Coumarin Based Highly Selective “off-on-off” Type Novel Fluorescent Sensor for Cu2+ and S2− in Aqueous Solution

Coumarin Based Fluorescent Probe for Detecting Heavy Metal Ions

Heavy metals such as Iron, Copper, and Zinc are micro-essential trace metal and involve animportant biological role, but it quickly turns toxic at exceeding the permissible limit, causing gastrointestinal irritation, liver, bone, and kidney damage, as well as disorders including Wilson's, Parkinson's, and Alzheimer's. It is important to detect the metal ions as well as their concentration quickly and affordable cost using organic probes. Among the organic probes,the coumarin fluorescent probe shows a very prominent candidate with heavy metal ions. Therefore, in the present review, we reviewed the very recent literature the identify the heavy metals using modified coumarin fluorescent probes. Readers will get information quickly about the method of preparation of modified coumarin core and their use as fluorescent probes with heavy metals using absorption and emission spectroscopic methods along with the probable mechanistic pathway of detection.

Coumarin-Phosphazenes: Enhanced Photophysical Properties from Hybrid Materials

Phosphazenes have drawn a great deal of interest over the past 20 years as a potentially useful building block for the fabrication of fluorescent materials. The main objective of this work is to explore novel derivatives produced by coumarins, a class of chemicals well-known for their photophysical importance, and cyclophosphazenes. UV absorbance, fluorescence emission, quantum yield, and lifetime measurements were conducted to comprehend the optical properties. Furthermore, single-crystal X-ray analysis and theoretical calculations were carried out to confirm the structure of the molecule. The obtained findings collectively confirm the commendable optical properties exhibited by the studied compounds. Moreover, a detailed study of the crystal packing arrangement of DPP-Et-Kum-Et compound crystallized in the P21/n monoclinic space group revealed the presence of stacking interactions between the nonplanar conjugated benzene rings of the coumarins and the rigid diphenyl groups attached to the phosphazene ring. The crystal structure of the DPP-Kum-Me-Me compound is mainly based on classical C-H···O intermolecular hydrogen bonding interactions with an average distance of 2.52 Å. Importantly, the calculated absorption spectra of the compounds are in close agreement with the experimental data, further supporting their interesting electronic properties. Given that the DPP-Et-Kum-Et and DPP-Kum-Et compounds have the theoretically lowest band gaps (4.31 and 4.30 eV, respectively), the activation energies of these compounds were determined by an impedance analyzer using dc conductance values measured at different temperatures. The calculated activation energies for DPP-Et-Kum-Et and DPP-Kum-Et are 104.49 and 100.92 meV, respectively. The results demonstrate that both theoretical and experimental calculations are in agreement with each other and that the DPP-Kum-Et compound has the lowest conductivity.

Small Molecule Optical Probes for Detection of H2S in Water Samples: A Review

Hydrogen sulfide (H2S) is closely linked to not only environmental hazards, but also it affects human health due to its toxic nature and the exposure risks associated with several occupational settings. Therefore, detection of this pollutant in water sources has garnered immense importance in the analytical research arena. Several research groups have devoted great efforts to explore the selective as well as sensitive methods to detect H2S concentrations in water. Recent studies describe different strategies for sensing this ubiquitous gas in real-life water samples. Though many of the designed and developed H2S detection approaches based on the use of organic small molecules facilitate qualitative/quantitative detection of the toxic contaminant in water, optical detection has been acknowledged as one of the best, attributed to the simple, highly sensitive, selective, and good repeatability features of the technique. Therefore, this review is an attempt to offer a general perspective of easy-to-use and fast response optical detection techniques for H2S, fluorimetry and colorimetry, over a wide variety of other instrumental platforms. The review affords a concise summary of the various design strategies adopted by various researchers in constructing small organic molecules as H2S sensors and offers insight into their mechanistic pathways. Moreover, it collates the salient aspects of optical detection techniques and highlights the future scope for prospective exploration in this field based on the limitations of the existing H2S probes.

A Fluorene based Fluorogenic ''Turn-off'' Chemosensor for the Recognition of Cu2+ and Fe2+: Computational Modeling and Living-cell Application

Background:

The traditional methods for the detection and quantification of Cu2+ and Fe3+ heavy metal ions are usually troublesome in terms of high-cost, non-portable, time-consuming, specialized personnel and complicated tools, so their applications in practical analyses is limited. Therefore, the development of cheap, fast and simple-use techniques/instruments with high sensitivity/selectivity for the detection of heavy metal ions is highly demanded and studied.

