Effect Of Solvent Polarity Research Articles

Exploring a new class of singlet fission fluorene derivatives with high-energy triplets.

In this study, we report strong experimental evidence for singlet fission (SF) in a new class of fluorene-based molecules, exhibiting two-branched donor–acceptor structures. The time-resolved spectroscopic results disclose ultrafast formation of a double triplet state (occurring in few picoseconds) and efficient triplet exciton separation (up to 145% triplet yield). The solvent polarity effect and the role of intramolecular charge transfer (ICT) on the SF mechanism have been thoroughly investigated with several advanced spectroscopies. We found that a stronger push–pull character favors SF, as long as the ICT does not act as a trap by opening a competitive pathway. Within the context of other widely-known SF chromophores, the unconventional property of generating high-energy triplet excitons (ca. 2 eV) via SF makes these materials outstanding candidates as photosensitizers for photovoltaic devices.

Unveiling the Effect of Solvent Polarity on the Excited State Intramolecular Proton Transfer and Hydrogen Bond Mechanisms of Dhp

Unveiling the Effect of Solvent Polarity on the Excited State Intramolecular Proton Transfer and Hydrogen Bond Mechanisms of Dhp

Unveiling the Effect of Solvent Polarity on the Excited State Intramolecular Proton Transfer and Hydrogen Bond Mechanisms of Dhp

Unveiling the Effect of Solvent Polarity on the Excited State Intramolecular Proton Transfer and Hydrogen Bond Mechanisms of Dhp

The Role of the Various Solvent Polarities on Piperine Reactivity and Stability

Piperine is a natural cytotoxic agent aware of various therapeutic acts. The aim of this study is to look into the effects of solvent polarity on solvent-free energy, dipole moment, polarizability, and hyper-polarizability of the first order, as well as various molecular properties including chemical hardness and softness, chemical potential, electronegativity, and electrophilicity index, in order to gain a better understanding of its reactivity and stability. The Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theory with the cc-pVDZ basis set was used to perform all forms of calculations in both the gas phase and in solution. The Solvation Model on Density (SMD) was used to measure the solvation-free energy, dipole moment, and molecular properties of five solvent systems: water, DMSO, ethanol, cyclohexane, and heptane. As the dielectric constant was reduced, the solving energies gradually decreased, i.e. free energy decreased with declining solvent polarity. Piperine's dipole moment has been found to increase when transitioning from non-polar to polar solvents. The dipole moment of piperine was greater than that of the gas phase in various solvents. PPN's dipole moment and first order hyper-polarizability gradually increased as the solvent polarity increased, while its polarizability decreased. In addition, the hardness, chemical potential and electrophilicity index were decreased from non-polar to polar solvent, but with the rise in solvent polarity for the PPN molecule, softness and electronegativity were increased. The determined free energy solvation, dipole moment, polarizability, hyper-polarizability of the first order, and molecular properties identified in this research may contribute to an understanding of the stability and reactivity of piperine in specific solvent systems.

Indazole versus indole-based cationic merocyanines with red shifted in-cellulo emission for selective mitochondria imaging

Selective fluorophores are seminal for the development of fluorescent cell imaging allowing the simultaneous monitoring of several biological parameters. Mitochondria are one of the main targets of optical microscopy as their dynamics are related to many biological events. One of the best strategy to target them, is to design cationic dyes which accumulate preferentially in their membranes due to their high electrochemical potential. In this work, indazole scaffold was explored to build new cationic merocyanine dyes and compared with indole scaffold. This nitrogen heteroaromatic structure is still very uncommon in dyes chemistry; therefore, a lot has to be discovered about the effects of pH, solvent polarity and methylation in cyclic nitrogen on their optical properties. Finally, fluorescent imaging revealed that a red shift occurred in the emission of these molecules inside the mitochondria.

