Effect Of Solvent Polarity Research Articles

C-PCM Study of Solvent Polarity Effect on Spin Crossover in Complex cis-[Fe(phen)2(NCS)2

C-PCM Study of Solvent Polarity Effect on Spin Crossover in Complex cis-[Fe(phen)2(NCS)2

Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive-Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties.

The introduction of an electron-donating triphenylamine motive into a 2,2′,6′,2′′-terpyridine (terpy) moiety, a cornerstone molecular unit in coordination chemistry, opens new ways for a rational design of photophysical properties of organic and inorganic compounds. A push-pull compound, 4′-(4-(di(4-tert-butylphenyl)amine)phenyl)-2,2′,6′,2′′-terpyridine (tBuTPAterpy), was thoroughly investigated with the use of steady-state and time-resolved spectroscopies and Density Functional Theory (DFT) calculations. Our results demonstrate that solvent parameters have an enormous influence on the optical properties of this molecule, acting as knobs for external control of its photophysics. The Intramolecular Charge Transfer (ICT) process introduces a remarkable solvent polarity effect on the emission spectra without affecting the lowest absorption band, as confirmed by DFT simulations, including solvation effects. The calculations ascribe the lowest absorption transitions to two singlet ICT excited states, S1 and S2, with S1 having several orders of magnitude higher oscillator strength than the “dark” S2 state. Temperature and viscosity investigations suggest the existence of two emitting excited states with different structural conformations. The phosphorescence emission band observed at 77 K is assigned to a localized 3terpy state. Finally, protonation studies show that tBuTPAterpy undergoes a reversible process, making it a promising probe of the pH level in the context of acidity determination.

Intramolecular H-type dimer and excimer formation in dibenzoylmethanatoboron difluoride dyads connected via diphenylsiloxane linkers

A series of new dibenzoylmethanatoboron difluoride (DBMBF2) and methoxy-substituted DBMBF2 dyads linked via flexible diphenylsiloxane linkers of various length have been synthesized and characterized. The structure and optical properties of these compounds were studied by X-ray single-crystal measurements, electron absorption, and steady-state and time-resolved fluorescence spectroscopy. In the dyads under study, which are in an equilibrium between the open and folded conformations, the formation of intramolecular H-dimers in the ground state are observed. For the dyads in dilute solutions in various solvents, both monomer and excimer (through intramolecular excimer formation) emissions are observed at room temperature. The effect of solvent polarity and linker length on the formation of intramolecular excimers has been studied. The contribution of excimers into the total fluorescence spectrum decreases with increasing the solvent polarity, and the length of the siloxane linker. The studied dyads in hexane and cyclohexane solutions have CIE chromaticity coordinates very close to the white color point. The mechanofluorochromic properties of the synthesized dyads were studied.

Roles of ligand and solvent for CsPbBr3 nanoplatelets

CsPbBr3 nanoplatelets (NPLs) have been considered as a promising candidate in the field of blue-emitting because of large exciton binding energies, thickness-tunable emission and excellent charge-transfer properties. In this paper, the effect of ligand concentration, solvent polarity, and ligand hydrocarbon chain on the photoluminescence (PL) and morphology properties of NPLs were studied. The PL properties of the NPLs depended strongly on the thickness which was controlled by ligands. The thickness of NPLs increased with increasing the amount of oleylamine. In contrast, the addition amount of oleic acid did not affect the PL properties of the NPLs. In addition, the thickness of NPLs becomes thinner with shortening carbon chain. Furthermore, the polarity of solvent (n-hexane instead of toluene) played an important role in the thickness of NPLs. The higher polarity of toluene induces the preparation of thicker NPLs. These results contribute to the further study of the formation mechanism of perovskite NPLs and promote the application of NPLs in the field of optoelectronic devices.

Uncovering and controlling the ESIPT behavior for 2,2‐dipicolylamino substituted 2‐(2′‐hydroxybenzofuranyl) benzoxazole: Solvent polarity

AbstractIn view of potential applications of fluorescent probe for the novel 2,2‐dipicolylamino substituted 2‐(2′‐hydroxybenzofuranyl) benzoxazole (HBBODipic) dye, herein, we mainly focus on exploring effect of solvent polarity on ESIPT behavior for HBBODipoc. First, we compare the dominating atomic charge distribution, geometric parameters, and infrared (IR) vibrational behaviors of HBBODipic, and we confirm that intramolecular hydrogen bond O–H···N could be strengthened in S1 state and nonpolar solvents are more conducive to the strengthening of hydrogen bonds. Via studying frontier molecular orbitals (MOs), we clarify that intramolecular charge transfer (ICT) occurs in excited molecule and charge redistribution facilitates ESIPT for HBBODipoc. In particular, nonpolar solvent is more propitious to ESIPT process of HBBODipic. Finally, we calculate and compare the potential energy curve of HBBODipic in solvent with different polarities. We present that the ESIPT process of HBBODipic could be regulated by solvent polarity; that is, nonpolar solvents are more favorable for ESIPT reaction for HBBODipic flurophore.

