Selective Fluorescent Chemosensor Research Articles

Novel highly selective quinoline-based fluorescent chemosensors for quantitative analysis of Cu(II) ion in water and food

While copper (Cu2+) is a vital cofactor in numerous enzymatic processes, its homeostasis is critical. Selective sensors for Cu2+ in food matrices are paramount for ensuring adherence to safety regulations and dietary interaction studies. In this work, novel derivatives of 8-aminoquinoline (L1-L4) with extended π-conjugation and various N-substituents were synthesized and evaluated as fluorescent sensors for Cu2+. The 2-pyridinecarbonyl-substituted derivative L3 exhibited sharp fluorescence quenching selectively in the presence of Cu2+. This compound presents high selectivity for Cu2+ even in the presence of other metal ions. The L3-based fluorescent sensor provides a Cu2+ detection limit of 77 nM, surpassing many existing sensors. The quantifications of Cu2+ in water, food supplements, and wines using this sensor have demonstrated good agreement with those obtained using the standard ICP technique. Notably, L3 also facilitates Cu2+ detection in microliter sample volumes at subnanomole levels using paper-based sensors, opening doors for portable and cost-effective on-site testing.

Green Synthesis of Carbon Quantum Dots Using Barks of Ficus religiosa and their Application as a Selective Fluorescence Chemosensor

Green Synthesis of Carbon Quantum Dots Using Barks of Ficus religiosa and their Application as a Selective Fluorescence Chemosensor

Photophysical Investigation of One Pot Synthesized Novel Indenofluorene Derivative (BDP) as a Fluorescent Chemosensor for the Detection of Fe3+ Ion.

An Indane-1-one derivative 11-(1-benzyl-1H-indol-3-yl)-10,12-dihydrodiindeno[1,2-b:2',1'-e]-pyridine (BDP) has been synthesized by the reaction of Indan-1-one with 1-benzyl-1H-indole-3-carbaldehyde. FT-IR, 1H-NMR, 13N-NMR and Mass spectroscopic techniques has been used to confirmed the structure of BDP. The observed photophysical changes in BDP across various solvents were associated. The impact of various interactions on photophysical parameters, including Stokes shift, dipole moment, oscillator strength, and fluorescence quantum yields, has been assessed in relation to solvent polarity. Moreover, BDP demonstrates potential as a selective fluorescent chemosensor for detecting Fe3+ ion within a range of cations in an aqueous DMSO environment. A thorough investigation into the recognition mechanism of BDP towards Fe3+ ion has been conducted using Benesi-Hildebrand and Stern-Volmer, measurements. BDP forms a 2:1 complex with the Fe3+ ion, exhibiting fluorescent quenching behaviour.

Novel pyrazine Schiff-base derivative functionalized water-soluble polymer as a highly selective fluorescent chemosensor for Al3+ ions in pure aqueous solution

A novel water-soluble polymer P1 functionalized with pyrazine Schiff-base derivative was successfully synthesized. As an efficient “turn-on” fluorescent chemosensor, P1 showed high selectivity and anti-interference ability for the detection of Al3+ ions in pure aqueous solutions. The detection limit of P1 for Al3+ ions was as low as 3.68 × 10−8 M. P1 displayed good detectability for Al3+ ions over a wide pH range of 5–10. The detection of Al3+ ions by P1 has been proven to have excellent reversibility by alternately adding Al3+ ions and EDTA to P1 aqueous solution. Furthermore, P1 could be applied to quantitative determination of Al3+ ions in real water samples. P1-based test strips were also facilely prepared for convenient on-site qualitative detection of Al3+ ions in realistic aqueous samples.

A highly selective and sensitive quinoline-based fluorescent turn-off chemosensor for the detection of picric acid

A simple turn-off quinoline-based fluorescent chemosensor, 1-(6-amino-2-methyl-4-phenylquinolin-3-yl)ethan-1-one (QN) has been developed, synthesized, and characterized by various spectroscopic methods. This probe is selective for the sequential recognition of picric acid (PA), using a fluorescent turn-off method. QN exhibits a broad emission band at 504 nm, but fluorescence quenching occurs upon the addition of picric acid over other nitro compounds. The binding stoichiometric ratio between QN and picric acid was calculated to be 1:1 through Job's plot analysis, and the binding constant was determined. The limit of detection towards picric acid was found to be 9.33 µM. Further, the mechanistic approach for binding has been investigated by spectroscopic methods like 1H NMR titration, FT-IR studies, and density functional theory (DFT) studies.

