Order Hyperpolarizability Research Articles

Modeling of graphene like structure by utilizing phenanthrocarbazole for tailoring the second-order nonlinear optical properties

Lower band gap with excellent intramolecular charge transfer plays a pivotal role towards developing the strong nonlinear optical (NLO) properties in a molecule. In the current investigation, we have designed a series of graphene like molecules with promising organic fragments that we have strategically adjoin the phenanthrocarbazole and tetracyanobuta-1,3-dienes (TCBD) fragment. Density functional theory (DFT) approach with CAM-B3LYPP/6-311+G(d,p) were performed to evaluate the nonlinear optical properties of designed derivative. The NLO characteristics were analysed the static polarizability (α0), first order hyperpolarizabilities (βtot) and band gap. The calculated results revealed that the designed molecules have better NLO response and highest βtot were observed for molecule 10 (117871 au). Time dependent density functional based theories at the same level of theory were also performed to calculate the absorption spectra. The calculated results observed that there was a red shift trend with reduced band gap of designed derivative. Further, to substantiate our finding, we have also calculated density of states (DOS), molecular electrostatic potential (MESP) and transition density matrix (TDM) at the same level of theory. As a consequence the designed derivative shed light that the efficient TCBD group with graphene like molecular system and donor group can be utilized to design new molecular motif for NLO applications.

Supramolecular structure, DFT calculation and vibrational characterization of melamin-1-ium oxalurate monohydrate

Crystallization from an aqueous solution of melamine with parabanic acid was taken in a molar ratio of 1:1 leads to the formation of melamin-1-ium oxalurate monohydrate (MOX) crystals. The compound crystallizes in the centrosymmetric space group P21/n of the monoclinic system with four molecules per unit cell. The molecular geometry and vibrational frequencies of MOX in the ground state have been calculated by using the density functional hybrid function B3LYP 6–31+G(d) basis set. The results of optimized molecular structure are presented and compared with the experimental X-ray diffraction data. Furthermore, Fourier Transform Infrared (FT-IR) and Raman Spectra were used to conduct vibrational characterization to study the compound's structural groups. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs in the molecule and other related electronic properties have also been calculated. Besides, Molecular Electrostatic Potential (MEP) was performed to identify the possible electrophilic and nucleophilic sites. First order hyperpolarizability results establish the nonlinear response of the grown MOX crystal with respect to the electric field. Further, the crystal packing behaviour of MOX was studied quantitatively with the aid of Hirshfeld surface analysis.

Integrating simulated and experimental studies on novel single crystal bis(guanidininium) n-carboxylatephenylalanine towards enhanced antitumor effect

A novel organic crystal bis(guanidininium) n-carboxylatephenylalanine (GUPA) was synthesized and X-ray diffraction outcomes exposed P21, triclinic space group with cell dimensions a = 6.6492(3) Å, b = 16.2440(7) Å, c = 7.8985(3) Å, β = 0.127(2) °, V = 853.11(6) Å3, Z = 2 and possess good agreement with experimental data. Intermolecular interactions were revealed through hirshfeld and major contribution from O-H interaction confirms the presence of intermolecular hydrogen bonds. Through B3LYP algorithm with set 6–311++ G (d, p), chemical reactivity forms and molecular structure of GUPA was investigated, confirming a good stability and hard electrophilic nature. While first order hyperpolarizability value (35.37 × 10−31 esu) was indicative of good nonlinear optical material and hyperconjugate interactions and charge delocalization was further confirmed by natural bond orbitals. To further investigate the electronic properties theoretical (TD-DFT) and experimental absorption wavelengths were compared and excitation energies, oscillator strength and type of electronic transition with contributions have also been studied. The topological properties were evaluated using ELF/LOL maps and RDG with NCI were used to establish the type of interaction present in the GUPA molecular system. The anti-breast cancer effect of GUPA was computationally studied through molecular docking against p53 gene and was further investigated through in vitro MDA-MB-231 cell line studies and GUPA showed better inhibition of cancer cells and their expression.

