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.

A Study of Small Molecule-Based Rhodamine-Derived Chemosensors and their Implications in Environmental and Biological Systems from 2012 to 2021: Latest Advancement and Future Prospects

Rhodamine-based chemosensors have sparked considerable interest in recent years due to their remarkable photophysical properties, which include high absorption coefficients, exceptional quantum yields, improved photostability, and significant red shifts. This article presents an overview of the diverse fluorometric, and colorimetric sensors produced from rhodamine, as well as their applications in a wide range of fields. The ability of rhodamine-based chemosensors to detect a wide range of metal ions, including Hg+2, Al3+, Cr3+, Cu2+, Fe3+, Fe2+, Cd2+, Sn4+, Zn2+, and Pb2+, is one of their major advantages. Other applications of these sensors include dual analytes, multianalytes, and relay recognition of dual analytes. Rhodamine-based probes can also detect noble metal ions such as Au3+, Ag+, and Pt2+. They have been used to detect pH, biological species, reactive oxygen and nitrogen species, anions, and nerve agents in addition to metal ions. The probes have been engineered to undergo colorimetric or fluorometric changes upon binding to specific analytes, rendering them highly selective and sensitive by ring-opening via different mechanisms such as Photoinduced Electron Transfer (PET), Chelation Enhanced Fluorescence (CHEF), Intramolecular Charge Transfer (ICT), and Fluorescence Resonance Energy Transfer (FRET). For improved sensing performance, light-harvesting dendritic systems based on rhodamine conjugates has also been explored for enhanced sensing performance. These dendritic arrangements permit the incorporation of numerous rhodamine units, resulting in an improvement in signal amplification and sensitivity. The probes have been utilised extensively for imaging biological samples, including imaging of living cells, and for environmental research. Moreover, they have been combined into logic gates for the construction of molecular computing systems. The usage of rhodamine-based chemosensors has created significant potential in a range of disciplines, including biological and environmental sensing as well as logic gate applications. This study focuses on the work published between 2012 and 2021 and emphasises the enormous research and development potential of these probes.

Network-Polymer-Modified Superparamagnetic Magnetic Silica Nanoparticles for the Adsorption and Regeneration of Heavy Metal Ions

Superparamagnetic magnetic nanoparticles (MNPs, Fe3O4) were first synthesized based on a chemical co-precipitation method, and the core-shell magnetic silica nanoparticles (MSNPs, Fe3O4@SiO2) were obtained via hydrolysis and the condensation of tetraethyl orthosilicate onto Fe3O4 seed using a sol-gel process. Following that, MSNPs were immobilized using a three-step grafting strategy, where 8-hloroacetyl-aminoquinoline (CAAQ) was employed as a metal ion affinity ligand for trapping specific heavy metal ions, and a macromolecular polymer (polyethylenimine (PEI)) was selected as a bridge between the surface hydroxyl group and CAAQ to fabricate a network of organic networks onto the MSNPs' surface. The as-synthesized MSNPs-CAAQ nanocomposites possessed abundant active functional groups and thus contained excellent removal features for heavy metal ions. Specifically, the maximum adsorption capacities at room temperature and without adjusting pH were 324.7, 306.8, and 293.3 mg/g for Fe3+, Cu2+, and Cr3+ ions, respectively, according to Langmuir linear fitting. The adsorption-desorption experiment results indicated that Na2EDTA proved to be more suitable as a desorbing agent for Cr3+ desorption on the MSNPs-CAAQ surface than HCl and HNO3. MSNPs-CAAQ exhibited a satisfactory adsorption capacity toward Cr3+ ions even after six consecutive adsorption-desorption cycles; the adsorption efficiency for Cr3+ ions was still 88.8% with 0.1 mol/L Na2EDTA as the desorbing agent. Furthermore, the MSNPs-CAAQ nanosorbent displayed a strong magnetic response with a saturated magnetization of 24.0 emu/g, and they could be easily separated from the aqueous medium under the attraction of a magnet, which could facilitate the sustainable removal of Cr3+ ions in practical applications.

