New fluorescent chemosensors for silver ion

New fluorescent chemosensors, 1,8-bis(pyrazolylmethyl)anthracene and 9,10-bis(pyrazolylmethyl)anthracene, were synthesized. The 1,8-isomer showed selective fluorescent quenching effects with Ag(I) and Cu(II). On the other hand, the 9,10-isomer displayed a selective fluorescent quenching effect only with Ag(I). From the association constants obtained from fluorescent titrations and by extraction, we conclude that rigid immobilization of the ligands, 1,8-isomer, plays a more important role in the binding with Ag(I) than the additional pi-cation interaction offered by the 9,10-isomer.