Akademik Veri Yönetim Sistemi
Tetrahedron, cilt.195, 2026 (SCI-Expanded, Scopus)
Herein, we present the synthesis of coumarin-indolium-based dyes containing 7-substituted coumarins and extended π-conjugated-coumarin-indolium using the well-known Knoevenagel condensation reaction. The dyes were characterized by 1H NMR, 13C NMR, HRMS, and elemental analysis. Moreover, the molecular structure of 4a was determined by X-ray. All the dyes exhibit fluorescence enhancement upon addition of cyanide via nucleophilic addition to the indolium moiety in both organic and aqueous media. Notably, fluoride (F−), acetate (AcO−), hydroxide (OH−), and dihydrogenphosphate (H2PO4−) anions also showed interaction with 4a, 4b, and 4d, where there was no acidic hydrogen, in DMSO. The interaction mechanism of these anions was proposed to be the addition of anions to the indolium moiety, similar to cyanide, based on absorption/emission, 1H NMR, and LC-MS studies, and supported by DFT calculations. The mechanistic investigation indicated that CN− interacts with 4c through deprotonation and nucleophilic addition mechanisms. However, for 4c, only the deprotonation mechanism was observed for the other anions. Moreover, sensor performance was evaluated in aqueous solution, and the best results were observed with 7-hydroxysubstituted coumarin-indolium dye, 4c. It exhibited highly selective and sensitive responses to CN−, with dramatic color and emission changes in both DMSO and aqueous solution, and no significant interference from competing anions. Limit of detection (LOD) values were determined in DMSO and DMSO/H2O systems as 0.15-0.60 μM and 1.16-1.18 μM, respectively.