9-Benzylidene-9H-fluorene Derivatives Linked to Monoaza-15-crown-5: Synthesis and Metal Ion Sensing

Two kinds of novel styryl chemosensory 2-FMNC and 3-FMNC, were designed and synthesized by an apporiate introduction of 9-benzylidene-9 H -fluorene group as fluorophore with the aim at avoiding photoisomerisation. These 9-benzylidene-9 H -fluorene derivatives showed the similar selectivity and sensitivity upon addition of metal ions. The sensitivity of FMNC to alkaline earth metal ions was Ba 2+ >Sr 2+ >Ca 2+ ≈Mg 2+ .