Methods:

In this study, a fluorene-based fluorescent 'turn-off' sensor, methyl 2-(2-((((9H-fluoren-9- yl)methoxy)carbonyl)amino)-3- phenylpropanamido) acetate (probe FLPG) was synthesized via onepot reaction and characterized by 1H-NMR, 13C-APT-NMR, HETCOR, ATR-FTIR and elemental analysis in detailed. All emission spectral studies of the probe FLPG have been performed in CH3CN/HEPES (9/1, v/v, pH=7.4) media at rt. The quantum (Φ) yield of probe FLPG decreased considerably in the presence of Cu2+ and Fe3+. The theoretical computation of probe FLPG and its complexes were also performed using density functional theory (DFT). Furthermore, bio-imaging experiments of the probe FLPG was successfully carried out for Cu2+ and Fe3+ monitoring in living-cells.

Results:

The probe FLPG could sense Cu2+ and Fe3+ with high selectivity and sensitivity, and quantitative correlations (R2>0.9000) between the Cu2+/Fe3+ concentrations (0.0−10.0 equiv). The limits of detection for Cu2+ and Fe3+ were found as 25.07 nM and 37.80 nM, respectively. The fluorescence quenching in the sensor is managed by ligand-to-metal charge transfer (LMCT) mechanism. Job’s plot was used to determine the binding stoichiometry (1:2) of the probe FLPG towards Cu2+ and Fe3+. The binding constants with strongly interacting Cu2+ and Fe3+ were determined as 4.56×108 M-2 and 2.02×1010 M-2, respectively, via the fluorescence titration experiments. The outcomes of the computational study supported the fluorescence data. Moreover, the practical application of the probe FLPG was successfully performed for living cells.

Conclusion:

This simple chemosensor system offers a highly selective and sensitive sensing platform for the routine detection of Cu2+ and Fe3+, and it keeps away from the usage of costly and sophisticated analysis systems.

3-Phenylcoumarins as a Privileged Scaffold in Medicinal Chemistry: The Landmarks of the Past Decade

3-Phenylcoumarins are a family of heterocyclic molecules that are widely used in both organic and medicinal chemistry. In this overview, research on this scaffold, since 2010, is included and discussed, focusing on aspects related to its natural origin, synthetic procedures and pharmacological applications. This review paper is based on the most relevant literature related to the role of 3-phenylcoumarins in the design of new drug candidates. The references presented in this review have been collected from multiple electronic databases, including SciFinder, Pubmed and Mendeley.

Synthesis of New Quinoline-Conjugated Calixarene as a Fluorescent Sensor for Selective Determination of Cu2+ Ion

A novel quinoline-functionalized calix [4] arene derivative (Quin-Calix) has been successfully synthesized at partial cone conformation and duly characterized by using FTIR, ¹H-NMR, ¹³C-NMR, ESI-MS and elemental analysis techniques. Moreover, the cation-binding property of the calix [4] arene derivative (Quin-Calix) has been investigated towards Cu²⁺, Ba²⁺, Cd²⁺, Co²⁺, Ni²⁺, Zn²⁺ and Fe³⁺ ions, and the recognition event monitored by UV-Vis absorption and fluorescence studies. The results indicated that Quin-Calix displays a remarkable affinity and selectivity only for Cu²⁺ ion. The binding constant and stoichiometry of the complex formed between Quin-Calix and Cu²⁺ ion have been also calculated from the fluorescence data. In addition, Stern-Vohmer equation has been used to elucidate the mechanism of quenching.

Fabrication and sensing properties of phenolphthalein based colorimetric and turn-on fluorogenic probe for CO32- detection and its living-cell imaging application

Herein, an easy assembled colorimetric and ''turn-on'' fluorescent sensor (probe P4SC) based on phenolphthalein was developed for carbonate ion (CO₃^2-) sensing in a mixture of EtOH/H₂O (v/v, 80/20, pH = 7, Britton-Robinson buffer) media. The probe P4SC demonstrated high sensitive and selective monitoring toward CO₃^2- over other competitive anions. Interaction of CO₃^2- with the probe P4SC resulted in a significant increment in emission intensity at λ_em = 498 nm (λ_ex = 384 nm) due to the strategy of blocking the photo induced electron transfer (PET) mechanism. ¹H NMR titration and Job's methods, as well as the theoretical study were carried out to support the probable stoichiometry of the reaction (1:2) between P4SC and CO₃^2-. The binding constant of the probe P4SC with CO₃^2- was calculated as 2.56 × 10¹⁰ M^-2. The probe P4SC providing rapid response time (~0.5 min) with a satisfactorily low detection limit (14.7 nM) may be useful as a valuable realistic sensor. The imaging studies on the liver cancer cells (HepG2) shows the great potential of the probe P4SC for the sensation of intracellular CO₃^2- anions. Furthermore, the satisfactory recovery and RSD values obtained for water application confirming that the probe P4SC could be applied to sensing of CO₃^2- ion.

