Phenolphthalein Conjugated Schiff Base as a Dual Emissive Fluorogenic Probe for the Recognition Aluminum (III) and Zinc (II) Ions

"Lighting up" fluorescence precise recognition of Al3+ with an effective fluorescence detection using a Bisphenol A-based sensor

Although aluminum is a ubiquitous metal in the ecosystem and has numerous critical roles in both the medicinal and biological fields, human daily life is seriously threatened by its assorted harmful influences. By this virtue, tracking the amount of aluminum byrapid sensitive and selective recognition methodologies is of great importance. Based on this, a novel fluorescent chemosensor 4,4'-(propane-2,2-diyl)bis(2-(((-2-hydroxybenzylidene) hydrazineylidene)-methyl)phenol) (BFASA) capable of recognizing Al³⁺ in a medium was constructed via an easy Schiff-base reaction between bisphenol A-containing molecule and the salicylaldehyde. The metal-binding studies of BFASA indicated a drastically enhanced emission with color alteration from colorless to green establishing the utility of BFASA against monitoring of Al³⁺ and only Cu²⁺/Al³⁺ significantly enhanced the absorbance intensity of the probe solution at 433 and 406, respectively. Its ability to selectively sense Al³⁺ demonstrated "switch-on" fluorescence responses for Al³⁺ with a low detection limit (LOD) of 0.56 μM and good selectivity, and pH adaptation range (5-8). The stoichiometric ratio of BFASA against the Al³⁺ was verified by the Job's plot and TOF-MS analysis and determined as 1:2. To make the recognition process inexpensively, viable and straightforward, Smartphone application of BFASA was effectively applied to Al³⁺ sensing, which could benefit the on-site Al³⁺ recognition. In the fluorescence bio-imaging aspect, the BFASA could effectively monitor Al³⁺ in living cells.