Search

Optimization of nine bis-Schiff bases derived from 5-substituted-8-aminoquinoline (I) and furan-2, 3-di-carbaldehyde (II) molecules was performed using density functional theory (DFT) in B3LYP/6-311G++ (d, p) level of theory and based on the optimized structures, structural parameters, dipole moments, as well as frontier molecular orbitals of the desired bis-Schiff bases (III) were calculated. The statistical thermodynamic functions, i.e., enthalpy changes (ΔHºr = 10.21 kcalmol−1) and Gibbs energy changes (ΔGºr = 12.62 kcalmol−1) were obtained from the theoretical harmonic frequencies (freq keyword). Each of these imines has four geometrical isomers (ZZ, EZ, ZE, and EE), and their relative stability for III-H was studied. It was found that ZZ (III-H) is the most unstable (9.20 kcalmol−1) in four isomers. To check the nonlinear optical (NLO) properties of these organic compounds the first hyperpolarizability (βtotal) and average polarizability (αave) parameters were calculated. All of these bis-Schiff bases (III) have βtotal values larger than the magnitude of the βtotal value for urea (a standard molecule) and III-NO2 is the best NLO material in studied compounds. So for III-NO2, Mulliken atomic charges analysis, frontier orbitals, and molecular electrostatic potential (MEP) surfaces have been studied. [ABSTRACT FROM AUTHOR]

ABSTRACT Para‐phenylene‐bridged pyridinium (acceptor)–dicyanomethanide (donor)‐based zwitterions were computationally investigated and are reported here. Reichardt's metamer was found to be twisted and Brooker's metamer in near‐planar conformation. Natural bond orbital (NBO) analysis showed that mesomeric resonance is helping Brooker's metamer but found to be not helpful for Reichardt's metamer. To assess the impacts of metamerism and aromatic bridges, fundamental molecular properties like dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β), and adiabatic absorptions of these two molecules were analyzed and then directly compared with their counterpart zwitterions without any bridges (previously reported). Results of impact of metamerism: Reichardt's metamer showed around three times enhanced hyperpolarizabilities (ωB97xD: β = 1577.1 × 10−30 esu) than the Brooker's metamer (ωB97xD: β = 532.5 × 10−30 esu). Impacts of p‐phenylene bridges: Compared to their respective D–A directly connected zwitterions reported previously (in ωB97xD methodology, Reichardt's: β = 257.2 × 10−30 esu and Brooker's: β = 67.2 × 10−30 esu), respective p‐phenylene‐bridged zwitterions showed five to eight times enhanced hyperpolarizabilities. This report highlights the better efficiencies of Reichardt's metamer over Brooker's metamer and aromatically bridged over the directly connected zwitterions. Current findings may be helpful in the designing of efficient functional molecular chromophores, and aromatic bridge combined with zwitterions can be solutions to nonlinear transparency trade‐off problem. [ABSTRACT FROM AUTHOR]

Context: This work reports structure–property correlations of 27 zwitterions Reichardt's types of zwitterions. Focuses are twofold, to see the (1) impacts of metamerism with Reichardt's vs Brooker's types of zwitterions and (2) impacts of monocyclic aromatic rings as bridges. All the molecules considered here have pyridinium (common acceptor: A) and p-phenylene-dicyanomethanide (common donor: D). Fundamental molecular properties like dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β), and adiabatic absorptions were computed only for the Reichardt types and compared with the literature reported respective Brooker's types of zwitterions. As an impact of metamerism, in general 2–3 times enhanced hyperpolarizabilities (β) were observed for Reichardt's compared to Brooker's types. Exceptions were observed with some triazine bridges and furan bridge, where Brooker's types were found to be more efficient. As impacts of aromatic bridges, in general, 6–sevenfold enhanced β compared to well-known traditional bridges and enhanced β were observed compared to D-A directly connected zwitterion (benzene bridge: sixfold enhanced β). Current findings show that the aromatic bridge control with Reichardt's types of zwitterions is more efficient and thus may be employed as an effective strategy for the designing of functional molecular chromophores for various other fundamental areas. Methods: All computations were performed with Gaussian 09. Geometry optimizations and computations of fundamental properties were carried out with HF, B3LYP, CAM-B3LYP, and ωB97xD methodologies, with 6-31G(d,p) and aug-cc-pVDZ basis sets. For adiabatic excitations, computations were carried out using TDDFT and TDHF approaches. For the computations of the response properties (like the nonlinear optical responses), CPHF approach was used. [ABSTRACT FROM AUTHOR]

Abstract The fascinating electronic applications attracted researchers to explore the field of nonlinear optical (NLO) materials. The slow evaporation of solvent technique (SEST) was employed to grow the 2-cyanopyridinium perchlorate (2-CPPC) NLO single crystals. The cell parameters of the grown 2-CPPC crystal are confirmed by the single crystal X-ray diffraction (SCXRD) study. The powder X-ray diffraction studies confirm the crystallinity of 2-CPPC crystals, and the peaks were indexed. The computation for the geometry optimization, HOMO–LUMO energy gap, global reactivity parameters, natural bond orbital (NBO) analysis, polarizability, and hyperpolarizability of the 2-CPPC molecule was done using B3LYP (6-311G basis set) functional of DFT method. The experimental FTIR and UV–Vis results of the 2-CPPC compound were compared with the simulated results. The second harmonic generation (SHG) study for the 2-CPPC crystal was employed using Kurtz–Perry powder technique. Single beam Z-scan technique using He–Ne laser is used to study the third-order NLO properties.

Due to their strong molecular hyperpolarizability, organic push–pull materials are gaining interest for nonlinear optical applications. We were able to characterize the intramolecular charge transfer and the distribution of the electron cloud within the molecular unit by exciting these materials under the influence of an electric field. The series products of conjugated monomers derived from acrylo–azobenzene containing in the para position the attracting groups (–H, –NO2, –COOC2H5, –SO3H and –COOH) exhibit good nonlinear optical activity. We computed the nonlinear optical characteristics of these compounds as well as exploiting the theoretical calculations of DFT and AM1 to determine their hyperpolarizabilities. Besides, we investigated the increase in hyperpolarizability in the push–pull model of organic compounds under the effect of the strength of attracting groups, the existence of the conjugated π -electron and the azo bridge. [ABSTRACT FROM AUTHOR]

Previously synthesized six selected Pyridinium‐Benzimidazolate based zwitterions were investigated in this contribution. Of the selected molecules, two are TICT, two are PICT (twisted and planar intramolecular charge transfer types respectively), and the other two are PICT+TICT types. Generally, TICT vs PICT is the most widely used strategy for chromophore design by earlier researchers. In this work, impacts of PICT+TICT effects (two effects combined in one chromophore), through p‐phenylene bridges, on various fundamental properties like, dipole moments, polarizabilities, hyperpolarizabilities, adiabatic excitations were analyzed. Nonlinear optical (NLO) responses of the six molecules indicate that PICT more efficient than TICT (6‐11‐times enhanced β), and PICT+TICT more efficient than both PICT (~4 times enhanced β) and TICT (20–40 times enhanced β). Current work also shows the role of aromatic p‐phenylene bridge as an efficient communicator between the donor and acceptor, in enhancing the NLO and other response properties. This work suggests that inducing bridge aromatic control to a TICT chromophore (making it to exhibit an amalgamation of PICT and TICT effects) is an effective and efficient strategy in the designing of molecular nonlinear optical chromophores, over either PICT or TICT only. [ABSTRACT FROM AUTHOR]