A Selective Ratiometric Receptor 2-((E)-(3-(prop-1-en-2-yl)phenylimino)methyl)-4-nitrophenol for the Detection of Cu2+ ions Supported By DFT Studies

A Schiff-base 2-((E)-(3-(prop-1-en-2-yl)phenylimino)methyl)-4-nitrophenol (Receptor 1) colorimetric probe was synthesized and its UV-visible and fluorescence spectral properties for the sensing of Cu^+ 2 ions in CH₃OH/H₂O (60:40,v/v) solvent system was explored. The Receptor 1 showed the discriminating spectral behavior with the addition of Cu²⁺ ions solution. The other metal ions showed no significant effect towards Receptor 1. Moreover, the addition of Cu²⁺ ions to the Receptor 1 demonstrated the shift in the peak towards longer wavelength of 405 nm due to the ligand to metal charge transfer (LMCT) effect. The red-shift and new peak at 405 nm are due to the deprotonation of the -OH group and formation of complex and O-Cu covalent bond, respectively. A slight increase in the Cu²⁺ ion concentration exhibited strong absorption and fluorescence properties, leading to the spontaneous change in color from pale yellow to orange. Additionally, Density Functional Theory (DFT) studies were performed to investigate the interaction of Cu²⁺ ions with Receptor 1. The decrease in the energies (3.59062 kcal/mol to 0.36028 kcal/mol) of Cu²⁺-Receptor-1 complex compared to Receptor 1 confirms the strong interaction with high stability. The association constant (Ka) of Cu²⁺-Receptor-1 complex was found as 175000 M^- 1. The limit of detection (LOD) was calculated and noted as 179 nM.

Pyridinyl Conjugate of UiO-66-NH2 as Chemosensor for the Sequential Detection of Iron and Pyrophosphate Ion in Aqueous Media

A new chemosensor UiO-66-N-Py (Py = 2-methinepyridine, N = imine nitrogen) based on isoreticular UiO-66 (University of Oslo) Metal–Organic Framework (MOF) containing 2-methinepyridine functionalized organic linker was solvothermally synthesized and characterized. This UiO-66-N-Py was very selective and sensitive for detecting the Fe3+ ion and sequential detection of the pyrophosphate (PPi) anion. The limits of detection for the Fe3+ ion and PPi were calculated to be 10 ppb (0.19 μM) and 50 ppb (0.3 μM), respectively. The quenching constant Ksv for Fe3+ and the binding constant for PPi were 1.4 × 105 M−1 and 1.7 × 105 M−1, respectively. The functionalization of UiO-66-NH2 with 2-methinepyridine enhanced its fluorescence emission properties and introduced more binding sites for the analytes. We additionally studied the interaction of the sensor and the analytes with Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This chemosensor also demonstrated a regenerative emission property without loss in the detection ability for six consecutive cycles.

A novel phenolphthalein-based fluorescent sensor for Al3+ sensing in drinking water and herbal tea samples

In this study, 3,3-bis(4-hydroxy-3-((E)-((4-hydroxyphenyl)imino)methyl) phenyl)isobenzofuran-1(3H)-one (HMBP) was designed as a ''turn-on″ fluorogenic chemosensor to detect Al³⁺. Studies were performed in C₂H₅OH-HEPES (v/v, 9/1, pH 7.0) media at λ_em = 475 nm. The LOD value was found to be 0.113 µM. The stoichiometric ratio of HMBP-Al³⁺ was determined as 1:2 by Job's plot and ESI-MS as well as ¹H NMR titration. The binding constant of chemosensor HMBP with Al³⁺ from the Benesi-Hildebrand equation was determined to be 1.21 × 10⁸ M^-1. The quantum (Φ) yields were obtained as 0.040 and 0.775 for the chemosensor HMBP and HMBP-Al³⁺, respectively. The response of the chemosensor HMBP towards Al³⁺ was attributed to the strategies of blocking the photo-induced electron transfer (PET) and CN isomerisation mechanisms. Finally, the sensing of the chemosensor HMBP for the determination of Al³⁺ in real food samples, drinking waters and herbal teas, were employed.

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.

