ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules

The need to explore possible benefits of molecular substituent derivatization on fluorescent chemosensor properties motivated the syntheses of six potentially pentadentate bis-(phenol-imine) fluorophores, which consist of five S-bridged O^N^S^N^O scaffolds 1–5 and an O-bridged O^N^O^N^O scaffold 6....

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Autores principales:	Raymond Akong Akong, Helmar Görls, Joseph Anthony Orighomisan Woods, Winfried Plass, Abiodun Omokehinde Eseola
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	Aluminium(III) sensor ESIPT application Structure-property correlation Fluorescent chemosensor Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/9b283944a01e41eab8464c5e489bee01
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spelling	oai:doaj.org-article:9b283944a01e41eab8464c5e489bee012021-11-18T04:48:21ZESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules2211-715610.1016/j.rechem.2021.100236https://doaj.org/article/9b283944a01e41eab8464c5e489bee012021-01-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S2211715621001417https://doaj.org/toc/2211-7156The need to explore possible benefits of molecular substituent derivatization on fluorescent chemosensor properties motivated the syntheses of six potentially pentadentate bis-(phenol-imine) fluorophores, which consist of five S-bridged O^N^S^N^O scaffolds 1–5 and an O-bridged O^N^O^N^O scaffold 6. The deliberate incorporation of multiple intramolecular N…HO donor–acceptor functions into the molecules helped to achieve Excited State Intramolecular Proton-electron Transfer (ESIPT) capability as well as the possession of low quantum yields in their ligand-only solutions. Interestingly, while the low quantum yield molecules 1, 2, 3 and 6 lacked the expected large Stokes shifted ESIPT fluorescence in their ligand-only solutions, they utilize the same ESIPT-oriented process to achieve varying extents of substituent-dependent fluorescent turn-on that produced sensitive and selective Al3+ detection. In particular, while molecules 1 and 3 gave dual-band fluorescence turn-on from both primary and secondary photoexcited states, the O-bridged ligand 6 is strongly turned on only at the large Stokes shifted ESIPT emission wavelength. Thus, with a 528-fold F/Fo turn-on ratio and a detection limit of 5.48 × 10−9 M, the efficiency of molecule 6 as chemosensor towards Al3+ detection can be considered to be outstanding. Based on results of Job plot experiment, fluorescent intensities during Al3+ titration, single crystal structural data and 1H NMR spectral analyses, we conclude that a 1:1 sensor-to-analyte stoichiometry is at play in the Al3+ sensing mechanism and that the sensor molecules form an unusual bidentate O^O coordination with the analyte as neutral iminium zwitterion. It could be concluded that synthetic designs leading to systematic substituent variation is a beneficial tool for tuning and isolating applicable molecular chemosensor species.Raymond Akong AkongHelmar GörlsJoseph Anthony Orighomisan WoodsWinfried PlassAbiodun Omokehinde EseolaElsevierarticleAluminium(III) sensorESIPT applicationStructure-property correlationFluorescent chemosensorChemistryQD1-999ENResults in Chemistry, Vol 3, Iss , Pp 100236- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Aluminium(III) sensor ESIPT application Structure-property correlation Fluorescent chemosensor Chemistry QD1-999
spellingShingle	Aluminium(III) sensor ESIPT application Structure-property correlation Fluorescent chemosensor Chemistry QD1-999 Raymond Akong Akong Helmar Görls Joseph Anthony Orighomisan Woods Winfried Plass Abiodun Omokehinde Eseola ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
description	The need to explore possible benefits of molecular substituent derivatization on fluorescent chemosensor properties motivated the syntheses of six potentially pentadentate bis-(phenol-imine) fluorophores, which consist of five S-bridged O^N^S^N^O scaffolds 1–5 and an O-bridged O^N^O^N^O scaffold 6. The deliberate incorporation of multiple intramolecular N…HO donor–acceptor functions into the molecules helped to achieve Excited State Intramolecular Proton-electron Transfer (ESIPT) capability as well as the possession of low quantum yields in their ligand-only solutions. Interestingly, while the low quantum yield molecules 1, 2, 3 and 6 lacked the expected large Stokes shifted ESIPT fluorescence in their ligand-only solutions, they utilize the same ESIPT-oriented process to achieve varying extents of substituent-dependent fluorescent turn-on that produced sensitive and selective Al3+ detection. In particular, while molecules 1 and 3 gave dual-band fluorescence turn-on from both primary and secondary photoexcited states, the O-bridged ligand 6 is strongly turned on only at the large Stokes shifted ESIPT emission wavelength. Thus, with a 528-fold F/Fo turn-on ratio and a detection limit of 5.48 × 10−9 M, the efficiency of molecule 6 as chemosensor towards Al3+ detection can be considered to be outstanding. Based on results of Job plot experiment, fluorescent intensities during Al3+ titration, single crystal structural data and 1H NMR spectral analyses, we conclude that a 1:1 sensor-to-analyte stoichiometry is at play in the Al3+ sensing mechanism and that the sensor molecules form an unusual bidentate O^O coordination with the analyte as neutral iminium zwitterion. It could be concluded that synthetic designs leading to systematic substituent variation is a beneficial tool for tuning and isolating applicable molecular chemosensor species.
format	article
author	Raymond Akong Akong Helmar Görls Joseph Anthony Orighomisan Woods Winfried Plass Abiodun Omokehinde Eseola
author_facet	Raymond Akong Akong Helmar Görls Joseph Anthony Orighomisan Woods Winfried Plass Abiodun Omokehinde Eseola
author_sort	Raymond Akong Akong
title	ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
title_short	ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
title_full	ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
title_fullStr	ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
title_full_unstemmed	ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules
title_sort	esipt-inspired fluorescent turn-on sensitivity towards aluminium(iii) detection by derivatives of o- and s-bridged bis-(phenol-imine) molecules
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/9b283944a01e41eab8464c5e489bee01
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ESIPT-inspired fluorescent turn-on sensitivity towards aluminium(III) detection by derivatives of O- and S-bridged bis-(phenol-imine) molecules

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