Selective Fe3 Research Articles

Synthesis and characterization of a sensitive and selective Fe3+ fluorescent sensor based on novel sulfonated calix[4]arene‐based host‐guest complex

A novel fluorescent sensor was prepared from sulfonated calix[4]arene (SC4A) by the host-guest complexation method using the fluorescent dye rhodamine B (RB) as a structure-directing agent. The crystal structure of the host-guest complex (RB@(SC4A)3) was confirmed by X-ray diffraction studies while its performance and sensing mechanism for metal ion pollutants were characterized using fluorescence and nuclear magnetic resonance spectroscopies. The results showed that RB@(SC4A)3 had a triangular branch structure resulting from host-guest mediation of the interactions between the three SC4A host molecules and the three terminal groups of the guest molecule RB. The host-guest complex exhibited sensitive and selective sensing towards Fe3+ ions via a fluorescence quenching mechanism. The results indicated that RB@(SC4A)3 could be a promising sensitive and selective fluorescent sensor for metal ion pollutants monitoring. It also provided new insights into the synthesis of calixarene-based host-guest complex.

Durable room-temperature phosphorescence of nitrogen-doped carbon dots-silica composites for Fe3+ detection and anti-counterfeiting

Developing durable room temperature phosphorescent carbon dot-based materials with high stability and easy preparation has been a great challenge. Here, through a one-step hydrolysis-assisted carbonization treatment, nitrogen-doped carbon dots encapsulated in silica (N-CDs@silica) are obtained, with outstanding stability and durable room temperature phosphorescence (RTP) lifetime (1.81 s, nearly 9 s to naked eye). Further investigations reveal that CO bonds from N-CDs are the main luminescence centers. The formation of Si–O–C bonds covalently linking N-CDs and silica matrice together within silica sphere, as well as the efficient crosslinking effect within N-CDs, are responsible for RTP emission. Based on the unique optical properties of N-CDs@silica, we have developed the RTP strip probe for selective Fe3+ detection. In addition, we explored N-CDs@silica as security ink for advanced anti-counterfeiting. This work not only provides a strategy to synergistically optimizes the structural and luminescent properties of N-CDs@silica in a simple and efficient manner, but more importantly opens a new perspective for developing simple RTP strip probes for sensor applications.

Tinospora cordifolia Leaves Derived Carbon dots for Cancer Cell Bioimaging, Free radical Scavenging, and Fe3+ Sensing Applications.

Herein, we report the fabrication of Tinospora cordifolia leaves-derived carbon dots (TCLCDs) from aqueous extract of leaves as carbon source via simple, environmentally friendly, hydrothermal carbonization (HTC) technique. The synthesized TCLCDs were characterized for their physicochemical properties and further explored for in-vitro cancer cell bioimaging, radical scavenging, and metal ion sensing. The synthesized TCLCDs showed excitation-dependent emission property with maximum emission at 435 nm under the excitation of 350 nm. The High-Resolution Transmission Electron Microscopy (HRTEM) results revealed a roughly spherical shape with an average diameter of 5.47 nm. The diffused ring pattern of Selected Area Electron Diffraction (SAED) and halo diffraction pattern of X-ray diffraction (XRD) disclosed their amorphous nature. The Energy Dispersive X-ray (EDX) showed the existence of C, N, and O. The Fourier-transform infrared spectroscopy (FTIR) revealed the presence of -OH, -NH, -CN, and -CH groups. The TCLCDs showed excellent cellular biocompatibility with dose-dependent bioimaging results in melanoma (B16F10) and cervical cancer (SiHa) cell lines. Also, they exhibited excellent scavenging of free radicals with an IC50 value of 0.524 mg/mL & selective Fe3+ ion sensing with a detection limit of 0.414 µM. Further, they exerted excellent bacterial biocompatibility, photostability, and thermal stability. The overall results reflected their potential for in-vitro cancer cell bioimaging, free radical scavenging, and selective Fe3+ ion sensing.

