Structural parameters, electronic, linear and nonlinear optical exploration of thiopyrimidine derivatives: A comparison between DFT/TDDFT and experimental study

Triphenylamine-Based Metal-Free Organic Dyes as Co-Sensitizers: Enhancing Dye-Sensitized Solar Cell Performance Through Innovative Molecular Design

A series of novel dye-based D-π-A-type metal-free organic dyes was prepared via the Wittig reaction. Dyes SAS-1-5 containing triphenylamine (TPA) as a strong electron donor was linked with an aryl ring as a π-conjugation spacer, cyanoacetamide, 2-(phenylsulfonyl)acetonitrile, and thiazolidine as the electron acceptors. Herein, we confirmed the chemical structures of the co-sensitized triphenylamine sensitizers using spectral analyses. In addition, their optical properties, electrochemical characteristics, and photovoltaic performances were estimated. Theoretical density functional theory (DFT) at the B3LYP/6-311G(d, p) level was used to elucidate the bridged effect on geometry. The SAS-1-5 sensitizers showed absorption bands in a dimethylformamide (DMF) solution in the range of (450-590 nm) which led to an obvious enhancement in the visible harvesting ability. To improve the efficiency of the DSSCs, SAS-1-5 dyes were co-sensitized with the standard dye N-719. The power conversion efficiencies (PCEs) of SAS-1-5 with N-719 ranged from 7.39 to 9.12%. By employing SAS-2 as a co-sensitizer, the DSSC system achieved an impressive 9.12% efficiency, which was 24% higher than that when using the N-719 ruthenium complex dye. Furthermore, all TPA-based co-sensitizers (SAS-1-5) demonstrated considerable promise for improving photovoltaic performance.

Design and evaluation of indacenothienothiophene based functional materials for second and third order nonlinear optics properties via DFT approach

Nonlinear optics (NLO) is a fascinating field that explores how intense light interacts with matter. Organic chromophores are regarded as promising materials for nonlinear optics research due to their properties i.e., easy of process, structural versatility, and instant response to NLO effects. Therefore, in current research, a comprehensive investigation was carried out on a series of organic indacenothienothiophene (ITT) based chromophores (AOR and AO1-AO6) to explore their NLO properties through quantum chemical calculations. The DFT and TD-DFT methods at M06/6-311G(d,p) level were employed to investigate the optoelectronic properties of new designed compounds. The parent compound, i.e., AOIC was taken for the designing of the reference molecule (AOR) by substituting one terminal acceptor with donor in AOIC to develop push-pull architecture. The other derivatives (AO1-AO6) were designed via modulation of end-capped acceptor of AOR with benzothiophene (BT) based acceptors. These investigations revealed a red-shift absorption spectra (λmax = 783-848 nm) with reduced HOMO-LUMO energy gap (Egap = 1.741-1.956 eV) in AO1-AO6 as compared to AOR (Egap = 2.040; λmax=743 nm) in chloroform. Significant charge transferred from donor to BT acceptors through ITT core in AO1-AO6 as illustrated by DOS, FMOs and TDM analyses. All entitled compounds (AO1-AO6) exhibited a notable NLO response relative to the AOR. Particularly, AO2 displayed the prominent results like < α >  = 2.790 × 10-22 esu, βtotal = 7.027 × 10-27 esu and γtotal = 11.440 × 10-32 esu among all the derivatives. This might be owing to unique optoelectronic characteristics such as lowest Egap (1.741 eV) and hardness (0.871 eV) with highest softness (0.574 eV) and absorption spectrum (820 nm) of AO2. Hence, these calculations illustrated that the end-capped substitution of acceptor moieties with BT acceptors and the incorporation of conjugated donor system played a vital role in improving the NLO aptitude. Overall, these ITT-based derivatives can be considered as potential materials for promising applications in NLO field.

