The derivatives can be used for the detection of cyanide ions in both technological waters and drinking water as well as various gaseous emissions by absorbing them by an appropriate solution.
By affecting the invented 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] derivatives by cyanide ions present in the analysed solution, 3,4-dihydropyran ring decyclization takes place and a coloured 4-nitrophenolate ion occurs, detected colorimetrically. Sensitivity threshold 10-6 M.
LR patent No. 6105 (2014-12- 29) and PCT application No. EP2999704 A1. (2016-03-30)