Understanding the effects of electrode meso-macropore structure and solvent polarity on electric double layer capacitors based on a continuum model

The structures of electrode meso-macropore and the solvent polarity are the crucial factors dominating the performance of the electric double layer capacitors (EDLCs), but their impacts are usually tangled and difficult to decouple and quantitate. Here the effects of electrode meso-macropore structure and solvent polarity on the specific capacitance of an EDLC are quantitatively investigated using a steady-state continuum model. The simulation results indicate the specific capacitances are significantly affected by the meso-macropore surface structure. The specific capacitances significantly decrease for both convex surface structures but obviously increase for both concave surface structures, with the increase of curvature radius from 1 to 20 nm. As for solvents, the polar solvent with high saturated dielectric permittivity improves the capacitance performance. Moreover, the electrode meso-macropore structure is of more concern compared with solvent polarity when aiming at enhancing the specific capacitance. These results provide fundamentals for the rational design of porous electrodes and polar electrolytes for EDLCs. © 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd.. All rights reserved.

Effect of Solvent Polarity on the Synergistic Effects in Radical Oxidation of Natural Phenols in the Presence of Mono- and Oligosaccharides

Effect of Solvent Polarity on the Synergistic Effects in Radical Oxidation of Natural Phenols in the Presence of Mono- and Oligosaccharides

Investigation of spectroscopic properties of mono and Di-styryl indole-containing BODIPYs

In the current study, two novel mono- and distyryl BODIPYs have been successfully synthesized employing the Knoevenagel type condensation reaction between 1,3,5,7‑tetramethyl BODIPY and 2,3-diphenyl-4,6-dimethoxyindole-7-carbaldehyde. This CC bond extension approach leads to change in hybridization of methyl carbon from sp3 to sp2 which play quite important role in the photophysical properties of BODIPYs by allowing extended conjugation. The absorption and fluorescence spectroscopy were used to determine the photophysical properties include molar extinction coefficient, fluorescence lifetime and fluorescence quantum yield. Moreover, the effect of solvent polarity on targeted BODIPY units were analysed with experimental investigations. The Density Functional Theory (DFT)-optimized structures were consisted with the experimental data obtained from the single-crystal X-ray structures.

Computational Studies Followed by Effect of Solvent Polarity and Salts on HOMO-LUMO Gap of 7-Hydroxy Coumarine Notabally Reflected by Absorption and Emission Spectra.

7-Hydroxycoumarin's FT-IR solid phase spectra were observed at 4000-400cm-1. The spectra were analyzed in aspects of significant approaches. DFT was used to optimize the structure of the compound and its structural properties. The molecular properties were also determined by the HF/3-21G level. The bond lengths and bond angles were obtained by the computational study of the optimized geometry. The vibrational frequencies were determined in all these approaches, which were then matched to experimental frequencies, yielding an excellent agreement between measured and estimated frequency ranges. The UV-visible spectrum of 7HC was obtained and the electronic characteristics HOMO and LUMO energies were monitored by the time-dependent TD-DFT method. The spectral behavior of 7-Hydroxycoumarin was studied using fluorescence spectroscopy in a wide range of polar and non-polar solvents. Solvatochromic effect was observed in both the fluorescence and absorption spectra. The structural properties, energies, IR intensities, absorption wavelengths, and harmonic vibrational frequencies were compared with the obtainable experimental information of the molecule.

