Molecular Modeling Investigation of Bonding, Spectroscopic, and Nonlinear Optical Properties of 2,5-Bis(4-chlorophenyl)-4,4,5-trifluoro-1,3-thiazole Derivatives

In this present work, we calculate the electronic, spectroscopic and nonlinear optical properties (NLO) of N-dialkyl-imidazolium hexafluorophosphate (CNMIM.PF6, where N = 10, 12, 14, 16, 18, 20) ionic liquid crystal molecules under the effect of alkyl chain length variation in cation moiety [CNMIM]+ with fixed anion [PF6]-. CONTEXT: The majority of research on ionic liquid crystal to date has been focused on experiments, while theoretical studies on the optical properties of ionic liquid crystal have been extremely rare. Nonlinear phenomena in optical devices have attracted many researchers. Therefore, results of NLO properties may favor facile synthesis and fabrication of novel-type of materials as well as optoelectronic devices. Spectroscopic studies elucidate further insight into ionic liquid crystal behavior. The results demonstrate that variations in alkyl chain length have an impact on the conformers' electrical, spectroscopic, and NLO properties as well as their stability. The stability of ionic liquid crystal molecules increases with increasein the alkyl chain length and the energy band gap range is 6.64-6.29 eV. Understanding ionic liquid crystal's physical behavior requires an understanding of their dipole moments and NLO features, which are covered in this article. The results of NLO characteristics for all ionic liquid crystal molecules show that their first-order hyperpolarizabilities are higher than the reference molecule (urea). METHODS: The electronic (molecular energy band gap, electrostatic potential map, as well as HOMO-LUMO orbitals) and spectroscopic (IR-RAMAN, UV) properties were evaluated with the help of theoretical model at B3LYP/6-31G(d) while the NLO study has been performed using B3LYP and M06-2X with different basis sets 6-31G(d) and 6-311++G(d,p), as implemented in Gaussian09 software.

ABSTRACTThis paper presents a combined experimental and theoretical study on an ortho-hydroxy Schiff base compound, (E)-1-(4-(2-hydroxybenzylideneamino)phenyl)ethanone. The spectroscopic and electrochemical properties of the compound were determined using IR, UV–vis and 1H, 13C NMR as well as cyclic voltammetry techniques. The hydrogen bond strength was studied using the spectroscopic results, geometry calculations, topological and NBO analysis. The results showed that the predicted nonlinear optical (NLO) properties of the title compound are much greater than those of urea. Thermodynamic properties in the range from 100 to 505 K were obtained. Furthermore, molecular electrostatic potential, Fukui functions, thermodynamic, frontier molecular orbital analysis, reactivity descriptors and NLO properties were found and discussed. Theoretical results show that the conductance of the two tautomers varies seriously, which offers that this molecule has potential usage as a molecular device.

Introduction Organic material with second-order nonlinear optical (NLO) material properties are useful in applications such as optical data processing or storage devices and can be easily processed and integrated into optical devices [1, 2]. Organic materials such as phthalocyanines (Pcs) exhibit large and fast nonlinearities, which can be fine-tuned by rational modification of the molecular structure [3, 4, 5]. Pc molecules are known to have large third-order optical nonlinearities which arise from the highly delocalised two dimensional 18-electron system [6, 7, 8, 5]. Pcs have been intensively investigated for their NLO properties. In most studies, NLO properties of tetra substituted Pcs have been studied as a mixture of isomers [9]. Aims In this work four constitutional isomers of unmetalated tert-butylphenoxy phthalocyanine were separated and their NLO properties measured, in order to identify which isomer contributes the most to the measured NLO response.This work presents spectroscopic and nonlinear optical properties of unmetalated 3, (4-tert-butylphenoxy) phthalocyanine constitutional isomers. Second order nonlinear polarizability, second order hyperpolarizability and third order imaginary susceptibility (Im[χ(3)]) values were determined for monomeric and aggregated constitutional isomers. Z-scan technique is employed in determining the second order NLO property. Spectroscopic and photophysical properties of the isomers, such as fluorescence lifetime and rotational correlation lifetimes are determined. Magnetic circular dichroism (MCD), time correlated single photon counting spectroscopy (TCSPC), ultra-violet visible (UV/vis) spectroscopy, Infra-red (IR) spectroscopy and density functional theory (DFT) are some of the techniques used to characterise physical properties of the isomers. References G. de la Torre, P. Va´zquez, F. Agullo´-Lo´pez, T. Torres, J. Mater. Chem., 1998, 8, 1671-1683.T. Verbiest, S. Houbrechts, M. Kauranen, K. Clays, A. Persoons, J. Mater. Chem., 1997, 7, 2175-2189J. M. Fox, T. J. Katz, S. V. Elshocht, T. Verbiest, M. Kauranen, A. Persoons, T. Thongpanchang, T. Krauss, L. Brus, J. Am. Chem. Soc.,1999, 121, 3453-3459E. M. Maya, A. W. Snow, J. S. Shirk, R. G. S. Pong, S. R. Flom, G. L. Roberts, J. Mater. Chem., 2003, 13, 1603-1613G. de la Torre, P. Vazquez, F. Agullo-Lopez and T. Torres, J. Mater. Chem., 1998, 8, 1671-1683.J. Britton, M. Durmus ̧ S. Khene, V.Chauke, T. Nyokong, J. Porphyrins Phthalocyanine, 2013, 17, 692-702.C. Mkhize, J. Britton, T. Nyokong, Polyhedron, 2014, 81, 607-613.J. Britton, M. Durmuş, V. Chauke, T. Nyokong, Journal of Molecular Structure, 2013, 1054-1055, 209-214.C. Nitschke, S. M. O’Flaherty, M. Kroll, J. J. Doyle, W. J. Blau, Chemical Physics Letters, 2004, 383, 555-560.