Herein, a series of N-pentylhydrazinylthiazole based compounds (EP1–EP7) were synthesized via three step synthetic strategy. The intermediates (TH1–TH7) were prepared with Hantzsch's approach followed by N-pentylation through substitution reaction to obtain targeted N-pentylhydrazinylthiazoles (EP1–EP7). The proposed structures were established with different spectroscopic methods like FTIR, 1H-, 13C-NMR, and HRMS. Further, the non-linear optical (NLO) effect of established structures was explored via quantum chemical investigations. NLO, ultraviolet–visible (UV–Vis), natural population analysis (NPA), global reactivity parameters (GRPs), and natural bond orbital (NBO) investigations were executed at M06/6-311G(d,p) level of density functional theory (DFT). UV–Vis analysis revealed that the yielded systems (EP1–EP7) exhibited absorption wavelength in UV–Vis spectrum in the range of 328.61–389.58 nm. EP1 exhibited the highest λmax value (389.58 nm) among all examined compounds due to its minimal Egap of 4.028 eV. The widening of the energy gap was observed from EP1 to EP7 (4.028–4.492 eV) as elucidated by Frontier molecular orbital (FMO) investigation. The GRPs were correlated with the results of energy gap. As EP1 depicted the minimum band gap (4.028 eV), so it exhibited the highest value of softness (0.248 eV−1) along with lower-most value of hardness (2.014 eV). NBO analysis revealed valuable insights into the charge delocalization and stability of the compounds (EP1–EP7). The dipole moment ( μ tot ) , average linear polarizability <α>, first and second order hyperpolarizabilities ( β to t and γ tot ) were also executed for EP1–EP7 at the above-mentioned level. Consequently, the maximum β tot (2.10 × 10−29 esu) and γ tot (9.31 × 10−35 esu) values were depicted by EP1 and EP3, respectively. Thus, all these outcomes unveiled that EP1 depicted robust response and proved to be the best NLO candidate for various hi-tech applications such as signal processing, fiber optics and data storage. [ABSTRACT FROM AUTHOR]

The widespread use of nonlinear optical (NLO) materials for contemporary technologies has sparked intense interest in their production with the creation of materials with a continuous endeavor. In this theoretical study, we investigate the NLO responses of doped superalkali (SA) metal salts with planar boron sheets (PBSs). We consider four different substrates (B10, B10F3, B16, and B16F3) to create 12 new surfaces ( 1-12) by doping SAs (Li2F, Li2OF, Li2O2) with them. We optimize the geometries of these surfaces and analyze their frontier molecular orbitals (FMOs) and natural bond orbitals (NBO) to obtain insights into their global chemical reactivity. We also examined their NLO responses ranging as 1.22–1.67×10−21, 3.39–7.59×10−24, and 3.5×10−24e.s.u. Our results reveal that the doped surfaces exhibit stronger NLO responses compared to the undoped surfaces, and that the strongest NLO response is found in the B16F3-doped surface. The role of various segments in FMOs is investigated using the TDOS and PDOS spectral analyses. To comprehend the relationship between the SA and the B10F3 substrates molecule more effectively, non-covalent interaction (NCI) investigation is carried out. Additionally, Time-dependent DFT (TD-DFT) simulations are done for UV–Vis analysis to observe significant redshifts up to 1050nm. All the SA-doped surfaces are thermodynamically stable NLO materials with improved NLO responses, so these materials are proposed to be used during the construction of advanced NLO responses. [ABSTRACT FROM AUTHOR]

This contribution reports extensive studies on structure–property correlations of two isoelectronic betaine metamers (positional isomers). These zwitterions differ from each other with respect to bonding modes of pyridinium acceptors (Reichardt's mode: through N‐atom versus Brooker's mode: through C‐atom) with the p‐phenylene bridged phenolate donors. Various quantum chemical methodologies are used in this investigation, with time‐dependent (TD) and coupled perturbed (CPHF) theories for computations of many molecular response properties. Analysis of first hyperpolarizabilities (β) indicates that Reichardt's metamer (ωB97xD: β = 349.5 × 10−30 esu) is more efficient chromophore (~5‐fold enhanced) than Brooker's metamer (ωB97xD: β = 69.4 × 10−30 esu). The gyratory abilities of the bridge junctions resulted in a cohort of metastable conformations, in the rotational potential energy surfaces (PES) of the two metamers. Moreover, rotational PES establishes that intermediary torsions are suitable for optimal chromophore design strategies (Reichardt's metamer: β = 956.5 × 10−30 esu, and Brooker's metamer: β = 1104.7 × 10−30 esu), Thus suitable conformational manipulations, can be used to obtain more efficient zwitterionic molecular chromophores. Compared unbridged prototype molecules, p‐phenylene bridged zwitterions showed ~6–9 times enhanced values of β. In addition, important aspects of suitable chromophore design strategies are suggested. [ABSTRACT FROM AUTHOR]

Earlier experimental works report the synthesis of zwitterions with anionic p-dicyanomethanide (coupled to benzene and thiophene) donors. In this report, four such zwitterions (two metameric pairs) are investigated using HF, B3LYP, CAM-B3LYP, HSE06, and raB97xD methodologies. This work is focused on (1) metameric (Reichardt's and Brooker's) induced conformational selectivity (twisted vs. planar) and (2) efficiency assessments of benzene- versus thiophene-based anionic donors. These effects were found to have significant influences on many tensorial and nontensorial properties. For Reichardt's type, large twisting was observed for the benzene case and lower twisting for the thiophene case. Enhanced first hyperpolarizability were observed for Reichardt's type (257.2 x 10-30 esu) than Brooker's type (67.2 x 10-30 esu), thus indicating the former type to be more efficient (approximately fourfold enhancement) chromophore (approximately seven-time enhancement for thiophene-based systems). Similarly, between the benzene versus thiophene cases, enhanced hyperpolarizabilities were observed for the former (257.2 x 10-30 esu) than the latter type (112.0 x 10-30 esu), indicating the benzene type as more efficient (more than twofold enhancement) donor (approximately four-time enhancement for Brooker's types). The structure-property manipulations strategies investigated here can be used as valuable tools in the designing of efficient functional molecular materials for various fundamental applications. [ABSTRACT FROM AUTHOR]

