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 (ε), 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.

     

Bulk crystal growth,spectral, optical,thermal, electrical and third-order NLO properties of benzylidene malononitrile derivative single crystal: a promising material for nonlinear optical device applications

Bulk organic intramolecular charge transfer nonlinear optical single crystal of 2-(2,4-dimethoxybenzylidene) malononitrile (DMM) with the sizes of 24?×?18?×?13 mm³ have been successfully grown by slow evaporation solution growth technique at 35 °C using acetone as the solvent. The lattice parameters of the grown DMM crystal was evaluated by single crystal X-ray diffraction analysis. The optical transmittance (T) data was taken from the well-polished crystal of DMM, and cut-off wavelength (λ?=?483 nm) was identified by UV–Vis spectral studies. Thermal stability and melting point (145.78 °C) were studied with TGA–DSC analysis. The low value of the dielectric constant (ε_r) of DMM suggests that the crystal can be used in the microelectronics industry. The laser-induced damage threshold experiment shows that the grown DMM bulk crystal possess an excellent resistance to laser radiation with a high threshold up to 1.75 GW/cm², much larger than those of several known organic and inorganic NLO materials. The DMM crystal exhibits positive optical non-linearity and reverse saturation absorption. It also exhibited a nonlinear refractive index (n₂) in the order of 10^?11 m²/W, a nonlinear absorption coefficient (β) in the order of 10^?5 m/W, third order non-linear susceptibility (χ⁽³⁾) in the order of 10^?5 esu and a second-order molecular hyperpolarizability (γ) in the order of 10^?33 esu. All the above results indicate that DMM has a potential application as a useful NLO candidate.     

Large third-order nonlinearity of nonpolar A-plane GaN film at 800 nm determined by Z-scan technology

We report an investigation on the optical third-order nonlinear property of the nonpolar A-plane GaN film. The film sample with a thickness of ~2?μm was grown on an r-plane sapphire substrate by metal-organic chemical vapor deposition system. By performing the Z-scan method combined with a mode-locked femtosecond Ti:sapphire laser (800?nm, 50?fs), the optical nonlinearity of the nonpolar A-plane GaN film was measured with the electric vector E of the laser beam being polarized parallel (//) and perpendicular (⊥) to the c axis of the film. The results show that both the third-order nonlinear absorption coefficient β and the nonlinear refractive index n₂ of the sample film possess negative and large values, i.e. β_//?=??135?±?29?cm/GW, n_2//?=??(4.0?±?0.3)?×?10^?3?cm²/GW and β_⊥?=??234?±?29?cm/GW, n_2⊥?=??(4.9?±?0.4)?×?10^?3?cm²/GW, which are much larger than those of conventional C-plane GaN film, GaN bulk, and even the other oxide semiconductors.     

Direct Measurements of the Strong Refractive Nonlinearity of Impurity Origin in Heavily-doped GaAs

Abstract

A strong dispersive nonlinearity below the band gap in heavily doped bulk n-GaAs is observed for differnet donor impurities. Negative refractive index changes of up to ?5 × 10^?3 are obtained in the spectral range 880–900 nm, induced by light of the same wavelength at an incident intensity of about 5 × 10⁵ W cm^?2. Since the lifetime of the nonlinearity is ～ 10^?10 s, it is suggested that a bistable device exploiting this effect could be constructed with a switching energy of (1?5) × 10^?14 J μm^?2.     

Structural,optical, electrical properties of new hybrid organic–inorganic NLO single crystal: bis(1H-benzotriazole) hexaaqua-zinc bis(sulfate) tetrahydrate (BZS)

A new hybrid organic–inorganic nonlinear (NLO) single crystal, Bis(1H-benzotriazole) hexaaqua-zinc bis(sulfate) tetrahydrate (BZS), has been successfully synthesized and the single crystals were grown by slow evaporation solution growth technique (SESG) using Millipore water as a solvent. The structure of the BZS crystal was solved and refined by single-crystal X-ray diffraction and demonstrates that the grown crystals belong to a triclinic system with the space group P-1. The asymmetric part of the titled compound contains isolated organic cation (C₆H₆N₃)₂, metallic cation [Zn(H₂O)₆]²⁺, sulfate anion (SO₄)^2? and free H₂O molecules. The interplay between the wide number of intermolecular interaction such as O–H···O, N–H···O, C–H···O and π–π stacking interactions were discussed. The optical transmittance spectrum shows that the crystal is excellent transmittance in the entire Vis–NIR region with the cutoff wavelength at 345 nm. The presences of expected functional groups were identified by Fourier transform infrared spectroscopy. The dielectric measurements were carried out at different temperature in the frequency range 100 Hz–5MHz. Furthermore, the studies of its third-order NLO properties using a Z-scan technique demonstrate that the BZS crystal possesses a strong reverse saturable absorption (RSA) and the self-focusing (SF) nature with large second order hyperpolarizability (γ?=?6.24?×?10^?34 esu). All the results indicate that BZS crystal might be the potential candidate for the third-order NLO applications.     

