Hyperpolarizability Components Research Articles

Nonlinear optical properties of natural hydroxyanthraquinones studied using density functional theory (DFT) technique

The present study reports the theoretical investigation of nonlinear optical (NLO) properties of natural hydroxyanthraquinones using the Density Functional Theory (DFT) method. The results show that all eleven compounds have appreciable NLO properties. The reported experimental results are supported by computational method. The optimized geometry, linear optical absorption, HOMO-LUMO energy gap, molecular electrostatic potential (MEP), and dipole moments were computed by employing the B3LYP/6-311++G(d,p) level of theory. The static and dynamic linear polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ) components were calculated. At the working wavelength of the device, 1064 nm, the Nd:YAG laser's wavelength, and the doubling wavelength of 532 nm, which is also used to detect electric field induced second harmonic (EFISH), the nonlinear response of the molecules was evaluated.

Nonlinear optical properties, structural and transition state analyses of ionic liquids: DFT and DFT-D2/D3 studies

This paper includes the structural properties, transition state analysis and NLO properties of the ionic liquids in quantum chemical calculations. Hydrogen bond geometries calculated by B3LYP and ωB97XD approaches have been compared with the crystallographic data in the literature. Transition state analysis have been carried out using Synchronous Transit-Guided Quasi-Newton (STQN) method with QST2 option and Density Functional Theory. Forms according to the positions of the proton on hydrogen bond axes and transition states have been evaluated by relative energy scanning. Interactions between anions and cations in ionic liquids optimizations have been studied by CP approach with D2 and D3 versions of Grimme’s dispersion correction. Electric dipole moments, dipole polarizability, first and second dipole hyper polarizability and important components have been calculated, statically and dynamically for ionic liquids. Effective and stable structures in terms of NLO have been evaluated. In addition, B3LYP and ωB97XD functionals approaches have been tested considering Grimme’s D2/D3 dispersion models for lithium interactions with bis(trifluoromethanesulfonyl)amide and methylsulfonate anions.

Molecular Orientation of Carboxylate Anions at the Water-Air Interface Studied with Heterodyne-Detected Vibrational Sum-Frequency Generation.

The carboxylate anion group plays an important role in many (bio)chemical systems and polymeric materials. In this work, we study the orientation of carboxylate anions with various aliphatic and aromatic substituents at the water-air interface by probing the carboxylate stretch vibrations with heterodyne-detected vibrational sum-frequency generation spectroscopy in different polarization configurations. We find that carboxylate groups with small aliphatic substituents show a large tilt angle with respect to the surface normal and that this angle decreases with increasing size of the substituent. We further use the information about the orientation of the carboxylate group to determine the hyperpolarizability components of this group.

Comprehensive quantum chemical calculations and molecular docking analysis of uracil mustard by first principle

Uracil mustard belongs to the nitrogen mustard family and is primarily used in anticancer drugs. The research that follows, investigates many quantum chemical features such as the computation of global minimum energies with no negative wavenumber values using the Density Functional Theory (DFT) with Becke three functional and 6-311G (d, p)/6–311++G (d, p) basis sets. All the vibrational modes have been calibrated and justified in comparison to their experimental counterparts. Mustard's polarizability and hyperpolarizability components, Natural Bond Analysis (NBO), electronic properties, Fukui function analysis, various global parameters, Quantum Theory of Atoms In Molecule (QTAIM) analysis, ADMET analysis, and docking analysis have all been investigated using the same theory and basis sets, indicating its biochemical significance. The biological activity of the molecule is reported by using PASS software. The Full fitness score and binding affinity parameters are utilized to determine the binding strength with 6cq3 protein. The acidity of the title molecule is calculated in water solvent by polarizable continuum model (PCM) solvent effects (estimated in water). The HOMO, LUMO, and MESP plots are used to explore the nature of binding and surfaces. The Fukui functions are computed using Mulliken atomic charges for neutral atoms, cations, and anions. The Ultraviolet–visible (UV–vis) of the molecule is computed employing the TD-DFT method.

