Pyridine-2-yl Quinoxaline (2-CPQ) Derivative As a Novel Pink Fluorophore: Synthesis,and Chemiluminescence Characteristics

Quinoxaline derivatives are well-known N-heterocycles with pharmacological and fluorescence activities. Almost all quinoxaline derivatives with extensive π-conjugation have been introduced as fluorophores which emit blue and green light. For the first time, we designed and synthesized 6-chloro-2,3 di(Pyridine-2yl) quinoxaline (2-CPQ) as a pink fluorophore in acetonitrile medium by simple route at room temperature whitin 30 min. The synthesized quinoxaline was identified using ¹H, ¹³C NMR, MS, and FT-IR spectroscopy. Our results showed that the iodine-catalyzed method for both oxidation and cyclization during the synthesis of quinoxaline from pyridine 2-carbaldehyde was straightforward, efficient, and clean. All of the mentioned characterization devices confirmed the synthesis of 2-CPQ.

Moreover, we studied the photophysical properties of the synthesized fluorophore in which The UV–Vis absorption spectrum of 2-CPQ in DMF were three peaks at 451, 518 and 556 nm. Based on photophysical properties investigation, 2-CPQ shows good fluorescence with maximum peaks 607 and 653 nm in DMF as solvent (ф_F?=?0.21). Hence, the fluorophore was applied in the peroxyoxalate chemiluminescence system. The reaction of imidazole, H₂O_2, and bis (2,4,6-trichlorophenyl) oxalate (TCPO) can transfer energy to a 6-chloro-2,3 di(pyridine-2yl) quinoxaline. In this process, dioxetane was synthesized, which chemically initiated the electron exchange luminescence (CIEEL) mechanism and led to pink light emission. We anticipate our synthesized fluorophores 2-CPQ will have great potential applications in imaging and medical markers.