural, optical and enhanced third order nonlinear optical properties of facilely synthesized Ce:CuS nanosheets

Current work reported facile chemical synthesis of hexagonal covellite CuS nanostructures with 0.0, 1.0, 3.0 and 5.0 wt% cerium doping concentrations. Scherrer’s equation used to determine the crystallites size and preferred orientation of growth plane is found along (110). Raman spectra of CuS nanostructures showed the characteristics sharp peak at the ∼ 472.21 cm−1. SEM images revealed the shape of nanostructures as nanosheets (NSs) for Ce:CuS. The band gap values of Ce:CuS NSs was computed from diffuse reflectance spectra (DRS) using Kubelka-Munk (K-M) theory which was found in range of 1.56–1.85 eV. Red and UV emission band of nanostructures can be seen in Photoluminescence spectra clearly. Third order nonlinear optics were performed by Z-scan techniques via femtosecond fiber pulsed laser. The nonlinear absorption coefficients (β) and nonlinear refractive index (n2) were found in range of 1.14 × 10-8–2.04 × 10-8 cm/W and 1.04 × 10-12–1.38 × 10-12 cm2/W, respectively. The value of third order nonlinear optical susceptibility (χ(3)) was noticed ∼ 3.36 × 10-8–5.48 × 10-8 esu. A significant improvement was observed in χ(3) with Ce incorporation in CuS lattice system. Therefore, Ce doping makes CuS potential nonlinear optical material for modern photonics device applications.

First principles investigations of the structural, electronic, mechanical, linear and nonlinear optical properties of RbIO2F2

Rubidium fluoroiodate has been reported to be a potential mid-infrared nonlinear optical material, due to its second harmonic generation (SHG) and Laser damage threshold value of 156 MW/cm2. In this study, the linear and nonlinear optical properties are investigated and analyzed using the density functional theory by full potential linearized augmented plane wave (FP-LAPW) and plane wave pseudo-potential (PP-PW). The FP-LAPW method is used to study the electronic properties and linear optical properties with the recently developed density functional of Tran and Blaha. Furthermore, optical features such as dielectric functions, absorption coefficient, refractive index, reflectivity, electron energy loss function are calculated for photon energies up to 40 eV. The elasticity, SHG response, linear electro-optical effect, and piezoelectricity are studied by the PP-PW approximation. Based on the semi-empirical relations, the Young's modulus, shear and bulk modulus, Poisson's ratio, anisotropic factors, sound velocities, Debye temperature, and hardness have been determined.

Spin engineering of triangulenes and application for nano nonlinear optical materials design.

The recently synthesized triangulenes with non-bonding edge states could have broad potential applications in magnetics, spintronics and electro-optics if they have appropriate electronic structure modulation. In the present work, strategies based on molecular orbital theory through heteroatom doping are proposed to redistribute, reduce or eliminate the spin of triangulenes for novel functional materials design, and the role of B, N, NBN, and BNB in such intended electronic structure manipulation is scrutinized. π-Extended triangulenes with tunable electronic properties could be potential nonlinear optical (NLO) materials with appropriate inhibition of their polyradical nature. The elimination of spin is achieved by B, N, NBN, and BNB doping with the intended geometric arrangement for enhanced polarity. Intended doping of BNB results in an optimal structure with large static first hyperpolarizability (〈β0〉) as well as strong Hyper-Rayleigh scattering (HRS) βHRS(-2ω; ω, ω) (ω = 1064.0 nm), TG7-BNB-ba with a large 〈β0〉 (18.85 × 10-30 esu per heavy atom) and βHRS (1.15 × 10-28 esu per heavy atom) much larger than that of a synthesized triangular molecule (1.12 × 10-30 esu of 〈β0〉 per heavy atom and 5.04 × 10-30 esu of βHRS per heavy atom). The strong second order NLO responses in the near-infrared and visible regions, particularly the strong sum frequency generation, make these B or (and) N doped triangulenes promising candidates for the fabrication of novel carbon-based optoelectronic devices and micro-NLO devices.

From oxides to oxysulfides: the mixed-anion GeS3O unit induces huge improvement in the nonlinear optical effect and optical anisotropy for potential nonlinear optical materials.

