Properties of a triazolopyridine system as a molecular chemosensor for metal ions, anions, and amino acids

The characteristics as a chemosensor of the compound 3-methyl-6,8-di( 2-pyridyl)-[ 1,2,3] triazolo[ 5', 1': 6,1] pyrido[ 2,3-d] pyrimidine ( 1) have been analyzed. Interaction with Cu2+ produces a quenching of the fluorescence, while interaction with Zn2+ leads to a quenching of the fluorescence followed by a bathochromic shift. The crystal structure of the [ Zn( 1)( H2O)(3)]( ClO4)(2)]center dot H2O complex shows the coordination of Zn2+ through the terpyridine moiety. The octahedral site is completed by three water molecules. Interactions of the Zn2+ complex with the anions sulfate, nitrate, nitrite, and dihydrogenphosphate in ethanol produce hypsochromic shifts and restoration of the fluorescence whose magnitude depends on the anion involved. The maximum interaction is observed for H2PO4-. Interactions of the Zn2+ complex with the amino acids L-aspartate and L-glutamate have also been explored showing a higher interaction with L-aspartate.