Effects Of Solute-solvent Interactions Research Articles

Environment polarity effects on the microscopic nonlinear optical properties of some asymmetrical azobenzene molecules

Solvent as a complex environment can surround solute molecules and modify their function. In this work, different solute–solvent interaction effects on the nonlinear optical behavior of some azo dyes were studied at the molecular level. In this case, spectroscopic technique and density functional theory were used. According to the results, molecular dipole transition, changes between ground and excited state dipole moments, substituent, and environment polarity play considerable effects on the molecular nonlinear optical responses. In addition to solvent effects on the molecular first- and second-order hyperpolarizability, the two-photon absorption cross-section is also modified due to solvent-induced interactions. Moreover, the determination of the contribution of dominant solvent effects on the molecular nonlinear optical behavior can facilitate the studies on the application of optical samples in designing various optical systems.

Media and solute–solvent interaction effects on the photo–physical behavior of some drugs of 4H–Pyran derivatives

In this work, spectral properties of four 4H–Pyran derivative compounds, (Pyran (I), Pyran (II), Pyran (III) and Pyran (IV)) which are used as drugs in the treatment of some diseases have been studied in various solvents with different polarities. As expected, the results indicate that photo–physical behavior of solute depends strongly on the nature of the solvent and solute, the solvent–solute interactions, and also different attached groups on their structures. Beside these aspects, delocalization of π electrons within various resonance forms of these molecules also found to be an important factor. The solvatochromic behavior of these drug materials and their solvent–solute interactions, both specific and non–specific types were analyzed by means of linear solvation energy relationships, suggested by Kamlet and Taft. Also, vertical excitations of studied molecules were studied by time dependent density functional theory. The ground and excited state dipole moments of these drug materials and their molecular resonance structures were also evaluated via solvatochromic shift method. Both of the experimental data and quantum chemical calculations confirm higher polarities of excited states of these molecules compared to their ground states. Moreover, calculations of the density functional theory propose a charge transfer from the ends of mentioned molecules toward their –CN terminals throughout the excitation process.

Environment and solute-solvent interaction effects on photo-physical behaviors of Folic acid and Folinic acid drugs

In this paper, spectral properties of Folic acid and Folinic acid as widely used drugs in the treatment of some diseases have been studied in various environments with different polarity. Our results show that the absorption, emission and stokes shifts of solute molecules depend strongly on molecular surrounding characteristics, solute-solvent interactions and, different active groups in their chemical structures. In order to investigate the contribution of specific and nonspecific interactions on various properties of drug samples, the linear solvation energy relationships concept is used. Moreover, the calculated dipole moments by means of solvatochromic method show that the high values of dipole moments in excited state are due to local intramolecular charge transfer. Furthermore, the obtained results about molecular interactions can be extended to biological systems and can indicate completely the behaviors of Folic acid and Folinic acid in polar solvents such as water in body system.

Solute–Solvent Interaction Effects on Protonation and Aggregation Constants of TTMAPP in Different Aqueous Solutions of Methanol

The protonation constants of 5,10,15,20-tetrakis(4-trimethyl-ammonio-phenyl)-porphine tetratosylate (TTMAPP) were determined in water–methanol mixed solvents, using a combination of spectrophotometric and potentiometric methods at 25 °C in 0.1 mol·dm−3 sodium perchlorate. Two protonation constants, K 1 and K 2, were characterized and analyzed in various media in terms of the normalized polarity parameter ( $$ E_{\text{T}}^{\text{N}} $$ ). A linear correlation is observed when the experimental log10 K 1 and log10 K 2 values are plotted versus the calculated ones over the range of 40–90 % (v/v) methanol. The self aggregation of TTMAPP was observed from acidic media (pH ≅ 3) to alkaline pH, where it reached its highest intensity, when methanol is lower than 40 % in solution. The formation of aggregate species prevents a quantitative analysis of titration curves and thus, the determination of the protonation constants of TTMAPP. Therefore, to evaluate the protonation constants of TTMAPP in low or zero percent of methanol, the Yasuda–Shedlovsky extrapolation approach has been used.