Fluorescence "Turn On-Off" Sensing of Copper (II) Ions Utilizing Coumarin-Based Chemosensor: Experimental Study, Theoretical Calculation, Mineral and Drinking Water Analysis

Herein, we report the preparation of a fluorescent sensor based on coumarin derivative for copper (II) ion sensing in CH₃CN/HEPES media. 6,7-dihydroxy-3-(4-(trifluoro)methylphenyl)coumarin (HMAC) sensor was fabricated and analyzed by spectroscopic techniques. The sensor demonstrates "turn on-off" fluorescence quenching in the presence of copper (II) ions at 458 nm. A clear complex between the chemosensor HMAC and copper (II) ions was characterized by ESI-MS as well as the Job's method. Also, the limit of detection (LOD, 3σ/k) value was determined as 24.5 nM in CH₃CN/HEPES (95/5, v/v) buffer media (pH = 7.0). This value is lower than the admissible level of copper (II) ions in drinking water (maximum 31.5 μM) reported by EU Water Framework Directive (WFD) and World Health Organization (WHO) guidelines. The theoretical calculations (density functional theory, DFT) have been performed for the geometric optimized structures. As a final stage, real sample analyses have successfully been performed by using HMAC, as well as ICP-OES method. The relative standard deviation for copper (II) in mineral and drinking water samples has been determined to be below 0.15% and recovery values are in the range of 95.48-109.20%.

A novel fluorescent probe based on isocoumarin for Hg2+ and Fe3+ ions and its application in live-cell imaging

Synthesis of the 2-amino-4-phenyl-6- (isocoumarin-3-yl) -3-cyanopyridine (APICP) containing both isocoumarin and pyridine ring in its structure was carried out, and this compound was characterized by ATR-FTIR, ¹H NMR, and ¹³C NMR spectral techniques. A fluorescence sensor determining Hg²⁺ and Fe³⁺ ions in DMSO/HEPES buffer solution (9/1 v/v, 5 μM, pH 7.0) was developed using the synthesized compound, and the detection limits of the sensor with exquisite selectivity were calculated as 8.12 nM and 5.51 nM for Hg²⁺ and Fe³⁺ ions, respectively. Jobs plot method was used to determine the stoichiometry of APICP-Hg²⁺/Fe³⁺ complexes as 2:1 and FT-IR and ESI-MS methods confirmed the results. Besides, cell growth inhibitory potentials of the sensor over HepG2 cells and in vivo fluorescent cell imaging experiments were conducted. Findings revealed the relatively low cytotoxic effects of the synthesized sensor (IC₅₀: 0.541 ± 0.039 mM), and it could be utilized as an intracellular imaging agent for the determination of Fe³⁺ and Hg²⁺ ions in biological systems.

A simple and sensitive fluorescent sensor platform for Al3+ sensing in aqueous media and monitoring through combined PET and ESIPT mechanisms: practical applications in drinking water and bio-imaging

A novel hydrazide-based probe was designed and prepared as a fluorogenic “turn-on” sensor for Al³⁺ sensing in aqueous media.

Coumarin-Based Small-Molecule Fluorescent Chemosensors

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

A dual-function probe based on naphthalene for fluorescent turn-on recognition of Cu2+ and colorimetric detection of Fe3+ in neat H2O

A simple naphthalene derivative, 6-hydroxy-2-naphthohydrazide (NAH), was designed and synthesized through two facile steps reactions with the 6-hydroxy-2-naphthoic acid (NCA) as the starting material. In neat H₂O (10% 0.01 M HEPES buffer, v/v, pH = 7.4), probe NAH showed a highly selective and sensitive response towards Fe³⁺ via perceptible color change and displayed "turn-on" dual-emission fluorescence response for Cu²⁺. The binding stoichiometry ratio of NAH/Cu²⁺ and NAH/Fe³⁺ were all confirmed as 1:1 by the method of fluorescence job's plot and UV-Vis job's plot, respectively. Probe NAH can be used over a wide pH range for the determination of Fe³⁺ (2.0-10.0) and Cu²⁺ (6.0-10.0) without interference from other co-existing metal ions. A possible detection mechanism was the hydrolysis of NAH upon the addition of Fe³⁺ or Cu²⁺, thereby leading to the formation of 6-hydroxy-naphthalene-2-carboxylic acid (NCA) which was further confirmed by the various spectroscopic techniques including FT-IR, ¹H NMR titration and HRMS. Moreover, NAH was successfully applied to the detection of Cu²⁺ and Fe³⁺ in tap water, ultrapure water and BSA.

Fluorescent Sensors for the Detection of Heavy Metal Ions in Aqueous Media

Due to the risks that water contamination implies for human health and environmental protection, monitoring the quality of water is a major concern of the present era. Therefore, in recent years several efforts have been dedicated to the development of fast, sensitive, and selective sensors for the detection of heavy metal ions. In particular, fluorescent sensors have gained in popularity due to their interesting features, such as high specificity, sensitivity, and reversibility. Thus, this review is devoted to the recent advances in fluorescent sensors for the monitoring of these contaminants, and special focus is placed on those devices based on fluorescent aptasensors, quantum dots, and organic dyes.

