Synthesis, Structure, Photophysics, Electrochemistry, and Ion-Binding Studies of Ruthenium(II) 1,10-Phenanthroline Complexes Containing Thia-, Selena-, and Aza-Crown Pendants

A series of ruthenium(II) diimine complexes containing thia-, selena- and aza-crowns derived from 1,10-phenanthroline
have been synthesized and characterized, and their photophysics and electrochemistry were studied. Their interaction
with metal ions was investigated by UV−vis, luminescence, and 1H NMR spectroscopy. The crystal structures of
[Ru(bpy)2(L1)](PF6)2, [Ru(bpy)2(L2)](ClO4)2, [Ru(bpy)2(L3)](ClO4)2, and [Ru(bpy)2(L4)](ClO4)2 have been determined.
The luminescence properties of [Ru(bpy)2(L1)](ClO4)2 were found to be sensitive and selective toward the presence
of Hg2+ ions in an acetonitrile solution. The addition of alkaline-earth metal ions, Zn2+, Cd2+, and Hg2+ ions, to the
solution of [Ru(bpy)2(L6)](ClO4)2 in acetonitrile gave rise to large changes in the UV−vis and emission spectra. The
binding of metal ions to [Ru(bpy)2(L6)](ClO4)2 was found to cause a strong enhancement in the emission intensities
of the complex, with high specificity toward Hg2+ ions.