Self-Assembly Assisted Tandem Sensing of Pd²⁺ and CN⁻ by a Perylenediimide-Peptide Conjugate

A tandem sensor for Pd²⁺ and CN⁻ ions based on perylenediimide-peptide conjugate is reported. The probe showed high selectivity toward Pd²⁺ ion over other metal cations and the sensitivity was observed to be 0.55 ppb, significantly lower than other similar chemosensors. Binding with Pd²⁺ leads to aggregation of the ligand and consequently results in quenching of its emission. The quenched emission can be turned on in presence of CN⁻ ions as the cyanides form stronger complex with Pd²⁺ leading to disaggregation of the aggregated system. The system was found to be extremely selective to CN⁻ and the detection limit in this case was calculated to be as low as 0.226 ppb. The sensor is also utilized to construct a practical and simple TLC based tool to sense these two ions efficiently.