Synthesis and Study of Crown Ether-Appended Tetraplatinum(II) Macrocylic Chemosensors for Cation Detection.

Two new functionalized platinum(II) rectangles, Pt1 and Pt2 , were designed and synthesized from phenanthro crown ether- and biphenyl polyether-bridged bicarboxylate ligands, respectively. The fluorescence titration study of rectangles Pt1 and Pt2 with alkali- and alkaline-earth-metal cations indicated that Pt1 can selectively recognize Na + , while Pt2 has selective binding ability for Mg 2+ . These selectivity findings suggest that the comparative size and conformational nature of the polyether receptor cavity have a crucial influence on the cation selection.