Nonlinear Refraction and Absorption in 4BCMU Planar Waveguides at 1·064 μm Wavelength

Abstract

We have measured the nonlinear refractive index, n ₂, and two-photon absorption coefficient, β, in 4BCMU planar waveguides at 1·064 μm wavelength using picosecond pulses. We use a beam propagation code, with n ₂ and β as fitting parameters, to make numerical comparison with the experimental data. Deduced values from this analysis are n₂ = ? 1·5 × 10^?13 cm²W^?1, confirming the negative sign of the nonlinearity at this wavelength, and β = 0·01 cm MW^?1.     

Nonlinear optical and optical limiting properties of phthalocyanines in solution and thin films of PMMA at 633 nm studied using a cw laser

We present our results on nonlinear optical (NLO) and optical limiting properties of Tetra tert-butyl phthalocyanine and Zinc tetra tert-butyl phthalocyanine studied at 633 nm using a continuous wave laser. We have evaluated the sign and magnitude of the third-order nonlinearity from the closed aperture Z-scan data while the nonlinear absorption properties were assessed using the open aperture data. We have observed low power optical limiting, with low limiting thresholds, based on nonlinear refraction in both the samples. We also present results on the NLO properties of the same dyes doped in Polymethylmethacrylate (PMMA). These studies indicate that both the phthalocyanines are potential candidates for low power optical limiting applications.     

Organic materials for nonlinear optics

This review discusses nonlinear optical (NLO) polymeric materials. As an example of a second-order NLO material, a novel copolymer with a diazo dye attached is investigated. The second-order NLO coefficient χ⁽²⁾ of the copolymer reaches 1.0 × 10^?6 esu, which is 7 times larger than that of LiNbO₃. A third-order NLO coefficient χ⁽³⁾ larger than 10^?10 esu is obtained for polymers where NLO dyes are introduced into the polymer backbone. The optical transmission loss of these polymers is revealed to be around 2 dB/cm. As these polymers can be formed into channel waveguides using the photo-bleaching technique, they show promise for use in NLO devices because of their processability, transparency and large optical nonlinearity.     

Microwave-assisted biosynthesis of gold–silver alloy nanoparticles and determination of their Au/Ag ratio by atomic absorption spectroscopy

In this investigation, our research interest focused on the microwave-assisted biosynthesis of Au–Ag alloy nanoparticles and their purification and characterisation. Dextrose and the ethanol extract of black tea (Camellia sinensis) were used as natural reducing agents for preparing Au–Ag alloy nanoparticles under microwave irradiation. The synthesised alloy nanoparticles were further purified with the agarose gel electrophoresis technique. The characterisation of the separated nanoparticles as particle shapes, size and their chemical composition was studied with UV–Vis spectroscopy, transmission electron microscopy and atomic absorption spectroscopy. Purified Ag–Au alloy nanoparticles were spherical in the size range of ≤200?nm, and possessed an average size of 92?nm. The results of atomic absorption spectroscopy show the presence of both metals (gold and silver) in the purified bimetal nanoparticles at a molar ratio of 3?:?1. Although we selected the Au³⁺/Ag⁺ mixture solution with a molar ratio of 1/1, we did not obtain Au–Ag alloy nanoparticles with the same portion. In the further investigation using resolution IV 2^(4?1) fractional factorial design, we established that the final concentrations of glucose and plant extract should be considered the main significant parameters affecting the Ag/Au ratio in the Ag–Au alloy nanoparticles.     