Facile Synthesis of Water-Soluble Rhodamine-Based Polymeric Chemosensors via Schiff Base Reaction for Fe3+ Detection and Living Cell Imaging

Quantitative and accurate determination of iron ions play a vital role in maintaining environment and human health, but very few polymeric chemosensors were available for the detection of Fe3+ in aqueous solutions. Herein, a water-soluble rhodamine-poly (ethylene glycol) conjugate (DRF-PEG), as a dual responsive colorimetric and fluorescent polymeric sensor for Fe3+ detection with high biocompatibility, was first synthesized through Schiff base reaction between rhodamine 6G hydrazide and benzaldehyde-functionalized polyethylene glycol. As expected, the introduction of PEG segment in DRF-PEG significantly improved the water solubility of rhodamine derivatives and resulted in a good biosensing performance. The detection limit of DRF-PEG for Fe3+ in pure water is 1.00 μM as a fluorescent sensor and 3.16 μM as a colorimetric sensor at pH 6.5. The specific sensing mechanism of DRF-PEG toward Fe3+ is proposed based on the intramolecular charge transfer (ICT) mechanism, in which the O and N atoms in rhodamine moiety, together with the benzene groups from benzaldehyde-modified PEG segment, participate in coordination with Fe3+. Furthermore, DRF-PEG was applied for the ratiometric imaging of Fe3+ in HeLa cells and showed the potential for quantitative determination of Fe3+ in fetal bovine serum samples. This work provides insights for the design of water-soluble chemosensors, which can be implemented in iron-related biological sensing and clinical diagnosis.

A novel [1,2,4]triazolo[1,5-a]pyrimidine derivative as a fluorescence probe for specific detection of Fe3+ ions and application in cell imaging

The detection of metal ions is of particular importance for monitoring environmental pollution and life metabolic activities. However, it is still a challenge to achieve Fe³⁺ detection with specific sensitivity and rapid response, especially in the presence of chelating agents for Fe³⁺ ions. Herein, a novel fluorescence probe for Fe³⁺, i.e., amide derivative of [1,2,4]triazolo[1,5-a] pyrimidine (TP, Id), was synthesized, featuring specific Fe³⁺ selectivity, rapid quenching (5 s), low limit of detection (0.82 μM), good permeability and low cytotoxicity. More importantly, Id can be used to identify and detect Fe³⁺ in the presence of existing strong chelating agents (e.g., EDTA) for Fe³⁺ ions. The results show that the as-synthesized fluorescence probe is particularly suitable as a bioimaging reagent to monitor intracellular Fe³⁺ in living HeLa cells. Furthermore, we proposed the binding mode for Id with Fe³⁺ ions and the light-emitting mechanism through high-resolution mass spectra and density function theory calculations, respectively. An Id-based test paper can be used to rapidly identify Fe³⁺. These results are expected to improve the development of new sensitive and specific fluorescent sensors for Fe³⁺.

A dual-response fluoran-phenothiazine hybrid fluorescent probe for selective sensing of Fe3+ and ClO- and cell imaging application

Bifunctional fluorescent probes with dual-emission response attract extensive attention. A novel fluorescent probe FP, a hybrid of fluoran and phenothiazine, has been designed and synthesized for selective sensing of Fe³⁺ and ClO^- with dual-emission changes, which involes mechanisms of Fe³⁺-promoted spirolactone ring opening and ClO^--induced oxidation of phenothiazine moiety, respectively. In addition, the detection limits for Fe³⁺ and ClO^- were estimated to be 49.1 and 35.9 nM, respectively. Significantly, FP can be employed as an tracer for the detection of Fe³⁺ ions within living HeLa cells by fluorescence imaging.

BODIPY-Pyridylhydrazone Probe for Fluorescence Turn-On Detection of Fe3+ and Its Bioimaging Application

A novel pyridylhydrazone-tethered BODIPY (BODIPY-PH) was synthesized, fully characterized via nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopic (FTIR), and single-crystal X-ray diffraction (SC-XRD) techniques, and developed for the selective detection of Fe3+ through fluorescent enhancement process. This derivative showed 1:1 binding with Fe3+ in an acetonitrile-water mixture (1:9 v/v) with the binding constant (K) of 5.4 × 104 M−1 and the limit of detection of 0.58 µM. The Fe3+ complexation reaction has been proved to be a reversible process and could be effectively repeated up to three cycles. The electronic properties of BODIPY-PH and its Fe3+ complex modeled by the density functional theory (DFT) method suggested the presence of chelation-enhanced fluorescence (CHEF) effect in the Fe3+ binding reaction. The X-ray absorption spectroscopy (XAS) probed at Fe K-edge confirmed the complex formation between BODIPY-PH and the Fe3+ in an octahedral geometry. Finally, bioimaging against human embryonic kidney (Hek293) cell, through confocal fluorescence microscopic technique indicated that the BODIPY-PH displayed good permeability and low toxicity toward the tested cell lines and showed enhanced fluorescent signal in the cells incubated with Fe3+ proving its capability for Fe3+ analysis in cellular matrix.

