Total Hyperpolarizability Research Articles

Theoretical investigation on the surrounding effects of second-order nonlinear properties for (N^C^N)Pt(II)Cl complexes

Pt(II) complexes are widely used as nonlinear optical (NLO) materials. The geometric and electronic structures, second-order NLO property and UV–Vis absorption spectra of (N^C^N)Pt(II)Cl complexes (1–4) N^C^N binding by central benzene and two lateral N-heterocycles) are evaluated by density functional theory (DFT) and time-dependent DFT calculations. The detailed environmental effect of total first hyperpolarizability (βtot) in the solution and crystal phases is simulated by polarized continuum model (PCM) and quantum mechanics/molecular mechanics (QM/MM) method, respectively. The results highlight that the complex 3 exhibits largest βtot value in the gas, solution and crystal phases which can be attributed to the higher electron π-delocalization of ligands. Further, an evident red shift towards longer wavelength is observed for the complex 3. The origin of larger βtot value can be reasonably interpreted by the two-level model. In addition, the surrounding exerts an important influence on modulating second-order NLO properties. The solvent effect results in the larger βtot value than that of gas phase. The intermolecular interaction plays an important role in crystal phase. The formation of dimer can reduce the βtot value in comparison with the βtot value of the monomer in the crystal phase, because the centrosymmetric configuration of dimer implies a decrease of dipole moment (μ) in contrast to the large μ value of monomer. It is expected that this work will provide some guidance for designing Pt(II) NLO materials.

Nonlinear optical properties of azo sulfonamide derivatives.

The present work deals with the linear and nonlinear optical properties such as the dipole moment, polarizability, total hyperpolarizability, electric field-induced second harmonic generation, and hyper-Rayleigh scattering first hyperpolarizability of four heterocyclic azo compounds containing the sulfonamide group considered promise in nonlinear optic. The obtained polarizability and hyperpolarizability were supported by the frontier molecular orbital analysis. The properties have been effectively estimated and thoroughly examined to shed light on the nonlinear optical activity based on the density functional theory. The observed results show a high total first hyperpolarizability up to 2503 a.u. and a low energy gap less than 1.41 eV. An inverse relationship has been obtained between the and . The calculated values confirm that charge occurs within the azo sulfonamides. The new study provides a promising avenue for the development of these azo sulfonamides as novel NLO materials. The molecular modeling and the theoretical studies were performed with Gaussian software packages. The B3LYP/6-311 + G** level was used for optimization. All the linear and nonlinear optical properties reported here are obtained using the DFT. The optimized structures and their frontier molecular orbitals were plotted using the GaussView 5.1 program.

Synthesis, characterization and DFT studies of fluorinated aryl derivatives: Electronic and optical responses

The current study was designed to synthesize biaryls compounds viz; 2-(3,4-difluorophenyl) benzothiophene (DFPBT), 3-(3,4-difluorophenyl) quinoline (DFPQ) and 1-(3,4-difluorophenyl) naphthalene (DFPN) by means of Suzuki-Miyaura Pd(0)-catalyzed protocol. Different characterization techniques were used to evaluate the structure of desired synthesized compounds viz; H1NMR, C13NMR, FT-IR and UV–Vis analyses. Besides, DFT computations were carried out at B3LYP/6–311++ G(d, p) functional to gain an insight of key electronic properties of the synthesized compounds. The natural bonding orbital (NBO) analysis showed that molecules of these compounds should interact quite noticeably with each other in the solid phase and with polar solvent molecules. The FMO findings revealed that the ∆E value are in order; DFPN > DFPQ > DFPBT. Accordingly, DFPBT exhibited better NLO properties and possessed a slightly strong electron transfer potential than DFPQ and DFPN. A good harmony between experimental (296.4, 304.7 and 298.4 nm) and simulated (306, 305 and 298 nm) UV–Vis values was investigated in studied compounds. Furthermore, multiple functional (M062X, CAM-B3LYP, HF, M06, B3LPY, and LCBLYP) with 6–311++G(d, p) basis set were used to investigate the total dipole moment, hyperpolarizability βtot and average polarizability ⟨α⟩ values. The average polarizability ⟨α⟩ values of DFPBT, DFPQ and DFPN were 5.7, 5.7 and 5.5 times greater than urea i.e., ⟨α⟩=34.055 a.u, while, the βtot values were 5.8, 7.8 and 6.1 times more than the total values of urea. i.e., 90.527 a. u, respectively. These efficient behavior of NLO in synthesized compounds indicated the significant use of these compounds in optoelectronic devices.