The radiation effects of electrons and protons on the spectroscopic and optical properties of oxide glasses doped with Yb3+ in various glass systems were investigated to understand the impact of the glass composition on the glass photo-response. Changes in the optical and emission properties were seen after the radiation treatment, and the magnitude of the changes depended on the irradiation source and dose. For all the investigated materials, the absorption coefficients in the 200–550 nm range increase post-irradiation, revealing the formation of defects in the glasses during the irradiation. While the spectroscopic properties of the tellurite glass remain unchanged, a small reduction in the Yb3+ emission intensity was seen after irradiating the phosphate, borosilicate, and germanate glasses, indicating that a reduction of Yb3+ to Yb2+ might occur in these glasses during the radiation treatment. The changes in the optical and spectroscopic properties after proton irradiation are small as they are localized at the surface of the glasses due to the shallow penetration depth of the proton in the glass. Even though the doses are small, the electron irradiation produces larger changes in the optical and spectroscopic properties since the electrons penetrate the entire volume of the glasses. All the changes in the optical and spectroscopic properties of the glasses were successfully reversed after a short heat treatment revealing the reversible nature of the photo-response of the investigated glasses.

This work evaluated the reliability of the one-dimensional potential energy surface for calculating the spectroscopic properties (rovibrational constants and rotational line energies) of hydrogen bonds in linear bonded complexes by comparing theoretical results with the corresponding experimental results. For this purpose, two hydrogen bonded complexes were selected: the HCN···HCN homodimer and the HCN···HF heterodimer. The one-dimensional potential energy surfaces related to the hydrogen bonds in these complexes were calculated using different computational methods and basis sets. The calculated potential curve of each complex was fitted to an analytical one-dimensional potential function to obtain the potential parameters. The obtained analytical potential function of each complex was used in a two-particle Schrödinger equation to obtain the rovibrational energy levels of the hydrogen bond. Using the calculated rovibrational levels, the rovibrational spectra and constants of each complex were calculated and compared with experimental data available from the literature. Compared with experimental data, the calculated one-dimensional potential energy surface at the QCISD/aug-cc-pVDZ level of theory was found to predict the spectroscopic properties of hydrogen bonds better than the potential curves obtained using other computational methods, especially for the HCN···HCN homodimer complex. Generally, the results obtained for the HCN···HCN homodimer complex were closer to experimental data than those obtained for the HCN···HF heterodimer complex. The investigation performed in this work showed that the one-dimensional potential curve related to the hydrogen bond between two linear molecules can be used to predict the spectroscopic constants of hydrogen bonds. Graphical abstract Potential energy curves of HCN···HCN and HCN···HF complexes calculated at the different computational levels.

Spectroscopic and molecular modeling investigation on the binding of a synthesized steroidal amide to protein

The spectroscopic and photochemical properties of the synthetic carotenoid, locked-15,15′-cis-spheroidene, were studied by absorption, fluorescence, circular dichroism, fast transient absorption and electron spin resonance spectroscopies in solution and after incorporation into the reaction center of Rhodobacter (Rb.) sphaeroides R-26.1. HPLC purification of the synthetic molecule reveals the presence of several di-cis geometric isomers in addition to the mono-cis isomer of locked-15,15′-cis-spheroidene. In solution, the absorption spectrum of the purified mono-cis sample was red-shifted and showed a large cis-peak at 351 nm compared to unlocked all-trans spheroidene. Molecular modeling and semi-empirical calculations reveal how geometric isomerization and structural factors affect the room temperature spectra. The spectroscopic studies of the purified locked-15,15′-mono-cis molecule in solution reveal a more stable manifold of excited states compared to the unlocked spheroidene. Reaction centers of Rb. sphaeroides R-26.1 in which the locked-15,15′-cis-spheroidene was incorporated show no difference in either the spectroscopic properties or photochemistry compared to reaction centers in which unlocked spheroidene was incorporated or to Rb. sphaeroides wild type strain 2.4.1 reaction centers which naturally contain spheroidene. The data suggest that the natural selection of a cis-isomer of spheroidene for incorporation into native reaction centers of Rb. sphaeroides wild type strain 2.4.1 is more determined by the structure or assembly of the reaction center protein than by any special quality of the cis-isomer of the carotenoid that would affect its ability to participate in triplet energy transfer or carry out photoprotection.