Spectroscopic elucidation, quantum chemical computations (FMO, HOMO–LUMO, MEP, NLO), and biological activity on some novel heterocyclic compounds using 3-substituted-6,8-dimethylchromones

The chemical transformations of substituted chromones 1a–c were examined toward some nucleophiles namely dimedone (R1), 4-hydroxycoumarin (R2) and 4-hydroxy-1-methylquinolin-2(1H)-one (R3). DFT computation at the B3LYP/6-311 G(d,p) level of theory was used to perform the theoretical computations for the produced compounds. HOMO and LUMO analyses were performed to determine the electronic charge distribution and reactivity of the molecules. Molecular electrostatic potential (MEP) surface analysis was utilized to predict the molecule’s reactive sites. Moreover, the studied compounds showed NLO characteristics, where they have first order hyperpolarizability greater than urea. In addition, the GIAO method was used to estimate the 1H-NMR and 13C-NMR chemical shifts; and the findings were compared with experimental values. Testing the generated compounds for antibacterial and anticancer activities revealed varied degrees of inhibitory effect. According to the Lipinski, Veber, and Egen rules, these compounds exhibit physicochemical properties.

CALCULATION of HOMA AND BIRD AROMATICITY INDICES, NLO and NBO PROPERTIES OF BENIDIPINE

Benidipine hydrochloride, being the derivate of 1,4-dihydropyridine is a calcium channel blocker antihypertensive drug. The aromaticity, natural bond orbital (NBO) and Nonlinear Optical (NLO) parameters properties of Benidipine (BEN) and BENHCl compounds were theoretically investigated using density functional theory (DFT) electronic structure method. Among the values of common aromaticity indices, the Harmonic Oscillator Aromaticity Model (HOMA) and BIRD's (Aromaticity Index) for electronic delocalization show that the aromaticity of the nitrophenyl group is higher in BEN and BENHCl compounds, and also the aromaticity in the gas phase is higher than that in water, octanol and DMF phase. In compound BEN, it was observed that as the dielectric constant of the medium increased, the aromaticity difference increased slightly. In the compound BEN, the correlation coefficient between HOMA values and aromatic fluctuation index (FLU), para delocalization index (PDI) and para-linear response (PLR) for the nitrophenyl group is higher than that the phenyl group. Donor-acceptor transitions, stabilization energies, intramolecular charge transfer were determined by natural population analyses. NLO parameters such as dipole moment, polarisibility and first order hyperpolarizability values of the BEN and BENHCl compound were also studied.

Spectral, optical, thermal, dielectric, micro hardness analysis and computational calculations of a novel crystal, 2-amino-3-methylpyridinium 2, 4-dinitrobenzoate

By adapting slow evaporation technique novel single crystals of 2-Amino-3- Methylpyridinium 2, 4-Dinitrobenzoate (AMPD) were synthesized. The grown crystal was subjected to Single crystal X‒Ray Diffraction technique to explicate the crystal structure. The spectral analyses were carried out to identify the vibrational modes of various functional groups. To explore the optical transparency of the synthesized crystal UV‒Visible study has been performed and its cut-off wavelength was found to be 209 nm. By Kurtz‒Perry powder technique, the assessment of second harmonic generation efficiency of the crystal has been calculated. Using TG/DTA analysis, the thermal behavior of the crystal was studied. The mechanical strength of the crystal was examined by Vicker′s micro hardness test and the work hardening coefficient was 3.59, affirming that the grown crystal belongs to soft material category. Optimized structural geometry, vibrational wavenumbers, frontier molecular orbitals energy, chemical reactivity indices and density of states were also computed using DFT method. Nonlinear optical property of the molecule was explored by the first‒order hyperpolarizability calculation. These experimental and theoretical studies reveal that the molecules can be suitable to use in optoelectronic devices.