The computational simulations of nonlinear optical (NLO) characteristics of silver (Ag) and alkaline earth metals (Be, Mg, and Ca) doped 15-crown-5 (15C5) complexes are the focus of this research. By accurately grabbing hypothetical computations, DFT and TD-DFT approached in-depth characterization of M(Ag@15C5) where (M = Be, Mg, and Ca) is achieved using WB97XD functional along with LANL2DZ basis set. The consequences of different analyses like FMOs (frontier molecular orbitals), hyperpolarizabilities, DOS (density of states), interaction energy (Eint), absorption maximum (λ max), dipole moment (μ ), TDM (transition density matrix), EDDM (electron density distribution map), electrostatic potential (ESP), and electrical conductivity (σ ) were investigated for pure surface 15C5 and all the doped complexes. NCI analysis was performed to study the nature of interaction between surface and dopants. The doping method for all complexes admirably improved charge transfer properties like enhanced λ max lie in the range of 332–491 nm with narrowing band gap (Eg) in the range of 3.28–3.78 eV in comparison to pure 15C5 with Eg of 4.76 eV and 132 nm λ max. Complexes Be(Ag@15C5), Mg(Ag@15C5), and Ca(Ag@15C5) showed a significant increase in linear polarizability (α o) and first hyperpolarizability ( β o ) due to the lowest excitation energies of these complexes as compared to pure 15C5. All these outcomes of mentioned systems revealed that these complexes can be used as efficient and promising NLO materials. [ABSTRACT FROM AUTHOR]

Today, materials with unique nonlinear optical characteristics improve the function of optical devices. In this case, biological molecules with medical properties can be studied as a new group of materials with nonlinear optical properties. In this research, the optical features of some medically important molecules with piperazine ring were investigated in environments with different polarities. For this reason, spectroscopy and DFT methods were used. The polarity of an environment plays a significant role in improving the nonlinearity of solute molecules. Environment polarity induces the same effects on biomolecules' hyperpolarizability in the first and second order. A comparison of environment polarity effects on the molecular linear and nonlinear optical characteristics leads to providing a simple method for studying the environment polarity effects on molecular nonlinearity. Moreover, selected materials with high nonlinearity can have a special place in optics and photonics. [ABSTRACT FROM AUTHOR]

Corannulene (C20H10) is a distinctive type of non-planar conjugated polycyclic aromatic buckybowl which possesses unique chemical and physical properties. In this study, superalkali doped corannulene complexes are theoretically designed and their structural, electronic, and optical properties are investigated using quantum chemical calculations. The superalkalis AM3O (AM = Li, Na, K) are doped over both convex and concave surfaces of corannulene. The interaction energies (− 26.39 to − 53.99 kcal/mol) reflect that the designed AM3O@ C20H10 complexes are thermodynamically stable. Doping of superalkalis has remarkably reduced the HOMO–LUMO energy gaps (0.67–1.47 eV) of the corannulene with enhanced semiconducting properties. The investigation of charge transfer has been performed using natural bond orbital analysis, and one of the K3O doped complex exhibits the largest charge transfer (0.95 |e|). The visualization of charge transfer from the super alkali and the corannulene has been carried out via deformation density analysis. The non-covalent interaction index and quantum theory of atoms in molecules analyses are also conducted to ascertain the nature of interactions in the designed complexes. The static polarizability (326 au) and static first hyperpolarizability (1.6 × 103 au) values of corannulene are considerably enhanced as a result of superalkali doping. Moreover, superalkali doping over convex face exhibited more remarkable enhancement of static hyperpolarizabilities (βo) as compared to concave face doped complexes. These findings might enable the development of effective NLO materials with improved optoelectronic properties. [ABSTRACT FROM AUTHOR]

An investigation of electro‐optical and nonlinear optical properties of pure and halogenated (−Cl, −Br) hexahexyloxytriphenylene (HAT6) molecule is presented employing a density functional theory (DFT) approach. The effect of halogenation on HAT6 molecule is studied by introducing single and double halogens (Cl, Br) in its molecular geometry. The geometries are optimized progressively to achieve stability using B3LYP method with 6‐311 basis sets. The physical properties encompassing electro‐optical, thermodynamic, and electronic properties of single molecule of HAT6 are computed using DFT method. The introduction of halogens to discotic HAT6 molecule to an augmentation in molecular polarizability, rendering halogenated HAT6 a suitable candidate for nonlinear optical devices due to its π–π conjugation and improved optical parameters. The UV‐Vis spectra indicate the predominant absorptions and changes in absorption depend on the halogenations of the HAT6 molecule. Also, the halogenation effect leads to a significant reduction in the energy bandgap directly associated with electron‐electron correlation, facilitating straightforward tuning. [ABSTRACT FROM AUTHOR]

A series of zwitterions with varying bridges, connecting N‐methyl pyridinium acceptor, with phenolate donor, are investigated using various methodologies like, HF, B3LYP, CAM‐B3LYP and ωB97xD. In this systematic study effects of various mono aromatic rings as bridges, on the response properties like, the dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β) and adiabatic absorptions were analyzed using CPHF and TDDFT (or TDHF) theories. Compared to many traditional bridges, as well as without a bridge, enhanced nonlinear optical (2ND order NLO) responses were observed for these aromatically bridged zwitterions (with benzene ring as bridge ~5.3 times and ~7.9 times enhanced hyperpolarizabilities were observed compared to either the ethylene bridge or without any bridge cases, respectively). Also, many significant differences and large enhancements in response properties were observed compared to our earlier works on non‐zwitterionic system (~4.3 times enhanced hyperpolarizability—benzene as bridge case). For some bridge cases, 10‐ to 15‐fold enhanced hyperpolarizabilities were observed compared to without any bridge case. This work reports a class of non‐TICT chromophores, promoting bridge aromaticity control on structure–property correlation, as a suitable and efficient chromophore design strategy to create a wide range of function molecular chromophores. Also, unidirectional natures of response properties and large dipole moments can make these zwitterions suitable 1D‐molecular materials for various contemporary technological applications, as poled polymer‐based materials. [ABSTRACT FROM AUTHOR]

This contribution reports the structure–property correlations for few already synthesized bi‐aryl types of zwitterionic molecules. Quantum mechanical methodologies like, HF, MP2, B3LYP, CAM‐B3LYP, LC‐ωPBE, M06‐2X, and ωB97xD were used to investigate the optoelectronic properties of some interesting metameric pairs, where the molecules were bonded either through Reichardt's or Brooker's modes. Different bonding modes and inter‐ring attractive forces are assigned to investigate three distinct cases (i) metameric enforcements & preferential resonance stabilizations, (ii) inter‐ring hydrogen bonded stabilizations through hetero‐atoms in the ring, and (iii) an amalgamation of these two forces. Computations indicate unusual structural preferences (planar vs. twisted) by the metameric pairs, and thus direct reflections of these behaviors on some of the important tensorial properties like, dipole moments, polarizabilities, hyperpolarizabilities, and so forth were observed. The metameric manipulation on structure–property correlations shown by these molecules can be utilized as useful strategies for efficient chromophore design, not only in the field of nonlinear optics, but also in other areas of research connecting to advanced functional materials for technological applications. [ABSTRACT FROM AUTHOR]

