The Trialkylbenzene Motif

Further development in the trialkylbenzene motif has led to receptor 76 by Schmuck and coworkers, which exhibits exceptionally high binding of tricarboxylates in water. The cationic guanidinium groups create a tricationic receptor which binds carboxylates in a 1 1 stoichiomeby largely by electrostatic interactions. A binding constant of > 10 M-i was measured for citrate, by UV-vis and fluorescence spectroscopy, with excellent selectivity over monoanionic... 

The design of indnced-fit anion sensors in not limited to the trialkylbenzene motif. Calixarenes with pendant binding arms have also been explored with pyrene derivatives typically nsed as the Unorophore. Pyrene excimer emission has been nsed as a Unorescent reporter which reqnires close contact between adjacent pyrene molecules for its formation. They are an ideal candidate for indnced-fit sensing as conformational changes can dramatically affect intramolecnlar pyrene-pyrene distances in both the gronnd and excited states. 

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