Novel Lipophilic Fluorophores with Highly Acidity-Dependent Two-Photon Response.
Chemistry
; 28(8): e202103707, 2022 Feb 07.
Article
em En
| MEDLINE
| ID: mdl-34964188
ABSTRACT
Lipophilic fluorophores are widely implemented in nonlinear microscopy; however, few existing membrane-specific probes combine the high brightness of two-photon excited fluorescence (2PEF) with pH sensitivity. Herein we describe four novel two-photon excited fluorophores, based on a coumarin 151 core structure, where lipophilicity is induced by a covalently attached phosphazene moiety. Changing the environmental acidity using trifluoromethanesulfonic (triflic) acid leads to profound changes in the linear fluorescence and 2PEF characteristics, due to chromophores' switching between neutral- and protonated forms. We characterize this dependence by measuring the two-photon absorption (2PA) spectra over the region λ2PA =550-1000â
nm, observing 2PA cross sections of σ2PA =10-20â
GM, with an associated 2PEF brightness of 10-13â
GM, in neutral solutions of both acetonitrile and n-octanol. Although quantum chemical modelling and NMR measurements show that, at high chromophore concentrations, protonation may be accompanied by a dimerization process, these dimers likely do not form at the lower concentrations used in optical spectroscopy.
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MEDLINE
Assunto principal:
Fótons
/
Corantes Fluorescentes
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article