Absorption and emission behaviour of trans- p-coumaric acid in aqueous solutions and some organic solvents

The absorption and fluorescence behaviour of trans- p-coumaric acid ( trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form ( p-CAH 2) and the single anionic form ( p-CAH −) at low pH (p K na ≈ 4.9), and between the single anionic and the double anionic form ( p-CA 2−) at high pH (p K aa ≈ 9.35). In the organic solvents studied trans- p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans- p-coumaric acid in aqueous solution is ϕ F ≈ 1.4 × 10 −4 for the neutral and the single anionic form, while it is ϕ F ≈ 1.3 × 10 −3 for the double anionic form. For trans- p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 × 10 −5 (acetonitrile) to 1.5 × 10 −4 (glycerol) were measured. The fluorescence spectra are 7700–10,000 cm −1 Stokes shifted in aqueous solution, and 5400–8200 cm −1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2−, solvent-assisted intra-molecular charge-transfer or ππ ∗ to nπ ∗ transfer and internal conversion for p-CAH 2 and p-CAH −). The solvent dependence of the first ππ ∗ electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute–solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted.

Solute–solvent interaction effects on second‐order rate constants of reaction between 1‐chloro‐2,4‐dinitrobenzene and aniline in alcohol–water mixtures

AbstractThe second‐order rate coefficients for aromatic nucleophilic substitution reaction between 1‐chloro‐2,4‐dinitrobenzene and aniline have been measured in aqueous solutions of ethanol and methanol at 25°C. The plots of rate constants versus mole fraction of water show a maximum in all‐aqueous solutions. The effect of four empirical solvent parameters including hydrogen bond donor acidity (α) dipolarity/polarizability (π*) normalized polarity (ENT) and solvophobicity (Sp) has been investigated. This investigation has been carried out by means of simple and multiple regression models. A dual‐parameter equation of log k2 versus Sp and α was obtained in all‐aqueous solutions (n = 41, r = 0.962, s = 0.053, p = 0.0000). This equation shows that solvophobicity and hydrogen bond donor acidity are important factors in the occurrence of the reaction and they have opposite effects on reaction rate. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 90–97, 2005

Natural J coupling (NJC) analysis of the electron lone pair effect on NMR couplings: 2. The anomeric effects on 1 J (C, H) couplings and its dependence on solvent

The electronic origin of the influence of the anomeric effect (negative hyperconjugative interaction, NHI) on the Fermi contact (FC) term of 1 J(C, H) couplings has been studied from a theoretical point of view at the DFT-B3LYP level. The HN=CH2, molecule was chosen as the primary model compound, in which both FC 1 J(C, H) couplings were decomposed into bond contributions with the natural J coupling dissection approach (NJC). Differences between the 1 J (C, H)FC couplings for C——H bonds in synperiplanar and antiperiplanar orientations with respect to the nitrogen non-bonding electron pair closely follow the experimental trend. They are made up chiefly of three NJC contributions: ‘bond’, ‘direct lone pair’ and the ‘carbon-core orbitals’. The NHI influence on these terms was studied by applying the natural bond orbital (NBO) deletion procedure to the charge transfer interaction into the antiperiplanar (C——H) antibond (n(N)→(C——H)*) prior to the NJC dissection calculation. The dielectric solvation effect on both the total FC terms and the respective NJC contributions was estimated by carrying out the calculations using the polarization continuum model. Inhibition of the anomeric effect is evident when the solvent polarity is increased. NHI saturates rapidly with increasing solvent dielectric. Specific solute-solvent interaction effects on 1 J(C, H) couplings were estimated by evaluating molecular complex models of the form CH2=HN…S (S = H2O and DMSO).

