A Pyrazine-Based Chromophore Photophysical Properties and its Detection for Hydrazine and Acid Vapors

Designed and synthesized linear pyrazine-based D-π-A-π-A probe is investigated to study the colorimetric and emission properties with different polarity index solvents. Their molar extinction coefficients were estimated for each solvent. This TLP probe was investigated in THF/water binary solution aggregates, and a redshifted AIE was observed reaching a water fraction of 70%. Also, this TLP probe was applied to the multifunctional, rapid, sensitive and selective detection of acid-base (TFA/TEA) and hydrazine (N₂H₄) in colorimetric and fluorimetric sensors. The pyrazine unit probe demonstrated an acidochromic effect and explored the acid-sensing behavior. The TLP probe containing malononitrile functional groups has extensively detected hazardous hydrazine species due to nucleophilic attack of hydrazine at the α-position of dicyano. This TLP probe allowed the quick and fast-sensitive detection of hydrazine hydride with a low detection limit of 1.08 nM. According to the results, the mechanism was confirmed by UV-Vis, PL, NMR and MS spectra for the detection of hydrazine, and further evidence of the protonation-deprotonation process in added TFA/TEA was made by titration studies by ¹H NMR. Therefore, this work can be used for test strip kits for multifunction applications.