Rare-earth ion doped TeO2 and GeO2 glasses as laser materials

Phosphate and borate crystals for high optical gain

Effect of gamma irradiation on physical, optical, spectroscopic and structural properties of Er3+-doped vitreous zinc borotellurite

Ternary indium (III) pyrophosphates with three-dimensional frameworks of MInP2O7 (M = Na, K, Rb, Cs) have been found, and the crystal structures have been first reported in this paper. The optical and bonding properties were investigated in terms of the absorption and emission spectra, as well as the calculated band structures and density of states. The crystal band structures calculated by the DFT method show that the solid compounds of MInP2O7 are insulators with direct band gaps, and the calculated average third-order susceptibilities are increasing in the order of K < Rb < Cs in the MInP2O7 crystal (M = K, Rb, Cs).

Hydration of HNO3–HOCl clusters: Bonding properties

Reported are the syntheses and characterization of six new heterometallic UO22+/Pb2+ compounds. These materials feature rare instances of M-oxo interactions, which influence bonding properties of the uranyl cation. The spectroscopic effects of these interactions were measured using diffuse reflectance, luminescence and Raman spectroscopy. Computational density functional theory (DFT) based natural bonding orbital (NBO) and quantum theory of atoms in molecules (QTAIM) methods indicate interactions arise predominantly through charge transfer between cationic units via the electron donating uranyl O spx lone pair orbitals and electron accepting Pb2+ p orbitals. The interaction strength varies as a function of Pb-oxo interaction distance and angle with energy values ranging from ranging from 0.47 kcal/mol in the longer contacts to 21.94 kcal/mol in the shorter contacts. Uranyl units with stronger interactions display an asymmetric bond weakening and a loss of covalent character in the U=O bonds interacting closely with the Pb2+ ion. Luminescence quenching is observed in cases where strong Pb-oxo interactions are present, and is accompanied by significant red-shifting of the uranyl symmetric Raman stretch. Changes to inner sphere uranyl bonding manifest as a weakening of the U=O bond as a result of interaction with the Pb2+ ion.

We have studied substituent effects on the properties of the intramolecular hydrogen bond of some ortho-hydroxy Schiff bases using density functional theory (DFT) based first-principle molecular dynamics (FPMD) and path integral molecular dynamics. The studied compounds possess a strong intramolecular hydrogen bond (r((O⋅⋅⋅N)) ≤ 2.6 Å), which can be tuned by substitution to either (i) enhance the basicity of the acceptor moiety by induction effects or (ii) decrease the hydrogen bond length through steric repulsion. DFT calculations and FPMD were employed to investigate structural and dynamical properties of the selected molecules, while quantum effects on the structural properties were assessed using path integral FPMD. The simulations were performed in vacuo and in the solid state to study the influence of the environment on the hydrogen bond and spectroscopic properties. We give computational support to the suggestion that induction effects are less effective to tune the intramolecular hydrogen bond properties of the discussed ortho-hydroxy Schiff bases than the steric or the environmental effects.

Reported are the syntheses and characterization of six new heterometallic UO22+/Pb2+ compounds. These materials feature rare instances of M-oxo interactions, which influence the bonding properties of the uranyl cation. The spectroscopic effects of these interactions were measured using luminescence and Raman spectroscopy. Computational density functional theory-based natural bonding orbital and quantum theory of atoms in molecules methods indicate interactions arise predominantly through charge transfer between cationic units via the electron-donating uranyl O spx lone pair orbitals and electron-accepting Pb2+ p orbitals. The interaction strength varies as a function of Pb-oxo interaction distance and angle with energy values ranging from 0.47 kcal/mol in the longer contacts to 21.94 kcal/mol in the shorter contacts. Uranyl units with stronger interactions at the oxo display an asymmetric bond weakening and a loss of covalent character in the U═O bonds interacting closely with the Pb2+ ion. Luminescence quenching is observed in cases in which strong Pb-oxo interactions are present and is accompanied by red-shifting of the uranyl symmetric Raman stretch. Changes to inner sphere uranyl bonding manifest as a weakening of the U═O bond as a result of interaction with the Pb2+ ion. Comprehensive evaluation of the effects of metal ions on uranyl spectra supports modeling efforts probing uranyl bonding and may inform applications such as forensic signatures.