A Highly Sensitive and Selective Quinazoline-Based Colorimetric Probe for Naked-Eye Detection of Fe3+ Ions.

A novel quinazoline-based colorimetric sensor (probe 1) that detected Fe3+ via naked-eye in a buffered MeOH: H2O (8:2) solvent system within a neutral pH range was synthesized and its structure was confirmed by 1H-NMR, 13C-NMR, FT-IR, and Mass spectroscopy. Its photophysical properties were also studied. The sensitivity and selectivity factor in the presence of 16 metal ions was examined by utilizing absorption titrations. Based on the selectivity test, probe 1 exhibited excellent selectivity and sensitivity toward Fe3+ ions among various other ions. The competitive effect indicated relatively low interference of other cations on the interaction of probe 1/Fe3+. To specify the sensing behavior of probe 1 to Fe 3+, the mole ratio method was carried out. After addition of around 500 µL of Fe3+, the absorption of probe1 reached saturation, and the reaction was completed. The effect of pH on the absorption and stability of probe 1 towards Fe3+ was examined. The pH range from 5.0 to 9.0 was appropriate for detection of Fe3+. To find the binding stoichiometric of the complex, Job's plot studies were carried out by varying the molar ratio of Fe3+. A 1:2 binding ratio was proposed. Under the optimal conditions, a good linear relationship (R2 = 0.9886) was at the concentration of Fe3+ over the range of 50-110 µM, with a detection limit of 47.44 nM. Our quinazoline-based probe has shown good results for the quantitative determination of Fe3+ in samples of urine with high recovery.

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 (фF = 0.21). Hence, the fluorophore was applied in the peroxyoxalate chemiluminescence system. The reaction of imidazole, H2O2, 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.

Silver nanoparticles enhanced a novel TCPO-H2O2-safranin O chemiluminescence system for determination of 6-mercaptopurine.

The present study deals with first attempt to introduce safranin O as the fluorophore for peroxyoxalate chemiluminescence system. The reaction of bis-(2,4,6-trichlorophenyl) oxalate (TCPO) with H2O2 catalyzed by silver nanoparticles can transfer energy to safranin O via the formation of dioxetanedione intermediate and emits orange-red light. The relationship between CL intensity and the concentration of TCPO, fluorophore, hydrogen peroxide and nanocatalyst was investigated. The Ag nanoparticles were synthesized by chemical reduction method and characterized using scanning electron microscopy, particle size analyzer and UV-spectroscopy. Moreover, the system was applied successfully to detect a drug, 6-mercaptopurine (6-MP) in pharmaceuticals. Under optimum conditions, a linear working range for 6-MP concentrations from 5.5 × 10(-7) to 5.5 × 10(-5)mol L(-1) (r>0.9831, n=6) was obtained with a detection limit of 1.6 × 10(-7)mol L(-1). The relative standard deviation for 6 repetitive determinations was less than 3.8% and recoveries of 98% and 103% were obtained.

ZnO nanoparticles as an oxidase mimic-mediated flow-injection chemiluminescence system for sensitive determination of carvedilol.

A simple, rapid and sensitive method was developed using ZnO nanoparticle (ZnO-NP) amplified flow-injection chemiluminescence to detect carvedilol, a non-cardioselective ß-blocker. It has been found that carvedilol strongly inhibits the chemiluminescence of luminol-H2O2 catalyzed by ZnO-NPs. Under optimum conditions, a linear working range for carvedilol concentrations from 5 × 10(-8) to 1.0 × 10(-6) mol L(-1) (r > 0.9894, n = 8) was obtained with a detection limit of 3.25 × 10(-9) mol L(-1). The relative standard deviation for 8 repetitive determinations was less than 2.9% and recoveries of 99% and 102% were obtained. ZnO-NPs were synthesized using a green mechanochemical route. Transmission electron microscopy and x-ray diffraction were used to characterize ZnO-NPs. The method was successfully applied to detect carvedilol in pharmaceutical formulations.

Effect of glutathione on peroxyoxalate chemiluminescence of hypericin as the fluorophore.

Herein, the effect of amino acid Glutathione (GSH) on Peroxyoxalate Chemiluminescence was studied for the first time. Hypericin (HYP) was employed as the efficient fluorophore. The investigated parameters included rise and fall rate constant for the chemiluminescence burst, theoretical and experimental maximum intensity, the time-needed to reach maximum intensity and the total light yield emission which theoretically was evaluated using the pooled intermediate model by a computerized non-linear least-squares curve fitting program (KINFIT). Furthermore, based on observed quenching effect of GSH, the Stern-Volmer plot in quencher concentration range of 2.8×10(-6) to 3.4×10(-5)M with KQ value of 1.59×10(4) was calculated. The bimolecular quenching rate constant (Kq) was also estimated about 2.8×10(12) and M(-1) S(-1). Moreover the system was applied successfully to determine glutathione in biological samples.

Effect of human and bovine serum albumin on kinetic chemiluminescence of Mn (III)-Tetrakis (4-sulfonatophenyl) porphyrin-luminol-hydrogen peroxide system.

The present work deals with an attempt to study the effect of human and bovine serum albumin on kinetic parameters of chemiluminescence of luminol-hydrogen peroxide system catalyzed by manganese tetrasulfonatophenyl porphyrin (MnTSPP). The investigated parameters involved pseudo-first-order rise and fall rate constant for the chemiluminescence burst, maximum level intensity, time to reach maximum intensity, total light yield, and values of the intensity at maximum CL which were evaluated by nonlinear least square program KINFIT. Because of interaction of metalloporphyrin with proteins, the CL parameters are drastically affected. The systems resulted in Stern-Volmer plots with k(Q) values of 3.17 × 10(5) and 3.7 × 10(5) M(-1) in the quencher concentration range of 1.5 × 10(-6) to 1.5 × 10(-5) M for human serum albumin (HSA) and bovine serum albumin (BSA), respectively.