Highly selective on-off fluorescence recognition of Fe3+ based on a coumarin derivative and its application in live-cell imaging

A ″On-Off″ Fluorescent Sensor Based on Coumarin-Furoic Hydrazide for Recognition of Fe3+: Drinking Water, Test Strip Applications and DFT Calculations

A coumarin based fluorescent probe (E)-N'-((7-hydroxy-2-oxo-2H-chromon-3-yl)methylene)furan-2-carbohydrazide (CFHZ) was synthesized for the detection of Fe3+ and its characterizations were carried out using spectroscopic methods such as FT-IR, mass spectrometry1H-NMR, 13C-NMR. The novel probe CFHZ showed a highly selective and sensitive "turn-off" response to Fe3+ ion without any interference from other analytes. Strong fuorescence quenching phenomena of the CFHZ were observed in EtOH:H2O (99/1, v/v) detection system (λem = 470 nm) upon the additions of Fe3+. The binding stoichiometry between CFHZ and Fe3+ was determined by Job's method, FT-IR and MALDI TOF-MS and found to be 2:1. Also, the binding constant was determined to be 1.82 × 105 M-1 and the limits of detection for the analysis of Fe3+ was measured as 25.7 nM. Besides, experimental applications were carried out for real-time monitoring of Fe3+ in water samples using developed sensor. Additionally, fluorescence imaging experiments for Fe3+ detection of CFHZ probe on test papers were successfully performed.

Luminous Insights: Exploring Organic Fluorescent "Turn-On" Chemosensors for Metal-Ion (Cu+2, Al+3, Zn+2, Fe+3) Detection

There are several metal ions that are vital for the growth of the environmental field as well as for the biological field but only up to the maximum limit. If they are present in excess, it could be hazardous for the human health. With the growing technology, a series of various detection techniques are employed in order to recognize those metal ions, some of them include voltammetry, electrochemical methods, inductively couples, etc. However, these techniques are expensive, time consuming, requires large storage, advanced instrumentation, and a skilled person to operate. So, here comes the need of a sensor and it is defined as a miniature device which detects the substance of interest by giving response in the form of energy change. So, from past few decades, many sensors have been formulated for detecting metal ions with some basic characteristics like selectivity, specificity, sensitivity, high accuracy, lower detection limit, and response time. Detecting various metal ions by employing chemosensors involves different techniques such as fluorescence, phosphorescence, chemiluminescence, electrochemical, and colorimetry. The fluorescence technique has certain advantages over the other techniques. This review mainly focuses on the chemosensors that show a signal in the form of fluorescence to detect Al+3, Zn+2, Cu+2, and Fe+3 ions.

Ferric ion detection mechanism of a dicarboxylic cellulose nanocrystal and a 7-amino-4-methylcoumarin based fluorescent chemosensor

As one of Earth's most widely distributed and abundant elements, iron impacts the natural environment and biological systems. Therefore, developing a simple, rapid, and accurate Fe3+ detection method is vital. Fluorescent dicarboxylic cellulose nanocrystals (FDCN) with selective quenching of Fe3+ were synthesized using 7-amino-4-methylcoumarin (AMC), and dicarboxylic cellulose nanocrystals (DCN) prepared by sequential periodate-chlorite oxidation. The sensing characteristics and detection mechanism of FDCN for Fe3+ were studied by fluorescence spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), the Stern-Volmer equation, Job's plot method, and the Benesi-Hildebrand equation. The results showed that FDCN was highly selective for Fe3+, and other metal ions did not reduce the selectivity. High sensitivity with a detection limit of 0.26 μM and a Stern-Volmer quenching constant of 0.1229 were also achieved. The coordination between Fe3+ and the carboxylic, hydroxyl, and amide groups on the surface of FDCN and the carbonyl of coumarin lactones to form FDCN/Fe3+ complexes prevented the intramolecular charge transfer (ICT) process and led to the fluorescence quenching of FDCN. EDTA restored the fluorescence emission of quenched FDCN. The complexation stoichiometry of Fe3+ to FDCN was 1 : 1, and the association constant was 3.23 × 104 M-1. The high hydrophilicity, sensitivity, and selectivity of FDCN for Fe3+ make the chemosensor suitable for Fe3+ trace detection in drinking water and biology.