Polaron Formation in Conducting Polymers: A Novel Approach to Designing Materials with a Larger NLO Response.

Substantial efforts have been made to design and investigate new approaches for high-performance nonlinear optical (NLO) materials. Herein, we report polaron formation in conducting polymers as a new approach to designing materials with a large NLO response. A comparative study of polypyrrole and polypyrrole-based polaron (nPy+ where n = 1, 3, 5, 7, and 9) is carried out for optoelectronic and NLO properties. The studied polarons (PPy+) show excellent electronic properties and have reduced ionization potential (IP) as compared to neutral PPy, and a monotonic decrease is observed with increased chain lengths (1Py to 9Py). Interesting trends of global reactivity descriptors can be seen; the softness (S) increases with an increase in the chain length of PPy, while the hardness (η) decreases in the same fashion. The EH-L gaps for the PPy+ polaronic state are significantly lower than their corresponding neutral PPy. In the polaronic model (PPy+), radicals decisively reduce the crucial excitation energy, reminiscent of excess electrons (alkali metals). The performed TDOS spectral analysis further justifies the better conductive and electronic properties of polarons (PPy+) with increased chain lengths (conjugation). The static hyperpolarizability response (βo) is recorded up to 1.3 × 102 au for 9Py, while for polaron 9Py+, it has increased up to 3.2 × 104 au. The static hyperpolarizability of the 9Py+ polaronic state is 246 times higher than that of the corresponding neutral analogue, 9Py. It is observed that the values of βo obtained at the CAM-B3LYP/6-311+G(d,p) level of theory are comparable to those obtained at the LC-BLYP and ωB97XD functionals. The βvec values show a strong correlation with the total hyperpolarizability (βo). Furthermore, the calculated second harmonic generation (SHG) values are up to 4.0 × 106 au at 532 nm, whereas electro-optic Pockel's effect (EOPE) is much more pronounced at the smaller dispersion frequency (1064 nm). The TD-DFT study reveal the red-shifted absorption maxima (λmax) with an increased length of PPy+. A significant reduction in excitation energy (ΔE) is observed with increased length of PPy and PPy+, which also favors the improved NLO response. Hence, the studied thermally conducting polypyrrole-based polarons (PPy+) are new entries into NLO materials with better electrical and optical features.

Deciphering ethynyl single crystal for NLO applications: Synergistic studies on the structural, Hirshfeld surface, photophysical and DFT assessment

In this contribution, we have integrated multiple approaches in investigating the profiles and behaviour of simple ethynyl derivative, 1-[4-(4-(dimethylaminophenyl)ethynyl)phenyl]ethanone (4DME) tolane which is known to be integrated widely in molecular electronics as conjugated building block in functional molecules. Prepared via simplified aerobic Sonogashira cross-couping reaction, symmetrical chromophore of 4DME crystallizes in monoclinic with complex framework containing the space group of P21/n and includes four molecules within a unit cell. The fingerprint plots and Hirshfeld surface analyses demonstrate the presence of synergism between molecules supporting nonlinear optical response of the compound. It was shown that C⋯H contact (44.5 %) is the major contribution of intermolecular interaction executed by Hirshfeld surface area. The investigation on their spectroscopic, thermal analysis and density functional theory (DFT) analysis operating under B3LYP/6-31G (d,p) were conducted to determine the energies of the LUMO and HOMO level, NLO behaviour, intermolecular charge transport facilitated by global chemical reactivity descriptors, molecular electrostatic potentials (MEP) and hyperpolarizability analyses. From the simulated DFT calculation, it shows that 4DME has good polarizability properties with HOMO-LUMO energy gap of 3.89 eV. Calculated total first hyperpolarizability βtot of 4DME were 1261.40 × 10−30 esu which can be potentially applied as good nonlinear optical materials. The preliminary outcomes prove that this simple ethynyl derivative is capable of being used in optoelectronic industry as NLO-based products. A CW diode laser operating at 532 nm wavelength was used to perform the Z-scan measurements and 4DME showed an effective value of χ(3) in order of 10−6, indicating good nonlinear properties.