The experimental and DFT approaches on electronic, thermal and conductivity properties of non-linear optical bearing fused aromatic chalcones towards prospective OLEDs

New derivatives of push-pull chalcone was successfully synthesized to demonstrate as NLO active on the impact of organic light emitting diode (OLED) materials. A total of three fused-aromatic chalcones (AA, AB, AC) with different substituents have been characterized through TGA, Z-scan analysis, 1H & 13C NMR, IR and UV–Vis. All the targeted compounds are nonlinear refraction (NLR) active with the range of χ(3) (∼ × 10–6 esu). AC reveals the highest value of first order hyperpolarizability (βtot) at 528.08 × 10–30 esu upon the substitution of strong electron acceptor. Theoretical investigation was performed by employing the theory of B3LYP/6–31 G (d,p) level via density functional theory (DFT) to optimize the geometries, molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO). The predicted electronic properties of the molecule are supported by the experimental results, confirming the theoretical conclusions. The examination of its potential as emissive layer in OLED application was constructed on ITO substrate for electroluminescence behaviour evaluation under various direct current (DC) voltages supply. The preliminary outcomes reveal that these simple chalcone derivatives are capable of being utilised in any optoelectronic application.

The electronic, structural and nonlinear optical properties of licochalcone L in the aqueous solution and gaseous phase: A DFT study

In the present article, various conformers of licochalcone L, a chalcone derivative extracted from the G. inflata root, have been analyzed in the aqueous solution and gaseous phase using calculation based on density functional theory (DFT). Nonlinear optical parameters such as dipole moment (μ), mean polarizability (α), polarizability anisotropy (Δα) and the first order hyperpolarizability (β) have been estimated to examine the NLO properties of the title molecule. These parameters were found to be significantly higher than those of standard molecules, indicating the potential NLO applications of licochalcone L. The analysis of natural bond orbitals (NBO) has been carried out to characterize various intramolecular interactions. The nucleus-independent chemical shift (NICS) technique has been used to investigate the aromaticity. Further, the pKa values have been computed for each hydroxyl group, revealing that the neutral form predominates at physiological pH, while the monoanionic form becomes predominant at pH greater than 9. The impact of solvation on the molecular electrostatic potentials and frontier molecular orbitals has been investigated for the neutral as well as monoanionic form of licochalcone L. A variety of global chemical reactivity descriptors have been calculated to highlight the structure-activity relationship.

A comparative study of second order Non-linear optical crystals derived from chloro- and dichloro- aniline

Followed by one-pot mechanism Schiff base products derived from the substituted anilines are crystallized by the slow-evaporation technique. Both crystals are characterized by FT-IR, 1H NMR and 13C NMR spectral studies. Single crystal XRD analysis provides data of both crystals and it is well fitted with NMR and IR spectral results. The obtained results of IR frequencies and NMR chemical shifts are compared with theoretical predicted results obtained from DFT method. The energy gap Eg was calculated by HOMO and LUMO and other theoretical parameters are determined by using DFT method with B3LYP/6–311++ G (d,p) basis set and the energy gap is very small 3.59, 3.52 eV for PCA and DCA crystals. The supramolecular investigation of crystal structure explained by Hirshfeld analysis. Using quantum computations techniques, the topological parameters LOL and ELF, scatter graph and diagram of the crystals was the further characterization. The first order hyperpolarizability (β0) was calculated by B3LYP/6–311++ G (d,p) basis set. Using the Kurtz-Powder technique, the second order Non-linear optical activity of the crystal was obtained. Based upon these crystals, which are outstanding Nonlinear optical activity material and best for the laser safety devices.