The Optical Properties, UV-Vis. Absorption and Fluorescence Spectra of 4-Pentylphenyl 4-n-benzoate Derivatives in Different Solvents

In this paper, electronic absorbance and fluorescence spectra of 4-Pentylphenyl 4-n-benzoate derivatives have been measured in 29 solvents, which are non-polar, polar protic and polar aprotic solvents, and electronic transitions that vary depending on the solvent are identified. As the solvent polarity increases, the forbidden energy difference between the frontier orbitals decreases. The statistical models in order to describe the solvent effect were derived using different solvent parameters. Quite complex and multiple absorbance transitions were observed in different solvent environments. Local fluorescence transition and intramolecular charge transfer occurred in the fluorescence spectra. Absorbance transitions are global transitions, and π*←π is the absorbance electronic transition. The frontier molecular orbitals and electrostatic potential surface were founded using quantum chemical calculations. Refractive indices were found with five different methods and forbidden energy gaps were found with the Tauc method. The forbidden energy ranges were found around 4.1 and 4.5, and the forbidden energy gap decreased as the alkyl chain became longer. All compounds can be defined as insulation materials according to the forbidden energy range. Refractive index values close to the E7 liquid crystal mixture used in liquid crystal display panels were found in the investigated liquid crystals.

Application of South African heulandite (HEU) zeolite for the adsorption and removal of Pb2+ and Cd2+ ions from aqueous water solution: Experimental and computational study

The capacity of South African Heulandite (HEU) zeolite to remove Pb2+ and Cd2+ ions from aqueous solution was investigated using batch experiments and molecular simulations studies. The effect of different factors on the adsorption of these ions onto the zeolite was investigated; contact time, initial metal ion concentration and the amount of HEU adsorbent. Molecular simulations was done using Monte Carlo and density functional theory. Experimental results obtained indicate that the maximum adsorption for the two ions occur at pH 5 and after 240 min of contact time. The percent removal based on contact time of Pb2+ and Cd2+ ions from water by the heulandite zeolite were 99.7 and 76.7 %, respectively. The adsorption of two metal ions onto the HEU zeolite follows the Langmuir adsorption isotherm. From the molecular simulation findings, the adsorption of Pb2+ ions onto the HEU window is equidistant from the two adjacent oxygen atoms within the HEU structure while the Cd2+ ion is adsorbed in the upper left side of the 8-ring HEU window. It was observed that the performance of the zeolite can significantly be improved by doping with germanium, aluminum, thallium indium, and sodium cations. These results indicate that the application of HEU zeolite as an adsorbent holds a great promise in heavy metal removal from aqueous solutions.

Remarkable enhancement of the nonlinear optical behavior towards asymmetric substituted D-π-A dithiophene-based compounds

CONTEXT

Nonlinear optics (NLO) is an interesting field that discloses the interaction between intense light and matter, leading to a deeper understanding of NLO phenomena. Organic chromophores are considered as promising materials for NLO due to their exceptional structural versatility, ease of processing, and rapid response to NLO effects. Functional materials based on thiophene have been indispensable in advancing organic optoelectronics. Specifically, dithiophene-based compounds display weaker aromaticity, reduced steric hindrance, and additional sulfur-sulfur interactions. Hence, by utilizing dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene (DTBDT) as the core structure, designing of a set of organic compounds with D1-π-D2-π-A-type framework, namely ZR1D1-ZR1D8, was carried out in this study. The analysis of frontier molecular orbitals (FMOs) revealed that compound ZR1D2 has the lowest band gap of 1.922 eV among all the investigated chromophores. The correlation of global reactivity parameters (GRPs) with the band gap values indicates that ZR1D2 displays a hardness of 0.961 eV and a softness of 0.520 eV-1. Among the studied compounds, ZR1D2 demonstrated a broad absorption spectrum that extended across the visible region. The maximum absorption wavelengths were observed at 766.470 nm for ZR1D2 and 749.783 nm for ZR1D5. These DTBDT-based dyes exhibit a remarkable NLO response with exceptionally high first hyperpolarizability (βtot) values. Among them, compound ZR1D2 stands out with the highest average linear polarizability (⟨α⟩ = 3.0 × 10-22 esu), first hyperpolarizability (βtot = 4.1 × 10-27 esu), and second hyperpolarizability (γtot = 7.5 × 10-32 esu) values. In summary, this investigation offers valuable insights into the potential use of DTBDT-based organic chromophores, particularly ZR1D2, for advanced applications in NLO. These findings suggest promising opportunities for researchers to synthesize these molecules and utilize these compounds in hi-tech NLO-based applications.

METHODOLOGY

The density functional theory computations were performed at the M06/6-311G(d,p) functional to explore their structural effects on electronic and NLO findings. Various analyses like highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps, absorption maxima, density of states, open circuit voltage, binding energies of electrons and holes, and transition density matrix are employed to investigate photovoltaic efficiencies of the derivatives. Different software packages like Avogadro, Multiwfn, Origin, GaussSum, PyMOlyze, and Chemcraft were used to deduce conclusions from the output files.