D-π-A push-pull chromophores based on N,N-Diethylaniline as a donor for NLO applications: Effects of structural modification of π-linkers

Three metal-free organic compounds based on N,N-Diethylaniline as a donor, and 2-(3-cyano-5,5-dimethylfuran-2(5H)-ylidene)malononitrile as an acceptor of electrons with the D-π-A architecture were investigated theoretically using DFT, LC-DFT and TD-DFT techniques for future usage as NLO materials. The effect of changing the π-linker of the parent compound M1 on the electronic, photophysical characteristics and the nonlinear optical response has been extensively studied and discussed. M1-M3 exhibit a band gap (Egap) in the 1.51 to 1.85 eV range with λabs of 600 to 900 nm. The results indicate that M3 possesses excellent polarization characteristics of the first total hyperpolarizability βtot at 15.48 × 10–28 esu associated with a low Egap at 1.51 eV. Examining the NBO, the DOS, and the TDM reveals that charge separation occurred following photoexcitation, and the electrons were migrated from the donor to the acceptor group.

Physical, chemical and antibacterial properties of benzethonium chloride: Experimental and ab-initio analysis

The present study investigates the properties of benzethonium chloride compound using experimental analysis (NMR, FT-Raman/FTIR, TGA/DTG and DSC) and DFT method. Three molecular structures (BZT, BZT-Cl and BZT-Cl-H2O) were considered and optimized using 6–311++G** method. The computed theoretical shifts depicted an excellent matching with 13C and 1HNMR peaks, as well for FT-Raman and FTIR spectroscopic data. On the other hand, it was found that BZT-Cl compound has a higher polarizability (α) along z-direction when compared to BZT and BZT-Cl-H2O; while adding of chlorine and water molecule increase significantly the total first-order hyper-polarizability (β). The electrostatic mapping potential depicted that chlorine and water enhanced the nucleophile character. The HOMO-LUMO energies and reactivity parameters significantly change in BZT-Cl and BZT-Cl-H2O. Furthermore, the thermal analysis showed a good stability up to 160 °C. Finally, antibacterial tests against several strains demonstrated an excellent activity and a mechanism structure/activity was proposed.

Experimental and Computational studies on Intramolecular charge transfer, Terahertz and Two photon absorption of 3-[(4-Nitrophenyl Azo)]-9H-Carbazole-9-Ethanol (NPACE) from their Vibrational spectra for Optical limiting and NLO applications

Non-linear optical (NLO) features of 3-[(4-Nitrophenyl Azo)]-9H-Carbazole-9-Ethanol (NPACE) chromophore were investigated by FT-IR, FT-Raman, and UV–visible spectra aided by Density Functional Theory (DFT) using the B3LYP/6–311++G(d,p) basis set of Gaussian 16 W package. It is observed from the DFT calculation that the slight increase in the endocyclic angle of C13 -C14 -C15 and the reduction in exocyclic angle of N40 –N39 -C14 and C15 -C14 –N39 ascertained by experimental XRD values indicating the intramolecular charge-transfer interaction between the carbazole and nitrophenyl group through the diazo bridge. The vibrational contribution to the linear electro-optic effect is 15% of the total hyperpolarizability being calculated at B3LYP/6–311++G (d, p) for the NPACE molecule. It is also observed that the 8a, 19a, and 19b modes of the carbazole ring and the 8a, 8b, and 19b modes of the phenyl ring are found to be simultaneously and intensely active in IR and Raman spectra explaining the charge transfer interactions throughout the molecule. The low value of the HOMO- LUMO energy gap (2.5843 eV) and the deviation between the measured absorption wavelength (3.36 eV) from the computed (3.87 eV), both these facts substantiate the intramolecular charge transfer. The polarizability and first-order hyperpolarizability were calculated as 6.48 × 10-24 and 3.8 × 10-29 esu, respectively. The second harmonic generation (SHG) measurement experiment of NPACE was carried out using the powder method. The SHG efficiency is measured in comparison with the urea standard. The calculated torsional mode at 20 cm−1 is in excellent quantitative agreement with the experimentally determined terahertz absorption peak. The two-photon absorption coefficient of NPACE was estimated to be 0.9 × 10-11 mW−1, which is mainly due to the D-π-A type of molecular structure, and the optical limiting threshold for NPACE was estimated to be 1.52 × 1013 Wm−2 enabling this material as a potential candidate for optical limiting applications.