This contribution reports influences of unusual conformational metamorphosis shown by Reichardt's and Brooker's metameric zwitterions by an earlier work, on various intrinsic electronic and optoelectronic properties. Detailed quantum mechanical investigations were carried out using HF, B3LYP, CAM‐B3LYP, and ωB97xD methodologies. Observations suggest that whereas certain properties were directly and strongly influenced by the conformation preferences (twisted vs. planar), others were not strongly inclined to such conformational transformations. Interestingly, even with inherent conformational differences, observed properties were found to have only one major contributing component in each molecule and can be beneficial in one dimensional (1D) or pseudo‐1D chromophore design strategies. Both coupled perturbed (CP) and finite field (FF) theories were used to compute dipole moments, polarizabilities, and hyperpolarizabilities, and so on, and excellent agreements (or exact matching results) were observed between the two theories. Reichardt's metamer was found to be more efficient in many aspects than Brooker's metamer. The direct and strong influences of metameric manipulations on structure–property correlations shown in this work can be adopted as a useful strategy for efficient chromophore design. Such a strategy is useful in the field of nonlinear optics, and may also find applications in various other areas of material sciences. [ABSTRACT FROM AUTHOR]

The kinetics and mechanism of osmium(VIII)-catalyzed oxidation of paracetamol (PAM) with N-bromosuccinimide (NBS) in acidic medium have been studied at a constant ionic strength of 0.50 M. The reaction is characterized by 1:1 stoichiometry. The main products were identified by spot test and IR and UV-visible spectroscopy. The activation parameters of the rate-determining step were computed and discussed, and the thermodynamic parameters were also calculated. First-order kinetics with respect to Os(VIII) was observed for the oxidation of paracetamol. The reaction rate decreased with increase in the acidity and NBS concentration. Variation of the ionic strength had no significant effect on the reaction rate. A plausible mechanism has been proposed on the basis of the kinetic studies, reaction stoichiometry, and product analysis. Quantum chemical study of the oxidation of paracetamol with NBS was performed in the framework of the density functional theory (DFT) using B3LYP/6-31G(d,p) basis set. The DFT studies included computation of various structural parameters, viz. electrostatic potential, electrophilicity, chemical potential, chemical hardness, thermodynamic properties at various temperatures, nonlinear optical (NLO) properties, Mulliken charges, electric dipole moments, polarizability, and first static hyperpolarizability, as well as natural bond orbital (NBO) and atom in molecule (AIM) analysis. [ABSTRACT FROM AUTHOR]

A semi organic crystalline salt - 1,3-diammonium propylarsenate (1-3-DAPSM) has been taken as the subject of theoretical investigation for its optical and nonlinear optical studies. Gaussian 09 program has been utilized to quantify the quantum chemical theoretical estimations with the aid of B3LYP exchange correlational function with 6-311++G(d,p) basis set. The electronic absorption spectra of the title compound have been recorded in the gas phase as well as in three different solvents, that is, ethanol, methanol, and water. Further frontier molecular orbital analysis has been done to identify the energy gap and charge transfer occurrence between the molecules. Further, the first-order hyperpolarizability (ß) of the 1,3-Diammonium Propylselenate Monohydrate molecule was computed to identify the nonlinear microscopic behavior of the studied compound. [ABSTRACT FROM AUTHOR]

The molecular properties of a biphenyl benzoate based ferroelectric liquid crystal compound were estimated using DFT/6-31G method. Non Linear Optical properties of the compound have been estimated by calculating its polarizability and hyperpolarizability. Frontier molecular orbital (FMO), Molecular electrostatic potential (MEP) and Infrared (IR) spectra have been simulated. Global parameter and a few thermodynamic parameters have also been calculated. The phase sequence has been confirmed by polarizing optical microscopy. The spontaneous polarization and rotational viscosity of the compound have been measured. From results the efficacy of the compound in NLO or electro optical applications have been inferred. [ABSTRACT FROM AUTHOR]

The properties of nonlinear optical (NLO) are examined, and the results confirm the 2.19 eV HOMO–LUMO mismatch. In the AlPc cluster, certain functional bond lengths and bond angles have been observed. Quantum chemical methods (density functional theory (DFT) and time-dependent density functional theory (TD-DFT)) and vibrational spectra properties of AlPc are studied. An X-ray pattern reveals the crystalline structure along the (242) orientation of AlPc organic thin layer. An ultraviolet-visible (UV–Vis) also shows the frequency selective behavior of the device. The absorbance of such layer exhibits a high value within UV range and two consecutive peaks within the visible range. Spin coating is used to make an organic diode based on the Aluminium phthalocyanine (AlPc-Cl) molecule. Under dark and light conditions, electrical characterization of Ag/AlPc/Si/Au is obtained. The diode's high rectifying capability (about 1 × 1 0 4) is subsequently discovered. While the height barrier is constant and saturation current is greatly reliant on light, the ideality factor of such a diode increases to 6.9 which confirms the nonideality of such a device. The Cheung–Cheung technique is employed to further the investigation and gain additional data such as series resistance and barrier height. [ABSTRACT FROM AUTHOR]

In current study, secondary ketamine derivatives (1–6) were synthesized through refluxing of 2-acetyl naphthalene, substituted phenyl and benzyl thiosemicarbazides solutions in ethanol. Different spectroscopic procedures like nuclear magnetic resonance (NMR), fourier transform infrared (FT-IR), and UV–Visible (UV–Vis) spectroscopy were used for the characterization of the synthesized compounds. Accompanying with experimental, DFT study was also made at M06/6-311 G (d,p) functional. A relative investigation of experimental and DFT spectroscopic outcomes expressed good harmony in results. Various kinds of analyses such as natural bond orbitals (NBOs), geometric optimization, molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs), UV–Vis, binding energy (Eb) and transition density matrix (TDM) were conducted to explore the non-linear optical (NLO) properties of secondary ketamine compounds. Interestingly, all the synthesized compounds expressed linear polarizability [⟨α⟩ = 416.71–429.91 a.u.], first hyperpolarizability (βtot = 795.768–1201.321 a.u.), and second hyperpolarizability (γtot = 4.967–6.176 a.u.) values than that of standard urea molecule which illustrated them as efficient optoelectronic materials for hi-tech NLO applications. [ABSTRACT FROM AUTHOR]

