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

Abstract

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.

Keywords: Colorimetric; Copper; DFT; Fluorescent; Food; Smartphone.