Luminescent metalloreceptors with pendant macrocyclic ionophore: Synthesis, characterization, electrochemistry and ion-binding study

摘要

Metalloreceptors containing ruthenium(II) bipyridine unit as fluorophore and pendant macrocyclic units as ionophore have been synthesized and their luminescence and electrochemical properties have been investigated. Ion-binding study of these fluoroionophore with the anions F-, Cl-, Br-, I-, H2PO4-, ClO4-, NO3-, BF4-, CH3COO-, and HSO4- and cations Na+, K+, Mg2+, Ca2+, Zn2+, Ba2+, Sr2+ Cd2+, Hg2+, Pb2+ and Cu2+, monitored by luminescence and H-1 NMR spectral changes, reveal strong interactions of H2PO4- and F- for 2 and 3 and of Cu2+ only for 3. Luminescence titrations for 2 and 3 have been carried out to determine binding constants (K-s), and the calculated values are in the range 2.85 x 10(2) to 4.48 x 10(4) M-1. The H-1 NMR spectral changes for 2 and 3 with the addition of increasing concentration of F- and H2PO4- exhibit substantial low-field shift of the CONH proton indicating its involvement in complex formation with the anions. The H2PO4- adduct of 2 and 3 have been isolated and characterized by H-1 and P-31 NMR, mass and IR spectroscopy. The results are discussed in light of selectivity, structures of the anion bound complexes and their luminescence property.