Immobilization of polyamine ligands onto a fluorophore framework: Their syntheses and fluorescent studies

Geometric immobilization of polyamine ligands is expected to change their binding properties toward metal ions. 1,8-Bis(1,4,7-triazacyclononylmethyl) anthracene (10) and 1,8-bis(1,5,9-triazacyclododecanylmethyl)anthracene (11) were synthesized from 1,8-bis(bromomethyl)anthracene (7) using appropriate azacrown type compounds. Purification of these compounds based on selective pH extraction methods is described. Chelation-enhanced fluorescence (CHEF) effect was observed when 10 complexed nonquenching metal ions such as Zn(II) and Cd(II). When compound 10 was titrated with Cu(II), we could observe chelation-enhanced quenching (CHEQ) effect in 100% aqueous solution. On the other hard, compound 11 showed no effect on fluorescence by any metal ion examined.