Critical Role of Protons for Emission Quenching of Indoline Dyes in Solution and on Semiconductor Surfaces.

Autor: El-Zohry AM; Department of Chemistry, Ångström Laboratories, Box 523, SE-75120 Uppsala, Sweden.; Department of Physics-AlbaNova Universitetscentrum, Stockholm University, SE-10691 Stockholm, Sweden., Agrawal S; Computational Laboratory for Hybrid/Organic Photovoltaics (CLHYO), Istituto CNR di Scienze e Tecnologie Chimiche 'Giulio Natta' (CNR-SCITEC), via Elce di Sotto 8, 06123 Perugia, Italy., De Angelis F; Department of Chemistry, Biology and Biotechnolgy, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy.; Computational Laboratory for Hybrid/Organic Photovoltaics (CLHYO), Istituto CNR di Scienze e Tecnologie Chimiche 'Giulio Natta' (CNR-SCITEC), via Elce di Sotto 8, 06123 Perugia, Italy.; CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy., Pastore M; Laboratoire de Physique et Chimie Théoriques (LPCT), Université de Lorraine & CNRS, F-54000 Nancy, France., Zietz B; Department of Chemistry, Ångström Laboratories, Box 523, SE-75120 Uppsala, Sweden.
Jazyk: angličtina
Zdroj: The journal of physical chemistry. C, Nanomaterials and interfaces [J Phys Chem C Nanomater Interfaces] 2020 Oct 01; Vol. 124 (39), pp. 21346-21356. Date of Electronic Publication: 2020 Sep 08.
DOI: 10.1021/acs.jpcc.0c07099
Abstrakt: By combining time-correlated single photon counting (TCSPC) measurements, density functional theory (DFT), and time-dependent DFT (TD-DFT) calculations, we herein investigate the role of protons, in solutions and on semiconductor surfaces, for the emission quenching of indoline dyes. We show that the rhodanine acceptor moieties, and in particular the carbonyl oxygens, undergo protonation, leading to nonradiative excited-state deactivation. The presence of the carboxylic acid anchoring group, close to the rhodanine moiety, further facilitates the emission quenching, by establishing stable H-bond complexes with carboxylic acid quenchers, with high association constants, in both ground and excited states. This complexation favors the proton transfer process, at a low quencher concentration, in two ways: bringing close to the rhodanine unit the quencher and assisting the proton release from the acid by a partial-concerted proton donation from the close-by carboxylic group to the deprotonated acid. Esterification of the carboxylic group, indeed, inhibits the ground-state complex formation with carboxylic acids and thus the quenching at a low quencher concentration. However, the rhodanine moiety in the ester form can still be the source of emission quenching through dynamic quenching mechanism with higher concentrations of protic solvents or carboxylic acids. Investigating this quenching process on mesoporous ZrO 2 , for solar cell applications, also reveals the sensitivity of the adsorbed excited rhodanine dyes toward adsorbed protons on surfaces. This has been confirmed by using an organic base to remove surface protons and utilizing cynao-acrylic dye as a reference dye. Our study highlights the impact of selecting such acceptor group in the structural design of organic dyes for solar cell applications and the overlooked role of protons to quench the excited state for such chemical structures.
Competing Interests: The authors declare no competing financial interest.
Databáze: MEDLINE
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