Possible NLO response and electrical/charge transfer capabilities of natural anthraquinones as p-type organic semiconductors: a DFT approach

CONTEXT

Organic semiconductors (OSCs) have attracted a great deal of interest in recent days. There are various types of OSCs, among which small molecules have various inherent benefits. Further research is needed to advance this new kind of material because the field is still developing, and the current focus is on creating small molecules that exist naturally for OSCs. OSCs with nonlinear optical (NLO) characteristics offer a significant advantage over others. Thus, this study theoretically investigates naturally occurring anthraquinones such as chrysophanol and rhein as potential OSCs, as well as their NLO properties. The calculated properties include the ionization potential (IP), electron affinity (EA), and bandgap (Eg). The FMO energy levels together with the Eg, IP (8.17-8.53 eV), and EA (1.87-2.44 eV) suggest the semiconductor nature of the studied compounds. The calculated values of reorganization energy (λ) and transfer integrals (V) suggest the p-type character of both molecules. Rhein has the lowest λh (0.19 eV) and Eg (3.28 eV) and the highest Vh, predominantly because of its better p-type character. The polarizability increases due to the presence of an electron-withdrawing substituent, leading to better NLO performance for Rhein, which is supported by its lower LUMO and Eg values.

METHODS

The studied molecules were optimized with the DFT/B3LYP-GD3/6-31+G(d,p) method using Gaussian 16 software. The crystal structure was simulated with Materials Studio 7.0, and the V values were calculated with the ADF package. The CDD and DOS plots were obtained with the Multiwfn 3.8 program.

One-pot multicomponent synthesis of novel pyridine derivatives for antidiabetic and antiproliferative activities

Background: Due to the close relationship of diabetes with hypertension reported in various research, a set of pyridine derivatives with US FDA-approved drug cores were designed and integrated by artificial intelligence. Methods: Novel pyridines were designed and synthesized. Compounds MNS-1-MNS-4 were evaluated for their structure and were screened for their in vitro antidiabetic (α-amylase) activity and anticancer (HepG2) activity by methyl thiazolyl tetrazolium assay. Comparative 3D quantitative structure-activity relationship analysis and pharmacophore generation were carried out. Results: The study revealed MNS-1 and MNS-4 as good alternatives to acarbose as antidiabetic agents, and MNS-2 as a more viable, better alternative to doxorubicin in the methyl thiazolyl tetrazolium assay. Conclusion: This combination of studies identifies new and more active analogs of existing FDA-approved drugs for the treatment of diabetes.

High-throughput virtual screening of marine algae metabolites as high-affinity inhibitors of ISKNV major capsid protein: An analysis of in-silico models and DFT calculation to find novel drug molecules for fighting infectious spleen and kidney necrosis virus (ISKNV)

Infectious Spleen and Kidney Necrosis Virus (ISKNV) is linked to severe infections that cause significant financial losses in global aquaculture. ISKNV enters the host cell through its major capsid protein (MCP), and the resulting infection can lead to mass mortality of fish. Even though several drugs and vaccines are at various stages of clinical testing, none are currently available. Thus, we sought to assess the potential of seaweed compounds to block viral entrance by inhibiting the MCP. The Seaweed Metabolite Database (1110 compounds) was assessed for potential antiviral activity against ISKNV using high throughput virtual screening. Forty compounds with docking scores of ≥8.0 kcal/mol were screened further. The inhibitory molecules BC012, BC014, BS032, and RC009 were predicted by the docking and MD techniques to bind the MCP protein significantly with binding affinities of -9.2, -9.2, -9.9, and -9.4 kcal/mol, respectively. Also, ADMET characteristics of the compounds indicated drug-likeness. According to this study, marine seaweed compounds may operate as viral entrance inhibitors. For their efficacy to be established, in-vitro and in-vivo testing is required.