Performance of 2-Hydroxy-1-Naphthaldehyde-2-Amino Thiazole as a Highly Selective Turn-on Fluorescent Chemosensor for Al(III) Ions Detection and Biological Applications

The thiazole based Schiff base 2-hydroxy-1-naphthaldehyde-2-amino thiazole (receptor1) was synthesized through a single step process and characterized by spectroscopic and analytical techniques. The cation detecting ability of the receptor1 was explored by fluorescent spectroscopic methods. The receptor1 has recognized Al3+ ions by a turn-on process over a panel of other potentially competing metal ions. The binding constant of receptor1 with Al3+ was found to be 8.27 × 103 M-1. Computational studies Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) were performed to provide detailed information on electronic states and photophysical property of receptor1 and receptor1-Al3+ ions. MTT (3-(4,5-dimethyl thiazole-2-yl)-2,5-diphenyl tetrazolium bromide) assay and bioimaging applications were made on breast carcinoma cells in humans.

Metal-free regioselective C5-cyanoalkylation of the 8-aminoquinolineamides/sulfonamides via oxidative cross-dehydrogenative coupling with alkylnitriles

A practical, versatile and Metal-free regioselective C5-cyanoalkylation of the 8-aminoquinolineamides/sulfonamides with acetonitrile has been described.

Novel rhodamine probe for colorimetric and fluorescent detection of Fe3+ ions in aqueous media with cellular imaging

A novel rhodamine-pyridine conjugated spectroscopic probe RhP was synthesized and its X-ray single crystalline properties were revealed with tabulation. The RhP displayed a distinct pale-pink colorimetric and "turn-on" fluorescent response to Fe³⁺ in aqueous media [H₂O:DMSO (95:5, v/v)] than that of other interfering ions. During the Fe³⁺ recognition, the absorption (UV-Vis) and photoluminescence (PL) spectral studies revealed new peaks at 561 and 592 nm, respectively. The 1:1 stoichiometry and binding sites were verified by Job's plot, ESI-mass, and ¹H NMR titrations. Subsequently, LOD and binding constant for RhP + Fe³⁺ complex were estimated as 102.3 nM and 6.265 × 10⁴ M^-1 from linear fitting and Benesi-Hildebrand plots, correspondingly. Sensor reversibility of RhP + Fe³⁺ by EDTA was demonstrated by UV/PL and TRPL investigations. Moreover, the photoinduced energy transfer mechanism and band gap changes were established from the DFT interrogations. Lastly, cellular imaging studies were carried out to authenticate the real applicability of RhP in Fe³⁺ detection.

A highly selective and sensitive boronic acid-based sensor for detecting Pd2+ ion under mild conditions

Herein, a boronic acid-based sensor was reported selectively to recognize Pd²⁺ ion. The fluorescence intensity increased 36-fold after sensor binding with 2.47 × 10^-5 M of Pd²⁺ ion. It was carried out in the 99% aqueous solution for binding tests, indicating sensor having good water solubility. In addition, it is discernible that Pd²⁺ ion turned on the blue fluorescence of sensor under a UV-lamp (365 nm), while other ions (Ag⁺, Al³⁺, Ba²⁺, Ca²⁺, Cr²⁺, Cd²⁺, Co²⁺, Cs²⁺, Cu²⁺, Fe²⁺, Fe³⁺, K⁺, Li⁺, Mg²⁺, Mn²⁺, Na⁺, Ni²⁺ and Zn²⁺) did not show the similar change. Furthermore, sensor has a low limit of detection (38 nM) and high selectivity, which exhibits the potential for the development of Pd²⁺ recognition in practical environments.