Microplasma nanoengineering of emission-tuneable colloidal nitrogen-doped graphene quantum dots as smart environmental-responsive nanosensors and nanothermometers

Nitrogen-doped graphene quantum dots (NGQDs) with controlled emission properties are useful materials for fundamental research and applications. However, the scalable and sustainable production of NGQDs with defined nanostructures from biomass precursors remains elusive. Here a bottom-up microplasma synthesis of emission-controlled colloidal NGQDs used as the multifunctional nanosensors for temperature and selective metal ion sensing is demonstrated. The emission-tuneable NGQDs are synthesized by engineering the N-doping configurations and surface functional groups on the NGQDs surfaces by carefully controlling the plasma conditions and electrolyte chemistry. In situ optical emission and UV–Vis absorbance spectroscopy measurement reveals that the plasma-induced hydroxyl radicals and solvated electrons define the N-dopant configuration and surface functionalization of NGQDs, leading to emission-tuneable NGQDs. The emission-tuneable NGQDs are applied as multifunctional nanosensors for selective Fe3+, Cu2+, and Hg2+ detection revealing broad linear detection range (0.5–300 μM) and low limit of detection (LOD) of 47.9 nM for Hg2+ and sensitive temperature detection from 10 to 80 °C. The developed PL sensing method shows high throughput of 5000 detections per hour. Our work demonstrates the possibility of the plasma-enabled nanoengineering of NGQDs with controlled optical properties and a step towards sustainable and scalable synthesis of graphene nanomaterials from renewable bioresources.

Four coordination polymers based on 5-(3,5-dicarboxybenzyloxy) isophthalic acid: Synthesis, structures, photocatalytic properties, fluorescence sensing and magnetic properties

Four coordination polymers named [Co(L)0.5(bib)]n(1), Zn(H2L)(bib)]·2H2O}n(2), Cd(L)0.5(1,2-bimb)]n(3) and Zn(L)0.5(bib)]n(4) (H4L ​= ​5-(3,5-dicarboxybenzyloxy) isophthalic acid, bib ​= ​1,4-bis(1-imidazolyl)benzene, and 1,2-bimb ​= ​1,2-bis(1-imidazolylmethyl)benzene) were synthesized by solvothermal method and structurally characterized by means of single-crystal X-ray diffraction, infrared spectra and elemental analyses. Complex 1 crystallized in orthorhombic space group Pbcn had a 2-fold interpenetrated framework. Complex 2 showed a 4-fold interpenetrated framework. Complex 3 presented a 3-fold interpenetrated framework that crystallized in the triclinic system Pī space group. Complex 4 was a three-dimensional (3D) porous framework. Remarkably, the photocatalytic degradation experiments of complexes 1–4 on methylene blue (MB) indicated that these complexes 1–4 exhibited obvious degradation effect on MB. Moreover, the investigation of the luminescent properties of complexes 2–4 revealed that these complexes 2–4 could be served as a potential highly selective Fe3+ ion luminescent sensor. In addition, the magnetic analyses of complex 1 indicated that there was antiferromagnetic interaction between the Co (II) ions in complex 1.

Green synthesis of biomass-derived carbon quantum dots as fluorescent probe for Fe3+ detection

Eco-friendly synthesis of Carbon quantum dots (CQDs) in water is reported, exploiting various typical crop biomasses as carbon sources. The resultant CQDs exhibit strong fluorescence, good dispersion in common solvents and uniformly dispersed particle size. The synthesized CQDs are highly dispersible in water, due to the presence of surface hydroxyl and carboxyl groups. The CQDs suspension exhibits strong blue fluorescence under UV irradiation, with an optimal excitation wavelength in the range from 350 to 390 nm, which varies with the change of CQD concentration. The emission corresponds to two band transitions, which are originated from π → π* of CC bonds and n → π* of CO bonds, respectively. Due to its strong fluorescence and energy transfer, the synthesized CQDs materials can be used as a fluorescent probe for the detection of Fe3+ ions with good selectivity and sensitivity, within the Fe3+ concentration range of 0–500 μM. The research is of significance for converting crop waste to high added-value products, and the obtained CQDs with selective Fe3+ ions determination ability are attractive for the environmental monitoring and medical diagnosis.