Effect of Solute-Solvent Interaction on the Molecular Association in a Hard Sphere Fluid

Effect of solute-solvent interaction on the solute-solute distribution function is studied for a system in which the solute molecules are dissolved in a hard-sphere fluid at infinite dilution. The solute-solvent interaction is a square-well potential and the solvent molecule in the well is assumed to have a bond with the solute molecule. An ideal-gas approximation reveals that a solute-solvent attractive interaction, as well as a repulsive interaction, can stabilize the solute pair through the fluctuation of the bond number. The Monte Carlo calculations showed that the ideal-gas approximation becomes invalid with increasing density. Solvent-solvent correlation at high densities brings about a complicated fluid structure around a solute pair and reduces the fluctuation of the bond-number.

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S2- and T1-States

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S₂- and T₁-States

Solvent effects on the Si-Cl stretching bands of dimethyldichlorosilane by IR spectroscopy

Abstract The effects of solute-solvent interactions on vibrational spectra (IR) of dimethyldichlorosilane, in a number of solvents have been obtained. The spectral vibrational frequency shifts observed in different solvents have been correlated with refractive indices and dielectric constants of the solvents. The results obtained were applied to Buckingham's modification of the Bauer-Magat formula for solute-solvent interactions. Generally, IR spectral frequencies in solution phase shift to lower wavenumber than those observed in the gas phase. However, solution in chloroform resulted in a shift to higher wavenumber, which is due to specific interactions. The calibration lines between |ΔX/X| vs e - 1 2 e + 1 were made to determine the specific and non-specific solute-solvent interactions. Results obtained from these calibration lines are also discussed in terms of solute-solvent interaction.

Solute-solvent interactions: dissolution of sparingly soluble silver salts in aqueous-organic solvent systems

The solubilities of the salts Ag 2X (where X is sulphate, chromate, tungstate, dichromate, oxalate, malonate, succinate, glutarate or adipate) and Ag 3Y (where Y is phosphate or arsenate) have been determined in various compositions of water+dioxan (5, 10, 15 and 20 wt.%), water+urea (11.52, 20.31, 29.64 and 36.83 wt.%), water+ mannitol (5 wt.%) and water + sorbitol (5 wt%) mixtures at different temperatures. The solubility data have been discussed in the light of electrostatic as well as solute—solvent interaction effects on the dissolution processes of the silver salts. Standard transfer thermodynamic quantities derived from the change in the solubility product are also examined.

The effects of solute-solvent interactions on the electronic visible spectra of bis(?-diketonato)oxovanadium(IV) complexes

The solvatochromic behaviour of bis(β-diketonato)oxovanadium(IV) complexes is quantitatively correlated by an approach that models specific and non-specific solute-solvent interactions. The applicability of the Selbin-Gutmann relation is discussed. The solvent-induced spectral shifts in VO(acac)2 are dominated by specific interactions of the donor-acceptor type, whereas for VO(tfa)2, the nonspecific solute-solvent interactions make the dominant contribution.

Solute—solvent interactions: dissolution of silver benzoate and silver salicylate in water + urea mixtures

Values for the solubility of silver benzoate and silver salicylate in equimolar solutions of sodium perchlorate and perchloric acid in four different compositions of water + urea (11.52, 20.31, 29.64 and 36.83 wt.%) mixtures have been determined at 15, 25, 35 and 45°C. From the solubility values in sodium perchlorate solutions, thermodynamic solubility products of the silver salts have been evaluated, and in perchloric acid solutions the thermodynamic dissociation constants of benzoic and salicyclic acids have been determined in water + urea mixtures. Solubility data have been discussed in the light of electrostatic as well as solute—solvent interaction effects on the dissolution processes of silver salts. Standard transfer thermodynamic quantities derived from the change in the solubility product are also examined. Standard potentials of the silver—silver benzoate and silver—silver salicylate electrodes have also been evaluated in these mixed solvents.

Solute—solvent interactions: dissolution of sparingly soluble silver salts of dibasic and tribasic inorganic and organic acids in water + acetic acid mixtures

Values for the solubilities of salts Ag 2X (where X is sulphate, chromate, tungstate, dichromate, oxalate, malonate, succinate, glutarate, or adipate) and Ag 3Y (where Y is phosphate, arsenate or ferrioxalate) in four different compositions of water + acetic acid (10, 20, 40 and 60 wt.% acid) have been determined at 25°C. Solubility data are discussed in the light of electrostatic and solute—solvent interaction effects on the dissolution processes of the silver salts.