Simple C3-symmetric triaminoguanidine-triphenylamine conjugate as an efficient colorimetric sensor for Cu(II) and fluorescent sensor for Fe(III) ions

The design and construction of novel C₃-symmetric triaminoguanidine-triphenylamine conjugate (L) has been demonstrated and it displays positive solvatochromic behaviour with an increase in solvent polarity. The probe L acts as a selective colorimetric sensor for Cu²⁺ ions over other metal ions. Further, it shows high selective and sensitive detection of Fe³⁺ ions through turn-on fluorescence response. Moreover, the detection limits for Cu²⁺ and Fe³⁺ ions were found to be within the allowable range of the World Health Organisation (30 μM). The real-time application of the probe was showed by paper strip experiments as well as detection of Fe³⁺ ions in pharmaceutical tablets.

A novel electrochemical sensor based on Au nanoparticles/8-aminoquinoline functionalized graphene oxide nanocomposite for paraquat detection

In this paper, a novel electrochemical sensor based on Au nanoparticles/8-aminoquinoline functionalized graphene oxide (AuNPs/GAQ) nanocomposite was developed and tested for the first time for detection of paraquat (PQ). The morphology and composition of AuNPs/GAQ nanocomposite were characterized by various techniques, including transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. Cyclic voltammetry and differential pulse voltammetry were utilized to investigate the electrochemical performances of AuNPs/GAQ nanocomposite modified glassy carbon electrode. The obtained modified electrode exhibited excellent electrocatalytic activity towards detection of PQ. Under the optimized conditions, the proposed sensor showed low detection limit (6 nM, S/N = 3), wide linear range (0.02-24 μM), high selectivity and good stability. In addition, it was successfully applied for detection of PQ in natural water samples with satisfactory results.

On-off-on relay fluorescence recognition of ferric and fluoride ions based on indicator displacement in living cells

A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential "on-off-on"-type relay fluorescence probe for Fe³⁺ ions and F^- ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe³⁺ to IOP boronic acid (IOPBA) formed an Fe³⁺IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe³⁺ ion in the Fe³⁺IOPBA complex was coordinated to two phenyl groups to form a π-complex. Upon addition of F^- to the Fe³⁺IOPBA complex, the original fluorescence was recovered due to formation of [FeF₆]^3‒, resulting in "on-off-on"-type sensor behavior. IOPBA showed high selectivity towards Fe³⁺ among other cations. Moreover, the Fe³⁺IOPBA complex showed specific selectivity towards F^-, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 10⁶ and 4.49 × 10⁶ mol^-1 L for Fe³⁺ with IOPBA and F^- with Fe³⁺IOPBA, respectively. The limits of detection for Fe³⁺ and F^- were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe³⁺ and F^- in living HeLa cells.

A multi stimuli responsive material with rhodamine B and carbazole groups

A facile material with multi stimuli responsive behaviors was developed. The chromic properties of the material can be observed by stimulating it with light, electricity and ions.

Layered rare-earth hydroxide (LRH, R = Tb, Y) composites with fluorescein: delamination, tunable luminescence and application in chemosensoring for detecting Fe(iii) ions

We demonstrate a novel example of tunable luminescence and the application of the delaminated FLN/OS-LRH composites (LRHs are layered rare-earth hydroxides, R = Tb, Y; FLN is the fluorescein named 2-(6-hydroxy-3-oxo-(3H)-xanthen-9-yl)benzoic acid; OS is the anionic surfactant 1-octane sulfonic acid sodium) in detecting Fe(iii) ions. The FLNxOS1-x species (x = 0.02, 0.05, 0.10, and 0.20) are intercalated into the LTbyY1-yH layers (y = 1, 0.9, 0.7, 0.5, 0.3, 0.1 and 0) by ion exchange reactions to yield the composites FLNxOS1-x-LTbyY1-yH. In the solid state, the LYH composites display green emission (564 nm) arising from the organic FLN, while in LTbH composites, the luminescence of the Tb3+ in the layers (545 nm) and the FLN in the interlayers is co-quenched. In the delaminated state in formamide (FM), FLNxOS1-x-LTbH composites display green to yellowish-green luminescence (540-574 nm) following the increasing FLN/OS ratio; while the FLN0.02OS0.98-LTbyY1-yH composites show green emission at ∼540 nm. The fluorescence lifetimes of the composites (4.22-4.63 ns) are comparable to the free FLN-Na, and the quantum yields (31.62-78.70%) of the composites especially that (78.70%) of the FLN0.02OS0.98-LYH are much higher than that (28.40%) of free FLN-Na. The recognition ability of the FLN0.02OS0.98-LYH composite for metal cations is researched. The delaminated FLN0.02OS0.98-LYH colloidal suspension exhibits high selectivity for Fe3+ over other ions (Mg2+, Al3+, Ni2+, Co2+, Cu2+, Zn2+, Mn2+, Pb2+, and Cd2+) with fluorescence quenching, which can work as a kind of turn-off fluorescence sensor for the detection of Fe3+. The detection limit of Fe3+ is determined to be 2.58 × 10-8 M and the quenching constant (Ksv) is 1.70 × 103 M-1. This is the first work on LRH materials working as a chemosensor for recognising metal cations. It provides a new approach for the design of LRH materials to be applied in fluorescence chemosensing.