Synthesis, spectral characterisations, biological evaluation, DFT calculation and molecular docking analysis of 3,5-diethyl-2,6-di(2-bromophenyl)piperidin-4-one picrate with topological indices studies

The 3,5-diethyl-2,6-di(2-bromophenyl)piperidin-4-one picrates (3,5-DEBPP) compound was synthesised and characterised by spectral techniques. The title molecule adopt a normal chair conformation with all of its substituents, such as the bromophenyl group at positions C-2 and C-6 and the ethyl group at locations C-3 and C-5, orientated equatorially, according to the measured chemical shifts and coupling constants. The DFT/B3LYP/6-311++G(d,p) basis set was used to optimise the molecular structure. The non-linear optical behaviour of the material was assessed by computing the first order hyperpolarisability. Using NBO analysis, it was determined whether the molecule's stability as a result of hyper conjugative interactions and charge delocalisation was satisfactory. The HOMO and LUMO values were used to compute the physico-chemical parameters. The electrophilic and nucleophilic attack of the current molecule is visible on the MEP surface. The Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Vibreo cholerae, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger, Aspergillus flavus and Trichophyton rubrum were among the bacterial strains that the 3,5-DEBPP was tested against. Docking investigations were thoroughly conducted to establish knowledge regarding the interactions between protein and this new chemical theoretically. Structure-based topological indices enable prediction of chemical properties and the bioactivities of this compound through quantitative structure–activity and structure–property relationships methods.

Design strategy of microbially produced semiconductor maquettes of Cu2Se4SnZn8+ crystal alloy for enhanced harmonic generations

During present study, we have attempted to present few nanosized maquettes of a semiconductor alloy which can be designed under the action of microbes to be utilize for their high-tech applications like their nonlinear optical (NLO) applications. All the designed maquettes are studied for their geometrical, optical, electronic transitions and bonding interactions. It was found that inclusion of late transition metals is more effective in tuning them as NLO switches. Also, the last three maquettes presented both electronegative and electropositive regions to display them as non-sized magnets. Their linear polarizability (<α0 > ), first hyper-polarizability (β0) and second order hyperpolarizability (γ0) values were found as: 0.08–11.42 × 10-24, 0.08.71–11.42 × 10-24, 1.42–71.30 × 10-24 esu respectively. These values were significantly higher than the one presented in literature The intention of this investigation was to investigate the NLO properties of Cu2Se4SnZn8+ crystals for future high-tech applications.

How much length of boron-nitride incorporated benzene like structures can produce efficient harmonic generation at their low-lying excited states?

In this study, exploring the nonlinear optical (NLO) responses by utilizing boron nitride (BN) units as benzene like fused ring chromophores (BTN1-BTN8) are made by correlating their planarity. The chromophore structures containing ring sizes of 3 and 4 (BTN3 and BTN4) demonstrates their significant NLO responses, while higher ring sizes show a decline as their structure become more curved. Their quantum chemical calculations are performed to optimize their molecular structures for their various chemical stability related parameters. Their dipole moments (µtot) ranges between 1.27D for BTN2 to 4.43 D for BTN8 while their average linear polarizability (<α0>) varies from 5.98–7.56 electrostatic units (e.s.u). The chromophore BTN4 exhibits its highest first order hyperpolarizability (β0) value of 9.91 e.s.u. The chromophore BTN3 has the largest second order hyperpolarizability (γ0) value of 11.98 e.s.u and it also has the highest ionization potential (IP) of 5.64 eV, while chromophore BTN4 had a remarkably low EA of −4.91 eV. Their vertical IP (VIP) values ranged from 6.21 eV for BTN1 to 7.56 eV for chromophore BTN7. The chromophore BTN1 displayed a maximum absorption (λmax) at 656 nm with an oscillator strength (f) of 0.0473 and an excitation energy (E) of 1.89 eV. The chromophore BTN4 exhibits a λmax of 366 nm, an f of 0.0012, and an E value of 3.39 eV. The chromophore BTN8 showed the highest λmax value of 1023 nm, an f of 0.0023, and an E value of 1.21 eV.

