NEW ALKYNYL-LINKED AND VINYL-LINKED BENZO-CROWN AND AZA-CROWN ETHER-BIPYRIDYL RUTHENIUM(II) COMPLEXES WHICH SPECTROCHEMICALLY RECOGNIZE GROUP-IA AND GROUP-IIA METAL-CATIONS

A new alkynyl-linked bis(benzo-15-crown-5) bipyridyl ligand and new mo no- and bis-benzo-15-crown-5 and aza-15-crown-5 bipyridyl ligands cont aining trans-conjugated olefinic linkages between the crown ethers and the 4,4'-disubstituted 2,2'-bipyridine (bipy) moieties have been synt hesised. The corresponding [RuL(bipy)2][PF6]2 and [RuL3][PF6]2 complex es have been prepared and the latter electropolymerized onto optically transparent conducting glass electrodes. Electronic absorption and fl uorescence-emission spectroscopic measurements have demonstrated spect rochemical recognition of Group IA and IIA metal cations by the novel functionalized crown ethers both as solution complexes and as polymeri c films. The lambda(max) and epsilon values for both the low-energy li gand-based pi-pi transition and the metal-to-ligand charge transfer b and observed for the complexes are sensitive to the binding of sodium and magnesium cations. The spectral measurements further demonstrate t he presence of residual unsaturated linkages in the electropolymerized films, providing a technique that could be applied to probe the mecha nisms and efficiencies of such electropolymerizations.