Synthesis, characterization and sol–gel entrapment of a crown ether-styryl fluoroionophore

✍ Scribed by Zhijie Sui; Nathan J. Hanan; Sam Phimphivong; Ronald J. Wysocki Jr; S. Scott Saavedra

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 375 KB
• Volume: 24
• Category: Article
• ISSN: 1522-7235
• DOI: 10.1002/bio.1106

✦ Synopsis

Abstract

The synthesis and initial evaluation of a new dye‐functionalized crown‐ether, 2‐[2‐(2,3,5,6,8,9,11,12,14,15‐decahydro‐1,4,7,10,13,16‐benzohexaoxacyclooctadecin)ethenyl]‐3‐methyl benzothiazolium iodide (denoted BSD), are reported. This molecule contains a benzyl 18‐crown‐6 moiety as the ionophore and a benzothiazolium to spectrally transduce ion binding. Binding of K^+^ to BSD in methanol causes shifts in the both absorbance and fluorescence emission maxima, as well as changes in the molar absorptivity and the emission intensity. Apparent dissociation constants (K~d~) in the range 30–65 µm were measured. In water and neutral buffer, K~d~ values were approximately 1 mm. BSD was entrapped in sol–gel films composed of methyltriethoxysilane (MTES) and tetraethylorthosilicate (TEOS) with retention of its spectral properties and minimal leaching. K^+^ binding to BSD in sol–gel films immersed in pH 7.4 buffer causes significant fluorescence quenching, with an apparent response time of approximately 2 min and an apparent K~d~ of 1.5 mm. Copyright © 2009 John Wiley & Sons, Ltd.