What is Solvatochromism?

Abstract

Solvatochromism is commonly used in many fields of chemical and biological research to study bulk and local polarity in macrosystems (membranes, etc.), or even the conformation and binding of proteins. Despite its wide use, solvatochromism still remains a largely unknown phenomenon due to the extremely complex coupling of many different interactions and dynamical processes which characterize it. In this study we analyze the influence of different solvents on the photophysical properties of selected charge-transfer probes (4-AP, PRODAN, and FR0). The purpose is to achieve a microscopic understanding of the intermolecular effects which govern the absorption and fluorescence properties of solvated molecular probes, such as solvent-induced structural modifications, polarization effects, solubility, solute-solvent hydrogen-bonding interactions, and solute aggregation. To this aim we have exploited a time dependent density functional theory (TDDFT) approach coupled to complementary solvation approaches (continuum, discrete and mixed discrete and continuum). Such an integration has allowed us to clearly disentangle the complex interplay between specific and nonspecific interactions of the solvent with the probes and show that strong H-bonding effects not only can lead to large solvatochromic shifts but also can affect the nature of the emitting species with resulting reduction of the quantum yield.

Polymer Nanoassemblies With solvato- and halo-fluorochromism for Drug Release Monitoring and Metastasis Imaging

“…Fluorescent dyes often change fluorescenceemitting spectra and quantum yields based on solvent polarity (solvato-fluorochromism) and pH (halofluorochromism) [19]. Solvato-and halo-fluorochromic properties are determined by electronic mobility and conformation of fluorophores in the environment where the dyes are present [20,21]. Fluorochromism is generally troublesome for the development of biomarkers that must provide reliable, quantitative imaging results.…”

Optimizing the oxygen evolution reaction for electrochemical water oxidation by tuning solvent properties

“…This acceleration was attributed 47 to the influence of the solvent on optical excitation energies, which in photochemistry goes under the name of solvatochromic effect. 48,49 The solvatochromic effect arises from the difference in the dipole moment of ground and excited electronic states, which produces a differential response to a change in solvent polarity. Indeed, an analogy can be drawn between the ground/excited state pair in solvatochromism and the reactant/transition-state pair in the rate determining step of catalytic processes -in both cases the response of the system to a change in the dielectric properties of the solvent is determined by the differential polarities of the two states.…”

Structure-related differences in the temperature-regulated fluorescence response of LCST type polymers

“…For a positive solvatochromic u-orophore, a decrease in environmental polarity, as is encountered upon heating the polymer above its LCST, is manifested via a hypsochromic (blue) shi in the emission (and absorption) spectrum. 20 Governed by specic dynamic interactions between the uorophore and the solvent molecules upon photoexcitation, and depending on the chemical structure of the uorophore, 21,22 this spectral shi can as well be accompanied by an enhancement of the emission intensity. Consequently, events triggering the phase transition can be detected via the emission output.…”

“…It was further proposed that intermolecular hydrogen-bonding of the carbonyl oxygen and/or the imide nitrogen with solvent molecules in protic solvents results in a drop of the quantum yield 26,29 accompanied by a pronounced red-shi of emission maxima. 21,23,31 Due to this strong environmental sensitivity, besides several reports regarding their use in chemosensors for detection of metal ions, 30,32,33 these uorophores were also exploited as a tool for monitoring protein-protein interactions, 27,34 or as a potential sensor for DNA. [35][36][37] Also, they have recently been used to signal the pH-induced conformational changes of a protein.…”