Estimation of Dipole Moments of New Coumarin Dye by Experimental and Theoretical Methods

AbstractThe absorption and fluorescence emission spectra of coumarin dye, 4‐((4‐methoxyphenoxy) methyl)‐6‐methoxy‐2H‐chromen‐2‐one (4‐MPMMC) in different polarity solvents are recorded. The effects of solvent polarity on the spectral properties are discussed. It is found that, spectrum peak shifts toward higher wavelength, as the solvent polarity changes. The ground (µg) and excited state (µe) dipole moments are estimated using Lippert's, Bakshiev's, and Kawski‐Chamma‐Viallet's equations. The µe values are found to be higher than µg values for all solvents. This suggests that the dye is more polar in excited state than in ground state. Computational studies are done using Time Dependent Density Functional Theory (TD‐DFT), DFT, and Zindo methods with the help of Gaussian16W; Integral Equation Formalism Polarizable Continuum Model (IEFPCM). Further, the excited state dipole moments are estimated in different solvents and are compared with the experimental results. The reactive centers like electrophilic and nucleophilic sites are identified along with contour action using electrostatic potential (ESP) 3D map using DFT analysis.

DFT-based theoretical simulation on electronic transition for graphene oxides in solvent media

Electron absorption spectra of graphene oxide (GO) nanosheets in solvents could provide a unique measure of the GO-solvent interaction, which is also important to the GOs-based optoelectronic and photocatalytic applications. In this work, the effects of solvent polarity and solvent-GO hydrogen bonding (HB) interaction on the electron absorption for GO nanosheets in liquid-phase solvents have been investigated by density functional theory. At first, we adopted various types of implicit solvent modes to study the polarity influence on the GO absorption spectra, including non-polar and polar solvents. Then, two representative explicit solvent molecules (NMP and water) have been considered to study the effect of HB interaction on the electronic excitation of GOs. The natural transition orbital (NTO) analysis elucidates that the hole-electron pair transition mechanism for GO electronic excitation is mainly featured by the charge transfer over GO surfaces. The solvatochromic effects were further elucidated by the correlation of the typical excitation energies with the solvent-induced GO dipole and the HB strength. The simulation results provide a new understanding of the influence of solvents on the electronic excitation of nanoscale GOs.

Influence of solute-solvent interactions at the crystal-solution interface on the growth and morphology of the nonlinear optical single crystal methyl-p-hydroxybenzoate (p-MHB)

• Solute-solvent interactions at different crystal faces of p -MHB were investigated. • Effect of solvent polarity on growth and morphology p -MHB crystal was revealed. • Solubility and nucleation time from solution with different solvents were studied. • Large dimensional optical quality monoclinic p -MHB single crystal was grown. • Morphological importance of different growth faces of p -MHB crystal was revealed. The influence of solute-solvent interactions was realized at the crystal-solution interface on the end crystal morphology of the nonlinear optical monoclinic methyl- p -hydroxybenzoate ( p - MHB) single crystal when growing from solutions with solvents of different in nature. Polar protic solvents such as methanol and ethanol and polar aprotic solvents such as acetone and ethyl acetate afforded p -MHB single crystals having a prismatic morphology and the nonpolar solvent toluene provided a crystal with columnar morphology. Because of the difference in their polar nature, these solvents show a significant difference in the solute solubility, rate of evaporation, level of supersaturation generated within the solution, time consumed for nucleation and growth rate along different crystallographic directions of the growing crystal. Slow evaporation method was employed for the growth of smaller size p -MHB single crystals from solutions with various solvents and a large dimensional p -MHB single crystal of size 45 × 42 × 62 mm 3 was grown through seeded controlled cooling of the solution method. The results indicate that the nature of hydrogen bonding interactions exists between different crystal faces and the corresponding solvent molecules used in the present study caused a significant change in the end habit and morphology of crystals.