Study of the Crystal Architecture, Optoelectronic Characteristics, and Nonlinear Optical Properties of 4-Amino Antipyrine Schiff Bases

Two Schiff bases, (E)-4-((2-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPOCB) and (E)-4-((4-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPPCB), have been synthesized and grown as single crystals. Single-crystal X-ray diffraction analysis was employed to determine the crystal structure of the compounds, and the results suggest that the compounds crystallized into an orthorhombic crystal system having P2₁2₁2₁ and Pbca space groups, respectively. Further, the crystallinity of the compounds was analyzed by the PXRD technique. The UV-vis-NIR spectra of the compounds demonstrate excellent transmittance in the entire visible region. The lower cutoff wavelengths of the compounds were determined to be 338 and 333 nm, respectively; additionally, optical band gaps of the compounds found were 4.60 and 4.35 eV. FTIR and NMR (¹H and ¹³C) spectral techniques were utilized to analyze the molecular structure of the compounds. The compounds emit photoluminescence with broad emission bands with centers at 401 and 418 nm. The thermal stability and phase transitions were assessed through thermogravimetric methods. The phase transition prior to melting was indicated by the endothermic event at around 190 °C in the DTA curves of both crystals, and the same was observed in the DSC curves. The second harmonic efficiencies of the powdered compounds I and II were found to be 3.52 and 1.13 times better than that of the standard reference KDP. The 4AAPOCB and 4AAPPCB compounds showed isotropic polarizability amplitudes of 46.02 × 10^-24 and 46.52 × 10^-24 esu, respectively. The calculation of linear polarizability and NLO second-order polarizability (β) along with other optical parameters was performed for optimized geometries. The nonzero amplitudes of the average β values for compounds 4AAPOCB and 4AAPPCB were found to be 14.74 × 10^-30 and 8.10 × 10^-30 esu, respectively, which show a decent potential of the synthesized molecules for NLO applications. The calculated β amplitudes were further explained based on calculated electronic parameters like molecular electrostatic potentials, frontier molecular orbitals, molecular orbital energies, transition energies, oscillator strengths, and unit spherical representation of NLO polarizability. The current analysis emphasizes the significance of synthesized compounds as prospective candidates for optical and NLO applications through the use of experiments and quantum computations.

Quantum mechanical studies of p-azoxyanisole and identification of its electro-optic activity

Liquid crystals (LCs) are used in displays, visors, navigation systems and many more. Amongst a wide range of LCs, p-azoxyanisole (PAA) is considered to be an active LC. Focusing on different properties of this molecule, in the reported study, the theoretical identification of quantum mechanical parameters and the identification of electro-optic properties are carried out. Different functional theories such as B3LYP, M06-2X and M06L are used along with three basis sets 6-31G**, 6-311G and 6-311G**. A comparative study revealed that the M06-2X method produces higher values of band gap, ionization potential, electronegativity and electronic global hardness while M06L produces lower values and B3LYP gives intermediate values. Nonlinear optical properties of liquid crystals are evaluated. The nonlinear optical properties obtained for a PAA liquid crystal are much higher than those of urea. Due to its high nonlinear optical properties, our liquid crystal can be used in the field of telecommunication and optical interconnection. The order parameter and birefringence are calculated with variable electric field. We found out that the order parameter and birefringence increase with a gradually increasing electric field, which suggests that the PAA liquid crystal can be used for developing electro-optic and tunable metamaterial devices.

Influence of Peripheral Modification of Electron Acceptors in Nonfullerene (O-IDTBR1)-Based Derivatives on Nonlinear Optical Response: DFT/TDDFT Study

Fullerene-based organic compounds have been reported as useful materials with some limitations; nonetheless, fullerene-free compounds are primarily considered to be the most substantial materials for the development of modern technology. Therefore, in this study, a series of compounds (NFBC2-NFBC7) having an A-π-D architecture were designed for the first time from a synthesized nonfullerene (O-IDTBR) compound by changing different acceptor groups. The synthesized nonfullerene (O-IDTBR1) compound and its designed derivatives were optimized with frequency analyses at the M06/6-311G(d,p) level. These optimized structures were further characterized by different quantum chemical approaches. The study required that the designed compounds possess a low energy gap in comparison to that of O-IDTBR1 (2.385 eV). Moreover, density of state (DOS) calculations supported the FMO analysis and displayed charge transfers from the HOMO to the LUMO in an effective manner. The λ_max values of the investigated chromophores were observed to be greater than that of the reference compound. Amazingly, the highest amplitude of linear polarizability ⟨α⟩ and first (β_tot) and second hyperpolarizability values were achieved by NFBC6 at 1956.433, 2155888.013, and 7.868 × 10⁸ au, respectively, among all other derivatives. Effective NLO findings revealed that nonfullerene-based derivatives may contribute significantly to NLO technology.

de la Torre A, Khan MU, Raza AR, Kamal GM, Rehman MF, Alam MM, Imran M, Braga AA, Pertino MW. Facile Synthesis of Diversely Functionalized Peptoids, Spectroscopic Characterization, and DFT-Based Nonlinear Optical Exploration

