title: Colorimetric Cyanide Chemosensor Based on 1',3,3',4-Tetrahydrospiro[chromene-2,2'-indole].
abstract: A new class of chemosensors based on the 1',3,3',4-tetrahydrospiro[chromene-2,2'-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L(-1), and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials.
authors.affiliation: Institute of Synthetic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania ; Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.
authors.forename: Miglė
authors.initials: M
authors.lastname: Dagilienė
authors.affiliation: Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.
authors.forename: Vytas
authors.initials: V
authors.lastname: Martynaitis
authors.affiliation: Institute of Synthetic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania ; Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.
authors.forename: Vilija
authors.initials: V
authors.lastname: Kriščiūnienė
authors.affiliation: Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.
authors.forename: Sonata
authors.initials: S
authors.lastname: Krikštolaitytė
authors.affiliation: Institute of Synthetic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania ; Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.
authors.forename: Algirdas
authors.initials: A
authors.lastname: Šačkus
keywords: 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indoles]; 2-chloromethyl-4-nitrophenols; 2-methylidene-2,3-dihydro-1H-indoles; chemosensors; cyanide; water quality