Norfloxacin-derivative functionalized octamolybdate: unusual carbonyl coordination and acidity sensitive luminescence

A novel γ-type octamolybdate functionalized by decarboxylated norfloxacin (dNF), (dNF)2[γ-Mo8O26(dNF)2]·10H2O (1), has been synthesized. In the broad range of acidic solutions, even in the pH < 0 range, the fluorescent intensities of 1 almost linearly changed with acidity, indicating that a solution of 1 could be used as an acidity fluorescent sensor. The enhancing and quenching behavior also makes complex 1 a potential acid–base switch system. The successful synthesis of 1 demonstrates a new acidity sensor based on a fluorescent medicine and polyoxometalate anions.