Compounds having nonlinear optical (NLO) characteristics have been proved to have a significant role in many academic and industrial areas; particularly, their leading role in surface interfaces, solid physics, materials, medicine, chemical dynamics, nuclear science, and biophysics is worth mentioning. In the present study, novel peptoids (1-4) were prepared in good yields via Ugi four-component reaction (Ugi-4CR). In addition to synthetic studies, computational calculations were executed to estimate the molecular electrostatic potential, natural bond orbital (NBO), frontier molecular orbital analysis, and NLO properties. The NBO analysis confirmed the stability of studied systems owing to containing intramolecular hydrogen bonding and hyperconjugative interactions. NLO analysis showed that investigated molecules hold noteworthy NLO response as compared to standard compounds that show potential for technology-related applications.

Structural, vibrational, electronic properties, hirshfeld surface analysis topological and molecular docking studies of N-[2-(diethylamino)ethyl]-2-methoxy-5-methylsulfonylbenzamide

The theoretical (Freebase, Cationic species) and experimental investigations on the molecular structural, spectroscopic characterization, and electronic properties of N2M5MB are reported. The most stable structure of the N2M5MB was analysed by employing Density Functional Theory (DFT) at different functional such as B3LYP, PBEPBE, TPSSTPSS and IEF-PCM (Freebase) and Cationic (B3LYP, IEF-PCM)/ 6-311++G (d,p) basis set level. The Potential Energy Scan (PES) analysis has been employed to investigate the conformational preference of the title molecule. The optimized molecular geometry, vibrational assignments (FT-IR, FT-Raman) of wavenumbers have been performed for freebase, cationic species (Gas, PCM) for the individual modes of vibration. The experimental UV-Vis absorption spectrum was obtained and compared with the simulated (Freebase, Cationic species) Time-Dependent (TD-DFT-M062X) method. The FMO's, electron-hole distributions, HOMA, FLU, Hirshfeld surface analysis, Electrostatic potential surface (ESP), Fukui functions, and topological parameters were discussed. Molecular docking studies were performed for the N2M5MB (ligand) into the active site of targeted proteins (1H22, 4DTL, 5OV9) which belong to AChE inhibitors with the minimum binding energy was detected.

Structural, Electronic and NLO Properties of 6-aminoquinoline: A DFT/TD-DFT Study

A computational study based on the DFT/TD-DFT approach was performed to explore various properties of 6-aminoquinoline (6AQ). The geometrical parameters, molecular orbitals (MOs), electronic spectra, electrostatic potential, molecular surface, reactivity parameters and thermodynamic properties of 6AQ were explored. The absorption and emission spectra of 6AQ in solvents have been estimated by TD-DFT coupled with the PCM model and correlated with the available experimental results. Depending on the solvents, the computed absorption maxima of 6AQ were noticed between 327 nm - 340 nm and ascribed to [Formula: see text] transition. The simulated emission maxima were obtained between 389 to 407 nm and ascribed to [Formula: see text] transition. On increasing the solvent polarity, both the emission and absorption maxima showed a bathochromic shift. The LUMO and HOMO were localized on the entire molecule. It was observed that the lowest excited state is possibly the [Formula: see text] charge-transfer (CT) state. The natural bonding orbital (NBO) study points out that ICT plays a significant role in stabilizing the molecular system. Moreover, the NLO (nonlinear optical) properties (polarizability, first-order hyperpolarizability and dipole moment) were computed using different hybrid functionals. The estimated values indicate that 6AQ can be considered a desirable molecule for further studies of the NLO applications.

Key Electronic, Linear and Nonlinear Optical Properties of Designed Disubstituted Quinoline with Carbazole Compounds