Picosecond solvation of electronically excited solutes in alcoholic solvents: non-debye behaviour of the time-dependent fluorescence shift related to h

Time-dependent fluorescence shifts (TDFS) of polar compounds in a series of alcoholic solvents have been studied on a pico-second time scale. A non-exponential TDFS kinetic behaviour is observed, particularly at short times (0< t< 50 ps). It cannot be represented by a sum of decreasing exponentials. The effects of solute-solvent interactions on the kinetics of TDFS have been analysed. It is shown that the non-standard kinetics is due to hydrogen bonding in the solvent, particularly to the presence of alcoholic hydrogen-bonded aggregates. Following electronic excitation of the polar solute reorganization of solvent aggregates controls the TDFS time development. Our results show that a simple Debye model is inadequate to explain such a process.

Effects of Solute-Solvent Interactions in Liquid Adsorption Chro- Matography with Mixed Mobile Phase

Abstract Two simple equations, involving formation of the multimolecular solvates in the mobile phase, are discussed. These equations define the dependence of the capacity ratio upon mobile phase composition. The LC data, available from the literature, for different alcohols chromatographed in binary mixtures of n-heptane with alkyl acetate and tetrahydrofuran on Partisil 10 at 298 K are used to examine these equations.

Solute–solvent interaction effects on tracer diffusion coefficients

Tracer diffusion coefficients (D) for a variety of dipolar and non-dipolar solutes have been measured at normal atmospheric pressure in solutions of acetonitrile, toluene, n-hexane and water at 298.15 K, and in octamethylcyclotetrasiloxane (OMCTS) at 323.15 K. The diffusion coefficients are linearly correlated with the reciprocals of the equivalent hard-sphere diameters (σ) of the solutes for all the solvents except OMCTS, for which ln D is a linear function of 1/σ.In acetonitrile the dipolar solutes are differentiated from the non-dipolar solutes, whereas in toluene that distinction disappears. In n-hexane the solutes again exhibit two classes of behaviour, but in this case the classes do not correspond to dipolar and non-dipolar solutes. Water as solvent appears to distinguish solutes which can undergo hydrogen-bonding interactions with it from those which cannot. The behaviour of solutes in OMCTS is similar, except that solutes with hydroxylic protons form a separate class from the other solutes.

Effects of solute-solvent interactions on electronic spectra: a predictive analysis

Ultraviolet-visible and fluorescence spectra have long been utilized for qualitative and quantitative purposes despite numerous complicating factors. In this study, anthracene, 1-naphthol, and 9-acetylanthracene are used as model systems to distinguish solventinduced effects via multiple regression techniques. The ability to predict changes in spectral peak locations and quantum efficiencies arising from solute—solvent interactions is critical to the development of a versatile computer-searchable library of electronic spectra.

Charge transfer to a solvent state. 5. Effect of solute-solvent interaction on the ionization potential of the solute. Mechanism for photoionization

Charge transfer to a solvent state. 5. Effect of solute-solvent interaction on the ionization potential of the solute. Mechanism for photoionization

Gas Chromatographic Behavior of Aliphatic Dinitriles on Different Types of Stationary Liquid Phases

Abstract Aliphatic dinitriles were studied on different stationary liquid phases including OV-1, OV-3, OV-25, DEGS, DEGGLU, DEGA, EGTCP, Carbowax 6000, Carbowax 600, and PPG(LB-550-x). The specific retention volumes were calculated and the values were further processed in the form of heat of solutions, ΔH. These values of ΔH indicated the effect of solute-solvent interactions on the gas chromatographic behavior of these compounds and correlated with their molecular structures. Furthermore, the relationship between the viscosity of these compounds and their specific retention volumes was also considered and a general equation was derived.