Solvent‐polarity‐dependent excited‐state behaviors for 2‐(2‐hydroxyphenyl) benzothiazole‐5‐(9H‐carbazol‐9‐yl)phenol fluorophore: A theoretical study

AbstractIn this work, we mainly focus on elaborating the effects of solvent polarity on excited state interactions and intramolecular proton transfer (ESIPT) behavior for the novel dye 2‐(2‐hydroxyphenyl) benzothiazole‐5‐(9H‐carbazol‐9‐yl)phenol (HBT‐Cz). Six aprotic solvents with different polarities are considered. Via comparing geometrical parameters, infrared (IR) vibrational spectra, and atomic charge distributions, we confirm that the hydrogen bond of HBT‐Cz is enhanced in S1 state. The enhancement of hydrogen bonding with low polarity is particularly important. Via exploring molecular orbitals, we find that intramolecular charge transfer happens and charge redistribution facilitates ESIPT reaction. Results show that low solvent polarity is more conducive to ESIPT process for HBT‐Cz. In order to clarify detailed reaction mechanism, we construct potential energy curves and determine that the ESIPT process of HBT‐Cz fluorophores could be controlled by solvent polarity. We not only elucidate the excited state behavior of HBT‐Cz systems but also present the polarity‐dependent ESIPT mechanism for HBT‐Cz fluorophore.

Effect of Solvent Polarity on the Emulsifying Properties of the Flexible Zein

Effect of Solvent Polarity on the Emulsifying Properties of the Flexible Zein

Unravelling the thermodynamics and binding interactions of bovine serum albumin (BSA) with thiazole based carbohydrazide: Multi-spectroscopic, DFT and molecular dynamics approach

In the present manuscript, a novel 2-((4-chlorophenyl)amino)-N'-(4-(diethylamino)-2-hydroxybenzylidene)thiazole-4-carbohydrazide (H1) has been synthesized and characterized using various spectroscopic techniques including 1D, 2D NMR, FT-IR and single-crystal XRD. Various electrostatic parameters such as frontier molecular orbital (FMO), natural bond orbital (NBO), Fukui functions and nonlinear optical (NLO) properties were explored by Density Functional Theory (DFT) using B3LYP/6-311+G(d,p) level of theory. The effect of solvent polarity on electronic absorption spectra was investigated using Time dependent-DFT. The thermodynamic parameters such as heat capacity, entropy and enthalpy were also investigated at different temperatures. Moreover, photophysical studies were performed to examine the effect of solvent polarity and viscosity. A positive solvatochromism and a 7 fold fluorescence enhancement were observed with the increase of solvent polarity and viscosity, respectively. The compound exhibit aggregation-induced emission in THF:H2O system. The binding interaction of H1 with BSA and its mechanism has been investigated using UV-visible absorption and fluorescence quenching techniques. The thermodynamics of binding suggest the presence of spontaneous hydrogen bonding interactions, as –ve values of ΔG, ΔS and ΔH were observed. The experimental results obtained from BSA binding studies were validated through in silico molecular docking and dynamics techniques. Molecular modelling studies perfectly corroborate the experimentally obtained results.

Spectrochemistry of Firefly Bioluminescence.

The chemical reactions underlying the emission of light in fireflies and other bioluminescent beetles are some of the most thoroughly studied processes by scientists worldwide. Despite these remarkable efforts, fierce academic arguments continue around even some of the most fundamental aspects of the reaction mechanism behind the beetle bioluminescence. In an attempt to reach a consensus, we made an exhaustive search of the available literature and compiled the key discoveries on the fluorescence and chemiluminescence spectrochemistry of the emitting molecule, the firefly oxyluciferin, and its chemical analogues reported over the past 50+ years. The factors that affect the light emission, including intermolecular interactions, solvent polarity, and electronic effects, were analyzed in the context of both the reaction mechanism and the different colors of light emitted by different luciferases. The collective data points toward a combined emission of multiple coexistent forms of oxyluciferin as the most probable explanation for the variation in color of the emitted light. We also highlight realistic research directions to eventually address some of the remaining questions related to firefly bioluminescence. It is our hope that this extensive compilation of data and detailed analysis will not only consolidate the existing body of knowledge on this important phenomenon but will also aid in reaching a wider consensus on some of the mechanistic details of firefly bioluminescence.