Second Harmonic Generation Signatures of Supramolecular Assemblies Based on Amide Moieties.

Targeting the use of the second harmonic generation (SHG) as a bioimaging technique to unravel the formation of aggregates, the SHG first hyperpolarizabilities ( ) of assemblies of benzene-1,3,5-tricarboxamide derivatives have been evaluated at the density functional theory level. Calculations have revealed that i) the assemblies exhibit SHG responses and the total first hyperpolarizability responses of the aggregates are evolving with their size. The largest aggregation effect is a 18-times increase for of B4 when going from the monomer to the pentamer, that ii) the intrinsic SHG responses described by the hyper-Rayleigh Scattering are enhanced in presence of iodine atoms on the phenyl core, that iii) the side chains affect the relative orientation of the dipole moment and first hyperpolarizability vectors, which impacts more the EFISHG quantities than their moduli, and that iv) the radial component to is dominant for the compounds having the largest responses. These results have been obtained using the sequential molecular dynamics then quantum mechanics approach to account for dynamic structural effects on the SHG responses.

Optimization of electron distribution for enhancing the SHG output using electron withdrawing substituents: evidence from imidazole-picrate hybrid model

In our earlier report, we perceived that the frequency doubling behavior of imidazole-picrate hybrid crystals are high upon attaching electron withdrawing groups than electron donating one. Therefore, in order to enhance non-linear optical behavior of the imidazole-picrate hybrid crystals, we trialed with electron-withdrawing groups. Hence, In this report, the substitution of the electron-withdrawing -Cl (chlorine) or -OCH3 (methoxy) group at the phenyl ring found to enhance the second harmonic generation-nonlinear optical (SHG-NLO) property of the imidazole-picrate hybrid crystals. The total dipole moment (μtotal), electronegativity and hyperpolarizability (β0) of -Cl (compound 1) and -OCH3 (compound 2) substituted hybrids were assessed through computations to estimate the SHG-NLO abilities. Although both groups (-Cl,-OCH3) exhibit electrons withdrawing behavior, the higher values of μtotal, electronegativity, and β0 values computed for -Cl substituted imidazole-picrate hybrid crystals are the indicative factor for the superior NLO behaviour of 1. The computed μtotal, electronegativity and β0 of 1 and 2 infers that the substitution of strong electron withdrawing group; Cl in the phenyl ring of imidazole-picrate maximizes the uneven distribution of electrons than -OCH3. The measured SHG of value for the single crystal of 1 is comparatively higher than 2. SHG of 1 is 1.75 (times that of KDP) and 2 is 1.20 (times that of KDP). In order to, confirm and demonstrate the relevant electronic and structural aspects of the crystals further experiments and computations were carried out and reported.

Optical and electrical properties of new NLO active ethynylated chalcone as solution-processed OLEDs material: Experimental and theoretical approaches

