Rhodamine 6G-based efficient chemosensor for trivalent metal ions (Al3+, Cr3+ and Fe3+) upon single excitation with applications in combinational logic circuits and memory devices

A new rhodamine 6G-based chemosensor (L-3) was synthesized and characterized by H-1, C-13, IR and mass spectroscopy studies. It exhibited an excellent selective and sensitive CHEF-based recognition of trivalent metal ions M3+ (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 Fe3+ (669-fold), Al3+ (653-fold) and Cr3+ (667-fold) upon the addition of 2.6 equivalent of these metal ions in the probe in H2O/CH3CN (7 : 3, v/v, pH 7.2). The corresponding K-d values were evaluated to be 1.94 x 10(-5) (Fe3+), 3.15 x 10(-5) (Al3+) and 2.26 x 10(-5) M (Cr3+). The quantum yields of L-3, [L-3-Fe3+], [L-3-Al3+] and [L-3-Cr3+] complexes in H2O/CH3CN (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 Fe3+, Al3+ and Cr3+ were determined by 3 sigma methods and found to be 2.57, 0.78 and 0.47 mu M, respectively. The cyanide ion snatched Fe3+ from the [Fe3+-L-3] complex and quenched its fluorescence via its ring-closed spirolactam form. Advanced level molecular logic devices using different inputs (2 and 4 input) and a memory device were constructed.

Automated summary

A new rhodamine 6G-based chemosensor (L-3) demonstrated excellent selectivity and sensitivity towards Fe3+, Al3+ and Cr3+ ions, with significant enhancement in absorption and fluorescence intensity. Furthermore, it was used to construct advanced molecular logic devices with different inputs.