Experimental and computational studies on second-and third-order nonlinear optical properties of a novel D-π-A type chalcone derivative: 3-(4-methoxyphenyl)-1-(4-nitrophenyl) prop-2-en-1-one

The present study reports the theoretical and experimental investigations of linear and nonlinear optical (static and dynamic) properties of 3-(4-methoxyphenyl)-1-(4-nitrophenyl)prop-2-en-1-one (MNC). The crystal structure was confirmed from powder X-ray diffraction (PXRD) analysis and evaluated the crystalline quality using high-resolution X-ray diffraction (HRXRD). Linear absorption and fluorescence spectra were recorded and the optical band gap was determined by Tauc’s relation. Third-order nonlinear optical (NLO) characteristics along with optical limiting behavior were explored using the femtosecond (fs) Z-scan technique at 800 and 900nm wavelengths (Ti: sapphire laser, 150fs, 80MHz). The experimental results are supported by theoretical calculations obtained from the density functional theory (DFT). The optimized geometry, linear optical absorption, HOMO-LUMO energy gap, molecular electrostatic potential (MEP), dipole moments and global chemical reactivity descriptors (GCRD) were computed by employing B3LYP/6-311+G(d) level of theory. The static and dynamic linear polarizability (α), first hyperpolarizability (β) and second hyperpolarizability (γ) components were calculated using time-dependent Hartree–Fock (TDHF) method. The computed first hyperpolarizability β(−2ω;ω,ω) at 1064nm wavelength was found to be 55 times greater than that of urea standard. The experimental and calculated dynamic molecular second hyperpolarizabilities γ(−3ω;ω,ω,ω) are in good accordance at 800 and 900nm wavelengths.

Tuning of Second-Order Nonlinear Optical Response Properties of Aryl-Substituted Boron-Dipyrromethene Dyes: Unidirectional Charge Transfer Coupled with Structural Tailoring

Controlling the nonlinear optical (NLO) response properties at the molecular level is a key to develop strong NLO active materials for technological applications. In this paper, we report quantum chemical investigation of NLO response properties of select aryl-substituted Boron-Dipyrromethene (BODIPY) dyes, a class of intramolecular charge transfer (ICT) probes. Density functional theory (DFT) with long-range corrected CAM-B3LYP functional and cc-pVTZ, 6-31G(d,p) and 6-31+G(d,p) basis sets are employed to compute the electronic structures and NLO response of the aforesaid molecules. Calculations at the second order M{\o}ller-Plesset perturbation (MP2) level of theory are performed for comparison. The results suggest that the charge transfer process in these molecules is mostly unidirectional and the total first hyperpolarizability (\b{eta}total) values of these molecules are dominantly dictated by the response in the direction of charge transfer. Alteration of conjugation strength through donor/acceptor substitution as well as twisting of the phenyl ring obtained through incorporation of methyl groups affect the NLO response of thesemolecules. The vector components of first hyperpolarizability (\b{eta}vec) of the probe molecules are also studied to analyze the angle between the vector components of \b{eta}vec and the dipole moment vector. The results presented here are expected to shed light on the origin of NLO response of several aryl-substituted BODIPY dyes and provide means to optimizing it for future technological applications.

Molecular Investigation and Nonlinear Optical Response of Dihydropyrimidinone: A Comparative Spectroscopic and Quantum Computational Studies

Organic molecule ethyl-4-(4-chloro-3-nitrophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate has been synthesized. The molecular structure has been characterized using FT-IR, FT-Raman, 1H and 13C-NMR spectral studies. The structure of the title molecule was theoretically investigated by DFT method using B3LYP/6-31G(d,p) basis set. The firm assignments of vibrational bands are allowed using experimental and computations. The nonlinear optical property of the title molecule has been calculated using first hyperpolarizability components. The intra-molecular charge transfer occurring in the molecule has been analyzed by NBO analysis. The electronic and charge transfer properties have been studied using frontier molecular orbitals. 1H and 13C-NMR spectra were recorded and calculated using the gauge independent atomic orbital (GIAO) method.