This present study investigated the contribution of new hybrid moieties of ethynylated (C≡C) and chalcone (–CO–CHCH-) units as nonlinear optically active and successfully applied to solution-processed OLEDs material. The simulated data from Density Functional Theory (DFT) indicates that 3-(pyren-1-yl)-1-((4-phenylethylyn)phenyl)-2-propen-1-one (MM-1a) reveals good polarizability properties of total first hyperpolarizability βtot at 842.32 × 10−30 esu associated with low HOMO-LUMO gap at 3.04 eV. The structure-property relationship also was highlighted using TD-DFT calculations for frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) maps and global chemical reactivity descriptors (GCRD). The photophysical behaviours of MM-1a presented emission maxima at 520 nm with large Stokes shifts at 95 nm where this emission shows fluoresce characters and intramolecular charge transfer (ICT) state. Remarkably, a response from the open and closed aperture Z-scan analysis reveals that MM-1a displays reverse saturable absorption (RSA) performance and self-defocusing effects under 532 nm continuous wave (CW) laser. Further, solution-processed OLED featuring single-layer of ITO/PEDOT:PSS/MM-1a/Au displayed electroluminescence effect by intense yellow emission obtained under direct current (DC) voltages supply. From the obtained result, the introduction of ethynyl as spacer in chalcone system facilitated intramolecular charge transfer and finely tuned the electronic properties to enhance NLO response and promising emissive layer for OLED applications.

M@[12-crown-4] and M@[15-crown-5] where (M=Li, Na, and K); the very first examples of non-conventional one alkali metal-containing alkalides with remarkable static and dynamic NLO response

Excess electron compounds , such as alkalides, were shown to be promising nonlinear optical (NLO) materials with higher static and frequency-dependent nonlinearities. The intriguing alkalides are obtained after doping the alkali metals with crown ethers M@[12-crown-4] and M@[15-crown-5] (where M=Li, Na, and K). The studied complexes are thermodynamically stable and their interactions energies range from −66.51 to −3.51 kcal mol −1 . The geometric, electronic, and nonlinear optical properties are validated through density functional theory at the CAM-B3LYP/6-31+G(d,p) level of theory. The significant (negative) NBO charge present on alkali metals reveals their alkalide characteristics. Furthermore, reduced HOMO-LUMO gaps for the designed complexes show their excellent electronic and conductive properties. Being excess electron candidate the significant static first hyperpolarizability value increased up to 1.2 × 10 7 au where the β vec response recorded up to 1.1 × 10 7 au. The total hyperpolarizability nicely correlates with hyperpolarizability ( β tl ) which suggests their excellent NLO properties. Besides, the dynamic hyperpolarizability response for electro-optical pockel's effect β(-2ω;ω,0) increases up to 3.5 × 10 7 au at dispersion frequency of 1064 nm. The dynamic hyperpolarizability responses for SHG are much pronounced at the larger dispersion frequency. The dynamic second hyperpolarizability response for the dc-Kerr effect increases up to 6.4 × 10 9 au. The frequency-dependent NLO response of M@[12-crown-4] alkalides is slightly larger than those of M@[12-crown-4]. Moreover, the hyper Rayleigh scattering hyperpolarizability (β HRS ) value is calculated up to 3.4 × 10 6 au. • Single alkali metal based non-conventional alkalides are proposed as excess electron compounds. • These shows better thermodynamic stabilities and significant interactions energies for M@[15-crown-5] complexes. • The higher hyperpolarizability response for Li@[15-crown-5] rose up to 1.2 × 10 7 au. • The remarkable frequency-dependent NLO properties at ω = 1064 nm.

Electronic Structure and IR Spectra Analysis of Tetrathiafulvelene (TTF) Using RHF and DFT Quantum Mechanical Methods

Tetrathiafulvalene (C6H4S4) is an organosulfur compound used in the manufacture of organic optoelectronic materials. Restricted Hartree-Fock (RHF) and Density Functional Theory (DFT) were employed for the study of the optimized molecular structure of TTF using different basis sets. All computations were performed using Gaussian 03 package. Parameters such as minimum energy, bond lengths and bond angles, HOMO-LUMO energy gap, chemical reactivity descriptors, Non-linear optical properties (such as isotropic polarizability (α), anisotropy of polarizability (∆∝), and total first hyper-polarizability (βtot)), density of states, vibrational frequencies, and intensities were computed and reported in order to determine the relative stability as well as chemical reactivity of the molecule. The results obtained show that RHF has the lowest average value of bond length of 1.0729Å while that obtained using DFT has the lowest average value of 1.0812Å using the same basis set 6-311++G (d, p). This shows that the value is a bit higher using DFT than RHF which implies that the bonds of TTF molecule will be slightly stronger when optimized using RHF than DFT. The bond angles were found to be slightly higher by using DFT than RHF. The calculated HOMO-LUMO energy gap shows that the molecule will be slightly more stable in chemical reaction using RHF than DFT. The DFT values, 3.59 eV and 3.60 eV obtained for the energy gap are closer to the reported value of 3.63eV compared to those obtained by RHF. From the results obtained for vibrational frequencies using both methods, TTF is stable due to the absence of imaginary frequencies. This confirms the stability of the molecule as stated in the results of HOMO-LUMO energy gap. The calculated vibrational frequencies show that the most intense frequency was obtained to be 752.6293 cm-1 at corresponding intensity of 145.9063KM/mole by RHF/6-31++G (d, p) while at B3LYP/6-31+G(d), the most intense frequency is about 635.0243 cm-1 with corresponding intensity of 138.5738MK/mole. By and large, the studyunveil the potential of Tetrathiafulvalene for optoelectronic applications.

