CHEF-Affected Fluorogenic Nanomolar Detection of Al(3+) by an Anthranilic Acid–Naphthalene Hybrid: Cell Imaging and Crystal Structure

[Image: see text] We report the synthesis of a novel hydrazine-bridged anthranilic acid–naphthalene conjugate (E)-2-(benzamido)-N′-((2-hydroxynaphthalen-1-yl) methylene) benzohydrazide (BBHAN) and its crystal structure. BBHAN can detect Al(3+) by a sharp increment in fluorescence intensity (∼40 times) in aqueous methanolic medium. The limit of detection of BBHAN towards Al(3+) is 1.68 × 10(–9) M, and the former undergoes a 2:1 binding with Al(3+) with a high binding constant of ∼1.15 × 10(11) M(2–). BBHAN detects Al(3+) by the well-known mechanism of chelation-enhanced fluorescence (CHEF), established by fluorescence time-resolved measurement. The mode of interaction between BBHAN and Al(3+) has been explored by (1)H NMR and electrospray ionization mass spectrometry techniques. Paper strips coated with BBHAN can detect Al(3+) under UV light observed through the naked eye. Lastly, BBHAN can detect Al(3+) in MDA-MB-468 cells.