DFT calculations, molecular docking, binding free energy analysis and cytotoxicity assay of 7,7-dimethylaporphine alkaloids with methylenedioxy ring in positions 1 and 2

In this paper, we present a comprehensive characterization of three 7,7-dimethylaporphine alkaloids at a molecular quantum mechanical level using Density Functional Theory (DFT) with the B3LYP/6-311G(2d,p) basis set. These alkaloids have a methylenedioxy group in positions 1 and 2, differing from each other only by the presence or absence of one OCH3 group, with the influence of this group on the properties of the investigated alkaloids being the object of study in this research. The accuracy of our findings is validated by comparing the infrared (IR) and UV–Visible (UV–Vis) spectra with experimental data previously reported by one of the authors. Theoretical geometry optimization data were further assessed against X-ray data from related structures in the literature, revealing close agreement. Additionally, various quantum properties, such as Natural Bond Orbitals (NBOs), HOMO-LUMO energy gap, mapped Molecular Electrostatic Potential (MEP) surface calculation, first and second order hyperpolarizabilities, were evaluated at the same calculation level. To understand the interactions between the alkaloids and important biological targets, molecular dynamics simulations were carried out using Gromacs 2019 software. The focus was on investigating the MM/PBSA binding free energies at the active sites of human Topoisomerase I DNA, Candida Albicans Dihydrofolate Reductase, Acetylcholinesterase, and Spike SARS-CoV-2. These results were compared to those obtained from molecular docking studies performed with the alkaloids at the same active sites. Remarkably, alkaloid 2, lacking OCH3 substituents, demonstrated the highest inhibitory potential for three out of the four enzymes, excluding C. Albicans according to docking results, which was subsequently confirmed through cytotoxicity experiments. These findings shed light on the molecular basis for the observed differences in the alkaloids' biological activities and contribute to the design of potential therapeutic agents targeting these enzymes.

Synthesis, crystal structure, spectroscopic and computational studies of NLO active 2-methylimdazolium 4-nitrobenzoic acid single crystal

In this report, we have presented the theoretical and experimental investigation of 2-Methylimdazolium 4-Nitrobenzoic Acid (2MI4NB) – an organic crystal. The good quality 2MI4NB single crystal was grown by slow evaporation technique. Both single and powder X-ray diffraction (XRD) analysis confirmed that the grown crystal structure is Triclinic with the P1 space group. The vibrational modes present in the chemical were validated through Fourier transform infrared (FT-IR) spectrum investigations. Density functional theory (DFT), a quantum chemical approach, has emerged as a potential or an effective tool for studying molecular structure and NLO properties and is being used frequently in applications involving NLO systems. HOMO-LUMO analysis and reactivity parameters were calculated. Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO) analysis and first order hyper polarizability were studied by B3LYP theoretical level with 6-311++G(d,p) basic set. In addition, the Mulliken Atomic Charge was calculated with the same basic set. The thermal properties of the 2MI4NB crystal was analysed by TG-DTA studies. It shows that the two endothermic peaks were observed. The optical absorption spectrum shows that there is no absorption in the region of 430–1200 nm. The Z-scan analysis gives the third order NLO properties like refractive index and third-order NLO susceptibility of 2MI4NB crystals.

Molecular level interaction, electrons excitation properties, solvent effect using IEFPCM investigation, topological surface, and docking analysis of 4-pyrrolidin-2-yl-pyridine

Abstract Optimisation of molecular geometry of the headline compound, 4-pyrrolidin-2-yl-pyridine (4P2YLP) was achieved theoretically exercising Density Functional Theory using B3LYP standard approach utilising basis set, 6-311++G(d,p). Using Gaussian 09, HOMO–LUMO analysis was achieved to comprehend the chemical activity and electronic properties of the heading compound. The least HOMO–LUMO gap was obtained for gas phase (5.6486). Bonding interlinkage of the fragments is accomplished by Natural Bonding Orbitals (NBO), as steadiness and chemical reactivity depend on the border molecular orbitals. The nucleophilic &amp; electrophilic spots along with 3D charge transmission areas are determined using the Molecular Electrostatic Potential (MEP). Multiwfn 3.8 software with Pauli Repulsion (PR) &amp; electron localization has been used to conduct ELF and LOL research. While LOL simply displays the most closely spaced orbitals overlapping, ELF displays the electron pair density. Non-linear response properties are analysed in a variety of solvents. The dipole moment (1.9039), polarizability (3.23017E-23 esu) &amp; first order hyperpolarizability (1.51981E-30 esu) of water are the highest values among the selected solvents. Different solvents endured UV–Vis analysis employing TD-DFT technique and the absorption of maximum wavelength is accomplished. Fructose 5-dehydrogenase inhibitor activity by docking is investigated using molecular modelling procedures.

