Rhodamine 6G-based efficient chemosensor for trivalent metal ions (Al, Cr and Fe) upon single excitation with applications in combinational logic circuits and memory devices.

A new rhodamine 6G-based chemosensor (L3) was synthesized and characterized by H, C, IR and mass spectroscopy studies. It exhibited an excellent selective and sensitive CHEF-based recognition of trivalent metal ions M (M = Fe, Al and Cr) over mono and di-valent and other trivalent metal ions with prominent enhancement in the absorption and fluorescence intensity for Fe (669-fold), Al (653-fold) and Cr (667-fold) upon the addition of 2.6 equivalent of these metal ions in the probe in HO/CHCN (7 : 3, v/v, pH 7.2). The corresponding values were evaluated to be 1.94 × 10 (Fe), 3.15 × 10 (Al) and 2.26 × 10 M (Cr). The quantum yields of L3, [L3-Fe], [L3-Al] and [L3-Cr] complexes in HO/CHCN (7 : 3, v/v, pH 7.2) were found to be 0.0005, 0.335, 0.327 and 0.333, respectively, using rhodamine-6G as the standard. The LODs for Fe, Al and Cr were determined by 3 methods and found to be 2.57, 0.78 and 0.47 μM, respectively. The cyanide ion snatched Fe from the [Fe-L3] complex and quenched its fluorescence its ring-closed spirolactam form. Advanced level molecular logic devices using different inputs (2 and 4 input) and a memory device were constructed.