Organic materials development, especially in terms of nonlinear optical (NLO) performance, has become progressively more significant owing to their rising and promising applications in potential photonic devices. Organic moieties such as carbazole and quinoline play a vital role in charge transfer applications in optoelectronics. This study reports and characterizes the donor-acceptor-donor-π-acceptor (D-A-D-π-A) configured novel designed compounds, namely, Q3D1-Q3D3, Q4D1-Q1D2, and Q5D1. We further analyze the structure-property relationship between the quinoline-carbazole compounds for which density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were performed at the B3LYP/6-311G(d,p) level to obtain the optimized geometries, natural bonding orbital (NBO), NLO analysis, electronic properties, and absorption spectra of all mentioned compounds. The computed values of λmax, 364, 360, and 361 nm for Q3, Q4, and Q5 show good agreement of their experimental values: 349, 347, and 323 nm, respectively. The designed compounds (Q3D1-Q5D1) exhibited a smaller energy gap with a maximum redshift than the reference molecules (Q3-Q5), which govern their promising NLO behavior. The NBO evaluation revealed that the extended hyperconjugation stabilizes these systems and caused a promising NLO response. The dipole polarizabilities and hyperpolarizability (β) values of Q3D1-Q3D3, Q4D1-Q1D2, and Q5D1 exceed those of the reference Q3, Q4, and Q5 molecules. These data suggest that the NLO active compounds, Q3D1-Q3D3, Q4D1-Q1D2, and Q5D1, may find their place in future hi-tech optical devices.

Synthesis, antioxidant, antimicrobial and antiviral docking studies of ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates

A series of ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates (2a-r) was synthesized in two steps from thiosemicarbazones (1a-r), which were cyclized with ethyl bromopyruvate to ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates (2a-r). The structures of compounds (2a-r) were established by FT-IR, ¹H- and ¹³C-NMR. The structure of compound 2a was confirmed by HRMS. The compounds (2a-r) were then evaluated for their antimicrobial and antioxidant assays. The antioxidant studies revealed, ethyl 2-(2-(4-hydroxy-3-methoxybenzylidene)hydrazinyl)thiazole-4-carboxylate (2g) and ethyl 2-(2-(1-phenylethylidene)hydrazinyl)thiazole-4-carboxylate (2h) as promising antioxidant agents with %FRSA: 84.46 ± 0.13 and 74.50 ± 0.37, TAC: 269.08 ± 0.92 and 269.11 ± 0.61 and TRP: 272.34 ± 0.87 and 231.11 ± 0.67 μg AAE/mg dry weight of compound. Beside bioactivities, density functional theory (DFT) methods were used to study the electronic structure and properties of synthesized compounds (2a-m). The potential of synthesized compounds for possible antiviral targets is also predicted through molecular docking methods. The compounds 2e and 2h showed good binding affinities and inhibition constants to be considered as therapeutic target for M^pro protein of SARS-CoV-2 (COVID-19). The present in-depth analysis of synthesized compounds will put them under the spot light for practical applications as antioxidants and the modification in structural motif may open the way for COVID-19 drug.

Synthesis of Diaminopyrimidine Sulfonate Derivatives and Exploration of Their Structural and Quantum Chemical Insights via SC-XRD and the DFT Approach

Two heterocyclic compounds named 2,6-diaminopyrimidin-4-ylnaphthalene-2-sulfonate (A) and 2,6-diaminopyrimidin-4-yl4-methylbenzene sulfonate (B) were synthesized. The structures of heterocyclic molecules were established by the X-ray crystallographic technique, which showed several noncovalent interactions as N···H···N, N···H···O, and C-H···O bonding and parallel offset stacking interaction. Hydrogen-bonding interactions were further explored by the Hirshfeld surface (HS) analysis. Nonlinear optical (NLO) and natural bond orbital (NBO) properties were calculated utilizing the B3LYP/6-311G(d,p) level. Frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP) were calculated utilizing the time-dependent density functional theory (TD-DFT) at the same level. The NBO analysis showed that the molecular stabilities of compounds A and B were attributed to their large stabilization energy values. The second hyperpolarizability (γ_tot) values for A and B were obtained as 3.7 × 10⁴ and 2.7 × 10⁴ au, respectively. The experimental X-ray crystallographic and theoretical structural parameters of A and B were found to be in close correspondence. Both the molecules reveal substantial NLO responses that can be significant for their utilization in advanced applications.

