An azine-based chromogenic, fluorogenic probe for specific cascade detection of Al3+ and PO43- ions

An azine-based chromo-fluorogenic sensor, 2,2′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylyidene)) bis(4-nitrophenol) (DBMN), has been introduced for cascade detection of Al3+ and PO43- ions with high selectivity and sensitivity with a detection limit in the nM to μM range. Upon introducing Al3+ ions into the DBMN solution, a remarkable colorimetric change from yellow to colorless has been noticed in the naked eye due to inhibiting the intramolecular charge transfer process. A 120 times photoluminescence intensity enhancement displaying bluish-green fluorescence under the exposure of a 365 nm UV lamp is observed because of chelation-enhanced fluorescence (CHEF) from the solution of Al3+ ions chelated DBMN complex, which is also well-supported by the color chromaticity diagram. Al3+ ions chelated DBMN complex is selective and sensitive to detecting PO43- ions by rebirthing DBMN. A paper strips-based test kit has been fabricated for on-site cascade detection of Al3+ and PO43- ions, respectively. By employing either Al3+ and PO43- ions as single chemically encoded input and photoluminescence intensity as optical output, we have framed YES and NOT single input and single output opto-chemical logic circuits. Also, based on the photoluminescence off–on-off mechanism, we have designed two inputs and one output-based INHIBIT logic gate with the help of sequential addition of Al3+ and PO43- ions as the two chemically encoded inputs and the luminosity at 500 nm as a single output. Also, a set-reset memorized molecular device has been framed based on photoluminescence as the optical output due to the sequential addition of Al3+ and PO43- ions in the DBMN solution.