title: Novel colorimetric sensors for cyanide based on azo-hydrazone tautomeric skeletons.
abstract: The monoazo dyes, 4-carboxyl-2, 6-dinitrophenylazohydroxynaphthalenes dyes (AZ-01, AZ-03 and AZ-04), were evaluated as a highly selective colorimetric chemosensor for cyanide ion. The recognition of cyanide ion gave an obvious colour change from light yellow to brownish red and upon dilution with acetone produced a purple to lilac colour. Optimum conditions for the reaction between the azo dyes and cyanide ion were established at 30°C for 5 min, and different variables affecting the reaction were carefully studied and optimised. Under the optimum conditions, linear relationships between the CN(-) concentrations and light absorption were established. Using these azo-hydrazone molecular switch entities, excellent selectivity towards the detection of CN(-) in aqueous solution over miscellaneous competitive anions was observed. Such selectivity mainly results from the possibility of nucleophilic attack on the azo-hydrazone chemosensors by cyanide anions in aqueous system, which is not afforded by other competing anions. The cyanide chemosensor method described here should have potential application as a new family probes for detecting cyanide in aqueous solution.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Orita UI, Ibadan, Nigeria. Electronic address: jireade@yahoo.com.
authors.forename: Olajire A
authors.initials: OA
authors.lastname: Adegoke
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Orita UI, Ibadan, Nigeria.
authors.forename: Temitope E
authors.initials: TE
authors.lastname: Adesuji
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Orita UI, Ibadan, Nigeria.
authors.forename: Olusegun E
authors.initials: OE
authors.lastname: Thomas
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods; D003486:Cyanides / Q000032:analysis*; D006835:Hydrazones / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D001391:Azo Compounds; D003486:Cyanides; D006835:Hydrazones
keywords: 4-carboxyl-2,6-dinitrophenylazohydroxylnaphthalenes; Aqueous medium; Azo-hydrazone tautomeric switch; Chemosensor; Cyanide