The special properties of organic compounds are due to the polyvalence of the carbon atom. In this research, the organic single crystal of N-(4-acetyl −5-(4-(nitro) phenyl) −4,5-dihydro-1,3,4-thiadiazol-2-yl) -N-phenylacetamide (NTDZ) was successfully synthesized and crystallized in isopropanol by using slow evaporation solution growth method. FT-IR, 1H and 13C NMR spectroscopic techniques were used to characterize the presence of various functional groups in the NTDZ molecular structure. Single crystal X-ray data have been collected and used for the structural determination of NTDZ. The title crystal crystallized in the monoclinic space group P21/c, according to X-ray analysis. Besides, quantum chemical studies were carried out using the density functional theory calculation method. The theoretical and experimental geometrical parameters were compared indicating a good accordance between them. Moreover, surface shapes were displayed using 3D-Hirshfeld surface analysis, and 2D-fingerprint graphs were used to quantify the contributions of C–H...O and C–H...N intermolecular interactions. Furthermore, the vibration spectrum of the NTDZ is calculated and compared with that obtained by FT-IR spectroscopy, and the predicted vibration assignments are made according to the potential energy distribution (PED). The chemical shifts of 1H and 13C-NMR were calculated using the GIAO approximation and compared to experimental values. Using the TD-DFT method, the theoretical UV-Vis absorption spectrum was calculated in chloroform solvent to obtain the most important electronic transitions. Frontier molecular orbitals (HOMO and LUMO) indicate the charge transfer within the molecule. The global chemical reactivity descriptors (GCRD) were calculated. In addition, the MEP was also computed showing the functional groups responsible for building interactions with other molecules. Finally, the nonlinear optical behavior was investigated by the determination of the dipole moment (μ), the polarizability (α), and the first and second hyperpolarizabilities using the same level of theory. All of these findings suggest that the NTDZ crystal may be a viable candidate for NLO applications. New 1,3,4-thiadiazol derivative was synthesized. X-ray geometry was determined and confirmed by theoretical calculation. Electronic behavior was investigated by DFT and TD-DFT. NLO properties of the compound were also computed. [ABSTRACT FROM AUTHOR]

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.

The nonlinear optical (NLO) characteristics exhibited by organic compounds hold significant value in the realm of photonics and optoelectronics applications. Herein, the Density Functional Theory method at MPW1PW91/6-311G (d,p) functional was utilized to evaluate the electronic and NLO behavior of novel compounds i.e., MTPBR1 having A-π-D-π-A and MTPBD2-MTPBD9 with D1-π-D2-π-A configurations. Quantum chemical computations revealed that structural tailoring of all the designed chromophores demonstrate reduced bandgaps with greater absorption properties than MTPBR1. The efficacy of charge transfer from the donor to the acceptor through a spacer was investigated using frontier molecular orbitals calculations. These calculations were substantiated by analyses of density of states and transition density matrices. Natural bonding orbitals indicated molecular stability in designed molecules due to hyper-conjugative interactions and extended conjugation. Among all the derivatives, MTPBD8 exhibited the lowest energy bandgap (1.891 eV) with bathochromic shift of 723.868 nm in chloroform and 546.688 nm in gaseous phase, and the highest global softness of 0.529 eV−1. MTPBD5 displayed the highest dipole moment (µtot) at 22.815 D. MTPBD2, MTPBD3, MTPBD5 and MTPBD8 demonstrated consistent linear polarizability 〈α〉 at 3.4 × 10−22 esu. Notably, MTPBD8 calculated the highest first and second hyperpolarizability (βtot, γtot) at 9.6 × 10–27 and 4.302 × 10−32 esu, respectively. To conclude, the novel chromophores, particularly MTPBD8, showed remarkable NLO properties, demonstrating their potential use in advanced nonlinear optical devices.

The synthesis and characterization of naphthalimide Bis-Schiff bases (5a) and (5b) using a dual approach comprising computational and experimental techniques. The synthesized Bis-Schiff base compounds (5) were successfully characterized using UV–visible, fluorescence, Fourier-transform infrared (FT-IR), and 1H nuclear magnetic resonance (NMR) spectroscopies. In ethanol solvent, the experimental absorption peak was observed at 339 nm for compound 5a and at 341 and 433 nm for compound 5b. The computationally calculated absorption peak for compounds 5a was at ~ 343 nm and those for 5b were at 337 and 425 nm. The fluorescence emission bands of compounds 5a and 5b were observed at 383 and 549 nm, respectively, at an excitation wavelength of 338 nm. Additionally, quantum chemical studies of the synthesized compounds were performed to study their molecular structures linear optical and nonlinear optical (NLO) response properties. The molecular geometries were optimized to minimum energy ground state. Compounds 5a and 5b showed third-order NLO polarizability amplitudes of 391.8 × 10–36 and 489.0 × 10–36 esu, respectively, which are significantly larger than those of some standard NLO compounds. The results indicate that the Bis-Schiff base is a promising molecule for use in electronic and optoelectronic devices and biosensors. [ABSTRACT FROM AUTHOR]

Using the ASEC-FEG approach in combination with atomistic simulations, we performed geometry optimizations of a Cs conformer of the lithium decahydroborate (Li@B10H14) complex in chloroform and in water, which has been shown to be the most stable in the gas phase and calculated its first hyperpolarizability. At room temperature, ASEC-FEG calculations show that this conformer is stable only in chloroform. However, it is found that the nonlinear response of the Cs conformer in chloroform is mild, and the result for the hyperpolarizability is markedly decreased in comparison with the result of the C2v conformer.

This protocol presents a complete theoretical study on the substituted benzalacetophenone molecules. In this study, eighteen chalcone derivatives 1–18 were evaluated with respect to their first‐ and second‐order hyperpolarizability parameters. For this purpose, the molecular geometries of 1–18 were optimized using set 631 g (d,p) and hybrid functional B3LYP. Spectroscopic characterizations for 1–18 were executed through the calculations of IR, UV‐Vis, 1H NMR and 13C NMR spectra. The quantum chemical parameters such as chemical potential, chemical hardness, electronegativity and electrophilicity indexes were obtained using the frontier molecular orbital (FMO) energies. The potential energy distribution (PED) analysis was used to provide a detailed assignment of vibrational bands. Important contributions to electronic absorption bands from FMOs were also evaluated. The distribution of FMOs to the whole molecule was investigated to determine the nature of electronic charge transfers in the target structures. The static and dynamic first‐ and second‐order hyperpolarizability parameters for 1–18 were calculated by using CAM‐B3LYP/6‐31++G(d,p). The static β and γ were calculated at the ranges of 1.348–2.967×10−29 esu and 82.50–136.2×10−36 esu. This wide range of β and γ values indicates that chalcone derivatives with rational substitution may be promising candidates for first‐ and second‐order NLO applications. The findings of this study contribute to the understanding of the relationships between molecular structure and non‐linear optical properties, thus paving the way for the design of new materials with improved non‐linear optical properties. [ABSTRACT FROM AUTHOR]

Solvent as a complex environment can surround solute molecules and modify their function. In this work, different solute–solvent interaction effects on the nonlinear optical behavior of some azo dyes were studied at the molecular level. In this case, spectroscopic technique and density functional theory were used. According to the results, molecular dipole transition, changes between ground and excited state dipole moments, substituent, and environment polarity play considerable effects on the molecular nonlinear optical responses. In addition to solvent effects on the molecular first- and second-order hyperpolarizability, the two-photon absorption cross-section is also modified due to solvent-induced interactions. Moreover, the determination of the contribution of dominant solvent effects on the molecular nonlinear optical behavior can facilitate the studies on the application of optical samples in designing various optical systems. [ABSTRACT FROM AUTHOR]

