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Photoinduced Proton Transfer Processes Within Heterocyclic Structures

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 8522

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Special Issue Editors

Dr. Julien Massue

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Guest Editor

Institut de Chimie et Procédés pour l’Energie, l’Environnement et la Santé (ICPEES), Groupe Chimie Organique pour les Matériaux, la Biologie et l'Optique (COMBO, UMR CNRS 7515, Ecole Européenne de Chimie, Polymères et Matériaux (ECPM), 25 Rue Becquerel, CEDEX 02, 67087 Strasbourg, France
Interests: heterocyclic chemistry; molecular materials; molecular fluorescence; proton transfer processes (ESIPT); fluorescence sensing

Dr. Gilles Ulrich

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Guest Editor

Institut de Chimie et Procédés pour l’Energie, l’Environnement et la Santé (ICPEES), Groupe Chimie Organique pour les Matériaux, la Biologie et l'Optique (COMBO, UMR CNRS 7515, Ecole Européenne de Chimie, Polymères et Matériaux (ECPM), 25 Rue Becquerel, CEDEX 02, 67087 Strasbourg, France
Interests: organic dyes; boron chemistry; molecular fluorescence; proton transfer processes (ESIPT); optoelectronic devices; bioinspired and biosourced fluorophores

Special Issue Information

Dear Colleagues,

Photoinduced proton transfer processes are very important in nature and have been observed in many heterocyclic systems, such as in green fluorescent protein (GFP), isolated from the jellyfish Aequorea Victoria. Over the years, a wide range of synthetic fluorophores have built upon this important elementary process to provide an important database of heterocyclic dyes displaying single, dual, or multiple photoinduced proton-transfer reactions, including excited-state proton transfer (ESPT), excited-state intramolecular proton transfer (ESIPT), and proton-coupled electron transfer (PCET). Intense research has been devoted to the understanding and dynamics of these processes for fundamental knowledge but also to engineer innovative applications in the fields of sensing, data storage, security, and optoelectronics. Probes featuring proton(s) dynamics including tautomerism are now a major topic in a growing number of areas. This Special Issue targets scientific contributions (original research or reviews) at the crossroads of synthetic, analytical, physical, and theoretical chemistry.

Dr. Julien Massue
Dr. Gilles Ulrich
Guest Editors

Manuscript Submission Information

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Keywords

Heterocyclic chemistry
Dyes/Pigments
Ultrafast hydrogen bonding dynamics
Excited-state proton transfer (ESPT)
Excited-state intramolecular proton transfer (ESIPT)
Proton-coupled electron transfer (PCET)
Molecular fluorescence
Ultrafast spectroscopy
Proton tautomerism
Ab initio calculations

Published Papers (3 papers)

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Research

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16 pages, 4866 KiB

Open AccessArticle

Excited State Proton Transfers in Hybrid Compound Based on Indoline Spiropyran of the Coumarin Type and Azomethinocoumarin in the Presence of Metal Ions

by Natalia L. Zaichenko, Tatyana M. Valova, Olga V. Venidiktova, Alexander V. Lyubimov, Andrey I. Shienok, Liubov S. Koltsova, Anton O. Ayt, Galina V. Lyubimova, Leonid D. Popov and Valery A. Barachevsky

Molecules 2021, 26(22), 6894; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26226894 - 16 Nov 2021

Cited by 3 | Viewed by 1664

Abstract

Spectral-luminescence properties of a hybrid compound containing a coumarin-type spiropyran and an azomethinocoumarin fragment in toluene-acetonitrile solution in the presence of Li⁺, Ca²⁺, Zn²⁺ and Mg²⁺ ions are reported. Two excited state proton transfers can occur in the hybrid compound—the transfer of a proton from the OH group of the 7-hydroxy coumarin tautomer to the N atom of the C=N bond of the azomethine fragment leading to green ESIPT fluorescence with a maximum at 540 nm and from the OH group of the 7-hydroxy coumarin tautomer to the carbonyl group of the pyrone chromophore, which leads to the formation of the 2-hydroxyl-tautomer T of coumarin with blue fluorescence with a maximum at 475 nm. Dependence of these excited state proton transfers on the metal nature and irradiation with an external UV source is discussed. Full article

