Open-chain polyamine ligands bearing an anthracene unit - Chemosensors forlogic operations at the molecular level

In this work, the absorption and the fluorescence emission properties as we ll as the protonation sequence of three open chain polyamine Ligands of dif ferent dimensions bearing an anthracene unit were studied. The protonation and stability constants with Ni2+, CU2+, Zn2+, and Cd2+ have been determine d in 0.15 mol . dm(-3) NaCl at 298.1 +/- 0.1 K. The values of both protonat ion and stability constants follow the expected trends according to the num ber of nitrogen donors, sequence of chelate rings and hydrophilic-hydrophob ic balance. Chechelation enhancement of the fluorescence emission (CHEF) wa s observed for some complexes of these Ligands with Zn2+ and Cd2+. In contr ast the analog complexes containing Cu2+ and Ni2+ exhibit a chelation enhan cement of the quenching (CHEQ) except for the complexes with the largest ch ain where some protonated metal complexes are emissive. These systems are e xplored from the point of view of chemosensors for logic operations at the molecular level.