Toward a Generalized Treatment of the Solvent Effect Based on Four Empirical Scales: Dipolarity (SdP, a New Scale), Polarizability (SP), Acidity (SA), and Basicity (SB) of the Medium

Abstract

This paper reports a methodology for analyzing the solvent effect from empirical measurements of solvent acidity (SA), basicity (SB), dipolarity (SdP), and polarizability (SP). The proposed methodology departs from the traditional single-parameter procedures for estimating nonspecific solvent effects by splitting them into a polarizability term and a dipolarity term. In this work, we examined the SA, SB, SP, and SdP values for 160 solvents, the gas phase (the absence of solvent) being the origin of these scales. As shown in this paper, this information allows one not only to accurately describe the solvent effect experienced by any solute whether polar or nonpolar and exhibiting some or no specific interaction with the solvent but also to understand the nature of the well-known solvent parameters E(T)(30), pi, S', and SPP, which are frequently used to describe the overall nonspecific contribution of solvents in terms of a single parameter. The high potential of the proposed empirical methodology is illustrated with its application to the solvatochromic analysis of the spectroscopic behavior of molecular chromophores, thus explaining, for example, the influence of solvent effects in the twist intramolecular charge transfer (TICT), the excited-state intramolecular proton transfer (ESIPT), or LASER (light amplification by stimulated emission of radiation) emissions. Also, this methodology is applied to understanding for the indole chromophore the feasible inversion of the electronic nature for the first electronic excited state due to solvent effects.

UV—vis spectroscopy of the coupling products of the palladium-catalyzed C—H arylation of the BODIPY core

“…The detailed analysis of the solvent effect using a set of four empirical, complementary, mutually independent solvent scales -proposed by Catalán 24 -can be found in the ESI. † In this method, the polarizability and dipolarity of a particular solvent are characterized by the parameters SP and SdP, respectively, whereas solvent acidity and basicity are described by the scales SA and SB, respectively.…”

“…For compound 5 we studied in detail the solvent effect on the position of the spectral maxima ν abs = 1/λ abs (max) and ν em = 1/λ em (max), employing the generalized treatment of the solvent effect based on a set of four empirical, mutually independent, complementary solvent scales (dipolarity, polarizability, acidity and basicity of the medium). 24 Chart 1 Structure of the BODIPY derivatives studied.…”

Effect of the substitution position (2, 3 or 8) on the spectroscopic and photophysical properties of BODIPY dyes with a phenyl, styryl or phenylethynyl group

“…We investigate the solvent effect on the spectroscopic properties of the dyes, according to a generalized procedure based on a set of four empirical solvent scales: dipolarity, polarizability, acidity and basicity of the medium. 36 Time-dependent density functional theory (TD-DFT) calculations provide insights into the structural and energetic properties concerning the spectroscopic parameters of the dyes investigated. …”

Photoswitchable fluorescent diheteroarylethenes: substituent effects on photochromic and solvatochromic properties

“…To elucidate the nature of the solvent effects, the Catalán formalism was used. 48 This relation divides the global solvent effects into four parameters: two general effects -solvent polarizability (SP) and dipolarity (SdP) -and two specific interactions -solvent acidity (SA) and basicity (SB). A linear regression is performed according to eqn (1), in which y is the spectroscopic observable of interest, SP, SdP, SA, and SB solvent-tabulated reference values, and a-d the corresponding weighing coefficients.…”