DFT study of alkali and alkaline earth metal-doped benzocryptand with remarkable NLO properties.

Strategies for designing remarkable nonlinear optical materials using excess electron compounds are well recognized in literature to enhance the applications of these compounds in nonlinear optics. In this study, density functional theory simulations are performed to study alkali and alkaline earth metal-doped benzocryptand using the B3LYP/6-31G+(d, p) level of theory. Vertical ionization energies (VIEs), reactivity parameters, interaction energies, and binding energies exposed the thermodynamic stability of these complexes. FMO analysis revealed that HOMO is located on alkali metals having polarized electrons, which are easy to excite. The doping strategy enhanced the charge transfer with low bandgap energy in the range of 0.68–2.23 eV, which is lower than that of the surface BC (5.50 eV). Also, the lower transition energies and higher oscillator strength indicate that these complexes exhibit excellent electronic and optical properties. Non-covalent interaction analysis suggested the presence of van der Waals interactions between dopants and surface. IR analysis provided information about the frequencies of stretching vibrations present in the complexes due to different bonds. UV-vis analysis revealed that all the newly designed excess electron complexes are transparent in the UV region and possessed maximum absorption in the visible and NIR region, ranging from 753.6 to 2150 nm, which is higher than the surface (244 nm). Thus, these complexes have a potential for high-performance NLO materials in the applications of optics. Natural bond orbital analysis (NBO), transition density matrix (TDM), electron density difference map (EDDM), and density of state (DOS) analyses were also performed to study the charge transfer properties. Moreover, these complexes possessed remarkable optoelectronic properties due to a significant increase in the isotropic linear polarizability (αiso) in the range of 629.59–1423.23 au. Further, these systems demonstrated an extraordinary large total first hyperpolarizability (βtl) in the range of 3695.55–910 706.43 au. The rationalization of hyperpolarizability by the two-level model reflected a noteworthy increase in βtl because of low transition energies (ΔE) and high transition dipole moment (Δμ). Thus, our results showed that alkali and alkaline earth metal-doped BC might be a competitor for efficient nonlinear optical properties with practical applications in the area of optoelectronics.

Superalkali-based alkalides Li3O@[12-crown-4]M (where M= Li, Na, and K) with remarkable static and dynamic NLO properties; A DFT study

Exploring new nonlinear optical materials with excess electron character is extremely important for promoting the application of excess electron compounds in nonlinear optics. Herein, by using density functional theory (DFT) computations, new superalkali-based alkalides Li3O@[12-crown-4]M− are designed as excess electron compounds. QTAIM studies suggest that the complexant interacts with alkali and superalkali clusters through non-covalent interactions. These complexes are thermodynamically stable and their interaction energies range from −33.40 ∼ −44.23 kcal mol-1. The alkalide nature of these compounds is guaranteed by their HOMOs values and NBO charge analysis. Being excess electron compounds, these alkalides shows potential electronic properties. Their HOMO-LUMO gaps ranging from 0.17–0.27 eV. With excellent properties, these complexes show remarkable total hyperpolarizability (βo) response (9.30×104–5.26×106au). Interestingly, the hyperpolarizability response is dependent on the size of alkali metals. The βvec values are quite comparable to total hyperpolarizability at the same level of theory. Furthermore, the hyperpolarizability calculated through two-level model (βtl) values show a trend similar to hyperpolarizability. Additionally, the dynamic hyperpolarizability response for EOPE effects is much pronounced at the dispersion frequency of 532 nm. The second hyperpolarizability response for the dc-Kerr constant is increased up to 2.75 × 1012 au which is much higher than those of previously reported alkalides. Strikingly, the frequency-dependent NLO response shows dependence on alkalide character rather than the size of alkali metal (M). Moreover, the βHRS value is recorded up to 2.16 × 106 au. The significant dipolar contribution to hyperpolarizabilities Φβ(J = 1) are observed for these complexes.