In the present work a new semiorganic single crystal p-nitrophenol sodium-bisulfate (PNSB) was synthesized and fully characterized by means of single crystal XRD, powder XRD, FT-IR, FT-Raman and UV-visible spectroscopic techniques. The optimized geometrical parameters were obtained at the DFT/B3LYP level of theory and correlate them with similar structures. Normal coordinate analysis, force constants, and potential energy distributions have been used to support the complete vibrational assignments for all vibrational modes. The computed IR and Raman frequencies correlate well with the experiments, as indicated by the correlation factor. The optimized molecular structure reveals the presence of C-H...O hydrogen bonding interaction. The stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using natural bonding orbital analysis. NBO analysis proved the presence of intermolecular O-H...Na22 hydrogen bonds caused by the interaction of the lone pair of oxygen with the anti-bonding orbital. HOMO, LUMO and ESP analyses were done using DFT, whereas, the absorption band in the UV–vis spectrum was predicted and compared with the experimental data. ESP is used to identify the nucleophilic region, which is located around the sodium atom, and the electrophilic region, which is primarily located at the oxygen atoms of the PNSB molecule. The frontier orbital gap denotes the charge transfer interaction within the compound required for optical activity. Electron Localization Function, Localized Orbital Locator and Reduced Density Gradient analysis were discussed. In order to study the nonlinear optical activity of PNSB, the dipole moment, polarizability and fihyperpolarizabilities were computed. It is found that the calculated first order hyperpolarizability of PNSB is 51.75 times greater than that of urea. [ABSTRACT FROM AUTHOR]

Electronic and nonlinear optical properties of endohedral metallofullerenes are presented. The endohedral metallofullerenes contain transition metal encapsulated in inorganic fullerenes X12Y12 (X = B, Al & Y = N, P). The endohedral metallofullerenes (endo-TM@X12Y12) possess quite interesting geometric and electronic properties, which are the function of the nature of the atom and the size of fullerene. NBO charge and frontier molecular orbital analyses reveal that the transition metal encapsulated Al12N12 fullerenes (endo-TM@Al12N12) are true metalides when the transition metals are Ni, Cu and Zn. Endo-Cr@Al12N12 and endo-Co@Al12N12 are at the borderline between metalides and electrides with predominantly electride characteristics. The other members of the series are excess electron systems, which offer interesting electronic and nonlinear optical properties. The diversity of nature possessed by endo-TM@Al12N12 is not prevalent for other fullerenes. Endo-TM@Al12P12 are true metalides when the transition metals are (Cr-Zn). HOMO-LUMO gaps (EH-L) are reduced significantly for these endohedral metallofullerenes, with a maximum percent decrease in EH-L of up to 70%. Many complexes show odd–even oscillating behavior for EH-L and dipole moments. Odd electron species contain large dipole moments and small EH-L, whereas even electron systems have the opposite behavior. Despite the decrease in EH-L, these systems show high kinetic and thermodynamic stabilities. The encapsulation of transition metals is a highly exergonic process. These endo-TM@X12Y12 possess remarkable nonlinear optical response in which the first hyperpolarizability reaches up to 2.79 × 105 au for endo-V@Al12N12. This study helps in the comparative analysis of the potential nonlinear optical responses of electrides, metalides and other excess electron systems. In general, the potential nonlinear optical response of electrides is higher than metalides but lower than those of simple excess electron compounds. The higher non-linear optical response and interesting electronic characteristics of endo-TM@Al12N12 complexes may be promising contenders for potential NLO applications. [ABSTRACT FROM AUTHOR]

The NLO property of a few designed inorganic–organic hybrid materials based on Nickel dithiolenes end-capped with donor–acceptor groups has been studied theoretically. All the designed molecules possess high first hyperpolarizability values indicating their potential use in optics, photonics, and as photosensitizers. Among the four designed systems, the BODIPY-containing systems significantly reduce the HOMO–LUMO energy gap resulting in a massive trek in the first hyperpolarizability (β) values. To judge their high NLO response, transition dipole moment (TDM) density has been plotted and it has been found that electron dissipation occurs through the molecular network with a large Δr index value. It is to be noted that high Δr index values are quantitative measurements to understand the type of transitions, and we noticed that a charge transfer transition occurs in all of our designed systems. Hence a nice correlation between the first hyperpolarizability, TDM density, and Δr index value has been observed. The global reactivity parameters are also studied and correlated nicely with polarizability and hole-electron transport ability. [ABSTRACT FROM AUTHOR]

In the current study, optical and nonlinear optical (NLO) properties of supersalt Al(BH4)3 doped boron nitride (BN) were studied by employing density functional theory (DFT) at the MPW1PW91/6-31 G (d,p) level of theory. HOMO–LUMO energy gap of 7.48 eV was found for pure BN which is reduced to 4.85 eV after doping. Supersalt doping has shown better results on the NLO properties including a decrease in the excitation energy, change in vertical ionization energies, increase in oscillator strength, and increase in dipole moment. Doped molecules have lesser transition energies (ΔE) that lead to higher hyperpolarizability. Electron density difference map was plotted which describes the distribution of electrons of doped compounds. The enhanced values of αiso and βstatic are observed which increases the NLO properties. Overall, the results have shown that supersalt doped boron nitride is an effective approach for designing efficient nonlinear material.

Four donor‐pi‐acceptor (D‐π‐A) type sensitizers containing coumarin as the donor unit and cyanoacrylic acid as the acceptor unit are investigated using density functional theory (DFT) and time‐dependent‐DFT methods. The effect of introducing auxiliary acceptor like benzothiadiazole and spacer bridge like 3,4‐ethylenedioxythiophene (EDOT) is analyzed. The EDOT bridge leads to increase in band gap whereas the introduction of benzothiadiazole lessens the band gap. The frontier molecular orbital diagram also shows an efficient intramolecular charge transfer for non‐EDOT based sensitizers. For benzothiadiazole‐based sensitizers, the electrophilicity index was higher and hyperhardness was lower in the estimated reactivity descriptors. The experimentally determined light harvesting efficiency (LHE) of the sensitizers is correlated with the calculated global descriptors. A direct relation of LHE is obtained with electrophilicity index and an inverse relation for hyperhardness. A reverse trend is seen on comparing these descriptors with the band gap of the sensitizers. The computed non‐linear optical (NLO) characteristics show that the benzothiadiazole acceptor increases NLO response, while EDOT‐based sensitizers show a reduced NLO response. The NLO properties also give a direct relation with the LHE and electrophilicity index. The hyperpolarizability exhibits an inverse relation with the transition energy which is in accordance with the Ouder's model. [ABSTRACT FROM AUTHOR]