Red emitting NLOphoric 3-styryl coumarins: Experimental and computational studies

The coumarin molecules are versatile fluorophores and can be modified synthetically to give desired properties. The molecules studied have 4-cyano group as an assistance to original chromophore and imparts a red shift. These coumarins were expected to show good non-linear optical (NLO) properties. The experimental and theoretical methods were employed to determine their NLO properties. Directional components of hyperpolarizabilities were calculated and showed a variation according to the placement of electron pulling groups. Studied molecules show a very high (494–794 times of urea) total first order hyperpolarizability. The NLO properties of the molecules were found to be solvent dependant.

Analysis on linear and nonlinear optical properties of two Bisphenols with DFT approach: A comparative study

Density functional theory (DFT) method with B3LYP functional has been employed for the polarizability (α) and first order hyperpolarizability (β) calculations of two Bisphenols (4,4′ thiodiphenol and 4,4′ sulfonyldiphenol). Correlation between the dipole moment, polarizability and charge distribution is analyzed extensively. The calculated octupolar over dipolar contribution ratio parameter ρ from the hyperpolarizability components gives rise to macroscopic second harmonic generation (SHG) phenomenon identifying with the dipole nature of 4,4′ thiodiphenol and the tendency towards the octupole nature of 4,4′ sulfonyldiphenol molecule. Discussions on the geometrical structures of both Bisphenol molecules have been extended based on the comparison of optimized gas phase with solid state geometrical parameters to explain the high coplanarity in 4,4′ sulfonyldiphenol molecule which leads to the extended π-conjugation. Theoretically predicted large value of SHG in 4,4′ sulfonyldiphenol and zero value in case of 4,4′ thiodiphenol are confirmed with Kurtz–Perry Powder technique.

Electron correlation effects and density analysis of the first-order hyperpolarizability of neutral guanine tautomers

Dipole moments (μ), charge distributions, and static electronic first-order hyperpolarizabilities (β(μ)) of the two lowest-energy keto tautomers of guanine (7H and 9H) were determined in the gas phase using Hartree-Fock, Møller-Plesset perturbation theory (MP2 and MP4), and DFT (PBE1PBE, B97-1, B3LYP, CAM-B3LYP) methods with Dunning's correlation-consistent aug-cc-pVDZ and d-aug-cc-pVDZ basis sets. The most stable isomer 7H exhibits a μ value smaller than that of the 9H form by a factor of ca. 3.5. The β μ value of the 9H tautomer is strongly dependent on the computational method employed, as it dramatically influences the β(μ) (9H)/β(μ) (7H) ratio, which at the highest correlated MP4/aug-cc-pVDZ level is predicted to be ca. 5. The Coulomb-attenuating hybrid exchange-correlation CAM-B3LYP method is superior to the conventional PBE1PBE, B3LYP, and B97-1 functionals in predicting the β(μ) values. Differences between the largest diagonal hyperpolarizability components were clarified through hyperpolarizability density analyses. Dipole moment and first-order hyperpolarizability are molecular properties that are potentially useful for distinguishing the 7H from the 9H tautomer.

Morphology of collisional nonlinear spectra in H2-Kr and H2-Xe mixtures

This article reports new results of theoretical and numerical studies of spectral features of the collision-induced hyper-Rayleigh light scattered in dihydrogen-noble gas (H2-Rg) mixtures. The most massive and polarizable scattering supermolecules with Rg = Kr and Xe have been added to the previously considered systems in order to gain a more complete insight into the evolution of the spectral properties. The symmetry adapted components of the first collisional hyperpolarizabilities are obtained by means of the quantum chemistry numerical routines supplemented with appropriate theoretical methods. Roto-translational spectral lines are calculated on the grounds of the quantum-mechanical as well as semi-classical approach. The role of particular hyperpolarizability components in forming the line shapes is discussed. The intensities of the lines are compared with those obtained for less massive scatterers. Advantages of prospective application of the new scattering systems for experimental detection of the nonlinear collisional effects are indicated.