Enhanced linear and nonlinear optical response of superhalogen (Al7) doped graphitic carbon nitride (g-C3N4)

• Effect of Al 7 on g-C 3 N 4 is investigated for the second- and third-order NLO polarizabilities. • Doping reduces the band gap by about 50 % in the single doped system. Similarly, linear optical properties increase from 55 to 108 %. • The single doped system exhibited the first and second hyperpolarizability of about 39 and 5 times greater than the pure g-C 3 N 4 . In this study, pure and superhalogen doped g-C 3 N 4 clusters are computed with the CAM-B3LYP method of DFT to investigate the electronic and optical properties. Single Al 7 @g-C 3 N 4 and double doped 2Al 7 @g-C 3 N 4 systems are investigated. The doping of the superhalogen cluster on g-C 3 N 4 especially in a single doped system significantly improves the charge transfer properties by reducing the band gap energies from 6.42 eV to 3.23 eV. The average and total first hyperpolarizabilities ( β o and β total ) remarkably increase from 82 to 3204 au and 136–5340 au, whereas average second hyperpolarizability ( γ o ) increases from 14 × 10 4 to 64 × 10 4 au due to their lower transition energies. The selected systems were also compared with the external reference molecule p -NA which is a well-known reference molecule for NLO applications. TD-DFT simulations reveal that among pure, single, and double doped systems, the only single doped system shows significantly better outcomes including interaction energies, vertical ionization potential, HOMO-LUMO energies, and UV–vis absorption. The single doped system shows high absorption in the far-red region that use in lasers. The entitled systems especially single doped systems have the potential to use them as an efficient NLO material.

Facile Synthesis, Spectral (IR, Mass, UV−Vis, NMR), Linear and Nonlinear Investigation of the Novel Phosphonate Compounds: A Combined Experimental and Simulation Study

AbstractHerein, we reported the imino phosphonate compounds: (4‐methoxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (MBPDE), 4‐hydroxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (HBPDE) and 4‐hydroxy‐3‐methoxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (HMBPD) form the chemical reaction of diethyl (α‐amino benzyl)phosphonate hydrochloride and substituted benzaldehyde. These compounds were characterized by various spectroscopic techniques: FT‐IR, Mass, UV–VIS, 1H NMR and 13 C NMR. Additionally, the optimized molecular structures, FT‐IR, natural bond orbitals (NBOs), frontier molecular orbitals (FMOs), non‐linear optical (NLO) properties were calculated by the density functional theory (DFT) using the B3LYP functional with the 6–311+G(d,p) basis set. Moreover, UV–Visible spectrum of MBPDE, HBPDE and HMBPD were predicted in different solvents using the time dependent TD‐DFT [B3LYP/6‐311+G(d,p)] method using Polarizable Continuum Model (PCM). The non‐linear optical (NLO) properties were calculated by M06 functional with the 6–311+G(d,p) basis set. A synergistic relationship is observed between the experimental and theoretical findings. NBO analysis provided insights about the stability and charge delocalization of the entitled molecules. The global reactivity descriptors were achieved through HOMO‐LUMO energies. The efficiency of the entitled molecules concerning charge transfer and participation in diverse chemical reactivities were figured out perceptibly by applying the frontier molecular orbitals (FMOs) analysis. The average polarizability values: 277.184, 261.332 and 280.254 a.u. of the MBPDE, HBPDE and HMBPD were determined respectively. The total first hyperpolarizability (βtot) values of the MBPDE, HBPDE and HMBPD were also obtained to be 992.900, 781.527 and 1107.526 a.u. respectively. The compound HMBPD comprising of higher magnitude of average polarizability and the total first hyperpolarizability (βtot) values than MBPDE and HBPDE molecules. Moreover, NLO properties of urea molecule were found smaller in comparison to the MBPDE, HBPDE and HMBPD. The medicinal importances of these novel compounds as well as its contribution towards nonlinear optical field are our future targets.

