Microchemical Journal | 2021
Optical properties of solute molecules: Environmental effects, challenges, and their practical implications
Abstract
Abstract This review explores and summarizes the environmental effects of various environments (aqueous, non-aqueous, and mixed liquids) and their practical implications. It focuses on a description of the particular aspects of the solvation processes under different environmental conditions and how they are reflected in the spectral and photophysical properties of the dissolved solute molecules. Many environmental factors (parameters of solvents (acidity, basicity, and polarity), pH, temperature, light power (irradiation), and effects of adding various small molecules (dye, metal ions, and biologically active molecules, etc.)) affects the optical properties of the dissolved solute molecules. Furthermore, the physicochemical properties of dissolved molecules may be modulated after exposure to the numerous stimuli, a combination of these stimuli (conditions), and changes in stimulus parameters. The optical properties of solute molecules show a remarkable dependence on the characteristics of their surrounding medium, which makes them difficult to establish/predict and evaluate. Aabbreviations: αCT, solute-centric solvent HBA-acidity parameter; βCT, solute-centric solvent HBA-basicity parameter; πSC*, solute-centric polarity parameter; βSC, solute-centric basicity parameter; αSC, solute-centric acidity parameter; e - dielectric constant; ν ∼ A,F n , maxima of absorption (A) and fluorescence (F) spectra in neat less polar (nonpolar) and polar solvents; ν ∼ A,F n + p , maxima of absorption (A) and fluorescence (F) spectra in binary mixtures ( ν ∼ A,F n + p ) of solvents; δ s 2 , preferential solvation parameter; π*, solvent polarity; AHM, 2-amino-3-((E)-((2-hydroxynaphthalen-1-yl)methylene)amino) maleonitrile; BBIQ-T, benzo[g]indolo[2,3-b]quinoxaline; DR19, disperse red 19 dye; DPTB, dipyren-1-yl(2,4,6-triisopropylphenyl)borane; DSSCs, dye sensitized solar cells; ET(30), Reichardt’s solvent polarity scale; f, volume fraction of each solvent; f12/1 , preferential solvation parameter measuring the tendency of the probe/solute to be solvated by the solvent complex S12 (Bosch and Roses model); f2/1, preferential solvation parameter measuring the tendency of the probe to be solvated by solvent S2 (Bosch and Roses model); ICT, intermolecular charge transfer; TFA, trifluoroacetic acid; HCl, hydrochloric acid; H3PO4, phosphoric acid; ILs, ionic liquids; % LMPC, local mole of the polar cosolvent; L1, azo-based pyridyl ligand; nPSs, non-polar solvents; Nm, solvation number; NIPAM -N-Isopropylacrylamide; PS, polar solvents; pKa, acidity values; PSs, polar solvents; RTILs, room temperature ionic liquids; SMs, solute molecules; SSnonpolar, Stokes shifts (cm-1) in the pure nonpolar solvents; SSpolar, Stokes shifts (cm-1) in the pure polar solvents; SSmixture, Stokes shifts (cm-1) in binary solvent mixture; WS, aqueous environment; SA, solvent acidity; SB, solvent acidity, basicity, SP, polarizability properties; SdP -dipolarity properties; X2, mole fraction of solvent 2 in the bulk solvent mixture; X 2 L , local mole fraction of solvent 2; Y, physicochemical property.