Crystal structures, Hirsfeld surface analysis and a computational study of four ethyl 2-oxo-2H-chromene-3-carboxylate derivatives: a survey of organyl 2-oxo-2H-chromene-3-carboxylate structures

Crystal structures, Hirshfeld surface analysis and a computational study have been carried out on 2-oxo-2H-chromene-3-carboxylates. Crystal structures are reported for ethyl R-2-oxo-2H-chromene-3-carboxylate derivatives, 2a: R=6-Me, 2b: 7-Me, 2c: 7-Me, 2d: R=7-MeO. In contrast to 2-oxo-2H-chromene-3-carboxamides, 1, in which classical intramolecular N–H···O hydrogen bonds stabilize planar structures and hinder rotation of the amido group out of the coumarin plane in 2, without an equivalent hydrogen bond, there is a greater rotational freedom of the carboxylate group. The interplanar angles between the coumarin core and its attached –C(O)–R substituent in crystalline 2a, 2b, 2c and 2d are 10.41(6), 36.65(6), 10.4(2) and 5.64(6)°, respectively, with distances between the carbonyl oxygen atoms of 2.8255(16), 2.9278(16), 4.226(2) and 2.8328(14) Å, respectively. A theoretical study of molecular conformations was carried out at the M06-2X density level with the 6-31+G(d) and aug-cc-pVTZ basis sets, in methanol solution modeled by PCM, indicated that the most stable conformations had the carbonyl group of the ester in the plane of the coumarin core: the s-cis arrangement of the ester carbonyl and the 2-oxo moieties being the slightly more stable than the s-trans form by less than 0.5 kcal/mol. The experimental conformations of 2a and 2d match well the low energy s-cis arrangement, and 2c matches the slightly lesser stable s-trans arrangement found in the theoretical study. A survey of the molecular conformations of more than 50 2H-chromene-3-carboxylates derivatives in the CCDC data base indicated two distinct groupings of conformations, s-cis and s-trans, each with interplanar angles <30°.

A fluorescent and colorimetric probe based on naphthalene diimide and its high sensitivity towards copper ions when used as test strips

Herein, a red fluorescent and colorimetric probe (NDI-Py) based on naphthalene diimide was designed and synthesized, which exhibited rapid response, high sensitivity and selectivity towards copper ions, and the detection limit was as low as 0.97 μM in solution. Furthermore, NDI-Py demonstrated a strong red emission in the aggregated state because of its non-planar structure. Thus, it can act as a test strip to conveniently monitor copper ions with the detection limit as low as 2.0 μM.

A red fluorescent and colorimetric probe (NDI-Py) exhibited high selectivity and sensitivity towards copper ions both in solution and on silica gel plates.

A multiple target chemosensor for the sequential fluorescence detection of Zn2+ and S2− and the colorimetric detection of Fe3+/2+ in aqueous media and living cells

A novel multiple target sensor DHIC was developed for the fluorescence detection of Zn²⁺ and S²⁻ and colorimetric detection of Fe^3+/2+. Moreover, DHIC could image sequentially Zn²⁺ and S²⁻ in living cells.

Selective and sensitive fluorescent and colorimetric chemosensor for detection of CO32- anions in aqueous solution and living cells

A new colorimetric and fluorescent chemosensor for visual determination of carbonate ions was developed by the microwave assisted solvent free synthesis of 7,8-dihydroxy-3-(4-methylphenyl) coumarin (DHMC). The structural characterization of DHMC was confirmed by microanalysis and spectroscopy methods (MALDI-TOF, FT-IR, ¹H NMR, ¹³C NMR, and 2D HETCOR). The binding behaviors of DHMC were investigated towards various anions by UV-vis and fluorescence spectroscopy. DHMC showed a selective and sensitive fluorometric and colorimetric responses towards carbonate ion over other anions. The detection limit of CO₃^2- was found to be 1.03 µM. Moreover, the fluorescence imaging in living cells suggests that DHMC has a great potential in the biological imaging application. It has been demonstrated that DHMC can be used as a rapid and reliable sensor for the determination of carbonate anion in a variety of practical applications.

Sequential detection of Fe3+/2+ and pyrophosphate by a colorimetric chemosensor in a near-perfect aqueous solution

A colorimetric chemosensor was developed for Fe^3+/2+ and pyrophosphate with low detection limit and practical application for Fe³⁺ in water samples.