The effect of extraction solvent polarity on cytotoxic properties of Sargassum crassifolium against B16-F10 melanoma cancer cell model

.The prevalence of skin cancer continues to increase from year to year. Skin cancer mainly caused bymelanin accumulation on the skin surface (hyperpigmentation) or excessive melanogenesisoccurs. The brown macroalgae S. crassifolium is one of marine natural resources which is abundant in Lombok, Indonesia coastal areas. However, information regarding its potential bioactive activities remains limited. This study aims to evaluate the effective extraction solvent for S. crassifolium for gaining optimum bioactive compounds with promising cytotoxμic activity against melanoma cell line. The three variations of the solvent used are ethanol, n-hexane, and ethyl acetate. Some major compounds that were detected by GC-MS analysis in S. crassifolium were state as follow: n-Hexadecanoic acid (Palmitic acid), Hexadecanoic acid, methyl ester (Methyl palmitate), Oleic Acid, Dodecanoic acid, methyl ester, 9-Octadecenoic acid, methyl ester, Tetradecanoic acid, methyl ester. SEA showed the higher amount of methyl palmitate compared toS. crassifolium extracted with other solvent. Accordingly, to the major chemical constituent, SEA showed highest IC50 against melanoma cell line (61.26 ± 2.13 μg/mL) compared to SET and SNX. SEA also induced apoptosis which characterized by increase in apoptotic nuclei.

Unlocking the power of resonance Raman spectroscopy: The case of amides in aqueous solution

We report a joined experimental and computational study of Raman and Resonance Raman spectra of amides in aqueous solution. By employing state-of-the-art QM/MM methods combined with synchrotron–based UV Resonance Raman spectroscopy, we propose a protocol to interpret and reliably predict Resonance Raman spectra for amide systems in water, which are prototypical system for the peptide bond. We demonstrate that the main experimental spectral features can be correctly reproduced by simultaneously taking into account the dynamical aspects of the solvation phenomenon, specific solute–solvent hydrogen bond interactions and mutual solute–solvent polarization effects.

Impact of Solvent Polarity on the molecular properties of Dimetridazole

Recently molecular activity of dimetridazole (DMZ) gained interested due to medical applications. In this study, a computational investigation of the solvent impact on solvation free energy, dipole moments, polarizability, hyper-polarizability and characteristic atomic properties; hardness and softness quality, chemical potential, electronegativity and electrophilicity have been accounted for DMZ. All forms of the calculation for both gas phase and solution phase used Becke 3-Parameter of Lee-Yang parr (B3LYP) theory with a 631++G basis set. Using the Solvation Model on Density (SMD), the effect of solvent polarity on solvation free energy, dipole moment, polarizability, hyper-polarizability and molecular properties were measured. The dipole moment of the DMZ was lower value in a gas phase comparative with solution phase. Furthermore, the electronegativity and chemical potential were increased from non-polar to polar solvents, while electrophilicity index was decreased. However, in case of chemical hardness & softness, the opposite relationship has been found. The results of this study contribute to an understanding of the molecular activity of DMZ, and stimulate its activity in solution phase. Keywords: Dimetrizole, Solvation model, Dipole moment, Solvent-free energy, Molecule polarizability.

Influence of solvent polarity of ethonal/water binary solvent on the structural, emulsifying, interfacial rheology properties of gliadin nanoparticles

Gliadin nanoparticles (GNPs) is a promising material for stabilizing Pickering emulsions. The present work aimed to investigate the effect of solvent polarity of ethonal/water binary solvent on the structure and emulsifying property of GNPs and provide reference information for the potential application of GNPs in alcoholic food system. The structural, emulsifying and interfacial rheology properties of GNPs in aqueous phases with different polarity (EN(T):1.00–0.94) were evaluated. The solvent polarity was regulated by changing the ethanol concentration in aqueous phase. Results showed that the emulsifying activity of GNPs significantly improved as the EN(T) decreased from 1.00 to 0.96, and then decreased as the EN(T) further decreased from 0.96 to 0.94 for the rising particle size. Meanwhile, the decrease of solvent polarity improved the diffusion rate, viscoelastic modulus (E) and the interparticle interaction of GNPs. The possible mechanism was investigated by discussing the relationship among the structural, emulsifying and interfacial rheology properties of GNPs. It was found that the decrease of solvent polarity triggered the increase of hydrophobic groups distributed on the particle surface, and then resulted in the decrease of zeta potential and the increase of surface hydrophobicity of GNPs, which benefited the diffusion/adsorption of particles and the formation of viscoelastic protein layers for lower electrostatic repulsion, moderate surface wettability and stronger hydrophobic interaction. The results also suggested that GNPs might be a natural and economical material for low-degree alcohol emulsion food.

