Second-order Hyperpolarizability Research Articles

Theoretically designed M@diaza[2.2.2]cryptand complexes: the role of non-covalent interactions in promoting NLO properties of organic electrides

ABSTRACT Organic excess electron compounds with significant nonlinear optical (NLO) properties are widely employed in optoelectronic applications. Herein, single-alkali metals with diaza[2.2.2] cryptand (M@crypt,M=Li, Na, and K) are investigated for optoelectronic and NLO properties by using the density functional theory. Thermodynamic and kinetic stabilities of present complexes are computed through interaction energy (Eint) and ab-initio molecular dynamic (AIMD) simulations. M@crypt complexes carry excess electrons and mimic molecular electrides. Quantum theory of atoms in molecules (QTAIM) analysis and reduced density gradient (RDG) spectra demonstrate the roles of the weak van der Waals (vdW) interactions between metal and complexant. The remarkable hyperpolarizability (βo) value up to 1.41 × 106 au may be credited to the presence of loosely bound excess electrons. The hyper Rayleigh scattering hyperpolarizability (βHRS) is recorded up to 1.31 × 106 au for the K@crypt. Furthermore, frequency-dependent first-order and second-order hyperpolarizability is more prominent at the applied frequency of ω = 0.042823 au. The electron localizing function (ELF) and localized orbital locator (LOL) analysis further disclose the nature of interaction between alkali metal and complexant. The TD-DFT method is adopted to get excited state parameters and absorbance properties. An electron density difference map (EDDM) is exploited to evaluate the orbital contributions in excited states. Hence, the studied electride may become a promising candidate for NLO materials. We anticipate that the present work will provide insight into further development of molecular electride for optoelectronic applications.

Synthesis, crystal structure, DFT calculations, NBO, Fukui function, NCI-RDG, Hirshfeld surface analysis, NLO properties and molecular docking analysis on (E)-N'-(3-methoxybenzylidene)-2-(quinolin-8-yloxy) acetohydrazide

In this study, we present the synthesis and characterization of a novel organic compound, (E)-N'-(3-methoxybenzylidene)-2-(quinolin-8-yloxy) acetohydrazide. Our characterization includes single crystal X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy. We also conducted Hirshfeld surface (HS) analysis to investigate intermolecular interactions. The compound crystallizes in the triclinic system with space group P−1. We employed density functional theory (DFT) with the B3LYP function and the 6–311 G (d, p) basis set to calculate its electronic properties. Additionally, we explored its nonlinear optical (NLO) behavior, determining the electric dipole moment (μ), polarizability (α), and hyperpolarizability (β), second-order hyperpolarizabilities (γ) using the same basis set. To evaluate the NLO properties of MBQA, we conducted frontier molecular orbitals (FMO) analysis, examined HOMO-LUMO energies, determined the energy band gap, studied the density of states (DOS), and assessed global chemical reactivity descriptors. We also performed a molecular electrostatic potential (MEP) simulation to identify optimal sites for both electrophilic and nucleophilic attacks. Our analysis further included a reduced density gradient (RDG) analysis to investigate various types of intermolecular interactions in MBQA, such as repulsive, attractive, and Van der Waals interactions while also distinguishing between strong and weak interactions. To understand the molecular stability and interactions, we conducted natural bond orbital (NBO) analysis, which provided insights into hyperconjugative interactions, charge delocalization and electron density ED among the molecular components. Finally, we assessed the biological activity of the MBQA molecule by predicting its potential pharmacological activities using the prediction of activity spectra for substances (PASS) and conducting molecular docking analyses. This comprehensive study provides valuable insights into the structural, electronic, and biological properties of (E)-N'-(3-methoxybenzylidene)-2-(quinolin-8-yloxy) acetohydrazide (MBQA).

