Fluorescent Probe For Fluoride Ions Research Articles

TDDFT Study on the ESIPT Properties of 2-(2'-Hydroxyphenyl)-Benzothiazole and Sensing Mechanism of a Derived Fluorescent Probe for Fluoride Ion.

The level of fluoride ions (F-) in the human body is closely related to various pathological and physiological states, and the rapid detection of F- is important for studying physiological processes and the early diagnosis of diseases. In this study, the detailed sensing mechanism of a novel high-efficiency probe (PBT) based on 2-(2'-hydroxyphenyl)-benzothiazole derivatives towards F- has been fully investigated based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. F- attacks the O-P bond of PBT to cleavage the dimethylphosphinothionyl group, and the potential products were evaluated by Gibbs free energy and spectroscopic analyses, which ultimately identified the product as HBT-Enol1 with an intramolecular hydrogen bond. Bond parameters, infrared vibrational spectroscopy and charge analysis indicate that the hydrogen bond is enhanced at the excited state (S1), favoring excited state intramolecular proton transfer (ESIPT). The mild energy barrier further evidences the occurrence of ESIPT. Combined with frontier molecular orbital (FMO) analysis, the fluorescence quenching of PBT was attributed to the photoinduced electron transfer (PET) mechanism and the fluorescence turn-on mechanism of the product was attributed to the ESIPT process of HBT-Enol1.

Phenothiazine-based fluorescent probe for fluoride ions and its applications in rapid detection of endemic disease

Fluoride detection is important in environmental monitoring and disease screening. In many of detection methods, small molecule fluorescent probes have been developed rapidly in recent years for their high efficiency, selectivity and low cost. To develop quickly fluorescent probe for detection fluoride ions, a novel phenothiazine-based fluorescent probe PHT was designed and synthesized. The response time of PHT was only 1 min and the detection line of PHT reached to 1.3 ppb. Moreover, the stoke shift of PHT was close to 140 nm, which was much better than the previous reports. At last, the probe PHT was successfully used for HepG2 imaging and detection of biological samples with endemic disease.

An efficient Turn-ON fluorescent probe for fluoride ions – Meticulous investigations and development of arduino microcomputer integrated smartphone device

Design and development of simple, affordable and ‘turn-ON’ fluorescent probes for fluoride ion sensing is an incessant research target over the decades. In this context, we have developed the new benzothiophene derivatives for the selective detection of trace-level fluoride ions. The synthesized derivatives were meticulously characterized using pivotal techniques and contented results were accomplished. Intriguingly, the developed probe is selectively responded to a trace amount of fluoride ions. The fluorescence quantum yield of the probe is also enhanced upon introducing the fluoride ion, thus this probe could be act as a ‘turn-ON’ fluorescent probe. The mechanism of fluoride ion detection was elucidated using 1H NMR and FT-IR investigations. The recovery and reversibility studies of the probe were conducted and the probe was stable upto 10 cycles. On the other hand, a portable Arduino-based platform is developed for the first time to validate the experimental results. The arduino microcomputer device is interfaced with the RGB sensors which identify the colour changes and quantifies fluoride concentration with respect to the RGB values. The RGB results were also shared to the developed android application through wired/wireless tethering. The application is also designed to share the data with remote users through cloud platform.

A Simple Water-Soluble ESIPT Fluorescent Probe for Fluoride Ion with Large Stokes Shift in Living Cells.

Developing an effective method for monitoring fluoride ion in biological samples is meaningful because fluoride ion plays a vital role in biological processes. In this contribution, a simple water-soluble ESIPT fluorescent probe 2-((4-((tert-butyldiphenylsilyl)oxy)-1,3-dioxoisoindolin-2-yl)methyl)-1-ethylpyridin-1-ium iodide (SPI) was constructed for monitoring fluoride ion. The probe SPI containing pyridinium salt group exhibited preeminent water solubility. The probe SPI introducing a trimethyldiphenylsilyl ether recognition group displayed excellent selectivity for fluoride ion over other biologically relevant species. Additionally, the probe SPI exhibited a fast response for a fluoride ion, suggesting that it could provide real-time fluoride ion detection. Importantly, the probe could detect fluoride ion with a linear range of 0–70.0 × 10–6 M and a low detection limit of 1.16 × 10–6 M. Furthermore, probe SPI could detect fluoride ion with a large Stokes shift (98 nm), which was attributed to ESIPT fluorescence sensing process. At last, probe SPI was successfully employed to monitor fluoride ion in living cells.

