Fluorescence "Off-On" Signalling upon Linear Recognition and Binding of α,ω-Alkanediyldiammonium Ions by 9,10-Bis{(1-aza-4,7,10,13,16-pentaoxacyclooctadecyl)methyl}anthracene

No Absract. A drastic increase in the fluorescence quantum yield is observed when 1, which contains two crown ether units and a rigid fluorescing spacer, is allowed to react with an α,ω‐alkanediyldiammonium ion of the “correct” chain length. Most effective is the pseudointramolecular cyclization when the alkanediyldiammonium ion has a C4 chain.