Solubility, dissolution thermodynamics, Hansen solubility parameter and molecular simulation of 4-chlorobenzophenone with different solvents

Equilibrium mole fraction solubility of 4-chlorobenzophenone in eleven organic solvents, as well as in neat water, was determined at temperatures ranging from 278.15 K to 323.15 K. Solubility of 4-chlorobenzophenone in these solvents increased with rising of temperatures, and the data was adequately correlated with several well-known thermodynamic models with the average relative deviations (100ARD) of 0.03 to 12.91%, suggesting good correlation. The effects of solvent polarity on solubility were also investigated, and 4-chlorobenzophenone dissolved more in less polar solvents (ester solvents) than in strong polar solvents (alcohol solvents) due to the weak polarity functional groups of 4-chlorobenzophenone. Respective apparent thermodynamic functions, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution process, were calculated using the Wilson equation. Results showed that the dissolution process of 4-chlorobenzophenone was endothermic and spontaneous. Furthermore, Hansen solubility parameters (HSPs) were applied to further discuss the miscibility of 4-chlorobenzophenone in the selected solvents. Molecular dynamics simulation explored the molecular interaction between 4-chlorobenzophenone and solvents, and strong interaction between 4-chlorobenzophenone and ester solvents contributed to the higher solubility.

DFT modelling studies of spectroscopic properties and Medium Effects on Molecular Reactivity of Secnidazole in different solvents

The spectroscopic and optoelectronic investigations of (hydroxyl-2-propyl)-1-methyl-2-nitro-5-imidazole (secnidazole, C_7 H_11 N_3 O_3) molecule were performed using C13 and H1 NMR chemical shifts, FT-IR spectroscopies. Molecular geometric optimizations, HOMO-LUMO properties and molecular electrostatic potential (MPE) were studied using B3LYP functional in DFT method at the cc-pVDZ basis set. UV-Vis spectra of the titled molecule in several solvents (water, dimethyl sulfoxide (DMSO), nitromethane, acetone, and tetrahydrofuran (THF) were investigated theoretically with the aforementioned model method. The solvents have an effective role in the optoelectronic properties of the secnidazole molecule. From non-polar to polar solvents, the (HOMO and LUMO) bandgap energy of secnidazole was found to be decreased except THF solvent. Furthermore, the research aims at investigating the medium effects on solvation free energy, polarizability, dipole moment, first-order hyper-polarizability as well as several molecular properties such as chemical potential, electronegativity, chemical hardness and softness, electrophilicity index of secnidazole (SNZ). The aforementioned method and basis set was used for all kinds of computations in the gas phase and solution. The Solvation Model on Density (SMD) was applied to the aforementioned solvent systems to calculate the solvent polarity effect on dipole moment, free energy, and molecular properties of the (SNZ) molecule. The free energies have gradually increased with a decrease in the solvent dielectric constant i.e. as solvent polarity decreases, the solvation energy increases. From polar to non-polar solvents, the dipole moment of secnidazole was found to be decreased. In various solvents, the dipole moment of secnidazole was greater than that of the gas phase. With the decrease of the solvent dielectric constant, the first-order hyperpolarizability and polarizability have also been decreased. Besides, electronegativity, the chemical potential, and electrophilicity index were decreased continuously from polar to non-polar solvent, except in THF. Secnidazole’s electronegativity, chemical potential, and electrophilicity index were higher in THF than in acetone. However, with increasing solvent polarity, chemical hardness decreased and the inverse relationship was noticed in the case of chemical softness. The obtaining results in this computational investigation may lead to a better understanding of the stability and reactivity of secnidazole and will be helpful for the use of the title compound as reaction intermediates and pharmaceuticals.

Computational investigation of the solvent and temperature effects on the tautomerization of 7-amino-1,3-dioxo-2,5-diphenyl-2,3-dihydro-1H, 5H-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile

This research examines the effects of solvent polarity and temperature on the tautomerization of 7-amino-1,3-dioxo-2, 5-diphenyl-2,3-dihydro-1H,5H-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile at CAM-B3LYP/6-311G (d,p) level of theory. The selected solvents are n-hexane, diethyl ether, pyridine, ethanol, methanol, and water. The solvent effects have been examined by the self-consistent reaction field theory (SCRF) based on conductor-like polarizable continuum model (CPCM). The solvent effects have been explored on the energy barrier, frontier orbitals energies, and HOMO-LUMO gap. Dependencies of thermodynamic parameters (DG andDH) on the dielectric constants of solvents have also been tested. Specifically, the temperature dependencies of the thermodynamics parameters have been studied within 100-1000 K range. The rate constant of the tautomerism reaction is computed from 300 to 1200 K, in the gas phase.