Oxysulfides combining intrinsic performance advantages between sulfides (strong NLO response) and oxides (wide optical bandgap) are proposed as potential infrared (IR) NLO materials. Theoretical calculation shows that the mixed-anion GeS3O tetrahedron has a stronger polarizability anisotropy and hyperpolarizability than that of the typical GeO4 unit. Based on this, two Sr2MGe2S6O (M = Zn, Cd) oxysulfides with the GeS3O unit show dozens of times improvement in critical birefringence and the NLO effect compared with those of isostructural Sr2ZnGe2O7. Moreover, structure–property study further verifies that the mixed-anion GeS3O ligand is a useful NLO-active unit and can offer great influence over the NLO origin. This research result also gives us a feasible design strategy and research system to explore new IR NLO candidates.

Experimental and Theoretical investigations on (E)-3-(4-ethoxyphenyl)-1-(2-(trifluoromethyl)phenyl)prop‑2-en-1-one and (E)-3-(naphthalen-2-yl)-1-(2-(trifluoromethyl) phenyl)prop‑2-en-1-one: DNA binding, Urease inhibition and Promising NLO response

In this work, we are presenting preparation of (E)-3-(4-ethoxyphenyl)-1-(2-(trifluoromethyl)phenyl)prop‑2-en-1-one (1) and (E)-3-(naphthalen-2-yl)-1-(2-(trifluoromethyl) phenyl)prop‑2-en-1-one (2) through Claisen-Schmidt reaction. The synthesized compounds were characterized by different analytical techniques (UV–visible, FT-IR 1HNMR and mass spectrometry). The Urease inhibition, antioxidant potential and DNA binding (Salmon sperm DNA) studies were conducted along with molecular docking for comparative analysis of theoretical and experimental findings. The ADMET properties (An acronym for absorption, distribution, metabolism, excretion, and toxicity) of aforesaid compounds were predicted. Density functional theory (DFT) calculations were performed for FMOs (frontier molecular orbitals) and nonlinear optical (NLO) properties of 1 and 2. Photophysical properties of title compounds were described by time dependent DFT (TD-DFT). Moreover, energy band gaps of aforementioned compounds were determined by Tauc's plot and were found as (3.0 eV) for 1 and (3.4 eV) for 2 respectively. Additionally, natural bond orbitals (NBOs) analysis was applied to evaluate conjugative interactions as well as inter and intra molecular interactions. The results revealed that 1 exhibits higher stabilization energy of electron's delocalization than 2. Moreover, second order NLO properties of 1 (3920.9 a.u.) and 2 (3018.6 a.u.), being much higher than Urea, reflects that synthesized compounds are potential NLO materials. The experimental data showed that the strong interactions of SS-DNA with entitled compounds took place through intercalative mode. Moreover, the synthesized compounds showed moderate behavior towards antioxidant assay and Urease inhibition.

NH4Sb2(C2O4)F5: A novel UV nonlinear optical material synthesized in deep eutectic solvents

The deep eutectic solvents was first employed to solve the hydrolysis of Sb3+ cations in Sb(III)-oxyacid system to explore new nonlinear optical materials, producing a novel antimony(III) fluoride oxalate named NH4Sb2(C2O4)F5. The title compound featured a 3D noncentrosymmetric structure composed of [Sb2(C2O4)F5]- anionic clusters and NH4+ cations. The cooperative effect of the planar π-conjugated [C2O4]2- anionic groups and the Sb3+ cations with stereochemically active lone pairs induce a relatively strong SHG response (1.1×KH2PO4) and a large birefringence (0.111@546 nm), which was confirmed by detailed theoretical calculations. The overall performances indicate that NH4Sb2(C2O4)F5 is a potential ultraviolet nonlinear optical material. The successful application of deep eutectic solvents in the synthesis for easy hydrolytic materials system opens the door to exploring new inorganic solid functional materials.

Physical and theoretical investigations on piperazinium 3,5-dinitrobenzoate (PDNB) single crystal: A potential candidate for third-order nonlinear optical (NLO) applications