Effect of spirocyclization of xanthene dyes on linear and nonlinear optical properties by considering D-π-A and D-A-D Systems: DFT and TD-DFT approach

Spirocyclization, a unique feature of xanthene dyes, makes it a promising candidate for developing fluorescent ratiometric probes for sensing, imaging, tracking, and labeling. How will this feature of xanthene dyes influence the linear and nonlinear optical properties? To examine the effect of spirocyclization of xanthene dyes, we have selected both the open-close form of rhodamine B and π-extended xanthene dyes substituted with thienyl and thieno[3,2-b]thienyl group at position 3 and 6. Here, rhodamine B will serve as the (Donor)D-π-A(Acceptor) system and thiophene-substituted xanthene dyes will serve as the D-A-D system. The geometry optimization of the close-open form of xanthene dyes at B3LYP/6–311++G(d,p) and CAM-B3LYP/6–311++G(d,p) revealed that the open form is energetically more stable in the S0 state than the closed form. The vertical excitation energy (ΔE), from Time-Dependent-Density Functional Theory (TD-DFT) calculation at B3LYP/6–311++G(d,p), CAM-B3LYP/6–311++G(d,p), ωB97XD/6–311++G(d,p) revealed that (ΔE)open < (ΔE)close. Further, the open form of xanthene dyes displays red-shifted absorption compared to the closed form. The λVt of xanthene dyes (open-close forms) is mainly assigned to HOMO → LUMO transition (S0 → S1) with % orbital contribution for open form ∼ 90 % and close form ∼ 60 %. The oscillator strength of xanthene dyes is obtained in the range of 0.01 – 1.74. The λVt of xanthene dyes is in agreement with experimental absorption. The static polarizability (α0), first-order hyperpolarizability (β0), second-order hyperpolarizability (γ), molecular hyperpolarizability (µβ0), and frequency-dependent hyperpolarizability (β1064), of the open form of xanthene dyes, were found to be higher than the close form. Thus, the open form of xanthene dyes will show superior linear and nonlinear optical properties than the closed form. The thienyl[3, 2-b] thieno substituted xanthene dye with red-shifted absorption shows higher α0, β0, γ, µβ0, β1064, and γ values, show better linear and NLO properties than thienyl and diethylamine substituted xanthene dyes.

Synthesis, crystal growth, physicochemical study of 1,3-dihexyl-2-methyl-1H-benzo[d]imidazol-3-ium bromide and in silico nonlinear optical property determination

This study encompasses the synthesis and characterization of 1,3-dihexyl-2-methyl-1H-benzo[d]imidazol-3-ium bromide (DHBIB) using techniques such as NMR, IR, and HRMS. The study also explores the influence of different solvents, specifically water and acetonitrile, on the growth of single crystals. An intriguing observation is the transformation of crystal packing from orthorhombic to monoclinic when solvent conditions change, illustrating the pivotal role of the cation in controlling the crystal structure of DHBIB salts. The analysis of its electronic properties reveal a deep-lying LUMO (−3.73 eV), suggesting DHBIB's electron-accepting characteristics. Furthermore, the study records absorption maxima (λmax) at 279 nm and 282 nm in various solvents, demonstrating that DHBIB lacks absorption in the visible range (400–800 nm), making it promising for non-linear optical (NLO) applications. Analysis of the natural bond orbital (NBO) stabilization energies 50.87, 42.12, and 45.33 kcal/mol along π(C3-C4)→π*(C6-C8), π(C3-C4)→π*(C10-C12), and π (C10-C12)→π*(C6-C8) reveal a preference for intramolecular charge transfer in DHBIB. Enhanced first and second-order hyperpolarizabilities (β; 13.47×10−30 esu, γ; 75.36×10−36 esu) compared to benzimidazole and benzimidazolium salicylate salt further supports its potential for NLO applications.

Comprehensive quantum chemical study of the associative complex of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin by adsorption and aromatic bridges.