Antioxidant and Enzyme Inhibitory Properties, and HPLC–MS/MS Profiles of Different Extracts of Arabis carduchorum Boiss.: An Endemic Plant to Turkey

In this study, six extracts of Arabis carduchorum prepared from solvents of varying polarity (water, methanol, ethyl acetate, dichloromethane, and n-hexane) were investigated for their chemical profiles and total phenolic and flavonoid contents (TPC/TFC) using HPLC–MS/MS and spectrophotometric/colorimetric assays, respectively, along with the assessment of their antioxidant and enzyme inhibitory effects. In general, the polar extracts (methanol, water, and infusion) showed higher TPC/TFC than the other extracts (range: 13.73–26.62 mg GAE/g; 2.66–52.95 mg RE/g, respectively). The total antioxidant capacity of the polar extracts ranged from 0.90–1.85 mmol TE/g in phosphomolybdenum assay, while the free radical scavenging potential ranged from 4.36–32.13 mg TE/g and 12.58–67.73 mg TE/g in DPPH and ABTS assays, respectively. While the water and infuse extract inhibited only butyrylcholinesterase (2.68 and 2.39 mg GALAE/g, respectively), the other extracts were found to inhibit both acetyl- and butyryl-cholinesterases (0.96–2.73 mg GALAE/g and 1.86–5.11 mg GALAE/g, respectively). On the contrary, all extracts exhibited anti-tyrosinase (40.24–59.22 mg KAE/g) and anti-amylase (0.09–0.63 mmol ACAE/g) activities. Overall, this study highlighted the effect of solvent polarity on the extraction of bioactive compounds and the biological properties of the extracts of A. carduchorum; hence, the results obtained could be used to guide optimum extraction in future studies.

Effects of solvents on the excited‐state intramolecular proton transfer in 3‐HTC

AbstractIt has been demonstrated experimentally that proton transfer can occur in the excited state of 3‐hydroxy‐2‐mercapto‐4‐one (3‐HTC) molecule. However, the effect of solvent polarity on excited‐state intramolecular proton transfer of 3‐HTC has not been reported. In this paper, the molecular structures of ground and excited states in different solvents are optimized by density functional theory and time‐dependent density functional theory. Based on the optimized structure, infrared vibration frequency, electronic spectra, natural bond orbital (NBO) population, and potential energy curves were calculated and analyzed. By analyzing the bond lengths and the bond angles related to the hydrogen bond, it can be seen that the intramolecular hydrogen bond intensity of 3‐HTC molecule in the S1state is strengthened in different solvents. With the increase of the solvent polarity, the degree of hydrogen bond strength decreases. Through the analysis of the infrared vibration frequency, it could be found that intramolecular hydrogen bond of 3‐HTC is weakened as the solvent polarity increases. By analyzing the frontier molecular orbitals and the charge density difference (CDD) maps, it is proved that charge transfer occurs during photoexcitation, which promotes the excited‐state proton transfer process. Further, the analysis of potential energy curves of 3‐HTC in the ground state and S1state shows that proton transfer can be realized in the S1state of 3‐HTC in different solvents. With the increase of solvent polarity, the difficulty of intramolecular proton transfer is increasing.

Positive Effect of Polar Solvents in Olefin Polymerization Catalysis

Positive Effect of Polar Solvents in Olefin Polymerization Catalysis

Solvent polarity dictates the anti-inflammatory potency and mechanism of two purslane (Portulaca oleracea) seed extracts.

This study aimed to assess the effect of solvent polarity on anti-inflammatory potency and the underlying mechanisms of two purslane seed extracts. Methanol and dichloromethane extracts were prepared using Soxhlet extraction and chromatographically analyzed. Antioxidant activities were assessed by different assays, while the anti-inflammatory potentials were assessed in RAW 264.7 macrophage cells. Methanol extraction yielded 15.5% water-soluble extract while dichloromethane produced 3.74% fixed oil. Nineteen phenolic compounds were chromatographically identified in methanol extract compared with 16 in the fixed oil including omega fatty acids and phytosterols. Methanol extract showed significantly higher capacity in radical scavenging assays (p < .001), but the fixed oil showed higher total antioxidant capacity (p < .001). Both extracts demonstrated anti-inflammatory potentials with different mechanisms, where the phenol-rich methanol extract significantly reduced TNF-α (p=.0371) and IL-1β (p=.0029) production through an antioxidant-mediated pathway, while the fixed oil inhibited COX1, COX2, and PGE2 gene expression through the upregulation of IL-10. PRACTICAL APPLICATIONS: Both purslane extracts presented herein demonstrated remarkable antioxidant/ anti-inflammatory potentials that could be safely utilized as natural antioxidants and inflammation remedies or as functional food products, particularly that they showed no cytotoxic effects.