Abstract
Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose.
Highlights
Materials showing external stimuli controlled fluorescence output, remained in the limelight during the past few decades
Different organic poly nitro aromatics are in the list of hazardous[57,58] as well as strong explosive
We have reported the selective detection of picric acid
Summary
Materials showing external stimuli controlled fluorescence output, remained in the limelight during the past few decades. Carbon dots being easier to synthesize, highly fluorescent, with low cost and low toxicity are the latest edition in this list These carbon dots have shortcomings as the code written by these materials may be visible by naked eye under ambient light[30,31] or the excitation of UV light[32,33]. Because in general for a zwitterionic spirocyclic Meisenheimer complex the hetero atom which forms bond with the spiro carbon should not possess any positive charge Because this will make the molecule unstable as the sp[3] carbon will become electron deficient and the system will be keen to rearomatize[37]. Besides these applications the overall synthetic methodology was applied to detect picric acid instantly in a highly selective and sensitive manner
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