The present study accounts for the quantum chemical and nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. Three different complexes were designed, surface interaction (adsorption) and two by connecting both molecules with π-bridge benzene and biphenyl. The amino and carboxyl groups were observed to behave as strong donor and acceptor sites in all the complexes. The band gap of the adsorbed complex was found more suitable. The absorption wavelength and intensity both were seen to increase with the increase in the number of benzene rings in the π-bridge. The values of first- and second-order hyperpolarizability suggest the improved nonlinear optical responses of the introduced complexes. Additionally, the negative value of second-order hyperpolarizability suggests the possibility of the occurrence of reverse saturable absorption in these combinations. The reported work gives theoretical insights into the nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. The molecular modeling and the quantum chemical studies were performed with Gaussian software packages. The standard B3LYP-6-311++G(d,p) basis functionals were used for energy minimization and other spectral calculations. All the surface analyses reported here are obtained by employing Multiwfn software. The chemical reactivity was established by the global reactivity descriptors. The intramolecular interactions and charge localization were stated using inter-fragment charge transfer analysis.

Investigation of nonlinear optical properties of a group of transition metal-decorated B12N12 nanocages: A DFT study

BN nanostructures are a promising group of materials with different technical applications. In this study, the electronic characteristics and NLO response of a group of B12N12 nanocages modified by transition metals have been studied using the DFT approach. Population analysis has been performed to investigate the role of transition metal in the delocalization of electronic charge on the surface of nanostructures. In this regard, molecular electrostatic potential (MEP) maps and density of state (DOS) plots have been surveyed. Based on frontier molecular orbitals (FMOs) energies, the reactivity of considered nanostructures has been discussed in the framework of global reactivity descriptors. NLO properties of considered nanostructures in terms of dipole moment, the mean polarizability, the anisotropy of the polarizability, the first-order hyperpolarizability, and the mean second-order hyperpolarizability have been studied in the gas phase and in the presence of Ethanol as solvent. The correlation between the NLO response of the nanocages and their different electronic characteristics has been studied. Results show that the presence of solvent makes an apparent increase in their NLO response. Electronic transitions responsible for absorption spectra of B12N12 nanocages have been considered, too.

Effect of π-extension and halogenation on the optical limiting properties of meso-pyrenylBODIPYdyes

The lack of suitable optical limiters that cover the entire UV-visible-NIR region has motivated research to identify novel efficient and stable optical limiting materials. There has been a strong focus on attenuating the second harmonic of Nd:YAG pulsed lasers at 532 nm on the nanosecond timescale. The photophysicochemical processes of a series of mono- and di-(4-dimethylamino)styryl-meso-pyrenylBODIPY and mono- and di-(4-dimethylamino)buta-1,3-dienyl-meso-pyrenylBODIPY dyes were studied by UV-visible absorption and fluorescence emission spectroscopy, and by determining the fluorescence and triplet state lifetimes. Z-scan measurements were carried out at a fixed concentration of 10 [Formula: see text]M so that the effective nonlinear coefficients, third-order susceptibilities, second-order hyperpolarizabilities and limiting fluences of the dyes can be compared and trends in the structure-property relationships for these optical limiting parameters can be identified.

TD-DFT calculation, equilibrium and kinetic adsorption study of removal of rose bengal dye by poly vinyl alcohol as a synthetic polymer adsorbent hybrid blend

Spectrophotometric study of the efficacy of the synthetic polymer such as polyvinyl alcohol in the removal of the dye Rose Bengal (RO) was examined. Different contact times, starting dye concentrations, adsorbent doses, dye solution temperatures, and pH values were tested. Density functional theory (DFT) with functional B3LYP and Hartree-Fock (HF) were used to investigate the optimal geometries, vibrational wavenumbers, vibrational band intensities, and atomic charges of 9VC. The researchers contrasted theoretical predictions for the basic vibrational modes with actual measurements. Using the functional B3LYP of DFT, we analyzed the hybrid organic dye (PVA+RO)HB such as the shape of geometry, electronic configuration, the capacity of polarizability, and second-order hyperpolarizability. The time-dependent density functional theory (TD- DFT), linked to a variety of hybrid functionals, was used in order to conduct research on the electronic absorption spectrum. Good agreement was found between the correlation coefficient values obtained from the Langmuir and Freundlich isotherm models, which were used to characterize the adsorption equilibrium. Pseudo-first-order kinetics was the best fit for the data on RO adsorption onto PVA. The values of enthalpy change and free energy change are negative and these confirm that our study concluded the exothermic and adsorption mechanism was spontaneous, respectively. The adsorption capacity was found to increase with increasing temperature. So, the kinetic parameters were evaluated from the temperature dependence of the adsorption capacity using the method of least squares.