Synthesis of biscarbazole derivative, detection of the “on-off” sensor property of Cu2+ by fluorimetry, and anti-cancer evaluation

Biscarbazole derivative probe (6) (Z)-2-(3-(((9-heptyl-9H-carbazol-3-yl)methylene)amino)-9H-carbazol-9-yl)ethan-1-ol containing an imine group, which is a sensitive and selective fluorescence chemosensor, was designed and synthesized for the effective evaluation of Cu2+ metal ion levels. The synthesized compounds were characterized using 1H NMR, 13C NMR, FT-IR, and MALDI-TOF MS (for compound 6) spectroscopic data. The interaction model between probe 6 and Cu2+ was determined by combining fluorescence methods, 1H NMR titration, Job’s plot, and theoretical calculations. For probe 6, the fluorogenic recognition of Cu2+ was investigated by fluorescence spectroscopy, and the optical changes caused by Cu2+ ions were carried out in ACN/H2O (50:50) solution at pH 7.0. Fluorescence probe 6 was found to “turn-off” its fluorescence in the presence of paramagnetic Cu2+ ions. Probe 6 was determined to have a rapid response within 40s and showed a fluorescence response to Cu2+ with a low detection limit of 0.16 μM. Additionally, in vitro anticancer activity and cell imaging studies of probe 6 against the prostate cell line (PC-3) were performed.

Development of a simple polymer-based sensor for detection of the Pirimicarb pesticide

In this study, a sensitive and selective fluorescent chemosensor was developed for the determination of pirimicarb pesticide by adopting the surface molecular imprinting approach. The magnetic molecularly imprinted polymer (MIP) nanocomposite was prepared using pirimicarb as the template molecule, CuFe2O4 nanoparticles, and graphene quantum dots as a fluorophore (MIP-CuFe2O4/GQDs). It was then characterized using X-ray diffraction (XRD) technique, Fourier transforms infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscopy (TEM). The response surface methodology (RSM) was also employed to optimize and estimate the effective parameters of pirimicarb adsorption by this polymer. According to the experimental results, the average particle size and imprinting factor (IF) of this polymer are 53.61 nm and 2.48, respectively. Moreover, this polymer has an excellent ability to adsorb pirimicarb with a removal percentage of 99.92 at pH = 7.54, initial pirimicarb concentration = 10.17 mg/L, polymer dosage = 840 mg/L, and contact time = 6.15 min. The detection of pirimicarb was performed by fluorescence spectroscopy at a concentration range of 0–50 mg/L, and a sensitivity of 15.808 a.u/mg and a limit of detection of 1.79 mg/L were obtained. Real samples with RSD less than 2 were measured using this chemosensor. Besides, the proposed chemosensor demonstrated remarkable selectivity by checking some other insecticides with similar and different molecular structures to pirimicarb, such as diazinon, deltamethrin, and chlorpyrifos.

A new water−soluble naphthalene diimide as a highly selective fluorescent chemosensor for Cu(II) ion: Synthesis, DFT calculations, photophysical and electrochemical properties

The highly selective, sensitive, and water-soluble fluorescent sensors are desideratum for optoelectronic, environmental, biological, and biomedical applications. An innovative fluorescence chemosensor, naphthalene diimide (3) with metal binding sites, was designed, synthesized and characterized. The chemosensor's optical, electrochemical, spectroelectrochemical, and morphological properties were investigated, and then the density functional theory (DFT) simulations were conducted. The selectivity of 3 for the metals Cu(II), Ag(I), Hg(II), Mg(II), Fe(III), Ca(II), Co(II), Zn(II), Pb(II) and Cd(II) were investigated through UV–visible and fluorescence spectroscopy techniques. 3 was highly selective and sensitive toward Cu(II) metal ions. The chemosensor can detect Cu(II) in water with a detection limit of 1.11 μM, which is lower than the WHO standard and has good repeatability. Further investigations through the IR, DPV, AFM, UV–visible and fluorescence spectroscopies, SEM, EDX and TEM techniques confirmed the binding capabilities of the 3 with Cu(II).

