[CMMIM][BF ₄ ^–] Ionic Liquid-Catalyzed Facile, One-Pot Synthesis of Chromeno[4,3- d]pyrido[1,2- a]pyrimidin-6-ones: Evaluation of Their Photophysical Properties and Theoretical Calculations

Abstract

Herein, we have developed a novel synthetic route for the synthesis of chromeno[4,3- d]pyrido[1,2- a]pyrimidin-6-one derivatives 8a-q using an acid ionic liquid [CMMIM][BF ₄ ^–] 4 via one-pot, three-component synthesis in aqueous ethanol at room temperature. A series of 17 derivatives have been successfully prepared with up to 93% yield. All the synthesized derivatives were well characterized using ¹H-NMR, ¹³C-NMR, and FT-IR spectral techniques. Additionally, the photophysical properties of 12 selected derivatives including molar extinction coefficient (ε), Stokes shift (Δυ̅), and quantum yield (Φ) varying from 0.52095 × 10 ⁴ to 0.93248 × 10 ⁴, 4216 to 4668 cm ^–1, and 0.0088 to 0.0459, respectively, have been determined. Furthermore, the experimental data are supported by density functional theory (DFT) and time-dependent DFT calculations. Theoretical investigations showed a trend similar to experimental results.