Spectroscopic Quantum Calculations Using Density Functional Theory and Molecular Docking Simulations on 2-(4-Methoxystyryl)-4,6-Bis(Trichloromethyl)-1,3,5-Triazine as Potent Inhibitor against SARS-CoV-2

The present investigation is insightful in discerning the experimental and computational spectroscopic behavior of 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5 triazine (MSTCMT) by employing density functional theory (DFT) at B3LYP/6–311++G(d,p)/cc-pVDZ basis sets. The detailed vibrational analysis has been carried out using FT-IR and Raman within 3500–400 cm−1 and 3500–600 cm−1 respectively assisted by VEDA. Chemical shifts obtained from nuclear magnetic resonance (NMR) provided essential information useful in analyzing the molecular structure of MSTCMT. The thermodynamic functions of the MSTCMT molecule have been calculated at 298.15 K using the B3LYP method at 6–311++G(d,p) and cc-pVDZ basis sets. The non-linear optical properties such as polarizability, first-order hyperpolarizability, and second-order hyperpolarizability of the MSTCMT molecule have been calculated using 6–311++G(d,p) and cc-pVDZ basis set at B3LYP level. Molecular docking has been performed to check the inhibitory effect of MSTCMT against the SARS-CoV-2 receptors.

DFT studies on structural stability, vibrational and linear and nonlinear optical properties of low-dimensional zinc sulfide: from the 3D bulk to the 2D monolayer and the 1D zigzag single-walled nanotubes

Through first-principles calculations, we investigate structural stability, vibrational and linear and nonlinear optical properties of the zinc sulfide (ZnS) in different periodic forms ranging from the 3D bulk to the 2D hexagonal monolayer and their corresponding 1D zigzag single-walled nanotubes. To first order, the electronic wave function on the ground state was constructed using linear combinations of Gaussian-type functions at the DFT/B3LYP level. Then, the Raman and IR spectrum is computed by adopting a Coupled-Perturbed-Hartree–Fock/Kohn–Sham (CPHF/KS) approach. Cohesive, relaxation, and rolling energies, elastic and piezoelectric constants, electronic and nuclear contributions to the polarizability tensor, and nonlinear first and second-order hyperpolarizability tensor components are reported. Our study shows that 3D and 2D forms are stable and show semiconducting behavior, good piezoelectric responses, and fascinating linear and nonlinear optical properties. For 1D single-walled nanotubes, dynamic stability is observed only for the smallest (6,0) nanotubes. For n > 6, imaginary mode frequencies in the simulated IR and Raman spectra indicate dynamic instability. A scanning mode procedure along the largest imaginary vibrational mode is applied in order to determine the stable structures of the largest (14,0), (18,0) and (22,0) ZnS nanotubes. After that, no more imaginary phonon frequencies are detected in their vibrational spectra. Their potential energy surface contains two minima between a saddle point corresponding to a slightly distorted nanotube structure. Our study proves that the zinc sulfide nanostructures possess diverse physical properties so useful for potential applications in nanoelectronics and for nanodevices.

Enhanced NLO response and switching self-focussing in benzodiazepine derivative with –NO2 and -Br substitution

Optoelectronic and the cubic nonlinear optical properties of 4-(4-Bromophenyl)-2-(4-nitrophenyl)-2, 3-dihydro-1H-1, 5-benzodiazepine have been studied. Z-scan technique was used for the third-order nonlinear optical measurements namely, nonlinear absorption, nonlinear refraction, and optical power limiting behaviour employing an Nd: YAG laser of 532 nm wavelength having 5 ns Gaussian pulses. B3LYP/6–311 ++ G (d, p) level of theory was employed for structural optimization, vibrational wavenumber, frontier molecular orbitals, natural bond orbital and population analysis. The MOLVIB programme was used to perform unambiguous vibrational assignments based on potential energy distribution values acquired from normal coordinate analysis. B3LYP and CAM-B3LYP hybrid functions have been employed at the DFT level to calculate the theoretical second-order hyperpolarizability. The substitution of –NO2 and -Br in this benzodiazepine compound enhances the second-order hyperpolarizability (γ) to the order of 10−34 esu and, switching of self-defocussing to self-focussing phenomenon. The HOMO-LUMO and optical band gap analysis illustrates that polarizing nature of the molecule vary with substituents. The obtained results indicate that this compound has potential applications in optoelectronics and photonics.