A novel fluorescent off-on probe for the sensitive and selective detection of fluoride ions.

A highly sensitive and selective fluorescent probe for fluoride ions has been developed by incorporating the dimethylphosphinothionyl group as a recognition moiety into the fluorophore of coumarin. The detection mechanism is based on the fluoride ion-triggered cleavage of the dimethylphosphinothionyl group, followed by the release of coumarin, which leads to a large fluorescence enhancement at 455 nm (λex = 385 nm). Under the optimized conditions, the fluorescence enhancement of the probe is directly proportional to the concentration of fluoride ions in the range of 0–30 μM with a detection limit of 0.29 μM, which is much lower than the maximum content of fluoride ions guided by WHO. Notably, satisfying results have been obtained by utilizing the probe to determine fluoride ions in real-water samples and commercially available toothpaste samples. The proposed probe is rather simple and may be useful in the detection of fluoride ions in more real samples.

A novel fluorescein-coumarin-based fluorescent probe for fluoride ions and its applications in imaging of living cells and zebrafish in vivo

A novel fluorescent probe (Flu-Si) based on fluorescein and coumarin fluorophores for highly selective and sensitive detection of F− was successfully developed. It was shown that the mechanism of recognition involves a desilylation reaction that takes place after addition of F− anions. A linear relationship between the ratio of emission intensities at 532 and 465 nm (I532/I465) and F− concentration over the range of 0–20 μmol L−1 with a LOD of 0.025 μmol L−1 was found. The sensing mechanism of Flu-Si with F− was confirmed by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculation. Moreover, it was demonstrated that Flu-Si is an efficient fluorescent probe for F− anions in living cells and zebrafish, indicating its sensing potential in clinical diagnosis.

Indolo[3,2-b]carbazole derivative as a fluorescent probe for fluoride ion and carbon dioxide detections

Fluorescent probes can detect fluoride ion and carbon dioxide to ensure their concentrations at reasonable levels to protect human health. Although numerous fluorescent probes have been developed in the last decades, these probes still face some performance challenges: complicated molecular structures, unremarkable changes and long responsive times. Moreover, the detections of fluoride ion and carbon dioxide are usually separated and fluorescent probes which can detect fluoride ion and carbon dioxide simultaneously are rare. To improve this situation, in this work, an indolo[3,2-b]carbazole derivative, DP-ICZ, was designed. This compound had simple structure and facile preparation procedure. It displayed high selectivity toward fluoride ion over other ions. Obvious changes of color, fluorescence band and intensity happened in a few seconds after the addition of fluoride ion. Meanwhile, after activated by fluoride ion, DP-ICZ was also suitable for carbon dioxide detection. Its detection limits for fluoride ion and carbon dioxide were 23.3μM and 1.07μM respectively. Through PL spectra and NMR analysis, its detection mechanisms were proved to be deprotonation by fluoride ion and recovery by carbon dioxide respectively. Our study presents an effective basic group based on which researchers can develop new fluorescent probes with simple structures, high sensitivities, short responsive times and the abilities to detect fluoride ion and carbon dioxide simultaneously.

A highly selective naked-eye and fluorescent probe for fluoride ion based on 1,8-naphalimide and benzothizazole

Based on benzothizazole and 1,8-naphalimide, a novel colorimetric and fluorescent probe (probe 1) for fluoride ion was synthesized by Schiff base reaction. The striking yellow-to-blue color change of the probe 1 in the CH3CN was observed with the naked eyes only in presence of F− among the eight anions (F−, Cl−, Br−, I−, NO3−, HSO4−, H2PO4−, AcO−). Besides that, upon addition of F−, both of the absorption and emission peaks shifted to near-infrared region (NIR) (>600 nm) in UV–vis and fluorescent spectra, and the detection limit reached as low as 0.41 μM. Furthermore, the 1H NMR titration and theoretical calculation based on TD-DFT indicated that the fluoride ion induced deprotonation of the probe 1 through hydrogen bonding interaction between amino group of probe 1 and fluoride ion.

A turn-on fluorescence probe for the selective and sensitive detection of fluoride ions.

