A naphthalenecarboxamide based fluorescent sensor for selective detection of Fe3+and CN?: Live cell imaging and INHIBIT logic gate operation

A new fluorescent chemosensor, N,N'-bis(1-hydroxynaphthalene-2-carboxamide)-2-aminobenzylamine (H4L) has been synthesized by a green ionic liquid-based method using tetrabutylammuniom bromide (TBAB) as an environmentally benign reaction medium, and utilized for detection of Fe3+ and CN? ions in DMSO-H2O (8:2 v/ v) solution. The selective fluorescence response of this chemosensor to Fe3+ is excellent with a fluorescent detection limit (LOD) of 5.16 x 10-7 M. The Job's plot and ESI-MS analysis indicated a stoichiometric binding ratio of 1:1 between the tri-anionic form of the chemosensor, HL3-, and Fe3+. H4L also displays rapid fluorescence "Turn-On" response to cyanide anion with high selectivity and sensitivity. The detection limit for CN? in solution is 2.65 x 10-7 M. This cell-permeable probe has also been utilized to image intracellular Fe3+ and CN? ions in HeLa cells. Furthermore, the "off-on-off" fluorescence behavior of H4L at 433 nm has been utilized in the fabrication of "INHIBIT" logic gate with Fe3+ and CN? as chemical inputs and fluorescence (I433 nm) as output.