Tandem Detection of Sub-Nano Molar Level CN^- and Hg²⁺ in Aqueous Medium by a Suitable Molecular Sensor: A Viable Solution for Detection of CN^- and Development of the RGB-Based Sensory Device

An inimitable urea-based multichannel chemosensor, DTPH [1,5-bis-(2,6-dichloro-4-(trifluoromethyl)phenyl)carbonohydrazide], was examined to be highly proficient to recognize CN^- based on the H-bonding interaction between sensor -NH moiety and CN^- in aqueous medium with explicit selectivity. In the absorption spectral titration of DTPH, a new peak at higher wavelength was emerged in titrimetric analytical studies of CN^- with the zero-order reaction kinetics affirming the substantial sensor-analyte interaction. The isothermal titration calorimetry (ITC) experiment further affirmed that the sensing process was highly spontaneous with the Gibbs free energy of -26 × 10⁴ cal/mol. The binding approach between DTPH and CN^- was also validated by more than a few experimental studies by means of several spectroscopic tools along with the theoretical calculations. A very low detection limit of the chemosensor toward CN^- (0.15 ppm) further instigated to design an RGB-based sensory device based on the colorimetric upshots of the chemosensor in order to develop a distinct perception regarding the presence of innocuous or precarious level of the CN^- in a contaminated solution. Moreover, the reversibility of the sensor in the presence of CN^- and Hg²⁺ originated a logic gate mimic ensemble. Additionally, the real-field along with the in vitro CN^- detection efficiency of the photostable DTPH was also accomplished by using various biological specimens.