Tailoring Distinct Reactive Environments in Lewis Acid Zeolites for Liquid Phase Catalysis

ConspectusLewis acidic zeolites are microporous crystalline materials that offer promise as catalysts for the activation and conversion of biomass-derived precursors in the liquid phase due to their unique water tolerance and synthetic versatility. The active site environment in zeolite catalysts is multifaceted in nature and is composed of a primary catalytic binding site, the secondary pore structure that confines such binding sites, and occluded solvent and reactant molecules that interact with adsorbed species. Moreover, Lewis acidic heteroatoms can adopt structurally diverse coordination that selectively catalyze different classes of chemical transformations and can be difficult to control synthetically or characterize spectroscopically. Thus, precise mechanistic interpretation of liquid-phase zeolite catalysis necessitates the development of synthetic, spectroscopic, and kinetic methods that can decouple such complex active site structures and probe the interactions that occur between confined active sites, solvent and reactant molecules, and adsorbed intermediates and transition states.In this Account, we describe the development and application of synthetic, spectroscopic, and kinetic methods to investigate chemically distinct Lewis acid zeolite environments in siliceous zeolites for liquid-phase catalysis. Identification of unique Lewis acidic active site structures relied on the development of direct and indirect solid-state nuclear magnetic resonance (NMR) methods that probe the number and connectivity of framework Lewis acid sites for a diverse range of metal heteroatoms. Such methods enabled the quantitative comparison of catalytic turnover rates, on a per active site basis, measured on different catalysts in order to establish structure–function relationships between active site structure and reactivity. Rigorous normalization of turnover rate further permits comparison of catalytic turnover rates across materials of varying topology, metal heteroatom identity, solvent, and framework polarity to extract salient thermodynamic descriptors of catalysis through kinetic probes. Ex situ interrogation of alcohols adsorbed within hydrophobic and hydrophilic Sn-containing zeolites revealed that hydrophobic voids induce structural order on confined alcohol hydrogen-bonding networks, which give rise to enhanced turnover rates of liquid-phase transfer hydrogenation catalysis. This acceleration of turnover rates arises because ordered alcohol networks occluded within the pores of hydrophobic zeolites stabilize adsorbed transfer hydrogenation intermediates and transition states to a greater extent than liquidlike solvent networks observed in hydrophilic zeolites. The effects of confined solvent molecules can also influence catalysis, independent of framework polarity, due to differences in solvent polarity and substituent effects, which alter turnover rates via changes in how different solvent molecules interact with adsorbed intermediates and transition states. These observations underscore new opportunities to leverage specific interactions between active sites and solvent molecules to influence solvent organization and transition state stability at confined solid–liquid interfaces.This work illustrates the importance of quantitative methods that count distinct active site structures in order to compare catalytic materials on a per active site basis. This information can be used to develop new synthetic procedures that predictably manipulate the functionalization of both the primary binding site and the secondary reaction environment to tailor catalytic function for a desired chemistry. Collectively, these advances highlight strategies to engineer and characterize microporous catalysts with unique reaction environments in order to capture salient mechanistic features and navigate the complex free energy landscape of catalysis in condensed solvent systems.