Enhancement of PMMA nonlinear optical properties by means of a quinoid molecule

In this paper we present the study of the linear and nonlinear optical properties of organic films based on mixing a polymeric matrix (PMMA) and a highly nonlinear organic material recently synthesised and characterised, namely (5,5^′-Bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-5,5^′-dihydro-2,2^′-bithiophene), with the prospective of reaching a good compromise between good processability and high nonlinear optical (NLO) properties of the solid solution. Linear optical characterisation is performed by means of variable angle spectroscopic ellipsometry in the spectral range between 260 and 1700 nm. Third order NLO properties of the samples have been investigated by third harmonic generation at fundamental wavelength of 1500 nm. Different guest/host concentrations have been studied. Due to the high solubility of the guest into the polymeric matrix, we have been able to reach concentration up to 50% in weight, reaching an enhancement of the NLO properties of PMMA by three order of magnitudes.     

In vitro and in vivo effects of morin on the intestinal absorption and pharmacokinetics of olmesartan medoxomil solid dispersions

Abstract

Purpose: In-situ evaluation to corroborate morin effects on the intestinal absorption and pharmacokinetic behavior of freeze-dried OLM-loaded solid dispersions with Caco-2 and in-vivo studies

Methods: Intestinal transport and absorption studies were examined by Caco-2 permeability, in-situ single pass perfusion and closed-loop models along with in-vivo pharmacokinetic studies to evaluate and confirm the effect of P-gp-mediated activity of morin. We evaluated the intestinal membrane damage in the presence of morin by measuring the release of protein and lactate dehydrogenase (LDH) followed by using qualitative and quantitative morphometric analysis to describe the surface characteristics of intestinal epithelium.

Results: Morin showed the highest P_eff value 13.8?±?0.34?×?10^?6?cm/s in jejunum than ileum (p?<?.01) at 100?µM with absorption enhancement of 1.31-fold together with enhanced (p?<?.01) secretory transport of 6.27?±?0.27?×?10?^?6?cm/s in Caco-2 monolayer cells. Our findings noticed 2.37 (in-situ); 2.39 (in-vivo) and 1.43 (in-situ); 1.36 (in-vivo) fold increase in AUC_0–t with elevated C_max and shortened T_max for freeze-dried solid dispersion in the presence of morin as compared to pure OLM and freeze-dried solid dispersions without morin, respectively.

Conclusions: Our study demonstrated that increased solubilization through freeze-dried OLM-loaded solid dispersion together with efflux inhibition improved intestinal permeability to one system that might lead to novel solubilization and efflux pump inhibition as a novel alternative potential to increase oral absorption and bioavailability of OLM.     

Evolution of nonlinear optical properties: from gold atomic clusters to plasmonic nanocrystals

Atomic clusters of metals are an emerging class of extremely interesting materials occupying the intermediate size regime between atoms and nanoparticles. Here we report the nonlinear optical (NLO) characteristics of ultrasmall, atomically precise clusters of gold, which are smaller than the critical size for electronic energy quantization (～2 nm). Our studies reveal remarkable features of the distinct evolution of the optical nonlinearity as the clusters progress in size from the nonplasmonic regime to the plasmonic regime. We ascertain that the smallest atomic clusters do not show saturable absorption at the surface plasmon wavelength of larger gold nanocrystals (>2 nm). Consequently, the third-order optical nonlinearity in these ultrasmall gold clusters exhibits a significantly lower threshold for optical power limiting. This limiting efficiency, which is superior to that of plasmonic nanocrystals, is highly beneficial for optical limiting applications.     

Ultrafast optical Kerr gate of bismuth–plumbum oxide glass for time-gated ballistic imaging

We demonstrated the time-gated ballistic imaging technique using a femtosecond optical Kerr gate (OKG) of bismuth–plumbum oxide glass, the nonlinear optical properties of which were also investigated. The third-order nonlinear refractive-index n₂ of the bismuth–plumbum oxide glass was measured to be 2.19?×?10^?15?cm²/W, and the nonlinear response time was estimated to be shorter than 180?fs. For the time-gated ballistic imaging, the maximum measurable optical density of turbid media using the OKG of bismuth–plumbum oxide glass was 9.3, while only 7.0 for the OKG of quartz glass. And the intensities of the images for the bismuth–plumbum oxide glass were approximately two orders of magnitude higher than that for the quartz glass. The experimental results indicated that the bismuth–plumbum oxide glass was an excellent optical material for nonlinear optical applications.     