Topologically enhanced nonlinear optical response of graphene nanoribbon heterojunctions

We study the nonlinear optical properties of heterojunctions made of graphene nanoribbons (GNRs) consisting of two segments with either the same or different topological properties. By utilizing a quantum mechanical approach that incorporates distant-neighbor interactions, we demonstrate that the presence of topological interface states significantly enhances the second- and third-order nonlinear optical response of GNR heterojunctions that are created by merging two topologically inequivalent GNRs. Specifically, GNR heterojunctions with topological interface states display third-order harmonic hyperpolarizabilities that are more than two orders of magnitude larger than those of their similarly sized counterparts without topological interface states, whereas the second-order harmonic hyperpolarizabilities exhibit a more than ten-fold contrast between heterojunctions with and without topological interface states. Additionally, we find that the topological state at the interface between two topologically distinct GNRs can induce a noticeable red-shift of the quantum plasmon frequency of the heterojunctions. Our results reveal a general and profound connection between the existence of topological states and an enhanced nonlinear optical response of graphene nanostructures and possible other photonic systems.

Crystal structure, vibrational analysis, electronic properties, static and dynamic NLO response and molecular docking study of oxadiazole/pyridine-based Zn(II) complex

In this study, a complex consisting of oxadiazole and pyridine groups coordinated with zinc(II) chloride was synthesized and characterized by using the experimental (FT-IR, Raman and UV spectroscopic techniques) and computational methods. The molecular coordination of the complex exhibited a different orientation due to the position of the Cl-Zn-Cl bond angle, resulting in a distorted octahedral molecular geometry around the central zinc(II) metal ion. The exact crystal molecular structure was uncovered with the experimental single crystal X-Ray diffraction (SCXRD) analysis. Theoretical modeling on the electronic structure properties was performed with the DFT/B3LYP method at the 6–311G(2d,2p)+LanL2DZ computational level. The computational molecular geometry analysis was used to support the experimental structural geometric parameters. Some significant characteristic vibrational bands such as intra-ligand, metal-ligand and metal-chloride groups were investigated by using the experimental FT-IR and Raman spectral techniques and computational method. The electronic transition features and the nature of metal-ligand/chloride coordination environment were determined via help of the UV–Vis., HOMO, LUMO and NBO analyses. The MEP analysis was investigated for the complex. The NLO profile was investigated by analyzing the polarizabilities and the first- and second-order hyperpolarizabilities (α, β and γ) at the static and dynamic (ω = 532 nm and 1064 nm) states with theoretical approach. Lastly, the molecular docking study was performed to determine the anxiolytic activity of the synthesized complex.

Theoretical Investigation of Structural, Spectroscopic (IR, 1H and 13C NMR), Static, and Frequency-Dependent Nonlinear Optical Properties of 4-[(1E)-3-(4-Methoxyphenyl)-3-Oxoprop-1-en-1-yl]Phenyl 4-Methylbenzene-1-Sulfonate