(This article belongs to the Special Issue Photoinduced Proton Transfer Processes Within Heterocyclic Structures)

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15 pages, 3478 KiB

Open AccessArticle

Interaction Study between ESIPT Fluorescent Lipophile-Based Benzazoles and BSA

by Thais Kroetz, Pablo Andrei Nogara, Fabiano da Silveira Santos, Lilian Camargo da Luz, Viktor Saraiva Câmara, João Batista Teixeira da Rocha, Alexandre Gonçalves Dal-Bó and Fabiano Severo Rodembusch

Molecules 2021, 26(21), 6728; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26216728 - 06 Nov 2021

Cited by 1 | Viewed by 2124

Abstract

In this study, the interactions of ESIPT fluorescent lipophile-based benzazoles with bovine serum albumin (BSA) were studied and their binding affinity was evaluated. In phosphate-buffered saline (PBS) solution these compounds produce absorption maxima in the UV region and a main fluorescence emission with a large Stokes shift in the blue–green regions due to a proton transfer process in the excited state. The interactions of the benzazoles with BSA were studied using UV-Vis absorption and steady-state fluorescence spectroscopy. The observed spectral quenching of BSA indicates that these compounds could bind to BSA through a strong binding affinity afforded by a static quenching mechanism (K_q~10¹² L·mol⁻¹·s⁻¹). The docking simulations indicate that compounds 13 and 16 bind closely to Trp134 in domain I, adopting similar binding poses and interactions. On the other hand, compounds 12, 14, 15, and 17 were bound between domains I and III and did not directly interact with Trp134. Full article

(This article belongs to the Special Issue Photoinduced Proton Transfer Processes Within Heterocyclic Structures)

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Review

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17 pages, 2836 KiB

Open AccessEditor’s ChoiceReview

Excited-State Intramolecular Proton Transfer Dyes with Dual-State Emission Properties: Concept, Examples and Applications

by Timothée Stoerkler, Thibault Pariat, Adèle D. Laurent, Denis Jacquemin, Gilles Ulrich and Julien Massue

Molecules 2022, 27(8), 2443; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27082443 - 10 Apr 2022

Cited by 51 | Viewed by 4128

Abstract

Dual-state emissive (DSE) fluorophores are organic dyes displaying fluorescence emission both in dilute and concentrated solution and in the solid-state, as amorphous, single crystal, polycrystalline samples or thin films. This comes in contrast to the vast majority of organic fluorescent dyes which typically show intense fluorescence in solution but are quenched in concentrated media and in the solid-state owing to π-stacking interactions; a well-known phenomenon called aggregation-caused quenching (ACQ). On the contrary, molecular rotors with a significant number of free rotations have been engineered to show quenched emission in solution but strong fluorescence in the aggregated-state thanks to restriction of the intramolecular motions. This is the concept of aggregation-induced emission (AIE). DSE fluorophores have been far less explored despite the fact that they are at the crossroad of ACQ and AIE phenomena and allow targeting applications both in solution (bio-conjugation, sensing, imaging) and solid-state (organic electronics, data encryption, lasing, luminescent displays). Excited-State Intramolecular Proton Transfer (ESIPT) fluorescence is particularly suitable to engineer DSE dyes. Indeed, ESIPT fluorescence, which relies on a phototautomerism between normal and tautomeric species, is characterized by a strong emission in the solid-state along with a large Stokes’ shift, an enhanced photostability and a strong sensitivity to the close environment, a feature prone to be used in bio-sensing. A drawback that needs to be overcome is their weak emission intensity in solution, owing to detrimental molecular motions in the excited-state. Several strategies have been proposed in that regard. In the past few years, a growing number of examples of DSE-ESIPT dyes have indeed emerged in the literature, enriching the database of such attractive dyes. This review aims at a brief but concise overview on the exploitation of ESIPT luminescence for the optimization of DSE dyes properties. In that perspective, a synergistic approach between organic synthesis, fluorescence spectroscopy and ab initio calculations has proven to be an efficient tool for the construction and optimization of DSE-ESIPT fluorophores. Full article

(This article belongs to the Special Issue Photoinduced Proton Transfer Processes Within Heterocyclic Structures)

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