Optical and dielectric properties of nitrophenolate based nonlinear optical crystal

A semi-organic nonlinear optical (NLO) material, lithium-p-nitrophenolate trihydrate (LPNP) was synthesized. Single crystals of dimensions 20 × 7 × 3 mm³ were harvested following the solvent evaporation technique. The functional groups present in the compound were identified from FT-IR and FT-Raman spectral analyses, and its molecular structure was confirmed. Identification of the compound was accomplished by X-ray diffraction technique (powder and single crystal XRD). The unit-cell dimensions and the morphology of the grown crystals were identified from single crystal XRD measurements. The thermal transport properties, thermal effusivity (e), thermal diffusivity (α), thermal conductivity (k) and heat capacity (C _p) were measured by the photopyroelectric technique at room temperature. Dielectric constant and dielectric loss were also measured as a function of frequency between 42 Hz and 5 MHz, and temperature between 32 and 100 °C. From optical transmittance measurements, the direct optical band gap of the LPNP crystal was estimated to be 2.47 eV. Laser damage threshold is 60.91 GW cm⁻². Powder second harmonic generation (SHG) measurement was carried out using a modified Kurtz–Perry technique. Third order nonlinear response was studied using Z-scan technique with a He–Ne laser (632.8 nm, 35 mW). The magnitude and the sign of the nonlinear absorption and nonlinear refraction are derived from a transmittance curve. The NLO parameters Intensity dependent refractive index n ₂, nonlinear absorption coefficient β and third order susceptibility χ⁽³⁾ were estimated.     

Development,optimization, and in vitro characterization of dasatinib-loaded PEG functionalized chitosan capped gold nanoparticles using Box–Behnken experimental design

Objective: The purpose of this research study was to develop, optimize, and characterize dasatinib loaded polyethylene glycol (PEG) stabilized chitosan capped gold nanoparticles (DSB-PEG-Ch-GNPs).

Methods: Gold (III) chloride hydrate was reduced with chitosan and the resulting nanoparticles were coated with thiol-terminated PEG and loaded with dasatinib (DSB). Plackett–Burman design (PBD) followed by Box–Behnken experimental design (BBD) were employed to optimize the process parameters. Polynomial equations, contour, and 3D response surface plots were generated to relate the factors and responses. The optimized DSB-PEG-Ch-GNPs were characterized by FTIR, XRD, HR-SEM, EDX, TEM, SAED, AFM, DLS, and ZP.

Results: The results of the optimized DSB-PEG-Ch-GNPs showed particle size (PS) of 24.39?±?1.82?nm, apparent drug content (ADC) of 72.06?±?0.86%, and zeta potential (ZP) of ?13.91?±?1.21?mV. The responses observed and the predicted values of the optimized process were found to be close. The shape and surface morphology studies showed that the resulting DSB-PEG-Ch-GNPs were spherical and smooth. The stability and in vitro drug release studies confirmed that the optimized formulation was stable at different conditions of storage and exhibited a sustained drug release of the drug of up to 76% in 48?h and followed Korsmeyer–Peppas release kinetic model.

Conclusions: A process for preparing gold nanoparticles using chitosan, anchoring PEG to the particle surface, and entrapping dasatinib in the chitosan-PEG surface corona was optimized.     

Development and validation of spectrophotometric and HPTLC methods for simultaneous determination of rosiglitazone maleate and metformin hydrochloride in the presence of interfering matrix excipients

Two simple methods have been developed and validated for the simultaneous determination of rosiglitazone maleate (ROS) and metformin hydrochloride (MET) in synthetic mixtures and coated tablets in a ratio of 1:250 (ROS:MET). The first method was a spectrophotometric one. The minor component, ROS was determined by measuring the values of absorbance at λ_max 312?nm and the D₁ amplitudes at 331?nm where MET shows no absorption contribution. However, absorbance interferences from tablet excipients were successfully corrected by D₁ at 331?nm zero-crossing technique. Study of spectral interference from tablet excipients was included in the text. Standard curves for A_max and D₁ methods were in the concentration range 20.0–80.0?μg?mL^?1. The major component, MET was determined both in binary mixtures and tablets by measuring its A_max at 236?nm. Extensive dilution eliminated any absorption contribution from the coexisting ROS or tablet matrix. Standard curves showed linearity in the concentration range 4.0–12.8?μg?mL^?1. The second method was based on high performance thin layer chromatography (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 230?nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using methanol:water:NH₄Cl 1% w/v (5:4:1 v/v/v) as the mobile phase. Linear calibration graphs of peak area values were obtained versus concentrations in the range of 0.4–2.0?μg?band^?1 and 20.0–100.0?μg?band^?1 for ROS and MET, respectively. According to International Conference on Harmonisation (ICH) guidelines, different validation parameters were verified for the two methods and presented.     