Exploring the Scope of Photo-Induced Electron Transfer-Chelation-Enhanced Fluorescence-Fluorescence Resonance Energy Transfer Processes for Recognition and Discrimination of Zn2+, Cd2+, Hg2+, and Al3+ in a Ratiometric Manner: Application to Sea Fish Analysis

A rhodamine-based smart probe (RHES) has been developed for trace-level detection and discrimination of multiple cations, viz. Al³⁺, Zn²⁺, Cd²⁺, and Hg²⁺ in a ratiometric manner involving photo-induced electron transfer-chelation-enhanced fluorescence-fluorescence resonance energy transfer processes. The method being very fast and highly selective allows their bare eye visualization at a physiological pH. The optimized geometry and spectral properties of RHES and its cation adducts have been analyzed by time-dependent density functional theory calculations. RHES detects as low as 1.5 × 10^-9 M Al³⁺, 1.2 × 10^-9 M Zn²⁺, 6.7 × 10^-9 M Cd²⁺, and 1.7 × 10^-10 M Hg²⁺, whereas the respective association constants are 1.33 × 10⁵ M^-1, 2.11 × 10⁴ M^-1, 1.35 × 10⁵ M^-1, and 4.09 × 10⁵ M^-1. The other common ions do not interfere. The probe is useful for intracellular imaging of Zn²⁺, Cd²⁺, and Hg²⁺ in squamous epithelial cells. RHES is useful for the determination of the ions in sea fish and real samples.

A thiourea-appended rhodamine chemodosimeter for mercury(II) and its bioimaging application

A rhodamine-thiourea conjugate RTP with an o-phenylenediamine linker was developed as a fluorogenic chemodosimeter for Hg²⁺ detection. In the presence of Hg²⁺, a colorless solution of RTP turned pink with a maximum absorption band at 555nm and with a 62-fold fluorescence enhancement at 578nm (Φ=0.34). RTP is highly selective to Hg²⁺ among other metal ions with a detection limit of 1.6nM (0.3ppb). A similar rhodamine analog with a flexible ethylenediamine spacer was less selective and less sensitive than RTP. Hg²⁺ induced cyclic guanylation to yield a benzimidazole moiety and a subsequent ring-opening of the spirolactam unit resulted in chromogenic and fluorogenic changes. The membrane-permeable RTP probe was successfully demonstrated in monitoring of Hg²⁺ in cultured HeLa cells.

Rhodamine based turn-on chemosensor for Fe3+ in aqueous medium and interactions of its Fe3+ complex with DNA

A novel di-coordinating rhodamine-based chemosensor, HL with NO donor atoms, selectively and rapidly recognizes Fe³⁺ in the presence of all biologically relevant as well as toxic metal ions and numerous anions and also with other reactive oxygen and nitrogen species.

Pyridine-antipyrine appended indole derivative for selective recognition of Fe3+: Concentration dependent coloration

Combination of pyridine, antipyrine and indole in a single molecule (L2) allows selective recognition of Fe³⁺ colorimetrically in CH₃CN. The structure of L2 is confirmed from single crystal X-ray diffraction analysis. The probe displays two different visible bands at 541nm and 715nm in the presence of Fe³⁺, associated with two different colors, viz. green and pink-violet allowing determination of unknown Fe³⁺ concentration. Interestingly, removal of 2-picolyl group from indole N-center of L2 generates L3 that behaves similarly at low Fe³⁺ concentration (>0 to 1.1mM) but differently at higher Fe³⁺ concentration (>1.1mM), indicating involvement of pyridyl-N donor towards Fe³⁺, and hence different coordination environment around Fe³⁺ at higher concentration.