Aggregation-Induced Emission of Quinoline Based Fluorescent and Colorimetric Sensors for Rapid Detection of Fe3+ and 4-Nitrophenol in Aqueous Medium

New quinoline based fluorescent sensors 4 and 5 were rationally synthesized that exhibited excellent aggregation induced emission (AIE) in an aqueous medium. High fluorescence emission of sensors was accompanied by a noticeable redshift in their absorption and emission spectra that corresponds to the formation of J-aggregates. An AIE feature of sensors 4 and 5 was used for selective detection of Fe³⁺ and 4-NP in an aqueous medium that is attributed to the involvement of intermolecular charge transfer (ICT). The interaction mechanism of sensors with Fe³⁺ and 4-NP was investigated through ¹H NMR titration, Jobs plots, dynamic light scattering (DLS), and DFT analysis. The fluorescence quenching response of sensors 4 and 5 displayed distinguished linear behavior with the concentrations of Fe³⁺ and limits of detection (LOD) were calculated to be 15 and 10 nM, respectively. Further, LOD of sensors 4 and 5 for 4-NP (7.3 and 4.1 nM, respectively) was very low compared to previously reported sensors. Moreover, sensors' coated test strips were fabricated for solid-supported detection of Fe³⁺ and 4-NP. Sensors were successfully applied for the detection and quantification of Fe³⁺ and 4-NP in real water samples. Additionally, sensors were used for the determination of trace amounts of Fe³⁺ in the human serum sample.

Idiosyncratic recognition of Zn2+ and CN- using Pyrazolyl-Hydroxy-Coumarin scaffold and live cell imaging: Depiction of Luminescent Zn(II)-Metallocryptand

Multi-responsive sensitive and selective sensor design is one of the stimulating researches in sensor field. We have designed a pyrazolyl-hydroxy-coumarin scaffold, 7-hydroxy-4-methyl-8-(((5-phenyl-1H-pyrazol-3-yl)imino)methyl)-2H-chromen-2-one (H2L) and characterized by spectroscopic data (1H-NMR,13C-NMR, ESI-MS,...

A chromone-based multi-selective sensor: applications in paper strips and real sample

A chromone-based multi-selective sensor: applications in a paper strip and real sample.

An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities

Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.

Furo[3,2-c]coumarin-derived Fe3+ Selective Fluorescence Sensor: Synthesis, Fluorescence Study and Application to Water Analysis

Furocoumarin (furo[3,2-c]coumarin) derivatives have been synthesized from single step, high yielding (82-92%) chemistry involving a 4-hydroxycoumarin 4 + 1 cycloaddition reaction. They are characterized by FTIR, 1H-NMR, and, for the first time, a comprehensive UV-Vis and fluorescence spectroscopy study has been carried out to determine if these compounds can serve as useful sensors. Based on the fluorescence data, the most promising furocoumarin derivative (2-(cyclohexylamino)-3-phenyl-4H-furo[3,2-c]chromen-4-one, FH), exhibits strong fluorescence (ФF = 0.48) with long fluorescence lifetime (5.6 ns) and large Stokes' shift, suggesting FH could be used as a novel fluorescent chemosensor. FH exhibits a highly selective, sensitive and instant turn-off fluorescence response to Fe3+ over other metal ions which was attributed to a charge transfer mechanism. Selectivity was demonstrated against 13 other competing metal ions (Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Al3+, Ni2+, Cu2+, Zn2+, Co2+, Pb2+ and Ru3+) and aqueous compatibility was demonstrated in 10% MeOH-H2O solution. The FH sensor coordinates Fe3+ in a 1:2 stoichiometry with a binding constant, Ka = 5.25 × 103 M-1. This novel sensor has a limit of detection of 1.93 µM, below that of the US environmental protection agency guidelines (5.37 µM), with a linear dynamic range of ~28 (~2-30 µM) and an R2 value of 0.9975. As an exemplar application we demonstrate the potential of this sensor for the rapid measurement of Fe3+ in mineral and tap water samples demonstrating the real-world application of FH as a "turn off" fluorescence sensor.