A potential third-order nonlinear optical (NLO) material of piperazinium 3,5-dinitrobenzoate (PDNB) has been synthesized from the pure aqueous solution through protonation reaction and its single crystals have been successfully grown by slow evaporation solution technique (SEST) within a span of 75 days. The structural properties of the grown single crystals have been evaluated by single-crystal X-ray diffraction (SXRD) analysis. It reveals that the grown crystal crystallizes in a triclinic crystal system with centrosymmetric space group Pī. The existence of various crystalline planes and phase purity of the title material were confirmed by powder X-ray diffraction (PXRD) analysis with the 2θ scanning range of 10° to 50° The proton (1H1) nuclear magnetic resonance (NMR) spectrum has been recorded to elucidate the molecular structure of the synthesized PDNB material. The presence of multiple functional groups and optical properties of the title material have been evaluated by Fourier transform infrared (FT–IR) and UV–Vis NIR spectroscopy analyses, respectively. The photoluminescence property of the PDNB crystal has been examined by the excitation and emission spectra. The grown crystal possesses good thermal stability (stable upto 197 °C), which is determined by thermogravimetric (TG) and differential thermal analysis (DTA). The grown crystal possesses excellent third-order NLO property when irradiation of He-Ne laser of wavelength 632.8 nm. Theoretical investigations such as optimized geometry, HOMO-LUMO, first-order hyperpolarizability and Hirshfeld surface analyses have been carried out and their interesting results have been discussed. The overall experimental and theoretical results lead to conclude that the title PDNB single crystal is a potential candidate for the NLO and optoelectronic applications.

Quantum chemical studies on structural, spectroscopic, nonlinear optical, and thermodynamic properties of the 1,2,4-triazole compound

AbstractIn this study, the structure of 4-[4-(diethylamino)-benzylideneamino]-5-benzyl-2H-1,2,4-triazol-3(4H)-one (DBT) was examined through spectroscopic and theoretical analyses. In this respect, the geometrical, vibrational frequency,1H and13C-nuclear magnetic resonance (NMR) chemical shifts, thermodynamic, hyperpolarizability, and electronic properties including the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energies of DBT as a potential non-linear optical (NLO) material were investigated using density functional theory at the B3LYP level with the 6-311G basis set.1H and13C-NMR chemical shifts of DBT with the gauge-invariant atomic orbital and continuous set of gauge transformation methods (in the solvents) were estimated, and the computed chemical shift values displayed excellent alignment with observed ones. Time-dependent density-functional theory (TD-DFT) calculations with the integral equation formalism polarizable continuum model within various solvents and gas phases in the ground state were used to evaluate UV-vis absorption and fluorescence emission wavelengths. Thermodynamic parameters including enthalpy, heat capacity, and entropy for DBT were also calculated at various temperatures. Moreover, calculations of the NLO were carried out to obtain the title compound’s electric dipole moment and polarizability properties. To illustrate the effect of the theoretical method on the spectroscopic and structural properties of DBT, experimental data of structural and spectroscopic parameters were used. The correlational analysis results were observed to indicate a strong relationship between the experimental and theoretical results.

A Potassium Tungsten Oxyfluoride with Strong Second-Harmonic Generation Response Derived from Anion-Ordered Functional Motif.

The unity of structure-property design and practical synthesis is a key to develop nonlinear optical (NLO) materials. However, many designed structures are hard to get because of the incapability of controlling the arrangement of structural motifs. After careful synthesis, we successfully obtained a new NLO crystal with expected properties, KWO3F, which features a long-range anion-ordered while directed parallel arrangement of [WO5F] d0 transition metal fluorooxo-functional (d0 [TMOF]) motifs. This arrangement is vital to achieve a strong second-harmonic generation (SHG) response, which is proved by dipole moment analyses and theoretical calculations. Remarkably, KWO3F possesses a strong phase-matching SHG response (3 × KDP), high thermal stability (stable up to 350 °C in air), a large laser damage threshold (LDT, 129.7 MW/cm2), a wide transparent window (0.5-10 μm), and a suitable birefringence (0.088 @ 1064 nm). Our research demonstrated that the introduction of the NLO-active d0 [TMOF] motif is an effective strategy to design new potential NLO materials.

In situ growth of an ethyl p-hydroxybenzoate single crystal by the vertical Bridgman technique: a potential nonlinear optical material for third-harmonic generation

Optically transparent single crystals of ethyl p-hydroxybenzoate (EPHB) were successfully grown by the vertical Bridgman technique. The crystalline phase and unit-cell dimensions were obtained from powder X-ray diffraction using Rietveld analysis. The presence of defects and grain boundaries was investigated by high-resolution X-ray diffraction. The optical quality of the grown single crystal was assessed by UV–Vis and photoluminescent spectroscopies. A blue emission, with a bi-exponential decay time, was obtained from time-resolved photoluminescence upon laser excitation at 266 nm. The mechanical strength of the EPHB single crystal was studied by Vickers hardness testing. A decrease in the laser-damage threshold was observed with a nanosecond Nd:YAG laser source for increased pulse repetition rates. The third-order nonlinearity, nonlinear absorption coefficient and nonlinear refractive index were measured using the Z-scan technique with a femtosecond Ti:sapphire laser. The third-order nonlinear coefficient values for the grown crystal were compared with those of a potassium dihydrogen phosphate single crystal.