The sensitive and selective determination of fluoride ions is particularly significant in environmental protection, food safety, and health care products. In this work, a highly selective turn-on fluorescent probe for fluoride ions has been synthesized by simply functionalizing fluorescent isophthalaldehyde with silicone-oxygen bonding. The selectivity of the probe is based on the specific reactivity ofthe silyl group toward fluoride ions in aqueous solution. The nucleophilic substitution reaction of fluoride ions triggers the cleavage of the Si-O bond to release a strongly fluorescent product, which can be used for the determination of fluoride ions by fluorescence intensity enhancement. The probe molecules are specifically responsive and highly selective for the fluoride anion over other relevant anions and cations. This fluorescent probe also shows high photostability and exhibits good sensitivity for fluoride ions, and the limit of detection is as low as 67ppb. We have demonstrated its application for on-site sensitive determination of fluoride ions for environmental monitoring and protection.

A ratiometric fluorescent probe for fluoride ion based on naphthoimidazolium receptor

Three imidazolium derivatives 3–5 were designed and synthesized, in which naphthaimidazolium group acted as both fluorophore and anion receptor. Compound 3 exhibited high selectivity for F− in CH3CN solution over all the other anions and acted as a ratiometric fluorescent probe for F− with an enhanced blue-shift in emission. However, the fluorescence of compound 4 and 5 displayed a quenched blue-shift in emission with fluoride ion and could be quenched by some other tested anions, where the degree of quenching depended on the characteristic of the anions. More importantly, only compound 3 could detect F− in DMSO–water (95 : 5, v/v) aqueous solution ratiometrically. Based on the analysis of the results of 1H-NMR and 19F-NMR, it was deduced that compound 3 bound with F− mainly by the force of hydrogen bonding, while compound 4 and 5 coordinated with F− through electrostatic interaction.

A colorimetric and fluorescent probe for fluoride ions based on 6‐acetyl‐2‐naphthol

A colorimetric and turn-on fluorescent probe for fluoride ions, tert-butyldimethylsilane 6-acetyl-2-naphtholate, was readily synthesized from 6-acetyl-2-naphthol and tert-butyldimethylchlorosilane (TBSCl). The probe exhibits high sensitivity and good selectivity for fluoride ions in acetonitrile. The inherent mechanism involves the cleavage of the Si-O bond in the probe, which induced yellow color formation and prominent fluorescence enhancement.

A ratiometric fluorescent probe for fluoride ions with a tridentate receptor of boronic acid and imidazolium

A new ratiometric fluorescent probe for fluoride ions was developed which complexed fluoride by a tridentate receptor of boronic acid and imidazolium. In the current study, a tridentate receptor 1 with one ortho boronic acid and two imidazolium groups was designed. The boron center can co-operate with imidazolium to bind F−. The formation of B–F complex stabilizes the interaction between fluoride and imidazolium which induces a ratiometric fluorescence response. With the addition of F−, a strongly increased fluorescent emission centered at 370nm appears at the expense of the fluorescent emission centered at 445nm.

A new diketopyrrolopyrrole (DPP) derivative bearing boronate group as fluorescent probe for fluoride ion

Abstract A new diketopyrrolopyrrole (DPP) derivative bearing pinacol boronate group has been synthesized via Suzuki–Miyaura reaction under mild conditions in good yield. The product could act as a colorimetric and ratiometric fluorescent probe for fluoride ion with high sensitivity and selectivity. The recognition mechanism was attributed to unique fluoride–boron interaction, which blocked the charge transfer (CT) between DPP chromophore and the empty p orbitals of boron atoms, and proved by the fluorescence spectra, 19F NMR spectra and 1H NMR spectra titration experiments.

A Highly Selective Colorimetric and “Off-on-off” Fluorescent Probe for Fluoride Ions

In this paper, a highly selective and sensitive probe for fluoride ions (F(-)), containing a phenylpyridylvinylene derivative reporter and a Si-O bond receptor, was designed and characterized. The reaction mechanism is based on the intramolecular charge transfer (ICT) mechanism. Upon addition of F(-), probe 1 showed a remarkable red-shift (183 nm) in the absorption spectra accompanying with the color changes from colorless to purple, so probe 1 could serve as a "naked-eye" probe for F(-). The absorbance of probe 1 at 545 nm increased linearly with the concentration of F(-) from 20 to 150 µM. The detection limit was calculated to be 0.1 µM. Besides, "off-on-off" fluorescence intensity changes were also observed in the fluorescence spectra. The present results may provide a useful approach for the development of highly selective dual-channel probes for F(-).

A fluorescent probe for fluoride ion based on 2-aminopyridyl-bridged calix[6]arene

An 2-aminopyridyl-bridged calix[6]arene on the upper rim fixed in cone conformation ( 3) was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and 1H NMR titration experiments.

Electrodes for blood pO2 and pCO2 determination.

Electrodes for blood pO2 and pCO2 determination.