Theoretical Investigation of Optical and Nonlinear Optical (NLO) Properties of 3‐Azabenzanthrone Analogues : DFT and TD‐DFT Approach.

Abstract3‐Azabenzanthrone based chromophores are investigated to study the effect of different substituents on optical and “non‐linear optical (NLO)” properties by means of density functional theory (DFT) with global hybrid functionals (GHs) ‐ B3LYP and BHandHLYP, range separated hybrid functionals (RSHs) CAM−B3LYP, wB97, wB97X, wB97XD and the basis sets 6–31+G(d), cc‐pVDZ, and cc‐pVTZ. It is observed that the incorporation of an electron withdrawing group at the 1 position and an electron donating group at the 2 and 6 positions of 3‐azabenzanthrone system led to more red shifted absorption maxima and showed better NLO response. Molecule 3 with electron withdrawing ‐CN at the 1 position exhibited the highest absorption wavelength (λ= 590 nm). The geometries, dipole moments, HOMO‐LUMO energy gaps, total hyperpolarizability are calculated to investigate the effect of different substituents on the photophysical and NLO properties of 3‐azabenzanthrone based chromophores. The insertion of ‐CN group at the 1 position of 3‐azabenzanthrone system resulted in higher first order hyperpolarizability (β0). The β0 values of 3, 5, 6 and 12 are found to be the maximum among other remaining molecules as the “Bond Length Alternation (BLA)” and “Bond Order Alternation (BOA)” parameters tend to zero. The charge transfer (CT) properties of these analogues are established using molecular electrostatic potential (MEP) analysis and quinoidal character at the same level of theory.

Computational study of new 1,2,3-triazole derivative of lithocholic acid: Structural aspects, non-linear optical properties and molecular docking studies as potential PTP 1B enzyme inhibitor

We have reported synthesis of a novel 1,2,3-triazole conjugate of lithocholic acid by 1,3-dipolar cycloaddition reaction. The molecular properties such as geometry, conformations, bond lengths and dihedral angles were investigated theoretically. The bond order analysis was performed using Wiberg bond order (WBO), Fuzzy bond order (FBO) and Laplacian bond order (MBO) method. Electronic properties of molecule such as electrostatic surface potential analysis, frontier molecular orbital analysis, reduced density gradient, total density of states, and global chemical reactivity indices have been investigated. The nonlinear optical properties were also investigated. Total dipole moment, mean polarizability and hyperpolarizability were found to be much higher than standard urea molecule which suggests that it could act as potential NLO material. The molecular docking calculations are also performed to investigate its potential as PTP 1B enzyme inhibitor.

Effects of Structural Modification on the Photoelectrical Properties of the D‐A‐π‐A‐Type Dyes in DSSCs: A Computational Investigation

AbstractThe structure‐activity relationships of the three D−A‐π‐A type dyes (LC6, LC7 and LC8) were investigated via density functional theory (DFT) and time‐dependent DFT methods. The results indicate the substitution of thiophene with benzene ring as π spacer has intensified the distortion in the structure of LC8, which will ease the aggregation of dye on the photocathode. The greatest shift of the conduction band of TiO2, driving force of electron injection, excited state lifetime and lowest lateral intermolecular charge transfer rate of LC8 leads to the prominent photoelectrical properties among the three dyes. In addition, three novel dyes (LC81, LC82 and LC83) were designed via introducing a ‐CN group into the structure of LC8. The obtained results imply that the designed dye LC81 would exhibit the outstanding photoelectrical characteristics among LC8 and its derivatives, owing to its lowest energy gap, chemical hardness, and the greatest polarizability, total first hyperpolarizability, electrophilicity and electroaccepting power, which can provide a theory evidence for the experimental synthesis of dyes with better efficiency.