Progress in Tuning Emission of the Excited-State Intramolecular Proton Transfer (ESIPT)-Based Fluorescent Probes

Abstract

In this review, we will summarize our recent progress in the design and application of novel organic sensors with emission in the near-infrared region (600–900 nm). By coupling different functional groups with excited-state intramolecular proton transfer (ESIPT) segments, new probes are developed to achieve a large Stokes shift, high sensitivity, and selectivity and to tune the emission toward the near-infrared region. The developed probes exhibit attractive optical properties for bioimaging and environmental science applications. In addition, we further discuss the photophysical properties of ESIPT dyes and how their fluorescence could be affected by structural/environmental factors, which should be considered during the development of robust ESIPT-based fluorescence probes. Their potential applications as imaging reagents are illustrated for intracellular membranes, mitochondria, lysosomes, and some biomolecules.

Recent Progress of Small‐Molecule Ratiometric Fluorescent Probes for Peroxynitrite in Biological Systems

“…endpoint due to excited-state intramolecular proton transfer (ESIPT). [44] With the increase in ONOO À concentration, the emission intensity of 1 at 405 nm decreased sharply, while the emission intensity at 483 nm increased gradually. The fluorescence emission intensity ratio (F 483 /F 405 ) of probe 1 (5 μM) increased approximately 35-fold after the addition of 14 μM ONOO À .…”

Acylhydrazone Subunits as a Proton Cargo Delivery System in 7‐Hydroxyquinoline

“…The developed, up to now, rotary switches, whether hydrazones [12,13] or enamines, [18–20] exist as a mixture of E and Z isomers in their initial state. Fundamental enol/keto ground or excited state short range tautomerism [21] has already being applied in different fields, ranging from photonics [22–26] to biomedicine [27–31] . However, the development of the long‐range proton cargo transport function could unveil new areas of application of smart switching materials and reveals a new horizon for designing cutting‐edge architectures tuned to perform specific functions like controlled cargo transport.…”

Modern Theoretical Approaches to Modeling the Excited-State Intramolecular Proton Transfer: An Overview

“…Among many chemical processes induced with photon absorption, the excited-state intramolecular proton transfer (ESIPT) stands out with its ultrashort timescale and strong impact on the molecular electronic structure, which is often manifested with large emission Stokes shifts. Relying on a proton exchange between two electronegative centers along a pre-existing intramolecular hydrogen bond, the ESIPT process is recognized to provide a mechanism of excellent photostability to natural and artificial molecular systems [ 1 , 2 , 3 ], finds applications in fluorescent probes and imaging agents [ 4 , 5 , 6 ], governs characteristic emission of the green fluorescent protein and its analogs [ 7 , 8 , 9 ], and opens rich possibilities for multicolor emission in organic light-emitting diodes (OLEDs) [ 10 , 11 , 12 , 13 , 14 ]. Last but not least, ESIPT may also activate other excited-state reaction channels, facilitating the design of complex molecular photo-devices [ 15 , 16 , 17 , 18 , 19 ].…”

“…In the following sections, we briefly outline their theoretical assumptions, comment on the scope of their applicability and performance in ESIPT studies, and highlight recent achievements in each field, focusing on the most illustrative results from the last 5 years. For a broader view of ESIPT-focused research, including also experimental insights, the interested reader is referred to other up-to-date reviews [ 4 , 6 , 21 , 27 , 28 ] and monographs [ 29 , 30 , 31 , 32 ] that have been published on the subject.…”