The present study reports the theoretical investigations of nonlinear optical properties of chalcone derivative namely 4-[(1E)-3-(4-methoxyphenyl)-3-oxoprop-1-en-1-yl]phenyl 4-methylbenzene-1-sulfonate (4MPMS). Density functional theory calculations on the geometry optimization, vibrational spectrum, 1H and 13C NMR chemical shifts, frontier molecular orbitals energies, and nonlinear optical properties are carried out by using B3LYP level in conjunction with 6–311++G(d,p) basis set. The static and frequency-dependent nonlinear optical properties (polarizability (α), anisotropy of polarizability (Δα), first and second-order hyperpolarizabilities (β and γ)) are investigated by using B3LYP level. The static NLO parameters (β(0;0,0) and γ(0;0.0.0)) were calculated as 16.240 × 10−30 and 213.77 × 10−36 esu. The second harmonic generation (SHG) β(-2w,w,w) and γ(-2w,w,w,0) parameters for the title molecule are found to be 213.97 × 10−30 esu and 485.90 × 10−36 esu, respectively. So, the frequency-dependence of β and γ parameters is clear. The obtained results demonstrated that there is a frequency dependence on the nonlinear optical properties of 4MPMS, and the title molecule is a possible candidate for first and second-order nonlinear optical materials.

Theoretical investigation of substitution effect on the sixth and seventh positions of coumarin derivatives

The linear and non-linear optical properties of 6-donor and 7-donor substituted coumarins were compared using density functional theory (DFT) and time-dependent-DFT (TD-DFT). Charge transfer characteristics were investigated through natural bond order analysis, frontier molecular orbital, and molecular electrostatic potential plots. TD-DFT results suggested that the 6-donor substituted coumarins (PS1, PS3, and PS5) showed red-shifted absorption than the 7-donor substituted coumarins (PS2, PS4, and PS6). The chemical potential (μ) and electrophilicity index (ω) showed direct relation with the band gap and an inverse relation with chemical hardness (η) and hyperhardness (Γ). The global reactivity descriptors μ and ω showed direct and η and Γ showed an inverse correlation with first-order hyperpolarizability (β0) and second-order hyperpolarizability (γ). The β0 and γ for 7-donor substituted coumarin are higher than for 6-donor substituted coumarin.

External field intensity and wavelength dependency from IR to deep UV of linear and nonlinear optical properties of 1-butyl-3-methylimidazolium dicyanamide ionic liquid

The electronic structure, inter-ionic interactions and charge transfer, polarizability, and first-order and second-order hyperpolarizabilities of 1-butyl-3-methylimidazolium dicyanamide ionic liquid have been explored via modeling at M06-2X/6-311++G(d,p) level of theory. External field intensity dependence of electronic properties was investigated by utilization of field intensity from 0.0001 to 0.002 au applied in the direction of anion-cation. Interionic interactions have been characterized through the reduced density gradient method to reveal and distinguish hydrogen bonding and other non-covalent interactions. Extraordinary bonding interactions were observed between the anion and ring system of the cation. Electronic excitation characteristics were analyzed based on the inter-fragment charge transfer method to distinguish charge transfer contributions from local excitations. Static and dynamic nonlinear optical parameters namely the total dipole moment μ, the mean polarizability α(0,0) and α(−ω; ω), the anisotropy of polarizability Δα(0,0) and Δα(−ω; ω) the first hyperpolarizability in the direction of dipole moment β(0,0,0), β(−ω; ω,0), and β (−2ω; ω,ω), the average second hyperpolarizability γ(0;0,0,0), γ(−ω; ω,0,0) and γ(−2ω; ω,ω,0) have been calculated for specific laser wavelengths corresponding to the UV, visible, and infrared region. Thus, a novel way of mapping the field intensity and wavelength dependence of NLO properties was achieved. The hyperpolarizability calculations indicate that 1-butyl-3-methylimidazolium dicyanamide has a significant potential to be used in electro-optics Pockels effect, second-harmonic generation, and electro-optical Kerr effect applications. NLO property maps indicate that the wavelength dependence in the IR and visible region is almost ignorable when compared with that of the UV region where the first hyperpolarizabilities can increase by ten thousand and the second hyperpolarizabilities can reach up to ten billion times.

Responsefun: Fun with Response Functions in the Algebraic Diagrammatic Construction Framework.