Context: A large number of heterocyclic compounds are used as drugs, mainly due to the duality of lipophilicity playing in hydrophobic interactions and solubility with at least one hydrogen bond acceptor. The study of electronic properties is then important to better understand not only these charge distribution effects but also some other physicochemical properties involved in bioactivity to directly assess the bioavailability of these compounds and a possible classification in related applications. Phytomolecules such as chromenes are very accessible molecules exhibiting a bioactivity. Our study is focused on the impact of a number of functional groups acting on some 2,2-dimethylchromene derivatives, namely their global reactivity from the frontier molecular orbitals and local reactivity from the Fukui functions, where the carbonyl group acting as an electron withdrawal group has the most relevant effect, the solubility from the partition coefficient Log P strongly depending on the charge distribution and electronegative sites, the optical effects from the delocalization in the vinyl group, as well as the evaluation of the entropy associated with the molecular flexibility also acting on the bioactivity. Despite the effects of the wave function or density methods on the order of magnitude of these properties, these compounds are consistent with the rules for a potential oral drug candidate. Methods: The calculations of the electronic properties were performed through two levels of theory: Hartree-Fock level as a wave function-based method as an ab initio reference including some physically consistent eigenvalues and density functional theory DFT as a correlation consistent method using different functionals: hybrid or with a long-range correction. The basis set used is a 6-311++G(d,p) Pople basis set including diffuse and polarization basis functions. The basis set is adapted to the size of the molecules and consequently to the degree of electronic localization. Gaussian 09 software was used for the computation. [ABSTRACT FROM AUTHOR]

Effects of complexant number on static and dynamic second hyperpolarizability of diffuse electron systems comprising aziridine (complexant) and alkaline earth metal dopant (i.e., Be, Mg, and Ca) are explored theoretically. Accordingly, the number of the complexant is increased up to three in a stepwise fashion. Aziridine unit, which is non-covalently linked with dopant, polarizes the ns electron of dopant. This polarizing effect results in higher second hyperpolarizability value of the complexes. Compared to pristine aziridine moiety, the γavg of Be-aziridine complex enhances significantly. Interestingly, with increase in complexant number, the static and dynamic second hyperpolarizability values enhance monotonically and attain the maximum value when three complexants are employed. Among the studied systems, the shamrock-shaped complex (Ca@(aziridine)3) exhibits higher non-linear refractive index as well as remarkably high second hyperpolarizability value (1.83 × 107 au). [ABSTRACT FROM AUTHOR]

The structural alteration with π-linkers was used to design a donor–acceptor type series of 2,2′-(pyrimidine-4,6-diyl)bis(2,3-dihydro-1,3-benzothiazole) (PB)-based chromophores (AH1–AH7) to exploit the adjustments in their optical characteristics. To investigate the electronic geometries, absorption wavelengths, charge transfer processes, and the effect of structural alterations on nonlinear optical (NLO) characteristics, density functional theory (DFT) simulations have been used. During the UV–visible study, several long-range and range separated functionals like B3LYP, CAM-B3LYP, B97XD, and APFD with the 6-311G + (d,p) basis set were used to select the efficient level at DFT. As a response, UV–vis data indicated an intriguing consistency at the B3LYP level across experimental and TD-DFT-based values of PB. All the designed molecules had a smaller energy band gap (0.84–3.67 eV) and wide absorption spectra inside the visible region. Natural bond orbital (NBO) results indicated a significant push–pull operation, with donors and π-conjugates exhibiting positive values and most acceptors exhibiting the minimum values. Electronic transformations between electron donors to acceptor moiety, Trifluoromethyl (TFM) via π-conjugated linkers were shown to have a superior linear ˂α > and nonlinear (βtotal) NLO values of 306–474 and 40–230 Debye-Angstrom−1 respectively. When chromophores with one phenyl π-linker were compared to those with the two π-linkers, the chromophores with the higher π-linker showed increased hyperpolarizability. The highest second-order hyperpolarizability (β) was found to be 230.11 Debye-Angstrom−1 which was about five times higher than urea (standard). This research has shown that by manipulating the kind of π-spacers, novel metal-free NLO compounds may be created, which might be used for high-tech NLO purposes. [ABSTRACT FROM AUTHOR]

The enhancement of Nonlinear optical (NLO) activity of the 2-nitrotoulene (2NT) after the substitution of the halogens (F, Cl, Br, and I) at the para position of the benzene ring was reported in the paper. All the computational details were mentioned using density functional theory with B3LYP/6-311++G(d,p) basis set. The engagement of the electrophilic and nucleophilic regions in molecules was established using contour plots. Mulliken charge analysis and frontier molecular orbital parameters laid the high chemical reactivity of 2NT molecule after the substitution of F, Cl, Br, and I. Using time-dependent density functional theory, electronic properties were analyzed by computing absorption and emission spectra. The higher Raman intensity modes and higher absorbance intensity curve for iodine-substituted 2NT (2NT-I) highlighted the highest reactivity. The lowest band gap was reported for 2NT-I (4.02 eV) which better correlates with the charge and spectral findings. The polarizability parameters set a fair comparison between the NLO activities of the molecules. 2NT-I has the highest values of polarizability parameters among the other molecules. [ABSTRACT FROM AUTHOR]

The structure geometry, vibrational frequencies, electronic and optical properties of a series of donor-acceptor substituted dodecadehydrotribenzo [18] annulenes ([18] DBA) were investigated using the B3LYP method at a 6-31+G (d, p) basis set. After optimization of the structures, HOMO and LUMO energies, gap energy (Eg), global hardness (η), chemical potential (µ), electrophilicity index (ω), maximum charge transfer (ΔNmax), electronegativity (χ), Fermi level (EFL), wavelength (λ), oscillator power (f0), and participation percentage (% Con) for [18] DBA derivatives. A significant increase in the first hyperpolarizability was observed by substitution on [18] DBA. The results of this study may be used to design and construct materials with adjustable electrical properties. The results indicate that the NLO response of [18] DBA could be enhanced by functionalizing different substitutions. In general, the NLO response and electronic properties of the S1-10 are more excellent than others. [ABSTRACT FROM AUTHOR]

In this work, 2-thioxo -3 N-(2-ethoxyphenyl -5[4′-methyl -3′N-(2′-ethoxyphenyl) thiazol-2′(3′H)-ylidene] thiazolidin-4-one (E2Th2) was synthesized and its molecular structure determined by FT-IR, UV-Vis and NMR spectroscopic techniques along with a single crystal X-ray diffraction study. Quantum chemical calculations were performed to better understand its structural, spectroscopic and electronic properties such as HOMO and LUMO energy gap, MEP and global reactivity descriptors. Theoretical calculations were performed using density functional theory (DFT) based on the B3LYP/6-311G (d,p). Vibrational frequencies were assigned on the basis of PED and electronic transitions are calculated according to time-dependent density functional theory (TD-DFT). The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. The NLO activity evaluation was based on the determination of the dipole moment, polarizability (α), first-order hyperpolarizability (β) and the second-order hyperpolarizability (γ) which were calculated using the same level of theory. The hyper-hardness descriptor (Γ) was explored and correlated with the NLO properties. Additionally, the stability of the molecule occurring from hyper-conjugative interaction, intramolecular hydrogen bond and charge delocalization were quantified using NBO analysis. The repulsive, attractive, and van der Waals strong and weak interactions were revealed by RDG and HS analyses. Finally, results have shown that the title compound can be used as attractive future NLO material. [ABSTRACT FROM AUTHOR]

