Ultrasensitive detection of Cu2+: A cyanobiphenyl-based colorimetric and fluorescence chemosensor and its Smartphone and food sample applications.

A new cyanobiphenyl-based compound 4-hydroxy-3-(((4-(phenylamino)phenyl)imino)methyl)-[1,1-biphenyl]-4-carbonitrile (PEBP) for Cu2+ detection was fabricated and successfully characterized. PEBP was employed as a sensor for Cu2+ sensing and used as an extremely fast responsive colorimetric and ''ON/OFF'' fluorescent sensor in H2O:CH3CN (40:60, v/v). Highly selective fluorescence response of PEBP to Cu2+ yielded an excellently low detection limit of 20.4 nM. Binding stoichiometry for PEBP-Cu2+ was found to be 2:1 by Job's plot study, as well MALDI TOF-MS data, and the binding constant was computed as 0.62 × 102 M-1/2. The validation study was employed using analytical parameters and statistical tests. To understand the binding capability, density functional theory (DFT) study was performed. Smartphone and applications for different food and drinking water samples were successfully constructed for Cu2+ detection, and the findings revealed that PEBP could be easily employed for in-site Cu2+detection without sophisticated instrument.