A naphthylamide based fluorescent probe for detection of Al3+, Fe3+, and CN- with high sensitivity and selectivity

A naphthylamide based fluorescent chemosensor, N,N'-(1,2-phenylene)bis(1-hydroxy-2-naphthamide) (H₄L), for detection of Fe³⁺ and Al³⁺ cations as well as CN^- anion is reported. This compound has been synthesized by a novel and facile synthetic method with high yield and characterized by FT-IR, ¹H NMR, elemental analysis, and UV-Vis spectroscopy. It could detect Fe³⁺ and Al³⁺ ions in different media with different excitation and emission wavelengths. In DMSO solution, H₄L showed selective ON-OFF quenching of its 451 nm emission in the presence of Fe³⁺. On the other hand, in DMF solution, H₄L exhibited selective OFF-ON fluorescence upon the addition of Al³⁺, the intensity at 429 nm increases drastically by 24-fold. Also, among the anions, the probe can selectively distinguish CN^- by deprotonation of OH and NH groups, as proved by ¹H NMR titration. TD-DFT calculation supports the UV-Vis and fluorescence measurements of the chemosensor.

A turn-on Schiff base fluorescent probe for the exogenous and endogenous Fe3+ ion sensing and bioimaging of living cells

A Schiff base fluorescent probe, namely naphthalic anhydride – (2-pyridine) hydrazone (NAH), has been synthesized and developed for the highly selective and sensitive monitoring of Fe³⁺ ions in an aqueous solution and living cells.

2-Sulfanylhydroquinone Dimer as a Switchable Fluorescent Dye

A new dye was developed, the photoluminescence properties of which are controlled by a chemical reaction. The fluorescence properties of 2-sulfanylhydroquinone dimers depend on the number of hydroxyl groups that are acylated. Unprotected or monoacylated 2-sulfanylhydroquinone dimers displayed good fluorescence properties, whereas diacylated and tetraacylated 2-sulfanylhydroquinone dimers showed dramatically decreased fluorescence. A monomesylated derivative was devised, which shows good fluorescence characteristics as a switching fluorescence dye through a chemical reaction.

A coumarin derivative as a "turn-on" fluorescence probe toward Cd2+ in live cells

A novel coumarin-derived Schiff base fluorescence probe (CTB) has been successfully designed and synthesized through exploiting tris-(2-aminothyl)-amine moiety as a recognition unit for the highly selective and sensitive detection of Cd²⁺. It is based on CN isomerization and the photo-induced electron transfer (PET) mechanism. The investigation into the sensing processes showed that CTB exhibited an excellent selectivity for Cd²⁺. The sensitivity exceeded that of other competing metal ions, and had a high sensitivity, a detection limit of 1.16 × 10^-7 M with the association constants of 1.37 × 10¹¹ M^-2. The experiments including Job's plot, UV-Vis titration, ¹H NMR titration and ESI-MS spectrum established that the probe CTB binds to Cd²⁺ in a 1:2 ratio. Further studies also demonstrated that probe CTB can be successfully applied to the fluorescence imaging of Cd²⁺ in HepG-2 cells.

Logic gate behavior and intracellular application of a fluorescent molecular switch for the detection of Fe3+ and cascade sensing of F− in pure aqueous media

The nature and coordination sites of a Schiff base 3,3′-(1E,1′E)-(1,3-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol (APHN), are tuned by its selective reduction to design a highly efficient fluorescent probe RAPHN.

Design of a coumarinyl-picolinoyl hydrazide Schiff base for the fluorescence turn-on–off sequential sensing of Al3+ and nitroaromatics, and electronic device fabrication

Designing a small organic molecule for fluorescence sensing and electrical conductivity is a challenging task.

A novel ratiometric and turn-on fluorescent coumarin-based probe for Fe(iii)

6-Methoxy-3-(pyridin-2-yl)-2H-chromen-2-one exhibited fluorescence enhancement in the presence of Fe(iii). This molecule was a selective fluorescent chemosensor for Fe(iii).