A fluorescent chemosensor for the copper(II) ion

The two-component system anthracene-9-carboxylic acid 1,4,8,I l-tetrathia-cyclotetradecan-6-yl ester ( 1) hasbeensynthesized, structurally characterized and investigated as a fluorescent chemosensor for the Cuts ion. Crystallographic details for 1: space group P2Jc with a=9.894(2), b=24.608(2), c= 10.75o(2) /~, a=90, ~0=*05.88, 7~90°; V=2519.7 J~3,Z=4 (R=0.088, R,,=0.066). In ethancflic solution I selectively incorporates CuRtinto its tetrathia crown component in the presence of otlmr 3d metal ions and signals the recognition through the quenching of the fluorescence of the anthracene fragment. Quenching of the photo-excited state (which has a charge transfer nature) takes place through a photo-induced electron transfer from the fluorophote to the metal center and involves the CuU/Cu~couple. The dmcation AgI competes successfully with Cuu for the tetrathia cavity of I in an ethanolic solution (not in an acetonitrile solution), lint the occurrence of the metal/receptor interaction cannot be signalled, due to the poor tedox activity of the non-transition cation Ag~.