Abstract

Hydrazine (H2N-NH2) is an important and widely used compound in both fine chemical and pharmaceutical industries including pharmaceuticals, pesticides, and chemical-blowing agents.1, 2 It is flammable, corrosive, toxic, and hazardous to health and the environment.3 More common applications of hydrazine include serving as rocket fuels, foaming agents.1 In addition, hydrazine is well-known as serving as an excellent reductant in chemical reactions because its reduction potential is up to +1.15 V,3 which makes it easy to form redox pairs with other species, particularly the oxidants such as iron(III) complexes. In this work, we synthesized a six-coordinated iron(III) pyridyl-imine complex via a one-pot reaction and proved the complex could be a fluorescent sensor for the detection of hydrazine in solution based on the redox reaction. The fluorescence signal generated was attributed to the reduction of the oxidative iron-center of Fe(III) to Fe(II) by the reductive hydrazine. A good linear relationship for the analysis of hydrazine was obtained with the concentration range of 0.06-0.15 mM (R2 = 0.99114) in DMF solution. The limit of detection (LOD) estimated was 14.8 µM and the limit of quantitation (LOQ) was 49 µM. Moreover, the color change of the iron(III) pyridyl-imine complex solution from dark green to reddish brown was able to observed by naked eye, indicating that the Fe(III)-complex may be also utilized as a colorimetric sensor for hydrazine at millimolar level. The present study demonstrated an interesting fluorescent sensing system based on redox chemistry of an iron(III) complex that generated fluorescence response upon reacting with its redox pair such as the reducing agent hydrazine.

Reference:

1. Zhu, R.; Reddy, R.; Ding, M.; Xu, M.; Deng, C.; Tadayon, S.; Li, H.; Depew, K.; Lane, B. Organic Process Research & Development, 2021, 25, 199-205.
2. Kapoor, M. P.; Gallot, J. E.; Raj, A.; Kaliaguine, S. Journal of the Chemical Society, Chemical Communications, 1995, 2281-2282.
3. Adhikari, M.; Echeverria, E.; Risica, G.; McIlroy, D. N.; Nippe, M.; Vasquez, Y. ACS omega, 2020, 5, 22440-22448.