New Coumarin-Schiff Bases: Synthesis, Electrochemical Behavior, Anion/Cation Sensing Capacities, Spectroscopic Analysis, DFT Studies and NLO Properties
JOURNAL OF FLUORESCENCE, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1007/s10895-026-04926-x
- Dergi Adı: JOURNAL OF FLUORESCENCE
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chimica, Compendex, EMBASE, MEDLINE, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Engineering Source (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Gazi Üniversitesi Adresli: Evet
Özet
This study reports the design, synthesis, and comprehensive experimental and theoretical investigation of a series of novel, cost-effective fluorescent Schiff base chemical sensors based on a high-emission 7-(N, N-diethylamino)coumarin fluorophore core. Three different derivatives containing pyrimidine (1a), 4-fluorophenyl (1b), and 2,4-difluorophenyl (1c) moieties were designed to systematically evaluate ion detection performance, intrinsic stability, and the effects of electronic modulations on electrochemical pathways. Within the series, sensor 1a demonstrated exceptional selectivity and sensitivity to Cu2+ and Ni2+ via a visible fluorescence shutdown mechanism. Importantly, the 1a-Cu2+ ensemble acts as a reversible cascade sensor for the highly toxic cyanide anion via a metal substitution mechanism, recovering its original intense fluorescence with a noticeable yellow-to-orange color shift visible to the naked eye. In DMSO, the LOD values were 1.51 & micro;M for Cu2+ and 2.76 & micro;M for Ni2+. The sensing performance of 1a was also retained in highly aqueous media containing 90% distilled or tap water. The corresponding LOD values were 1.22 and 4.16 & micro;M for Cu2+ and 4.22 and 1.93 & micro;M for Ni2+ in distilled and tap water, respectively. The Cu2+/CN- turn-off/turn-on response was also preserved in both aqueous media. Cyclic voltammetric (CV) analysis revealed irreversible, diffusion-controlled redox properties. Experimental HOMO/LUMO energy gap values closely correlated with trends predicted by DFT calculations. Furthermore, the calculated hyperpolarizations (beta) for 1(a-c) are 91, 30, and 9 times higher, respectively, than those of the reference urea standard. These findings demonstrate that the synthesized coumarin-based Schiff bases have enormous potential not only as selective "naked-eye" detectable chemical sensors but also as high-performance candidate materials for advanced nonlinear optics (NLO) applications.