American Chemical Society
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Rational Design of a Chromo- and Fluorogenic Hybrid Chemosensor Material for the Detection of Long-Chain Carboxylates

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journal contribution
posted on 2005-01-12, 00:00 authored by Ana B. Descalzo, Knut Rurack, Hardy Weisshoff, Ramón Martínez-Máñez, M. Dolores Marcos, Pedro Amorós, Katrin Hoffmann, Juan Soto
A strategy for the rational design of a new optical sensor material for the selective recognition of long-chain carboxylates in water is presented. The approach relies on the combination of structure−property relationships to single out the optimal molecular sensor unit and the tuning of the sensing characteristics of an inorganic support material. A spacer-substituted 7-urea-phenoxazin-3-one was employed as the signaling moiety and a mesoporous trimethylsilylated UVM-7 (MCM-41 type) material served as the solid support. The sensor material shows the advantageous features of both modules that is absorption and emission in the visible spectral range, a fluorescence red-shift and enhancement upon analyte coordination, and the amplification of noncovalent (binding) and hydrogen-bonding (recognition) interactions in the detection event. Besides these basic results that are related to the design and performance of the sensor material, the paper discusses general aspects of amido-substituted phenoxazinone photophysics and addresses some general features of molecular anion recognition chemistry in aqueous vs nonaqueous media, utilizing steady-state and time-resolved optical as well as NMR spectroscopies. Detailed studies on potentially competing biochemical species and a first access to the schematic model of the response of the sensor material as obtained by a combination of fluorescence lifetime distribution analysis and Langmuir-type fitting of the gross binding constants complement the key issues of the paper.