RETRACTED: Two Zn(II) coordination polymers: Selective detection Fe3+ ion and inhibitory activity on the liver cancer viability by regulating the prolyl hydroxylase-3

Abstract In the current study, via utilizing a mixed-ligand method, two new coordination polymers (CPs) of {[Zn5(pmbcd)2(μ3-OH)2(H2O)4(DMF)2]·4DMF}n (1) and {[Zn2(pmbcd)(bpea)2]·2H2O·2DMF}n (2) (in which bpea = 1,2-bis(4-pyridyl)ethane and H4pmbcd = 9,9′-(1,4-phenylenebis(methylene))bis(9H-carbazole-3,6-dicarboxylic acid)) have been successfully prepared using a tetracarboxylate ligand H4pmbcd without or with the present of the second co-ligand bpea. Furthermore, in the water, the complex 1 containing Zn5 clusters exhibits the strong blue luminescence, which can only be selectively quenched via the contaminant Fe3+ ion. For the treatment of liver cancer, the Cell Counting Kit-8 assay was implemented for the assessment of the compounds’ inhibition on the HepG2 liver cancer cells viability. Moreover, the prolyl hydroxylase-3 relative expression in HepG2 liver cancer cells was also detected by the real time reverse transcription polymerase chain reaction.

Highly fluorescent nitrogen and boron doped carbon quantum dots for selective and sensitive detection of Fe3+

Due to the essential role of Fe3+ in physiological and pathological processes, the detection of Fe3+ has drawn increasing attention in the field of disease diagnosis and environmental protection. However, most existing methods require either cumbersome sample pretreatment or sophisticated and expensive test equipment. Recently, carbon quantum dots have found a wide range of applications such as nanoprobes for Fe3+ determination, albeit with limited sensitivity and selectivity. Herein, we report core-shell carbon quantum dots B1N2CQDs via a two-step hydrothermal approach using citric acid, boric acid and ethylenediamine as precursors. The obtained B1N2CQDs exhibit excellent water solubility and remarkable stability as well as a high fluorescence quantum yield of 15.4%. In addition, the fluorescence of B1N2CQDs is quenched exclusively by Fe3+ with minimal interference from other metal ions. A linear relationship with R2 = 0.998 was observed between the fluorescence quenching capacity and the Fe3+ concentration in the range of 2-160 μM, with the limit of detection calculated to be 80 nM. Finally, the as-prepared B1N2CQDs were successfully applied as a highly efficient fluorescent probe for Fe3+ detection in river water samples and intracellular Fe3+ imaging in biological systems.

Chromene–triazole-pyrimidine based chemosensor therapeutics for the in vivo and in vitro detection of Fe3+ ions

MCR and click synthesis of selective and sensitive Fe3+ sensors that can interact with CDK2 proteins and cytotoxicity against the human cervical cancer cell line HeLa is developed.

Blue-LED-excited Ce3+-doped alkaline-earth sulfide luminescent nanocrystals for selective and sensitive Fe3+ ions sensing

Novel blue LED excitable Ce3+-doped alkaline-earth sulfide nanocrystals are exploited for selective and sensitive Fe3+ ions sensing in this work. The detection limit is calculated to be as low as 92.5 nM, which is better than most previous ultra-violet light excited fluorescence probes. The decreased radiative probability of the Ce3+: 5d by the NC surface environmental variation activates the sensing capability.

Synthesis and spectral studies of coumarin derivatives as fluorescent probes for Fe3+

Three novel coumarin derivatives were designed and facilely synthesized, namely 6-[bis-(2-acetoxyethyl)aminomethyl]-4-methyl coumarin (BAMC), 4-(trans-4-methylformate-styryl)-6-[bis-(2-acetoxyethyl)aminomethyl]-coumarin (TSAC) and Trans-4-[2-(benzimidazole-2-substituted)vinyl]-6-methyl coumarin (TBVC). The synthesis route via various reactions including Pechmann, Wittig and substitution, etc. Three strategies are applied in the construction of the coumarin fluorescent probe. That is the electron push-pull effect, extended electronic conjugated system, as well as the strong fluorescence emission group. The compounds BAMC and TSAC are proved to be selective Fe3+ fluorescent probes based on ICT mechanism. TBVC exhibits strong fluorescent emission in tetrahydrofuran. The relationship between the structure and fluorescence mechanism for coumarin probes were explored.

