A new azo Schiff base probe for detection of Cr3+, HSO4−, and CN−: Computational studies, 4-to-2 encoder, and integrated molecular logic circuits

Abstract

A novel azo Schiff base chemosensor was synthesized via condensation reaction of azo chromophore with benzylamine. This chemosensor as a highly sensitive and selective probe indicated colorimetric response toward Cr3+ (from yellow to colorless) as well as CN− and HSO4− anions (from yellow to orange and yellow to colorless, respectively). The sensory behavior of this probe was investigated in CH3CN: H2O (4: 1 v/v) solution. Via UV–vis titration and Benesi– Hildebrand method, the binding constants (Ka) were determined. The limit of detection for Cr3+, HSO4−, and CN− was 1.76 × 10−10, 1.01 × 10−10, and 5.24 × 10−6 M, respectively. The stoichiometry binding ratios of chemosensor to Cr3+, HSO4−, and CN− were 2: 1, 1: 1, and 1: 2, respectively. L as a colorimetric chemosensor could successfully detect CN− in apple seed samples. DFT and TD-DFT calculations were used to investigate the colorimetric mechanism which was in line with the experimental results. The combinatorial circuit was designed by three logic gates (NOT, OR, and AND) using different output signals towards CN−, HSO4−, and Cr3+. If the suitable experimental condition is selected, the molecule shows the truth table in accordance to the 4-to-2 encoder characteristics. In the 4-to-2 encoder, four chemical inputs are compacted into two photonic outputs, out1 and out2, with absorption at 340 nm and 500 nm, respectively.