Tactfully unveiling the effect of solvent polarity on the ESIPT mechanism and photophysical property of the 3-hydroxylflavone derivative

In this contribution, the solvent effects on the excited-state intramolecular proton transfer (ESIPT) and photophysical properties of 2-(4-(diphenylamine)phenyl)-3-hydroxy-4H-chromen-4-one (3HF-OH, Dyes Pigm. 2021, 184, 108865) in the dimethylsulfoxide (DMSO), acetonitrile (ACN), dichloromethane (DCM) and cyclohexane (CYH) phases have been comprehensively explored by using the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The obtained bond lengths, bond angles and infrared (IR) vibration analysis related to the intramolecular hydrogen bond (IHB) reveal that the IHB intensity of 3HF-OH is weakened as the solvent polarity increased. Besides, the ESIPT process changes from the endothermic to the exothermic with the enlargement of solvent polarity, and the reaction barrier increases gradually. It is worth noting that the molecular configuration torsion of 3HF-OH is gradually intensified with the decline of solvent polarity, which aggravates the twisted intramolecular charge transfer (TICT) state and thereby partially attenuates the short-wavelength fluorescence of 3HF-OH in the CYH solvent. In addition to these, the structural torsion has restrained the occurrence of the ESIPT behavior by means of elevating the energy barrier. This theoretical research would provide valuable guidance for regulating and controlling the photophysical behavior of compounds via the strategy of changing solvent polarity.

Solvent effect on the Molecular structure and Global, Local and Dual Descriptors: A Density Functional Theory Study

This study aims to explore the effects of solvent polarity on the geometry, energy of solvation, dipole moment, polarizability, charge distribution, frontier molecular orbital analysis, and global, local, and dual descriptors for β Carboline. The effects of eight solvents were treated using a conductor-like polarized continuum model. Density Functional Theory calculations were performed at B3LYP level at 6-311++g (d,p) basis set. The computed results showed that the dipole moment, polarizability, the solvation free energy, and atomic charge of β Carboline increased with the increasing polarity of the solvent. Also, the solvation modified the values of the reactivity descriptors as a result of the interaction between the solvent and β Carboline. The dual descriptor provided a clearer difference between electrophilic and nucleophilic attack at specific atomic site than presented by Fukui functions of β Carboline.

Chain-Length-Dependent Photophysical Properties of α,ω-Di(4-pyridyl)polyenes: Effects of Solvent Polarity, Hydrogen Bond Formation, Protonation, and N-Alkylation.

In this study, we investigated the solvent effects on the photophysical properties of α,ω-di(4-pyridyl)polyenes 1-5 having 1-5 double bonds. The solution photoproperties depend strongly on conjugation chain length. The absorption maximum (λa) of dipyridylethylene 1 is observed at around 290 nm and only slightly redshifts as the solvent polarity increases, whereas its fluorescence maximum (λf) redshifts from 368 nm in hexane to 403 nm in acetonitrile. Although 1 is a centrosymmetric molecule, its fluorescence energy linearly correlates with the Onsager solvent polarity function f(ε) - f(n2) = (ε - 1)/(2ε + 1)-(n2 - 1)/(2n2 + 1), indicating that the emission originates from an intramolecular charge transfer (CT) excited state. Exceptionally, λf in methanol is largely blue-shifted to 341 nm from those in other aprotic solvents. The fluorescence solvatochromism of longer polyenes 2-5 is much less significant than that of 1. Upon protonation and N-alkylation, both the absorption and fluorescence spectra of all five compounds are red-shifted in methanol. The largest shifts in λa and λf on protonation are observed for pentaene 5 (73 nm) and diene 2 (57 nm), respectively.

Unravelling the ambiguity of the emission pattern of donor–acceptor salicylaldimines

Four donor–acceptor salicylaldimines with benzoheterocyclic substituents at nitrogen imine were prepared and characterised by means of optical spectroscopy. Their luminescent properties were compared with two isoelectronic carbocyclic analogues. In contrast to the typical salicylaldimines, our reported benzoheterocyclic compounds exhibit solely local emissive behaviour in all media whereas for the carbocyclic analogues we expectedly observe dominant ESIPT emission in the majority of instances. Low temperature (5 K - liquid helium) fluorescence measurements revealed the effect of the restriction of the molecular rotation which was manifested by significant increment of the fluorescence intensity. The comprehensive experimental and ab initio study reveal effect of solvent polarity, viscosity and temperature on the complex photophysics of heterocyclic and carbocyclic substituted salicylaldimines with several degrees of freedom for molecular transformations. This work adds considerable insight in emission lifetime data which greatly facilitates understanding of the fluorescence mechanism of the molecules with environmentally dependent restrictions.

