Excited state intramolecular proton transfer (ESIPT): from principal photophysics to the development of new chromophores and applications in fluorescent molecular probes and luminescent materials

Abstract

In this perspective we introduce the basic photophysics of the excited-state intramolecular proton transfer (ESIPT) chromophores, then the state-of-the-art development of the ESIPT chromophores and their applications in chemosensors, biological imaging and white-light emitting materials are summarized. Most of the applications of the ESIPT chromophores are based on the photophysics properties, such as design of fluorescent chemosensors by perturbation of the ESIPT process upon interaction with the analytes, their use as biological fluorescent tags to study DNA-protein interaction by probing the variation of the hydration, or design of white-light emitting materials by employing the large Stokes shift of the ESIPT chromophores (to inhibit the Föster energy transfer of the components). The photophysical mechanism of these applications is discussed. Furthermore, a new research topic concerning the ESIPT chromophores is proposed based on our group's results, that is, to develop organic triplet sensitizers with ESIPT chromophores.

Badania spektroskopowe efektów podwójnej fluorescencji w wybranym związku z grupy 1,3,4-tiadiazoli w rozpuszczalnikach organicznych oraz roztworach wodnych

“…Comparison with other compounds which demonstrate dual fluorescence leads to the conclusion that this phenomenon in FABT is not related to TICT, PICT or ESPIT and cannot be fully explained based on these theories [25][26][27][28][29][30][31][32][33][34]. The results obtained suggest that the dual fluorescence effect in FABT and similar thiadiazole derivatives is more likely resultant of both chromophore aggregation and molecular conformation.…”

“…Importantly, the acceptor and donor fragments of the electron have to be located in close proximity to molecules exhibiting CT (or TICT). An excited-state intramolecular proton transfer (ESIPT) is another process that allows the explanation of dual fluorescence effects [31][32][33]. This model requires a close proximity between the potential proton acceptor and the proton donor group [34].…”

A Water‐Soluble ESIPT Fluorescent Probe with High Quantum Yield and Red Emission for Ratiometric Detection of Inorganic and Organic Palladium

“…Among the reports probe based on ESIPT(excited-state intramolecular proton transfer), 2-(2-hydroxyphenyl) benzothiazole (HBT) and 2-(2-hydroxyphenyl) benzoxazole (HBO) 16 , and promote us to tune the emission to longer wavelength while retaining the ESIPT process optimal in aqueous solution.…”

Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution

“…23 Numerous applications can be found in chemistry, biology and biochemistry based on these ESIPT features. [24][25][26][27][28][29][30] The ESIPT process is characterized by a dual fluorescence emission tailored by the solvent polarity, 31 with the emission from the tautomeric form (T*) showing a large Stokes' shift (even in the solid state) compared to normal forms (N*). 32 This particular aspect of photophysics can present potential applications in the optical sensor field, as it drastically reduces the inner filter effect, improving the fluorescence analysis.…”

“…32 This particular aspect of photophysics can present potential applications in the optical sensor field, as it drastically reduces the inner filter effect, improving the fluorescence analysis. 25 ESIPT compounds can be classified as photoacids, as after absorption (usually in the UV region), a donor group (generally OH or NH 2 from a phenol or aniline group, respectively) is significantly more acid. In addition, an acceptor group present in these compounds (generally imino/azonitrogen-or carbonyl-oxygen-moieties) is also more basic, and enhances proton transfer.…”