Synthesis, structure, growth, characterization and quantum chemical studies on 2-amino-5-bromopyridinium trichloroacetate: A novel phasematchable organic NLO single crystal

Organic crystals have become excellent candidates towards nonlinear optical (NLO) applications as they possess superior second and third order optical nonlinearities and high electro-optic coefficients when compared with their inorganic counterparts. In this direction, 2-Amino-5-bromopyridinium trichloroacetate (2A5BPT), a new organic second-order nonlinear optical compound is synthesized and optical grade single crystals are formed utilizing a slow evaporation solution growth approach at room temperature while using methanol as the solvent. Single crystal X-ray diffraction study shows that the title compound is assigned to monoclinic crystal system having non-centrosymmetric space group Cc. The crystal is transparent ( ̴ 85%) throughout the whole visible spectrum, according to the Ultraviolet-Visble (UV–Vis) spectra, with a cutoff wavelength of 367 nm and an optical energy band gap Eg of 3.32 eV. The crystal possesses good thermal stability. The compound has a 1.6 times greater powder second harmonic generation (SHG) efficiency than potassium dihydrogen phosphate (KDP). The phase matchability of the 2A5BPT is studied through particle size dependence of SHG. The intermolecular connection demonstrated by numerous inter contacts has been shown by a molecular Hirshfeld surface analysis of the crystal structure, and the related 2-dimensional finger print analysis further evaluates the individual contribution from each atom. In order to examine the first order hyperpolarizability, molecular electrostatic potential, and Highest occupied molecular orbital-Lowest unoccupied molecular orbital (HOMO-LUMO) energies, the quantum chemical calculations for the title molecule (2A5BPT) were carried out by density functional theory (DFT) utilizing the B3LYP/6–311++G(d,p) basis set. According to these results, the 2A5BPT crystal could be suitable for optoelectronic applications.

O,S-Chelated bis(pentafluorophenyl)boron and diphenylboron-β-thioketonates: synthesis, photophysical, electrochemical and NLO properties.

Boron-β-diketonates are classical emissive materials that have been utilized in various fields, however, boron monothio-β-thioketonates, where one oxygen atom is exchanged for a sulphur atom, have not been explored in detail. To gain a better understanding of this class of materials, we synthesised various aryl substituted monothio-β-diketonate boron complexes with two different aryl substitutions on the boron center and studied their structural, optical and electrochemical properties. Single crystal X-ray analysis revealed that there is considerable deviation in B-O and B-S bond lengths for bis(pentafluorophenyl)boron complexes against diphenyl boron complexes. The bis(pentafluorophenyl)boron complexes have a relatively high absorption coefficient over diphenyl boron complexes. More importantly, a striking difference was observed for the emission behaviour of these compounds. The bis(pentafluorophenyl)boron complexes exhibit weak emission in the solution as well as in the solid state, whereas diphenyl boron complexes do not show any emission in either solution or the solid state. Further, the electrochemical study reveals that diphenyl boron complexes show a reduction potential that is more negative compared to the bis(pentafluorophenyl)boron complexes. The high absorption coefficient of the compounds pointed towards the possibility of high first order hyperpolarizability upon optical excitation, which motivated us to ascertain the nonlinear optical coefficients in the near infrared range, towards applicability of such compounds in optical limiting and switching. The open aperture Z-scan measurements at ultrashort time scales elucidated a few critical features of such compounds towards optical limiting applications.

Superalkali-alkaline earthide ion pairs of δ+(AM-HMHC)-AM'δ- (AM = Li, Na and K; AM' = Be, Mg and Ca) possessing large NLO responses and excellent electronic stabilities and alkalide characteristics: a DFT study.