Measurement of second hyperpolarizability components of a conjugated polymer

A method has been proposed to determine the components of the second hyperpolarizability γ(-ω4;ω3,ω2,ω1) of a conjugated polymer in the off-resonant region based on the attenuated- total-reflection technique. By doing a least-square fit to the experimental data of γ(-ω;0,0,ω) for the quadratic electro-optic effect, the frequency-independent term of the components of γ(-ω4;ω3,ω2,ω1) is obtained, from which the components of γ(-ω4;ω3,ω2,ω1) are determined .

ChemInform Abstract: Electron Crystallography and Organic Materials with Non-Linear Optical Properties

Results of electron microscopic studies of crystal structures of a number of bis-benzylidene cyclohexanones are presented. It is shown that some of these compounds are efficient crystalline non-linear optically active (NLO) chromophores with second harmonic generation (SHG) properties. Appropriately functionalized chromophores of this type can be used as a polycondensation comonomer to produce partly crystalline main-chain NLO-active polymers. Electron diffraction crystal structural data, obtained for very small crystals, allowed us to get reasonable estimations of macroscopic crystal NLO-coefficients, relating quantum-chemically calculated molecular first hyperpolarizability components to crystal axes.

Organic salts of biguanide – An attempt to crystal engineering of novel materials for second harmonic generation

Three organic salts of biguanide with oxalic, succinic and l-tartaric acids have been prepared and X-ray structural analysis has been performed. Biguanidium(1+) oxalate hemihydrate ( a = 6.8330(2) Å, b = 10.0430(2) Å, c = 14.6230(4) Å, α = 90.236(1) , β = 90.333(1) , γ = 105.605(2) , V = 966.46(4) Å 3, Z = 1, R = 0.0393 for 3704 observed reflections) and biguanidium(1+) hydrogen succinate ( a = 6.4600(1) Å, b = 6.7670(2) Å, c = 11.4150(3) Å, α = 91.822(1) , β = 105.312(1) , γ = 90.922(1) , V = 480.89(2) Å 3, Z = 2, R = 0.0357 for 1880 observed reflections) belong to the triclinic space group P 1 ¯ . Their crystal structures are based on biguanidium(1+) pairs connected by intermolecular N–H⋯N hydrogen bonds. The remaining ions (eventually water molecules) form a 3D structural network with these pairs. Furthermore, the formation of the cationic and anionic layers interconnected by intermolecular N–H⋯O hydrogen bonds was observed in the crystal structure of biguanidium(1+) hydrogen succinate. Biguanidium(2+) l-tartrate crystallizes in the orthorhombic space group P 2 12 12 1 ( a = 6.7170(2) Å, b = 9.2740(2) Å, c = 16.1500(4) Å, V = 1006.04(4) Å 3, Z = 4, R = 0.0432 for 2193 observed reflections). The crystal structure is based on l-tartrate chains, which are interconnected by isolated biguanidium(2+) cations via several types of N–H⋯O hydrogen bonds. The formation of l-tartrate chains is mediated by two types of intermolecular O–H⋯O hydrogen bonds connecting the hydroxyl and carboxylate groups. The FTIR and FT Raman spectra of all the compounds were recorded and discussed. The theoretical values of the first hyperpolarizability components were calculated for biguanidium(1+) and biguanidium(2+) cations at the B3LYP level with the 6-311G(d,p) basis set. Quantitative measurements of the second harmonic generation of powdered biguanidium(2+) l-tartrate at 800 nm were performed and a relative efficiency of 2% (compared to KDP) was observed. The thermal behaviour of all the prepared compounds was studied by the DSC method in the temperature interval from 90 K up to a temperature close to the melting points of the crystals. The FTIR and FT Raman spectra of biguanidium(2+) l-tartrate were investigated down to 130 K.