Copper(i) and N-fluorobenzenesulfonimide-mediated direct regioselective halogenation of 8-amidoquinolines on the C5 position

Direct regioselective halogenation of 8-amidoquinolines on the C5 position in the presence of NFSI and CuX under mild conditions.

Copper-catalyzed C5-selective thio/selenocyanation of 8-aminoquinolines

Copper-catalyzed direct C5-position thio/selenocyanation of quinolines using commercially available, inexpensive KSCN/SeCN as the thio/selenocyanation reagent was developed, which had good tolerance toward various aliphatic or aromatic 8-aminoquinoline derivatives.

A rhodamine based turn-on chemosensor for Fe3+ in aqueous medium and interactions of its Fe3+ complex with HSA

A novel hexa-coordinating rhodamine-based chemosensor, HL6, selectively and rapidly recognizes Fe³⁺ in the presence of a number of metal cations, numerous anions and amino acids in purely aqueous medium with live cell imaging applications.

A novel and simple solvent-dependent fluorescent probe based on a click generated 8-aminoquinoline–steroid conjugate for multi-detection of Cu(ii), oxalate and pyrophosphate

A novel and simple deoxycholic acid-based fluorescent probe was facilely constructed for solvent-dependent multi-detection of Cu²⁺, C₂O₄²⁻and P₂O₇⁴⁻.

A reversible rhodamine 6G-based fluorescence turn-on probe for Fe3+ in water and its application in living cell imaging

A reversible fluorescent probe L based on rhodamine 6G was synthesized for the optical detection of Fe³⁺ in water.

FRET-based fluorescence ratiometric and colorimetric sensor to discriminate Fe3+ from Fe2+

A new benzothiazole–quinoline–rhodamine-6G-based probe was synthesised. The probe can exclusively detect Fe³⁺ through a ratiometric manner in a mixed aqueous system with a detection limit in the 10⁻⁸ M range.

Multifunctional Fe3O4@SiO2nanoparticles for selective detection and removal of Hg2+ion in aqueous solution

A multifunctional magnetic core–shell Fe₃O₄@SiO₂nanoparticle decorated with rhodamine-based receptor has been successfully synthesized, aiming to detect and remove Hg²⁺from aqueous media.

A fast-response, fluorescent ‘turn-on’ chemosensor for selective detection of Cr3+

A highly selective and sensitive chemosensor 3 for Cr³⁺ detection was designed and synthesized, which showed a fast turn-on fluorescence response under physiological conditions.

An anion induced multisignaling probe for Hg2+ and its application for fish kidney and liver tissue imaging studies

A highly efficient binder for the selective recognition and determination of Hg(NO₃)₂ concentration in kidney and liver tissues of fish using a fluorescence method is described.

A dual-responsive “turn-on” bifunctional receptor: a chemosensor for Fe3+ and chemodosimeter for Hg2+

Synthesis and characterization of L1–L3 along with their selective detection toward Fe³⁺ and Hg²⁺ at ppb level, exhibiting bifunctional behaviour have been presented.

Fluorescent, MRI, and colorimetric chemical sensors for the first-row d-block metal ions

Transition metals (d-blocks) are recognized as playing critical roles in biology, and they most often act as cofactors in diverse enzymes; however, improper regulation of transition metal stores is also connected to serious disorders. Therefore, the monitoring and imaging of transition metals are significant for biological research as well as clinical diagnosis. In this article, efforts have been made to review the chemical sensors that have been developed for the detection of the first-row d-block metals (except Cu and Zn): Cr, Mn, Fe, Co, and Ni. We focus on the development of fluorescent sensors (fall into three classes: "turn-off", "turn-on", and ratiometric), colorimetric sensors, and responsive MRI contrast agents for these transition metals (242 references). Future work will be likely to fill in the blanks: (1) sensors for Sc, Ti, and V; (2) MRI sensors for Cr, Mn, Co, Ni; (3) ratiometric fluorescent sensors for Cr(6+), Mn(2+), and Ni(2+), explore new ways of sensing Fe(3+) or Cr(3+) without the proton interference, as well as extend applications of MRI sensors to living systems.

A rhodamine derivative as a highly sensitive chemosensor for iron(iii)

A novel rhodamine-based fluorescent probe P1 was synthesized for the optical detection of Fe³⁺. This fluorescent probe was proved to be effective for detecting Fe³⁺ in living cells and zebrafish.