Donor/acceptor effects on the nonlinear optical properties of 1,3 diphenyl propenones

Employing the single beam Z-scan technique with nanosecond laser pulses at 532 nm, the refractive and absorptive nonlinearities of donor and acceptor substituted (2E)-1-(3,4-dimethoxyphenyl)-3-phenylprop-2-en-1-one have been studied. The sign of the nonlinear index of refraction (n ₂) is found to be negative and the magnitude of n ₂ is in the order of 10^?11 esu. The second-order molecular hyperpolarizability (γ_h) is calculated to be in the order of 10^?32 esu. The variation of nonlinear absorption coefficient (β_eff) with input intensity (I ₀) is studied and the nonlinear absorption mechanism is found to be reverse saturable absorption (RSA). The enhancement of nonlinearity due to the donor and acceptor substitution is in accordance with the variation in π electron delocalization in the molecules. The compounds exhibit good optical limiting as well.     

Synthesis of gold nanoparticles of variable morphologies using aqueous leaf extracts of Cocculus hirsutus

Spherical, triangular (prismatic) and square plate shaped gold nanoparticles have been synthesised from HAuCl₄?·?3H₂O solution using the aqueous leaf extract of Cocculus hirsutus. Nanoparticles are characterised using higher resolution transmission electron microscope, X-ray diffraction and UV–Vis absorption spectroscopic study. FT-IR analysis reveals that the gold nanostructures are mostly stabilised by the carbonyl and amide groups present in the active component of C. hirsutus leaf extract. Formation of gold nanostructures of variable morphologies has been explained due to slow reduction of gold ions by the mild reducing ascorbic acid present within the extract and this controlled reduction assists the preferential deposition of Au atom on different lesser-protected faces of initially grown gold nanostructure.     

Synthesis,growth, and two-photon absorption induced optical limiting action of cytosinium benzoate single crystal

Two-photon absorption induced optical limiting action was demonstrated in cytosinium benzoate (CB) under nanosecond laser (532 nm, 9 ns, and 10 Hz) excitation. Intensity dependent open aperture Z-scan experiment exposed the presence of reverse saturable absorption ascribed due to sequential two-photon absorption. Initially CB single crystals were grown at room temperature by slow evaporation solution technique. Single crystal XRD shows that CB belongs to monoclinic crystal system with P2₁/c space group. Fourier Transform Infrared spectrum was recorded to identify the presence of functional groups. Thermal studies shows that the crystal is stable upto 168 °C. Vickers microhardness studies confirm that the grown crystal was belongs to soft material category. Etching study shows linear rectangular etch patterns (5 s) and well defined stacking planes (10 s) for water etchant. Optical studies demonstrate that CB crystal possess lower cut-off (287 nm) and moderate linear transmittance in visible region. The optical energy band gap of CB crystal was estimated from photoluminescence studies as 3.1 eV. CB with higher two-photon absorption coefficient (1.26?×?10^–10 m/W) and lower onset limiting threshold (1.92?×?10¹² W/m²) can be a potential candidate for developing laser safety devices under nanosecond green laser excitation regime.

     

Optical nonlinearity and optical limiting of CdSeS/ZnS quantum dots

CdSeS/ZnS quantum dots (QDs) were synthesized through the chemical route. The optical limiting behavior of these QDs was observed. The quantum dots’ nonlinear absorption and nonlinear refraction were investigated by the Z-scan technique using a Nd:YAG laser second-harmonic radiation (λ = 532 nm, t = 35 ps). Based on the absorption and fluorescence spectra, it is reasonable for us to infer that the nonlinear absorption arises from free carrier absorption (FCA). These QDs have average absorption cross-section of 1.26 × 10^?16cm² and nonlinear refractive index in the order of 10^?8esu. The large nonlinear absorption perhaps allows them to be candidate material for the optical limiting devices.