Orientation determination of protein helical secondary structures using linear and nonlinear vibrational spectroscopy.

In this paper, we systematically presented the orientation determination of protein helical secondary structures using vibrational spectroscopic methods, particularly, nonlinear sum frequency generation (SFG) vibrational spectroscopy, along with linear vibrational spectroscopic techniques such as infrared spectroscopy and Raman scattering. SFG amide I signals can be collected using different polarization combinations of the input laser beams and output signal beam to measure the second-order nonlinear optical susceptibility components of the helical amide I modes, which are related to their molecular hyperpolarizability elements through the orientation distribution of these helices. The molecular hyperpolarizability elements of amide I modes of a helix can be calculated based on the infrared transition dipole moment and Raman polarizability tensor of the helix; these quantities are determined by using the bond additivity model to sum over the individual infrared transition dipole moments and Raman polarizability tensors, respectively, of the peptide units (or the amino acid residues). The computed overall infrared transition dipole moment and Raman polarizability tensor of a helix can be validated by experimental data using polarized infrared and polarized Raman spectroscopy on samples with well-aligned helical structures. From the deduced SFG hyperpolarizability elements and measured SFG second-order nonlinear susceptibility components, orientation information regarding helical structures can be determined. Even though such orientation information can also be measured using polarized infrared or polarized Raman amide I signals, SFG has a much lower detection limit, which can be used to study the orientation of a helix when its surface coverage is much lower than a monolayer. In addition, the combination of different vibrational spectroscopic techniques, for example, SFG and attenuated total reflectance Fourier transform infrared spectroscopy, provides more measured parameters for orientation determination, aiding in the deduction of more complicated orientation distributions. In this paper, we discussed two types of helices, the alpha-helix and 3-10 helix. However, the orientation determination method presented here is general and thus can be applied to study other helices as well. The calculations of SFG amide I hyperpolarizability components for alpha-helical and 3-10 helical structures with different chain lengths have also been performed. It was found that when the helices reached a certain length, the number of peptide units in the helix should not alter the data analysis substantially. It was shown in the calculation, however, that when the helix chain is short, the SFG hyperpolarizability component ratios can vary substantially when the chain length is changed. Because 3-10 helical structures can be quite short in proteins, the orientation determination for a short 3-10 helix needs to take into account the number of peptide units in the helix.

Theoretical investigation on the linear and nonlinear susceptibilities of urea crystal

The linear and second-order nonlinear susceptibilities of the urea crystal have been evaluated by applying the supermolecule approach. Calculations performed at the time-dependent Hartree-Fock (TDHF) level using the Austin model (AM1) semiempirical Hamiltonian have first demonstrated the almost additive character of the essential polarizability and first hyperpolarizability components. In fact, the only exception concerns the chi(cc) ((1)) component when stacking urea molecules along the c axis, i.e., the axis of the hydrogen bonds. This behavior has been confirmed by ab initio calculations on small clusters. The macroscopic quantities have then been determined by adopting the multiplicative scheme and by correcting the TDHF/AM1 values for missing electron correlation by means of density functional theory and coupled cluster method. The reliability of the multiplicative scheme was demonstrated for clusters as large as 3ax3bx3c. While the electron correlation correction factors are similar for a single molecule and different small clusters, the global performance of the scheme differs for the linear and nonlinear responses. For the second-order nonlinear susceptibility, our predictions are in good agreement with experiment, while for the linear susceptibility and the associated refractive index, our predictions underestimate the experimental values. The limitations of our approach may be attributed to its inability to account for more subtle cooperative effects, like those associated with a network of hydrogen bonds. Together with other works, the supermolecule calculations confirm that the sign of chi(abc) ((2)) is negative, contrary to an estimate from band structure calculation.