Phenoxazine-based fluorescence chemosensor for selective detection of cyanide

Purpose A highly selective cyanide phenoxazine-based fluorescence chemosensor POH was created to detect cyanide (CN) ions. Design/methodology/approach A malonitrile was added to a phenoxazine fluorophore to make this widely available chemosensor. By fluorescence spectroscopy, the sensor POH showed turn-off fluorescence emission for CN with 2:1 binding stoichiometry in CH3CN/H2O (90:10 v/v) medium. Findings The detection limits for CN were 9.8 × 10−9 M, which were much lower than WHO standards. NMR and FT-IR investigations backed up the suggested sensor POH mechanism. Originality/value The detection CN method should be applicable in a number of situations, where the CN anion for fresh water and drinking water has to be quickly and accurately analyzed. Graphical abstract

Chromene Carbohydrazide- Schiff Base as a Highly Selective Turn-Off Fluorescence Chemosensor for In3+ Ion and its Application.

A new 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide design to synthesize a simple Schiff-base condition. The synthesized molecules' (probe L) photophysical properties were investigated in various solvent systems and solvent-poor-solvent assays. Probe L exhibits the absorbance band at 440nm and the emission band at 488nm in DMSO: H2O (7:3, v/v). Further, probe L shows selective turn-off emission recognition of In3+ ions in DMSO: H2O (7:3, pH = 7.4). By Job's plot and ESI mass analysis, probe L forms a 1:2 stoichiometry complex with an estimated association constant of 4.04 × 104 M- 2 with In3+ ions. Metal induces CHEQ (chelation-caused fluorescence quenching) to reduce the intensity of probe L's emission, and the estimated quenching constant was 4.52 × 104 M- 1. The limit of detection was found to be 5.93 nM; the time response of the sensor is instantaneous, and its reversible nature was confirmed using EDTA additions. Solid substrates (test strips) were designed and tested for fast, reliable, user-friendly, and real-time sensing of In3+ ions for on-site applications. The binding mechanism of probe L with In3+ ions was investigated using 1H NMR titration and DFT/TD-DFT studies.

A novel chromone Schiff base as Zn2+ turn-on fluorescent chemosensor in a mixed solution.

In this study, a novel fluorescent chemosensor 1 based on chromone-3-carboxaldehyde Schiff base was synthesized and featured through nuclear magnetic resonance (NMR) and mass spectra. Spectroscopic investigation indicated that the fluorescent sensor showed high selectivity toward Zn2+ over other metal ions and that the detection limit of 1 could reach 10-7 M. These indicated that 1 acted as a highly selective and sensitive fluorescence chemosensor for Zn2+ .

Starch/rhodamine 6G conjugate as a non-cytotoxic, effective, and selective fluorescent chemosensor for detection of Fe3+ ion

Iron is a crucial trace mineral vital for maintaining optimal human health and well-being. Despite being needed in small amounts, its importance cannot be overstated as it plays an important role in various physiological processes. In this research, we have developed a fluorescence probe utilizing starch functionalized with derivatives of rhodamine 6G to efficiently detect Fe3+ ions. This structure forms self-assembled starch/rhodamine 6G (RS0) fluorescent nanoparticles that exhibit strong fluorescence intensity under ultraviolet light. The ability of Fe3+ ions to increase the fluorescence of the RS0 probe enables the effective detection of Fe3+ ions. Importantly, this fluorescence increasing effect is specific to Fe3+ ions and remains unaffected by the presence of other metal ions. MTT assay against SH-SY5Y cells showed that RS0 was rather cytocompatible. Finally, SH-SY5Y cells were used to measure cell uptake and fluorescence imaging performances of RS0 which showed a good ability for live-cell fluorescence imaging.

Bodipy-based quinoline derivative as a highly Hg2+-selective fluorescent chemosensor and its potential applications

A highly efficient sensor has been successfully developed using quinoline-based BODIPY compounds (8-quinoline-4,4-difluoro-4-boro-3a, 4a-diazaindacene (C1) and 7-hydroxy-8-quinoline-4,4-difluoro-4-boro-3a, 4a-diazindacene (C2) to detect Hg2+ ions. The sensor C1 exhibits remarkable selectivity in detecting Hg2+ with a limit of detection 3.06 × 10-8 mol/L. The developed chemical sensors have shown stability, cost-effectiveness, ease of preparation, and remarkable selectivity towards Hg2+ ions compared to other commonly occurring metal ions. The total recovery of the sensor C1 can be achieved by using a 0.1 mol/L solution of KI. The proposed sensor C1 has been applied to determine Hg2+ in tap and distilled water, yielding excellent results. In addition, the binding mode of C1-Hg2+ and C2-Hg2+ complexes was a 1:1 ratio confirmed by mass spectra, Job’s plot, and DFT study. Moreover, the sensor C1 successfully applied for the biological studies results in negligible cytotoxicity, which demonstrates it can be used to determine Hg2+ in HT22 cells.

