Unsymmetrically urea silatranes: Synthesis, characterization and a selective on–off fluorescence response to acetate anion

Abstract New unsymmetrically Substituted Urea enclosed Silatranes (USUS) 2 – 5 are prepared in good yield by nucleophilic attack of pyrrolidine, piperidine, 3-methylpyridine-2-amine and N-methylbenzenamine containing active hydrogen atom on newly synthesized 3-isocyanatopropylsilatrane 1 . All the compounds have been characterized by elemental analysis, IR, multinuclear ( 1 H and 13 C) NMR and mass spectrometry. The single crystal X-ray crystallography technique facilitates the establishment of exact structures of silatranes 2 , 3 and 4 . The fluorescence titration results have revealed a selective on–off fluorescence response of silatranes toward acetate anion.