An Experimental and Computational Exploration on the Electronic, Spectroscopic, and Reactivity Properties of Novel Halo-Functionalized Hydrazones

Herein, halo-functionalized hydrazone derivatives "2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-fluorobenzylidene) aceto-hydrazone (CPFH), 2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-chlorobenzylidene) aceto-hydrazones (CCPH), 2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-bromobenzylidene) aceto-hydrazones (BCPH)" were synthesized and structurally characterized using FTIR, 1H-NMR, 13C-NMR, and UV-vis spectroscopic techniques. Computational studies using density functional theory (DFT) and time dependent DFT at CAM-B3LYP/6-311G (d,p) level of theory were performed for comparison with spectroscopic data (FT-IR, UV-vis) and for elucidation of the structural parameters, natural bond orbitals (NBOs), natural population analysis, frontier molecular orbital (FMO) analysis and nonlinear optical (NLO) properties of hydrazones derivatives (CPFH, CCPH, and BCPH). Consequently, an excellent complement between the experimental data and the DFT-based results was achieved. The NBO analysis confirmed that the presence of hyper conjugative interactions was pivotal cause for stability of the investigated compounds. The energy gaps in CPFH, CCPH, and BCPH were found as 7.278, 7.241, and 7.229 eV, respectively. Furthermore, global reactivity descriptors were calculated using the FMO energies in which global hardness revealed that CPFH was more stable and less reactive as compared to BCPH and CCPH. NLO findings disclosed that CPFH, CCPH, and BCPH have superior properties as compared to the prototype standard compound, which unveiled their potential applications for optoelectronic technology.

Exploration of Noncovalent Interactions, Chemical Reactivity, and Nonlinear Optical Properties of Piperidone Derivatives: A Concise Theoretical Approach

The organic compounds with a π-bond system lead to electric charge delocalization which enables them to reveal fascinating nonlinear optical properties. Mono-carbonyl curcuminoids also have an appealing skeleton from the conjugation view point. Interesting chemical structures of the 3,5-bis(arylidene)-N-benzenesulfonyl-4-piperidone derivatives motivated us to perform density functional theory (DFT)-based studies. Therefore, computations using the B3LYP/6-311G(d,p) functional of DFT were executed to explore geometric parameters, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies, and natural bond orbital (NBO) analyses. Moreover, three different functionals such as HF, B3LYP, and M06 with the 6-311G(d,p) basis set were used to investigate the average polarizability ⟨α⟩ and first hyperpolarizability (β_tot)-based properties of all compounds. A good concurrence among calculated and experimental parameters was obtained through root mean square error calculations. The molecular stability of piperidone derivatives was examined using the Hirshfeld surface and NBO analyses. Natural population analysis was also performed to obtain insights about atomic charges. Calculated HOMO-LUMO energies showed that charge transfer interactions take place within the molecules. Moreover, global reactivity parameters including electronegativity, chemical hardness, softness, ionization potential, and electrophilicity were calculated using the HOMO and LUMO energies. The average polarizability ⟨α⟩ and first hyperpolarizability (β_tot) values of all compounds were observed to be larger in magnitude at the aforesaid functional than the standard compound.

A facile microwave assisted synthesis and structure elucidation of (3R)-3-alkyl-4,1-benzoxazepine-2,5-diones by crystallographic, spectroscopic and DFT studies

The use of microwave (MW) irradiation in organic synthesis has become increasingly popular within the pharmaceutical and academic arenas because it is a new enabling technology for drug discovery and development. It is a rapid way of synthesis, which involves faster reaction rates and high selectivity to conventional heating method of syntheses. The MW-assisted 7-exo-tet cyclization of N-acylanthranilic acids afforded (3R)-3-alkyl-4,1-benzoxazepines-2,5-diones in very short duration (20 min) with extraordinary high yields in comparison to conventional heating mode of synthesis. The method development, comparative yields of MW-assisted and thermal method of syntheses, crystallographic, spectroscopic and density functional theory (DFT) studies are reported herein. Four novel compounds with chemical formulas C₁₀H₉BrClNO₃5m, C₁₉H₁₉NO₃6e, C₁₃H₁₄ClNO₃6h and C₁₂H₁₁Br₂NO₃6h were synthesized, validated by ¹HNMR, ¹³CNMR, FT-IR, UVVis, EIMS spectroscopic techniques and confirmed by using single crystal X-ray diffraction (SC-XRD) study. The DFT and TDDFT calculations at B3LYP/6-311 + G(d,p) level of theory were performed for comparative analysis of spectroscopic data, optimized geometries, frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of 5m, 6e, 6h and 6o. Overall, experimental findings were supported nicely by corresponding DFT computed results. The NBO analysis confirmed that the presence of non-covalent interactions, hydrogen bonding and hyper- conjugative interactions are pivotal cause for the existence of 5m, 6e, 6h and 6o in the solid-state. NLO analysis showed that 5m, 6e, 6h and 6o have significant NLO properties as compared to prototype standard compound which disclosed their potential for technology related applications.