Spectrochemical Investigations of Preferential Solvation. 2. Compatibility of Thermodynamic Models versus Spectrofluorometric Probe Methods for Tautomeric Solutes Dissolved in Binary Mixtures

Abstract

Two previously developed spectrofluorometric probe methods are critically examined regarding their ability to model preferential solvation around probe molecules dissolved in binary solvents. The first method assumes that each fluorophore is solvated by only one type of solvent molecule and that the observed spectral wavelength shift results from additivity of emission spectrum for the two solvational fluorophore species. The second method treats the solvational sphere as a binary solvent microphase, with the fluorophore's energy in both the ground and excited states mathematically expressed in terms of the "nearly ideal binary solvent" (NIBS) model.Expressions derived from each model are illustrated using observed fluorescence emission behavior of 9,9'-bianthracene and 9,9'-bianthracene-lO-carboxaldehyde dissolved in binary toluene + acetonitrile and dibutyl ether + acetonitrile mixtures, which were measured as part of the present study. Also discussed is the compatibility of the inherent assumptions upon which the various spectrofluorometric probe methods are based, versus the thermodynamic principles that govern the conformational equilibria responsible for the observed solvatochromic behavior.

Polarity Behaviour and Specific Interactions of Imidazolium-Based Ionic Liquids in Ethylene Glycol

“…The variation of I 1 /I 3 in the studied binary mixtures as a function of increasing IL concentration is shown in Figure 1 OSO 3 ] mixture showed a significant hypo-polarity in the mole fraction region of 0.12 < x 1 < 0.70, wherein the dipolarity of pyrene's surroundings was less than that of the individual components of the Deviations in dipolarity from ideality DðI 1 =I 3 Þ assessed by the pyrene probe in EG-IL mixtures were calculated using the linear relation of the solvent mole fraction developed by Acree et al [27] [Eq. (1)]:…”

Single X-ray crystal and spectroscopic investigation of novel biologically active donor–acceptor chalcones as specific application for opto-electronics and photonics

“…where ν st is the Stokes-shift [25], which increases with increasing the solvent polarity pointing to stronger stabilization of the excited state in polar solvents, h denotes Planck's constant, c refers to the speed of light in vacuum and a is the Onsager cavity radius. Parameters D and n, in equation (2), correspond to the dielectric constant and refractive index of the solvent, respectively.…”

One-Pot Synthesis, Spectroscopic and Physicochemical Studies of Quinoline Based Blue Emitting Donor—Acceptor Chromophores with Their Biological Application

“…where Δν st is the Stokes-shift [29], which increases with increasing the solvent polarity pointing to stronger stabilization of the excited state in polar solvents, h denotes Planck's constant, c refers to the speed of light in vacuum and a is the Onsager cavity radius. Parameters D and n, in Eq.…”