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

Highly Selective and Sensitive Visual Detection of Fe3+ using a Simple Quinazoline-Based Colorimetric Sensor

Among the various cations, the Fe3+ ion is one of the most critical transition metal ions in living cells for many cellular functions and enzymatic activities. The decrease or overloading of Fe3+ can lead to different disruptions in humans. Also, Fe3+, highly toxic, is very common in all industrial wastewater. So, the design and synthesis of Fe3+ chelators as high-selective chemosensors are essential for detecting Fe3+. In this paper, 6-(6-bromopyridin-2-yl)benzo[4,5]imidazo[1,2-c]quinazoline (BQ) as a novel colorimetric sensor for sensing of Fe3+ was synthesized and characterized by 1H-NMR, 13C-NMR, IR, and mass spectrometry. The sensing behavior of BQ toward various cations has been analyzed via colorimetric detection and UV-vis spectroscopy. The BQ was observed to have excellent selectivity and sensitivity to the presence of Fe3+ among the tested ions in aqueous media. Interestingly, the BQ can selectively recognize Fe3+ ions with the naked eye via the color change of colorless to yellow. The effect of pH on the stability and absorption of BQ towards Fe3+ was studied. The results of pH studies showed that the absorbance of complex BQ/Fe3+ remains stable between pH 5-10. Moreover, to determine the sensing behavior of BQ to Fe3+, the mole ratio method was carried out. The binding stoichiometry of BQ/Fe3+ was assessed by using Job's plot and indicated the 1:1 binding ratio between BQ and Fe3+. Under the optimal conditions, there was a good linear relationship (correlation coefficient R2 = 0.9886) in Fe3+ concentration in the 58-114 μM range, with a detection limit of 53.39 nM.

Recent Methods for the Synthesis of Quinoxaline Derivatives and their Biological Activities

Quinoxaline derivatives have been incorporated into numerous marketed drugs used for the treatment of various diseases. Examples include glecaprevir (Mavyret), voxilaprevir (Vosevi), Balversa (L01EX16) (erdafitinib), carbadox, XK469R (NSC698215), and becampanel (AMP397). These quinoxaline derivatives exhibit a diverse range of pharmacological activities, including antibacterial, antitubercular, antiviral, anti-HIV, anti-inflammatory, antifungal, anticancer, antiproliferative, antitumor, kinase inhibition, antimicrobial, antioxidant, and analgesic effects. Recognizing the significance of these bioactive quinoxaline derivatives, researchers have dedicated their efforts to developing various synthetic methods for their production. This review aimed to compile the most recent findings on the synthesis and biological properties of quinoxaline derivatives from 2015 to 2023.

A new peroxyoxalate chemiluminescence of bis (2, 4-dinitrophenyl) oxalate (DNPO) using pyronin Y as the fluorophore and its application to the flow-based determination of cysteamine

Peroxyoxalate chemiluminescence (POCL) systems have received great attention due to their high quantum yield and the ability to emit a wide-range colors by the utilizing different fluorophores. In this research, Pyronin Y (PY) was first introduced as the fluorophore for a POCL system. Our results indicated that the reaction of (2, 4-dinitroophenyl) oxalate (DNPO) with hydrogen peroxide (H₂O₂) catalyzed by sodium salicylate (SS) could transfer energy to Pyronin Y via the formation of the dioxetanedione intermediate and emit orange-red light. The relationships between chemiluminescence (CL) intensity and the concentrations of DNPO, fluorophore, H₂O₂, and the catalyst were investigated. Moreover, the analytical utilization of the new CL system was evaluated by detecting a drug, cysteamine, in pharmaceuticals. A linear working range for cysteamine concentrations from 3 × 10 ^-8 to 7.5 × 10 ^-6 molL^-1 (r > 0.9907, n = 5) and a detection limit of 7.8 × 10^-9 molL^-1 were obtained, respectively. The relative standard deviation for five repetitive determinations was less than 3.8 %, with estimated recoveries of 100.1 % and 103.4 %. This method shows high sensitivity for the assay of cysteamine.