Current research has focused on utilization of non-fullerene based organic materials for the advancement of nonlinear optical (NLO) based technology. The reference compound (DTPSR1) was used in tailoring process to design seven new derivatives (DTPSD2-DTPSD8) via various acceptor moieties. The M06-2X level with 6-311G(d,p) basis set was used for assessing frontier molecular orbitals (FMOs), natural bonding orbital (NBO), nonlinear optical properties [average polarizability < α > , first hyperpolarizability (βtotal), second hyperpolarizability (γtotal)], transition density matrix (TDM) and UV–Vis analyses of DTPSR1 and DTPSD2-DTPSD8. The UV–Vis analysis indicated that the designed derivatives show comparable results (515.462–586.269 nm) with reference molecule (583.592 nm), except DTPSD7, that exhibited slight red shift (586.269 nm). Smaller LUMO–HOMO energy gaps were reported as in DTPSD3 (3.53 eV), DTPSD7 (3.53 eV) and DTPSD8 (3.55 eV) as compared to DTPSR1 (3.60 eV) which was further supported by TDM analysis. The global reactivity descriptors have also shown close correlation with LUMO–HOMO energy gaps; smaller value of energy gap showed lower hardness value 1.77 eV for DTPSD3, DTPSD7 and DTPSD8 and greater softness values 0.283 eV for DTPSD3, DTPSD7 and 0.281 eV for DTPSD8, respectively. The hyper conjugative interactions, stability, and electron-transfer mechanism were elucidated by using NBO analysis. DTPSD2-DTPSD8 also exhibited comparatively closer NLO results with DTPSR1. Among DTPSD2–DTPSD8, the highest ⟨α⟩1439.16 a.u, βtotal 189,720.546 a.u and γtotal 1.980890 × 107 a.u were observed for DTPSD7. It is anticipated that our study would provide a springboard to attain the NLO materials exhibiting significant future applications such as in telecommunication, data storage and optical poling. [ABSTRACT FROM AUTHOR]

Using the ASEC-FEG approach in combination with atomistic simulations, we performed geometry optimizations of a Cs conformer of the lithium decahydroborate (Li@B10H14) complex in chloroform and in water, which has been shown to be the most stable in the gas phase and calculated its first hyperpolarizability. At room temperature, ASEC-FEG calculations show that this conformer is stable only in chloroform. However, it is found that the nonlinear response of the Cs conformer in chloroform is mild, and the result for the hyperpolarizability is markedly decreased in comparison with the result of the C2v conformer. [ABSTRACT FROM AUTHOR]

Pure carbon-based nanomaterials with good π conjugation and thermal stability, e.g., nanotubes and nanoribbons, have long served as promising conjugated materials for application in second-order nonlinear-optical (NLO) devices but suffer from two inherent structural problems: weak polarity (or even nonpolarity) and high chemical reactivity ascribed to zigzag edge states. In the present work, boron nitride (BN) chains are used to divide carbon nanotubes and nanoribbons, forming a functional block to tune the electronic structure, and thus induce charge redistribution or modify the molecular energy gap for second-order NLO materials or integrated electronic materials. A balance between the electronic kinetic stability and second-order NLO properties is established by structural manipulation. The strong second-order NLO responses in the visible and near-infrared regions make these hybridized carbon-based molecules potential NLO materials for applications in biological nonlinear optics. The application of BN to tune the electronic structure of carbon nanomaterials paves a path for fabricating nanoelectronic and nano-NLO devices. [ABSTRACT FROM AUTHOR]

A supramolecular cocrystal of 2-ammino-5-nitropyridine (ANP) with 2,4-dinitrophenol (DNP) has been successfully grown by the slow evaporation solution growth technique. The crystal structure of 2-amino-5-nitropyridine-2,4-dinitrophenol (ANDP) was elucidated by the single-crystal X-ray diffraction analysis, and it belongs to a monoclinic system with centrosymmetric space group P21/n. The bulk phase purity and homogeneity of the material were confirmed by powder X-ray diffraction analysis. The functional groups present in the molecule are identified by FT-IR analysis, and the band gap energy was estimated using diffuse reflectance data by the application of the Kubelka–Munk algorithm. The thermal stability of the compound was investigated by carrying out TG–DTA analysis. Theoretical calculations were performed using the density functional theory method to derive the dipole moment and hyperpolarizability. The high value of first-order molecular hyperpolarizability (β) suggests that it is a potential microlevel NLO candidate. [ABSTRACT FROM AUTHOR]

For the first time, a systematic investigation of optimization in the geometrical, vibrational, natural bonding orbital (NBO), electronic, linear and nonlinear optical properties, and Hirshfeld surface analysis for the L-histidinium-l-tartrate hemihydrate (HT) crystal is reported by employing the density functional theory (DFT). The geometrical parameters and vibrational frequencies obtained from the B3LYP/6–311++G(d,p) level of theory are in good agreement with the experimental values. The presence of strong hydrogen bonding interactions in the molecule causes an intense absorption peak in the infrared spectrum below 2000 cm−1. Quantum Theory of Atoms in Molecules (QTAIM) has been used to evaluate the topology of the electron density of a particular molecule to identify the critical points of the system using Multiwfn 3.8. These studies included ELF, LOL, and RDG studies. A time-dependent DFT approach is employed to obtain the excitation energies, oscillator strengths, and UV–Vis spectra for different solvents, such as methanol, ethanol, and water. The NBO analysis of the chosen compound, HT, is performed in terms of atom hybridization and electronic structure. The HOMO-LUMO energies and other associated electronic parameters are also computed. The nucleophilic sites are identified from MEP and Fukui functions analysis. The electrostatic potential and total density of states spectra of HT are discussed in detail. The theoretically obtained polarizability and first order hyperpolarizability values confirm that the grown material HT has NLO efficiency 15.771 times that of urea, and is proposed to be an exceptional nonlinear optical material. In addition, Hirshfeld surface analysis is performed to determine the inter-and intramolecular interactions in the title compound.

A thermal stability, vibrational spectroscopy, electric response, linear and nonlinear optical (NLO) properties and optical properties of pure PVP polymer for solar cell device are investigated. The optimized geometry of the structural unit and oligomer (10 structural unit) of PVP polymer are shown. Absorption peaks in IR and Raman spectra are analyzed. The net atomic charges of PVP, obtained by means of Mulliken population analysis are studied. The electrostatic potential with respect to the surface at constant electron density is portrayed. Optical absorbance A (λ) spectrum of pure PVP is illustrated. The absorption spectrum of PVP polymer is studied and optical gap of PVP is determined. The DOS spectrum and the distributions of the HOMO and LUMO orbitals are represented. Effect of light on current–voltage measurement is evidenced recording an open circuit voltage of 0.25 V and short circuit current of 3.9 µA at 150 W/cm2. [ABSTRACT FROM AUTHOR]

In this paper, we theoretically investigate the linear and nonlinear optical activity of polymers based on poly(ortho-anisidine) and polyaniline using density functional theory. The PBE0 exchange correlation functional is used to predict their dipole moment, mean polarizability, polarizability anisotropy, and the static first hyperpolarizability. The polymers show high hyper–Rayleigh scattering first hyperpolarizability, which make them suitable for nonlinear optical devices. The relationship between the first hyperpolarizability and the energy gap is also taken into account. [ABSTRACT FROM AUTHOR]