To identify superalkali-alkaline earthide ion pairs, it's theoretically shown that, as a novel class of excess electron superalkali compounds, both chair and boat forms of (AM-HMHC)-AM' (AM = Li, Na, and K; AM' = Be, Mg, and Ca; HMHC = 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane) are good candidates. An attractive superalkali-alkaline earthide ion pair in δ+(AM-HMHC)-AM'δ- is firstly exhibited, which possesses alkaline-earthide characteristics and nonlinear optical response superior to similar M+(calix[4]pyrrole)M'- (M = Li, Na, and K; M' = Be, Mg, and Ca) with high stability. The electronic and vibrational second order hyperpolarizabilities and the frequency-dependent first hyperpolarizabilities of δ+(AM-HMHC)-AM'δ- are presented. For each pair of (AM-HMHC)-AM', the boat conformation is preferred to its chair one in the case of Hyper-Rayleigh scattering response (βHRS). These alkaline earthides suggest prominently high βHRS up to 2.59 × 104 a.u. (boat forms of δ+(Na-HMHC)-Caδ-). We expect that this work will inspire the preparation and characterization of these new alkaline earthides as high-performance NLO materials.

Excited state dependent fast switching NLO behavior investigation of sp2 hybridized donor crystal as D-π-A push–pull switches

This research focused on the investigating electronic and optical properties of designed chromophores (TPTP1-TPTP5) to involve their comprehensive analysis, including geometry optimization, UV–Vis spectroscopy, analysis of the transition density matrix (TDM), and exploration of their nonlinear optical (NLO) responses. The chromophore TPTP1 and TPTP2 exhibit significant transitions, making them suitable for optical switching applications. The chromophore TPTP5 stood out with high values for linear polarizability (<α0>, 8.53 × 10-24 esu), first order polarizability β0 (3.86 × 10-24 esu), and second order hyperpolarizability (γ0, 6.41 × 10-24 esu), making it notable for its nonlinear optical response. A positive correlation was observed between their vertical ionization potential (VIP) and the γ0 related NLO response, indicating that higher VIP values correspond to stronger γ0 responses. Their UV–Vis spectroscopy was employed to examine the absorption properties of the chromophores, revealing the wavelengths (λmax) at which they absorbed light and their potential for light harvesting applications. The analysis of the TDM allowed for a deeper understanding of the redistribution of electron density during electronic transitions within the chromophores. This analysis provided valuable insights into the characteristics and nature of their excited states. Additionally, the research investigated the NLO responses of the chromophores, particularly focusing on their third harmonic generation (THG) properties. These NLO properties are crucial for potential applications in optical switches, frequency conversion, and optical signal processing. Overall, the findings from this research contribute to a comprehensive understanding of the electronic and optical properties of the designed chromophores. The obtained results open up new possibilities for their utilization in various technological fields, including light harvesting, photonics, and nonlinear optics.

Molecular structure, HOMO–LUMO, and NLO studies of some quinoxaline 1,4-dioxide derivatives: Computational (HF and DFT) analysis

The theoretical investigation results of quinoxaline-1, 4-dioxide (I), and some of its derivatives (II-VII) were reported in this paper. Quantum chemical calculations were performed on seven molecules at ab initio/RHF/6–311++G (d, p) and DFT/B3LYP/6–311++G (d, p) levels of theory. Calculated optimized molecular structures, dipole moments, polarizabilities, and first order hyperpolarizabilities for all molecules were dedicated. Also, the frontier molecular orbitals (FMOs), EHOMO (the highest occupied molecular orbital energy), ELUMO (the lowest unoccupied molecular orbital energy), HOMO-LUMO energy gap (ΔE), quantum chemical parameters such as chemical potential (Pi), absolute electronegativity (χ), chemical hardness (η), global softness (S), and global electrophilicity (ω) are investigated. 1HNMR spectrum for quinoxaline-1, 4-dioxide (I) was calculated and compared with experimental data. The results of two theoretical methods have been analyzed using the Excel program in the linear regression method.