Mechanosynthesis of Diaminobiphenyls-Based Schiff's Bases as Simple Probes for the Naked-Eye Detection of Cyanide Ion

Cyanide ions are known to be lethal for insects and mammals and harmful for the environment, and new methods for their selective detection are in high demand. Herein, the mechanosynthesis of simple Schiff's bases-based probes S1-S3 for visual detection of CN- anion is reported. These probes were obtained by means of a reaction between isomeric 4,4-, 3,3- and 2,2-diaminobiphenyls and 4-nitrobenzaldehyde under ball milling conditions. The probes showed high selectivity and sensitivity toward CN- anion via a dramatic yellow-to-dark purple color change with a detection limit of 26 x 10(3), 8.7 x 10(3) and 14 x 10(3) ppm for S1-S3, respectively. The proposed mechanism of the detection suggests the deprotonation of a proton from an imine moiety, followed by the formation of charge transfer complexes (CTC).

Automated summary

The mechanosynthesis of simple Schiff's bases-based probes S1-S3 for visual detection of CN- anion is reported. These probes were obtained by reacting isomeric 4,4-, 3,3- and 2,2-diaminobiphenyls with 4-nitrobenzaldehyde under ball milling conditions. The probes showed high selectivity and sensitivity toward CN- anion through a dramatic color change, with detection limits in the ppm range.