Studies of the effect of halide ions on the fluorescence of quinine sulfate

Abstract

The effect of halide ions (Cl − , Br − and I − ) on the fluorescence of quinine sulfate in dilute sulfuric acid solution was studied by fluorescence spectra, ultraviolet-visible (UV-visible) absorption spectra and fluorescence decay technique. The results exhibited that halide ions with heavier atomic mass could significantly reduce the fluorescence intensity of quinine sulfate, as a result, the order of fluorescence quenching caused by halide ions is Cl − < Br − < I − . Therefore, halide ions with high concentration could seriously quench the fluorescence of quinine sulfate. The UVvisible absorption spectra and fluorescence decay technique revealed that the fluorescence quenching of quinine sulfate caused by halide ions was attributed to dynamic quenching, static quenching process, self-quenching fluorescence effect and electronic transfer.

Sequence-Specific Fluorescence Turn-On Sensing of RNA by DNA Probes Incorporating the Tricyclic Cytidine Analogue DEAtC

“…The two halides, chloride and iodide, differ in their ionic radii as well as their quenching potency, which has been correlated to their ionization energies . Chloride has an ionic diameter of about 334 pm, while iodide has an ionic diameter of approximately 412 pm and is a stronger quencher. − Experiments were performed using the DNA–RNA oligonucleotides GXC, TXA, and CXA (Figures and S8, and Table ). GXC was the brightest sequence observed, while TXA and CXA showed the most pronounced fluorescence increase in A-form DNA–RNA duplexes relative to fluorescence in B-form dsDNA.…”

Fluorescence Quenching of Chlorophyll by Sea Water Components

“…If pyrene undergoes a more facile ISC to a triplet state due to interactions with halides, it would then be expected to be less subject to photo-oxidation. Another study, which looked at quinine in a solution of sulfuric acid, also demonstrated the heavy atom effect on the fluorescence quenching, although the authors note that the fluorescence quenching of quinine could be by a dynamic and static quenching mechanism. In both cases, the effects are shown to be strongly related to the ability of the halide to alter the n-pi* energy separation of the quinoline ring, which facilitates ISC to the triplet electronic state …”

“…15−18 Common quenchers that are found in natural waters are metals, singlet oxygen, and halides. 19−22 In particular, halides show a strong quenching ability toward several other organic molecules, such as quinine, 20 metal porphyrins, 24 and polyaromatic hydrocarbons. 25 In this fundamental study, we use a Stern−Volmer analysis to quantify the chlorophyll fluorescence quenching by common seawater components as well as that of an artificial seawater solution at a natural seawater salinity.…”

“…Given the importance of understanding chlorophyll fluorescence quenching in natural waters, it is notable that there have been no systematic studies reported to date on the quenching of chlorophyll in any state (free or bound in plant matter) by seawater components. Studies on fluorescence quenching of other species in natural waters, such as natural or dissolved organic matter (NOM/DOM), by halides (chloride, bromide, and iodide), sulphate, and ferric ions, as well as pH effects on their fluorescent intensity have been reported. − Common quenchers that are found in natural waters are metals, singlet oxygen, and halides. − In particular, halides show a strong quenching ability toward several other organic molecules, such as quinine, metal porphyrins, and polyaromatic hydrocarbons …”

The study of plasma effects on quinine solutions

“…Excitation spectra were measured in the wavelength range of 250−370 nm and the emission wavelength was 332 nm. The wavelength ranges were selected based on the literature [ 19,20 ] and adjusted according to the previous measurements. The scan speed was 6000 nm min –1 and the interval was 1 nm.…”