Two Ni-Substituted Trilacunary Keggin-Type Polyoxometalates: Syntheses, Crystal Structures, NLO Studies, and Magnetic Properties.

Two Ni-substituted polyoxometalates (NiSPs), [Ni6(Py)6(H2O)5(μ3-OH)3(PW9O34)]2·10H2O (1), [Ni7(Py)6(Im)(H2O)5O(WO4)(μ3-OH)3(H2PW9O34)]·3H2O (2) (Py = pyridine, Im = imidazole), were successfully hydrothermally synthesized. Compounds 1 and 2 have significantly different configurations by introducing different amounts of imidazole ligands. For compound 1, two malposed {Ni6(Py)6PW9} units that are face to face are bridged by two Ni-O-W bonds to constitute an isolated dimeric structure. Differently, the {Ni7(Py)6(Im)PW9}2 dimer in compound 2 connects with four adjacent dimers by four {WO4} groups in an interesting two-dimensional (2-D) arrangement. The magnetism of compounds 1 and 2 was studied, and magnetic test results demonstrated that both compounds have ferromagnetic interactions between the nickel centers. Meanwhile, the third-order nonlinear optical (NLO) measurements indicated that compound 1 can serve as potential nonlinear optical materials.

Investigation on nucleation, growth and physical properties of low soluble 4-N, N-dimethylamino-4-N’-methylstilbazolium 4-aminotoluene-3-sulfonate crystal – A potential NLO material

Terahertz generation requires materials with excellent nonlinear optical (NLO) properties and environment stability. 4-N, N-dimethylamino-4-N’-methylstilbazolium 4-aminotoluene-3-sulfonate (DAAS) an organic ionic compound is found to match these conditions but it is one of the sparingly soluble compounds among the stilbazolium derivatives causing difficulty in crystal growth. Therefore, in this article, the nucleation and growth kinetics of DAAS in different solvents are examined in order to understand and improve its crystal growth. The structural properties like symmetry, hydrogen bonding that contribute to crystal growth and morphology are studied and discussed. As nonlinear optical properties in organic compound is affected by vibration of the molecules, the existence of functional groups and various modes of vibration present in the molecule are identified and categorized by Fourier transform infrared (FT-IR) and FT-Raman analyses. Linear optical properties of the DAAS at molecular level, liquid and solid phases are investigated using density functional theory and UV-Visible spectroscopic technique. The NLO properties of DAAS molecule like the first order hyperpolarizability and mean polarizability is predicted using density function theory and the second harmonic generation efficiency is determined using Kurtz powder test. The thermal stability of DAAS is compared with other highly nonlinear optical stilbazolium derivatives.

Structural, thermal, dielectric, nonlinear optical properties and DFT investigations of a novel material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide for optoelectronic applications

A new organic nonlinear optical (NLO) material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide (CDA) has been synthesized by reflux method. Single crystals were grown by slow evaporation technique and the crystal structure was elucidated by single crystal X-ray diffraction method. Density functional theory (DFT) calculations at B3LYP/6–31+ + G(d, p) basis set was used to predict the molecular geometry and were carried out further to comprehend the electronic structure, vibrational spectra, natural bonding orbitals (NBO), frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP). An optical transparency at the cut-off wavelength of 355 nm was determined by UV–Vis–NIR spectroscopy. Thermal behavior of CDA was studied by TGA/DTA analysis. The dielectric constant (e), dielectric loss (tan δ) and AC conductivity as a function of frequency and temperature was studied. Second Harmonic Generation (SHG) efficiency of the CDA was determined using Kurtz and Perry powder technique and was 0.5 times greater than that of the KDP crystal. The third-order nonlinear optical properties were investigated in solution by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title compound exhibited significant two-photon absorption (β = 2.228 × 10–4 cm W−1), nonlinear refraction (n2 = 1.095 × 10–8 cm2 W−1) and optical limiting (OL threshold = 2.511 × 103 W cm−2) under the CW regime. The nonlinear optical parameters were calculated using time-dependent Hartree–Fock (TDHF) method. The overall obtained results suggested that the studied CDA molecule could be a potential NLO material for frequency generator, optical limiters and optical switching applications.