Effect of solvent polarity on the formation of flexible zein nanoparticles and their environmental adaptability

Zein possesses strong self-assembly ability due to its amphiphilicity. To investigate the effect of solvent polarity on both the flexibility of zein and the formation of flexible zein nanoparticles, various ethanol aqueous solutions were chosen. Alkaline modification was applied to improve the flexibility of the zein and a liquid-liquid method was used to produce zein nanoparticles. Solvent polarity plays a positive role in improving the flexibility of zein. Furthermore, native and flexible zein nanoparticles were formed from native zein and flexible zein, respectively. However, nanoparticles could not form from highly flexible zein due to their strong adaptability to changes in solvent. Compared with the emulsifying activity index (EAI) and emulsifying stability index (ESI) of native zein nanoparticles, a higher EAI and ESI of flexible zein nanoparticles were acquired. These results may be attributed to the strong adaptability of flexible zein to the medium changing through changing their secondary structure. Furthermore, the adaptability of flexible zein nanoparticles significantly depended on the initial polarity of the solvent. The deamidation reaction of zein was responsible for the change in zein flexibility. These findings thus provide clear evidence of the relationship between the solvent polarity and structural flexibility of modified zein.

Solvent polarity dependent ESIPT behavior for the novel flavonoid-based solvatofluorochromic chemosensors

In this work, we explore the excited-state intramolecular proton transfer (ESIPT) mechanisms and relative solvent effects for three novel 3-hydroxylflavone derivatives (i.e., HOF, SHOF, and NSHOF) in acetonitrile, dichloromethane, and toluene solvents. Through calculations, we optimize the structures of HOF, SHOF, and NSHOF. Through the analysis of a series of structural parameters related to hydrogen bonding interactions, it could be found that the hydrogen bonds of the three derivatives are all enhanced in the S1 state, and more importantly, the excited-state hydrogen bonds of HOF are stronger than those of SHOF and NSHOF. In order to explore the effects of solvent polarity, we analyze the core-valence bifurcation (CVB) index, infrared (IR) vibration spectrum, and the potential energy curves. We find that for HOF, SHOF, and NSHOF, the strength of the excited-state hydrogen bonds increases as the solvent polarity decreases. The solvent polarity dependent ESIPT mechanisms pave the way for further designing novel flavonoid-based solvatofluorochromic probes in future.

Spectroscopic investigation, DFT and TD-DFT calculations of 7-(Diethylamino) Coumarin (C466)

The UV-Vis electronic absorption and excited-emission spectra of the 7-(Diethylamino) Coumarin were monitored experimentally in different solvents. The effect of solvent polarity on fluorescence quantum yield for C466 molecular structure is studied. Also, the critical micelle concentration (cmc) value calculated from the plot of the fluorescence intensity varies the concentrations of the cetrimonium bromide (CTAB) and sodium dodecyl sulfate (SDS). In addition to, the photostability of the studied molecular structure in different solvents such as acetone, methylisobutylketone and amyl alcohol in terms of half-life method (utilizing nitrogen laser 337.1 nm in pumping), as the number of pulses necessary to reduce the studied molecule intensity to 50% of its original value.The C466 molecular structurewas optimized using B3LYP/6-31G(d) level of theory. The computational electronic UV-Visabsorption spectra of the C466 compound, in gas and various solvents, were calculated using time dependent density functional theory (TDDFT) at B3LYP/ 6-311G++(2d, 2p) level. The obtained theoretical results were compared to experimental ones. The results show that, the computational optical properties of the studied molecular structureis in agreement with experimental results.