Rapid synthesis of a BODIPY derivative serving as a highly selective and sensitive fluorescence chemosensor for Hg2+ ion detection

A 2-amino-1,3-propanediol-modified BODIPY was synthesized in 6 hours, exhibiting high selectivity and a fourfold emission increase with Hg2+ ions in polar solvents.

5-Aminoisophthalate-based kojic acid-appended bis-1,2,3-triazole: a fluorescent chemosensor for Cu2+ sensing and in silico study.

A new, easy-to-prepare, and highly selective fluorescent chemosensor, i.e., 5-aminoisophthalate-based kojic acid-appended bis-1,2,3-triazole, was synthesized from an alkyne of 5-aminoisophthalic acid and azido-kojic acid using Cu(i)-catalyzed click chemistry and then successfully characterized. The alkyne structure of 5-aminoisophthalic acid, 1, was supported by the single-crystal X-ray crystallographic data. The fluorescent probe 3 was found to be highly selective for Cu2+ ions supported by the Job's plot with a stoichiometric ligand : metal ratio of 2 : 1, exhibiting almost a two-fold enhancement in the emission intensity upon the addition of Cu2+ ions (0-25 μM) with a detection limit of 8.82 μM. A comparison with LODs from previously developed chemosensors for Cu2+ ions was also conducted. Reversibility analysis indicated that probe 3 could be used as both a reusable sensor and as a scavenger of copper ions. DFT calculations with the basis sets B3LYP/6-311G(d,p) and LanL2DZ were employed for geometrical optimizations of structures of the alkyne 1, azide 2, probe 3, and complex 3.Cu2+. Hirshfeld surface analysis revealed significant intermolecular interactions in compound 1. Additionally, molecular docking for the antimicrobial activity showed the better antibacterial efficacy of probe 3.

Isatin-Schiff base functionalized graphene oxide as a highly selective turn-on fluorescent probe for the detection of Pd(II) via photoinduced electron transfer pathway

We investigated the use of isatin-Schiff base functionalized graphene oxide (ISBGO) as a selective fluorescent chemosensor for the detection of palladium ions. Selectivity tests indicated that over 23 metal ions tested, ISBGO (λex = 340 nm, λem = 504 nm) showed the highest affinity for Pd(II), displaying a 10.1-fold enhancement. Also, interference tests proved that in the presence of both Pd(II) and other metal ions, there was still high fluorescence intensity and no considerable quenching occurred. According to DFT and TD-DFT calculations, photo-induced electron transfer (PET) is responsible for the turn-on response produced by the chemosensor. Coordination of Pd(II) with ISBGO in fact blocks PET from imine nitrogen of 3-iminoindolin-2-one moiety to the benzene ring, which in turn leads to a turn-on response. In addition, Job’s plot analysis and Benesi-Hildebrand approach suggest that ISBGO preferably forms a 1:1 complex with Pd(II) with an association constant of 1.020 × 105 M−1. Moreover, FT-IR spectroscopy and DFT study showed that amide oxygen and imine nitrogen of 3-iminoindolin-2-one moiety acted as binding sites of ISBGO. High sensitivity, fast response, great degree of sensitivity, short life time, low detection limit of 32 nM combined with high association constant (Kf) of 1.020 × 105 M−1 and increased fluorescence quantum yield (Φf) of roughly 1.5-fold in the presence of Pd (II), highlight the role of ISBGO as an excellent probe for sensing Pd(II) in aqueous solution.