Designing of alternative polymeric nano-chelator for treatment in acute iron poisoning by molecular imprinting approach

The aim of this study is to develop an alternative polymeric chelating agent for rapid and selectively removal with high capacity of Fe3+ ions from the gastrointestinal tract for the oral treatment of acute iron poisoning. For this purpose, Fe3+ imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(l)- glutamic acid) (HEMA-MAGA) nanoparticles synthesized by surfactant free emülsiyon polymerization. Molecular imprinting (MIP) technique is used to enhance the selectivity of nanoparticles. Due to being carboxyl and amide groups on the MAGA monomer, it was chosen as a chelating agent for Fe3+ ions. Before the synthesizing of Fe3+ imprinted polymer, Fe3+ ions were complexed with MAGA and then Fe3+ imprinted nanoparticles were synthesized in the presence of this Fe3+-MAGA complexes. Poly(HEMA-MAGA) nanoparticles were characterized by infrared spectroscopy (FTIR), atomic force microscopy (AFM). Average particle size and size distribution also determined by Zeta sizer. The specific surface area and mead diameter of the Fe3+ imprinted poly(HEMA-MAGA) nanoparticles was 895 m2.g-1 and 95.3 nm, respectively. The maximum Fe3+ ions binding capacity of the poly(HEMA-MAGA) nanoparticles at pH:4.0 were 206.4 mg.g-1 nanoparticles. Fe3+ removal performance of the Fe3+ imprinted poly(HEMA-MAGA) nanoparticles with presence of other ions, optimum medium pH, temperature and equilibrium binding time were also investigated. Fe3+ removal studies were performed in both aqueous solution and intestinal mimicking solution.The results indicate that Fe3+ imprinted poly(HEMA-MAGA) nanoparticles is an alternative chelating agent for the selective Fe3+ ions removal with a short time and very high capacity.

Anthrone‐spirolactam and quinoline hybrid based sensor for selective fluorescent detection of Fe3+ ions

The synthesis of a novel, and highly selective Fe3+ ion sensor based on anthrone‐spirolactam and its quinoline hybrid ligand is reported. The designed ligand displayed selective detection of Fe3+ ions with enhanced fluorescence emission. The complexation of Fe3+ ion led to a red shift of 32 nm from 420 nm to 452 nm, and a several fold increase in intensity with fluorescent green emission. The complexation (detection) of Fe3+ ions with ligand resulted in chelation enhanced fluorescence and intramolecular charge transfer through the inhibition of C=N isomerization. This hybrid sensor shows high sensitivity and selectivity, spontaneous response, and works on a wide pH range a minimum detection limit of 6.83 × 10−8 M. Importantly, the sensor works through the fluorescence turn‐on mechanism that overcomes the paramagnetic effect of Fe3+ ions. The binding mechanism between the ligand and the Fe3+ ions was established from the Job's plot method, optical studies, Fourier transfor infrared spectroscopy, NMR titration, fluorescence life‐time studies, and density functional theory optimization. The sensor displayed excellent results in the quantification of Fe3+ ions from real water samples. Furthermore, due to its biocompatibility nature, fluorescent spotting of Fe3+ ions in live cells revealed its bioimaging applications.

Green synthesis of fluorescent carbon dots using chloroplast dispersions as precursors and application for Fe3+ ion sensing.

