Anion sensors based on collisional quenching

The drawback of these molecular sensors is their lack of selectivity, as shown by the Stern-Volmer constants (Table 10.4). For instance A-l, 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) is mainly used as a Cl -sensitive fluorescent indicator, but its fluorescence is also quenched by several other anions (I-, Br and SCN-, but not by NO ). 

Abbreviations SPQ 6-methoxy-N -(sulfopropyl)quinolinium SPA N-(sulfopropyl)acridinium lucigenin bis-N-methylacridinium nitrate MACA 10-methylacridinium-9-carboxamide MAMC N-methylacridinium-9-methyl carboxylate. 

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