Nonlinear optical response from periodic molecular structures

The explicit expressions of all independent components of the molecular crystal nonlinear susceptibility (NS) tensor (of any order) are given through the independent components of hyperpolarizability (HP) tensors of the constituting molecules. This expression has a polynomial form of convolutions of HP components and includes local field tensor components; each product contains from 1 to k−1 HP cofactors of all preceding ranks, and k is NS rank. The Bloembergen-Armstrong formula for the first NS and Hurst-Munn for the second NS are particular cases of this expression. The reciprocal equation for molecular HP in terms of crystal NS is also presented. The Lorentz formula of the phenomenological reaction field theory is derived from the microscopic crystal Hartree-Fock HP equations with the Madelung polarization potential included. The derivation is based on the expansion of the Madelung polarization interaction over the inter-ion distances. The second order term of this expansion is expressed through the Lorentz tensor components. The expansion is obtained due to a convenient method of calculation of the Madelung crystal sums. This technique enabled to reformulate for a molecular crystal the existing computational quantum methods for lone molecules. In particular, Hartree-Fock equations for HP of molecules are adjusted for the optical properties of molecular crystals and layers. The illustrative examples, demonstrating various aspects of the mentioned techniques, are presented.

On the cooperativity of the interaction-induced (hyper)polarizabilities of the selected hydrogen-bonded trimers

The intermolecular interaction effects on the static electronic electric properties of three hydrogen-bonded systems (trimers of urea, fluoroacetylene and diformamide) have been investigated. The two- and three-body components of interaction-induced dipole moment, polarizability and first-order hyperpolarizability have been calculated and analyzed at the SCF and MP2 levels of theory. The cooperativity of the three-body effects of the interaction-induced properties as well as the electron correlation effects have been investigated. In addition to the study of interaction-induced properties, the performance of recently developed polarized Z3Pol basis set has been tested against the following systematically extended Dunning’s correlation consistent basis sets: aug-cc-pVDZ, aug-cc-pVTZ and d-aug-cc-pVDZ.

Determination of the Hyperpolarizability Components of Hemicyanine Dyes by Measuring the Anisotropic Fluorescence and Second Harmonic of the Dyes Uniformly Aligned within Zeolite Channels

A unidirectional ensemble of hemicyanine molecules was prepared by inserting the molecules into the vertical channels of a uniformly oriented zeolite (silicalite-1) film grown on a glass substrate. Fluorescence from this sample excited with light polarized along the vertical channel was 50 times larger than that excited with light polarized orthogonal to the vertical channel direction. These vertically aligned hemicyanine dyes were used to determine the ratio of the molecular hyperpolarizability components beta(zxx)/beta(zzz) of hemicyanine.

Capability of X-ray diffraction to the determination of the macroscopic linear susceptibility in a crystalline environment: the case of 3-Methyl 4-Nitropyridine N-oxide (POM)

In a recent work we have reported an investigation of the applicability of ground state electron density inferred from X-ray diffraction to the determination of the linear polarizability of an ‘in situ’ conjugated molecule labelled POM and corresponding to a nonlinear optical organic compound (F. Hamzaoui, A. Zanoun, G. Vergoten, J. Mol. Struct. 397 (1–3) (2004) 17–22). In this work and using the Unsöld approximation one can connect the susceptibility tensor of rank n to the multipolar charge distribution (in the fundamental state) of order 2 n . Thus, the linear polarizability is associated to the quadrupole moment, whereas the first order hyperpolarizability is linked to the octupolar moment of the charge distribution. Using an approach similar to the one used for the determination of the linear polarizability, we present here the estimated values of the tensor β derived from the X-ray experiment. However more surprising is the good agreement between the calculation of the lowest order macroscopic optical nonlinearity as a tensor sum of molecular polarizabilities of the free molecule and the macroscopic non linear measurements, the generalization of this remark means that the crystalline effects are negligible in the estimation of nonlinear optical properties. However, it seems difficult to infer from the Unsöld approximation a faithful description of the molecular optical properties, whereas an estimation of the first order hyperpolarizability components of β seems out of reach.