Water-soluble carbon dots (CDs) were synthesized using a one-step hydrothermal treatment of chloroplast dispersions extracted from fresh leaves as a green carbon source. The CD solution showed an emission peak centred at 445 nm when excited at 300 nm. The synthesized CDs were uniform and monodispersed with an average size of 5.6 nm. When adding ferric(III) ions (Fe3+ ) to the solution of the original CDs, the fluorescence intensity decreased significantly. Based on the linear relationship between fluorescence intensity and concentration of Fe3+ ions, an effective method for rapid, sensitive and selective Fe3+ sensing in aqueous solution could be established. Under optimum conditions, the extent of the fluorescence quenching of prepared CDs strongly depended on the Fe3+ ions over a wide concentration range 1.0-100.0 μM with a detection limit (3σ/k) of 0.3 μM. Furthermore, the quantitative determination of Fe3+ ions in environmental water samples was realized.

Topology-Controlled Selective Fe3+ Binding in Water by δ-Peptides with a Dihydropyrimidinone-Containing Amino Acid

The effect of topology on the structure, self-assembly, and selective Fe3+ binding of δ-peptides has been investigated. A series of δ-peptides with an amino acid containing dihydropyrimidinone and o-, m-, and p-aminobenzoic acids have been designed to study the structure–function relationship. A new amino acid containing dihydropyrimidinone was synthesized by the Biginelli reaction of ethyl acetoacetate, urea, and o-nitrobenzaldehyde followed by reduction with iron powder and acetic acid. X-ray crystallography sheds some light on the conformations, self-assembly, and the diverse degrees of π–π stacking of adjacent δ-peptide molecules. Peptides with o- or m-aminobenzoic acid form eight-membered intramolecular hydrogen-bonded turn conformations and self-assemble through intermolecular hydrogen bonds between dihydropyrimidinone units to form a butterfly-like structure. However, the δ-peptide containing p-aminobenzoic acid forms a water-mediated cage-like structure. Irrespective of the presence of the same functional groups, only the δ-peptide with o-aminobenzoic acid can selectively bind Fe3+ in methanol as well as in water. The topology plays a crucial role in the selective Fe3+ ion binding by the δ-peptide.

Two-dimensional metal-organic framework nanobelts for selective Fe3+ removal from aqueous solution with high adsorption capacity

Ultrathin metal-organic frameworks (MOFs) have emerged as a novel class of two-dimensional materials for their unique properties, such as the larger surface area, enriched unsaturated coordination centers and more accessible active sites, which are beneficial for improving their performances in catalysis, sensing and separation. In this work, the MOF (named YNU-1 nanobelts) was exploited to selectively remove Fe3+ from aqueous solutions, which showed an excellent adsorption performance with the adsorption capacity of 456.37 mg/g. The value is the highest among all reported adsorbents of Fe3+, owing to the coordination between the Fe3+ and abundant carboxyl groups on the surface of YNU-1 nanobelts. The adsorption behavior can be well-described with a pseudo-second-order kinetic model, which revealed a chemisorption process. The α-Fe2O3 on the surface of YNU-1 nanobelts after adsorption was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and element mapping measurements. The YNU-1 nanobelts was successfully applied for iron treatment in real sample. Our study provided a facile and efficient method for the removal of iron ions from water.

A highly selective probe for fluorescence turn-on detection of Fe3+ ion based on a novel spiropyran derivative

A new spiropyran bearing multiple phenolic hydroxyl groups is synthesized. It acts as a chemosensor for selective detection of Fe3+ ions in both organic and aqueous solution. The optimal pH range for Fe3+ fluorescent detection by the sensor is pH 4.5–10.5. Upon addition of Fe3+ to the sensor solution the fluorescence emission intensity is enhanced by around 50 fold. Other common competitive metal ions including Li+, Na+, K+, Ag+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+, Mn2+, Sr2+, Hg2+, Ca2+, Mg2+, Al3+ and Cr3+ do not substantially interfere with the selective detection of Fe3+ by the sensor. Changes in the fluorescence emission intensity with the equivalent ratio of Fe3+/sensor exhibits an approximate linear relationship, from which the concentration of Fe3+ ion may be estimated. The detection limit of Fe3+ ion by the sensor is measured to be 1.93 × 10–7 M. A plausible sensing mechanism for selective Fe3+ ion detection by the sensor is proposed based on the Job’s plot measurement.