We present the open-source responsefun package, which implements a universally applicable procedure for computing molecular response properties within the algebraic diagrammatic construction (ADC) framework, exploiting the intermediate state representation (ISR) approach. With symbolic mathematics, the user can simply enter textbook sum-over-states (SOS) expressions from time-dependent perturbation theory, which are then automatically translated into the corresponding symbolic ADC/ISR formulations. Using the data structures provided by the hybrid Python/C++ module adcc for calculating excited states with ADC, the specified response property is directly evaluated, and the result is returned to the user. Employing the novel responsefun package, we present the first ADC/ISR calculations of second-order hyperpolarizability tensors and three-photon-absorption matrix elements.

Extraction of Natural Pigment Curcumin from Curcuma Longa: Spectral, DFT, Third-order Nonlinear Optical and Optical Limiting Study.

Herein, we report the extraction of natural pigment curcumin from curcuma longa and their linear and third-order nonlinear optical (NLO) characteristics. The characterization techniques viz., UV-Visible absorption, FT-IR, Micro Raman and Gas Chromatography Mass Spectrum (GC-MS) are used to study the spectral characteristics of curcumin.Third-order NLO features of curcumin are studied using Z‒scan technique with a semiconductor diode laser working at 405nm wavelength. The natural pigment exhibits negative nonlinear index of refraction resulting from self-defocusing and positive coefficient of absorption is the consequence of reverse saturable absorption (RSA). The order of nonlinear index of refraction (n2) and nonlinear coefficient of absorption (β) is measured to be 10-7 cm2/W and 10-2cm/W, respectively. Third-order NLO susceptibility (χ(3)) and second-order hyperpolarizability (γ) of curcumin is measured to be 2.73 × 10‒7 esu and 1.67 × 10‒31 esu, respectively. A low optical limiting (OL) threshold of 0.71 mW is observed in the extracted pigment. The experimental results are supplemented by quantum mechanical calculations of the NLO parameters. The overall result finding is that curcumin extracted from curcuma longa has the potential to be novel optical candidates for photonics and optoelectronics applications.

Density functional theory study of Ni-modified B12N12 nanocages as promising nonlinear optical materials

In this research, the electronic features of perfect B12N12 nanocages and a group of its Ni-modified derivatives, including doped NiB11N12 and B12N11Ni, decorated, and encapsulated NiB12N12, have been investigated via the DFT approach. It has been demonstrated that the Ni-modification of B12N12 causes a remarkable alteration in its electronic properties, especially NLO features. There are meaningful correlations between NLO characteristics and dipole moment and energy gap of studied species. Interaction with small alien molecules dramatically affects the electrostatic characteristic and NLO properties of the nanocages. Depending on the presence of different interacting molecules/ solvents, the second-order hyperpolarizability of the complex may become higher or lower than the non-interacting nanostructures.

Unraveling the structure–property relationship of a chalcone-based push–pull molecule for optical limiting application in high-powered laser

In this work, the optical limiting response of a highly π-conjugated push–pull chalcone derivative (2E)-3-(2,3-dimethoxyphenyl)-1-(3-nitrophenyl)prop-2-en-1-one (abbreviated as 3DPNP) has been investigated. The structure–property relationship of 3DPNP was explored through spectroscopic investigation and quantum chemical computations. The existence of weak-non-covalent interactions and charge transfer species that responsible for the chemical stability of 3DPNP were studied by AIM and NBO analyses. The quantitative and qualitative analysis of vibrational and electronic contribution to non-linear optical (NLO) response of 3DPNP were discussed in detail. The normal vibrational modes associated with a change in the dipole moment, polarizability, first- and second-order hyperpolarizabilities of 3DPNP were identified using DFT calculations followed by potential energy distribution (PED) analysis using Gaussian 09 W software and Gar2ped program, respectively. The changes in the NLO parameters with respect to the varying frequencies and electric dipole fields were studied. The abrupt changes in the NLO properties were noticed when the frequency doubled, confirming the second harmonic generation (SHG) efficiency of 3DPNP. From the non-linear absorption and refraction studies through the z-scan experiment, the optical limiting threshold value of 3DPNP is determined to be 3.26 kJ/cm2, which shows the suitability of the material for optical limiting applications in the continuous wave (CW) laser regime.