New graphene oxide-loaded probe as a highly selective fluorescent chemosensor for the detection of iron ions in water samples using optical methods

A highly selective Graphene Schiff base Probe, GP chemosensor was synthesized by modification of functionalized graphene oxide with Naphthaldehyde-diaminobenzophenone Schiff base probe, NDABSB. The loading of the NDABSB on graphene oxide (GO) was carried out by ultrasonication method and characterized by FT-IR, PXRD, 1H NMR, EDX, TGA, Raman spectroscopy, and microscopic SEM techniques. All the characterization techniques validated the successful loading of the NDABSB on GO. The optical properties of GP were investigated by absorption and fluorescence titration studies, which revealed that GP displayed selective fluorescence sensing for Fe2+ and Fe3+ ions over other metal ions viz., Cr3+, Cd2+, Cu2+, Co2+, Mn2+, Ni2+, V3+, Li+, and Zn2+. The binding ratio was determined by Job's plot, and 2:1 stoichiometry was observed. The detection limit of GP for Fe2+ and Fe3+ was found to be 0.277 × 10−5 mol L−1 and 0.337 × 10−5 mol L−1, respectively. The lower detection limit of the GP for Fe2+ and Fe3+ ions proved its application in the sensing phenomenon and showed its sensitivity. Furthermore, density functional theory (DFT) and confocal fluorescence imaging studies were carried out to support the results of optical sensing experiments. The practical applicability of GP was investigated by examining iron content in different water samples.

Ultrasound-Assisted Synthesis of Chalcone: A Highly Sensitive and Selective Fluorescent Chemosensor for the Detection of Fe3+ in Aqueous Media.

The chalcone compound DHPO was synthesized through a chemical reaction between 1-(2-hydroxyphenyl)-ethanone and 3,4-dimethoxy benzaldehyde under ultrasound irradiation. The interaction between the DHPO compound and several metal ions was studied using fluorescence behavior, revealing that the chalcone function as a "turn on and turn off" switch fluorescent sensor, for selectively and sensitively detecting Fe3+ ions. The process of fluorescence quenching and complexation of DHPO with Fe3+ ion was further studied using methods such as Benesi-Hildebrand, Stern-Volmer plot, and job plot.

A multi responsive phosphonic acid based fluorescent sensor for sensing Fe3+, benzaldehyde and antibiotics

Herein, we report a multi responsive and selective fluorescent chemo sensor with anthracene as a fluorophore and phosphonic acid group as receptor (anthracene-9,10-diylbis(methylene)) diphosphonic acid (ANDP) for detecting Fe3+, benzaldehyde and few antibiotics. The sensor was characterised by single crystal X-ray diffraction and 1H NMR. ANDP could selectively and sensitively detect Fe3+ and benzaldehyde in DMSO-water with the detection limits of 5.09 µM and 39.8 µM respectively. 1H NMR, FT-IR and Fluorescence life time measurements suggests the interaction of Fe3+ with the sensor and the oxygen of phosphonic acid group is responsible for the interaction in both the sensing of iron ion and benzaldehyde. Mainly nitro group based antibiotics (NFZ, MDZ, FZD) and TCL sensitively quenched the fluorescence of the sensor with the detection limit of 2.07 µM, 1.25 µM, 1.19 µM and 0.66 µM. The quenching mechanism was further discussed and it was found that the photo induced electron transfer (PET) was responsible for the quenching of fluorescence intensity of ANDP. The HOMO and LUMO energies were estimated by DFT calculations.

The new coumarin derivative cyclotetraphosphazene fluorometric chemosensor with reversible, high selective and sensitive for Fe3+ ion detection

A new coumarin-based cyclotetraphosphazene molecule (OCCTP) that can show fluorescence and chemosensory properties has been designed and synthesized. For this purpose, the 7-hydroxy-3-(3,4,5-trimethoxyphenyl)coumarin (4) was synthesized.For the first time in this study, compound 4 which solid state structure and geometry were determined by using crystal X-ray structural analysis were crystallized in the orthorhombic Fdd2 space group. The purified compounds were structurally characterized by elemental analysis, NMR (1H, 13C and 31P) and FT-IR spectroscopy, and mass analysis. Photophysical and chemosensory properties of OCCTP against a range of analytes (various metal ions) were investigated by UV–vis and Fluorescent Spectrophotometer. As a result of fluorimetric studies, OCCTP was found to be a Turn-Off fluorescent chemosensor against Fe3+ ions. The limit of detection (LOD) of OCCTP for Fe3+ was calculated as 1.87 µM and its complex stoichiometry was determined as 1:2 (L/M) as a result of Job's plot. The reversibility study of the iron complex with EDTA showed that the free OCCTP chemosensor regenerated causing an increase in the fluorescence intensity of EDTA. The results showed that the newly synthesized coumarin-based cyclotetraphosphazene compound (OCCTP) can be used as a reversible, highly selective and sensitive fluorescent chemosensor (Turn- Off) which responds immediately against Fe3+ ions.