A porous luminescent Zn-MOF for selective probing Fe3+ and nitrophenolic compounds

A porous luminescent MOF {[Zn(L)]·4H2O·2CH3CN}n (HPU-12) based on a bifunctional ligand, 5-(3,5-Di-pyridin-4-yl-[1,2,4]triazol-1-ylmethyl)-isophthalic acid (H2L), has been synthesized. Structural analysis shows that the two-fold interpenetrated HPU-12 contains 3D pore channels covered with N- and O-coordinated active sites. The luminescence investigation demonstrates that the luminescent HPU-12 can realize the selective detection for Fe3+ by quenching the emission of the HPU-12 via the interaction between the Fe3+ and N and O atoms in the pore channels. In addition, the luminescence of the HPU-12 could be selectively and sensitively quenched by nitrophenolic compound because of the overlap of the absorption of the nitrophenolic compound with the excitation and emission of HPU-12.

Highly sensitive and selective Fe3+ detection by a water-stable Tb3+-doped nickel coordination polymer-based turn-off fluorescence sensor

A Nickel coordination polymer, [Ni2(HBTC)2(NH2CONH2)2(H2O)4]·3H2O (Ni-BTC, H3BTC = 1,3,5-benzenetricarboxylic acid) was synthesized under ionothermal condition, which acted as parent framework to load Ln3+ (Ln3+ = Tb3+, Eu3+, Dy3+ and Sm3+) respectively from the ethanol solutions to prepare Ln3+-doped Ni-BTC (Ln3+@Ni-BTC) composites. The screened Tb3+@Ni-BTC displays bright green fluorescence and water stability, which was used to detect seventeen metal cations in their aqueous solutions, including Fe3+, Al3+, Li+, Na+, K+, Ag+, Mg2+, Ca2+, Ba2+, Zn2+, Mn2+, Cd2+, Co2+, Ni2+, Cr3+, Cu2+ and Hg2+. Tb3+@Ni-BTC showed a rapid fluorescence quenching to Fe3+. The sensitivity tests of Tb3+@Ni-BTC toward CFe3+ detection inferred a linear response of I0/I = 103673.4 × CFe3+ + 1.0844 ​at Fe3+ concentration ranging 1 × 10−6‒4 × 10−5 mol L−1 and limit of detection (LOD) calculated as 2.82 μmol L−1. Anti-inference tests also demonstrated Fe3+ cannot be interfered by other sixteen single metal cations or all metal cations as co-existed ions. The emission intensities at 543 nm of Tb3+ (5D4) can completely recover during the ten-time quenching-recovery cycle in the durability test. Tb3+@Ni-BTC can be regarded as a candidate of quantitative fluorescence sensor to Fe3+ detection with high sensitivity, anti-interference, rapid response and durability.

Carbon Dot-functionalized Interferometric Optical Fiber Sensor for Detection of Ferric Ions in Biological Samples.

This work reports an interferometric optical microfiber sensor functionalized with nitrogen- and sulfur-codoped carbon dots (CDs) for the detection of ferric ions (Fe3+). Compared to other CD-based ferric ion sensors, the sensing mechanism of this presented sensor is dependent on the refractive index modulations due to selective Fe3+ adsorption onto the CD binding sites at the tapered region. This is the first study in which CD-based sensing was performed at the solid phase as a chelator, which does not rely on its fluorescence properties. The detection performance of the proposed sensor is not only comparable to a conventional fluorescence-based CD nanoprobe sensor but also capable of delivering quantitative analysis results and ease of translation to a sensor device for on-site detection. The presented sensor exhibits Fe3+ detection sensitivity of 0.0061 nm/(μg/L) in the linear detection range between 0 and 300 μg/L and a detection limit of 0.77 μg/L based on the Langmuir isotherm model. Finally, the potential use of the CD-functionalized optical microfiber sensor in the real environmental and biological Fe3+ monitoring applications has also been validated in this work.