A New Schiff Base Chemodosimeter: Selective Colorimetric and Fluorescent Detection of Fe (III) Ion

A new efficient chemosensor 1 was prepared, for the detection of Fe³⁺ in solutions as a colorimetric and fluorescent sensor. The visual and fluorescent behaviors of the receptor toward various metal ions were also explored. The receptor shows exclusive response toward Fe³⁺ ions and also distinguishes Fe³⁺ from other cations by color change and fluorescence enhancement in hydroalcoholic solution (MeOH/H₂O = 9/1, v/v). Thus, the receptor can be used as a colorometric and fluorescent sensor for the determination of Fe³⁺ ion. The fluorescence microscopy experiments showed that the chemosensor is efficient for detection of Fe³⁺ in vitro, developing a good image of the biological organelles.

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Calix Receptor Edifice; Scrupulous Turn Off Fluorescent Sensor for Fe(III), Co(II) and Cu(II)

Novel Supramolecular fluorescence receptor derived from calix-system i.e. calix[4]resorcinarene bearing dansylchloride as fluorophore was designed and synthesized. The compound was purified by column chromatography and characterized by elemental analysis, NMR and Mass spectroscopy. Tetradansylated calix[4] resorcinarene (TDCR) shows a boat conformation with C₂v symmetry. The complexation behaviour of metal cations [Ag(I), Cd(II), Co(II), Fe(III), Hg(II), Cu(II), Pb(II), Zn(II), U(VI) (1?×?10^-4?M)] with tetra dansylated calix[4]resorcinarene (1?×?10^-6?M) was studied by spectophotometry and spectrofluorometry. Red shift in the absorption spectra led us to conclude that there is strong complexation Fe(III), Co(II) and Cu(II) with TDCR. These metal cations also produce quenching with red shifts in the emission spectra. The maximum quenching in emission intensity was observed in the case of Fe(III) and its binding constant was also found to be significantly higher than that of Co(II) and Cu(II). Quantum yield of metal complexes of Fe(III) was found to be lower in comparison with Co(II) and Cu(II) complexes. Stern Volmer analysis indicates that the mechanism of fluorescence quenching is either purely dynamic, or purely static.     

Synthesis and Characterization of New Cationic Fe(III),Co(II) and Ni(II) Complexes Containing Isatin/Triphenylphosphine Mixed Ligands

New cationic Fe(III),Co(II) and Ni(II) mixed ligand complexes containing both triphenylphosphine and isatin ligands were prepared and characterized using conventional physical and chemical methods of analysis

(I.R., UV-Vis., and ¹H NMR). Microanalytical data of the investigated complexes are consistent with the formulations. [Fe(Isa)₂ {P(Ph)₃}₂]³⁺, [Co(Isa)₂ {P(Ph)₃}₂]²⁺ and [Ni(Isa)₂ {P(Ph)₃}₂]²⁺, (Where Isa = Isatin and P(Ph)₃ = Triphenylphosphine).

The prepared complexes are soluble in polar solvents and could be of potential use in bio-inorganic applications.     

Nanoparticles of Ni(II) and Co(II) metallo-organic molecular materials

We have investigated the effect of thermal annealing on the diode characteristics of solution-processed novel core–shell coaxial n–p nanorods heterojunction consisting of n-type ZnO as a core and p-type CuS as a shell material. The values of turn-on-voltage, rectification ratio, reverse saturation current density, barrier height, and ideality factors have been improved as the as-prepared heterojunction is annealed at higher temperatures owing to the improvement in the interface between ZnO and CuS as evidenced from the high-resolution transmission electron microscopy. The X-ray diffraction results also confirm the improvement in the crystalline quality of ZnO and CuS through annealing. The experimental current–voltage data are consistent with the presence of dominating recombination-tunneling conduction occurring through the interface defect states between ZnO and CuS. The results demonstrate that an annealing process plays a dominant role in the interfacial defects which helps to modify the diode performance paving a way to cheaper electronic nanodevices.     

Formation,Structure and Magnetic Properties of Polymer Matrix Nanocomposites Processed by Thermal Decomposition of the Fe(III)Co(II) Acrylate Complex

Structure and magnetic properties of polymer matrix nanocomposites, processed by pyrolysis of the Fe(III)Co(II) acrylate complex, were investigated. It was shown that thermal transformation of the complex studied consisted of three macrostages: dehydration, solid state polymerisation and decarboxylation of a metallopolymer form. The main products of the decomposition were nanoparticles stabilised by polymeric matrix. The crystalline phases, which were found in the fully processed material, were Fe₃O₄, CoFe₂O₄ and CoO. The mean crystallite size was 10nm. In the intermediate stages of the thermolysis iron was present in the forms of Fe^III (trivalent low – spin iron), Fe²⁺(divalent high – spin iron) and Fe₃O₄. The hysteresis loops measured at temperatures below 200K were opened and shifted towards negative field. The coercivity and remanence showed room temperature values of 0.18T and 15.5mT, respectively.     

U(VI) reduction by Fe(II) on hematite nanoparticles

Nanoscale size effects on U(VI) reduction by Fe(II) on hematite were investigated with four aerosol-synthesized hematite nanoparticles (12, 30, 50, 125 nm) and one aqueous-synthesized hematite (70 nm). Batch experiments were conducted at loadings of 0.01 mM U(VI) and 5 mM Fe(II) at pH 7.5 and 9.0. Rate constants for reduction of U(VI) to U(IV) were determined using a pseudo-first order reaction rate law. Reduction was faster at pH 7.5 than at pH 9.0. Rate constants were higher for aerosol-synthesized hematite than for aqueous-synthesized hematite. Rate constants were not significantly different for the 30, 50, and 125 nm particles. However, reduction was two orders of magnitude faster for the 12 nm hematite particles. Possible explanations for the dramatically faster reduction with the 12 nm hematite include the formation of a more reactive solid such as magnetite, effects on electron conduction through hematite, and quantum confinement effects.     

Solvent Controlled Colorimetric and Fluorometric Detection of Fe2+ and Cu2+ Ions by Naphthaldimine-Glucofuranose Conjugate

Journal of Fluorescence - The sensing properties of naphthaldimine-glucofuranose conjugates 1 and 2 towards metal ions were investigated by 1H NMR titration, Fourier-transform infrared spectroscopy...     

Co adsorption on potassium promoted Fe(110)

CO adsorption on potassium covered Fe(110) has been studied using UPS, XPS, AES and flash desorption. It was found that CO adsorbs molecularly at room temperature with a larger binding energy than on clean Fe(110). The CO saturation coverage increases and the sticking coefficient decreases with increasing potassium coverage. On heating, the probability of adsorbed CO dissociating increases with the amount of potassium present. The UPS spectra show that the CO 4σ peak is shifted by 0.8 eV to higher binding energies on Fe(110) + K and that at 21.2 eV the peak due to the 1π + 5σ orbitals is split into a double peak. The catalytic relevance of the measurements is discussed with reference to the Fischer-Tropsch synthesis.     

Surface vs. bulk magnetic properties of Co/Fe(0 0 1) and Fe/Co/Fe(0 0 1) as probed by linear magnetic dichroism in photoemission

The atomic-like behavior of the photoionization cross-section of core levels in solids is remarkably displayed in the observation of linear magnetic dichroism in the angular distribution (LMDAD) of photoelectrons. Nevertheless, structure-related effects are clearly visible as modulations of the dichroism signal, induced by photoelectron diffraction (PED). In this paper a comparison between the PED and LMDAD behaviours is presented for Fe 3p in Fe(0 0 1). In order to separate experimentally the surface and bulk contributions, ultrathin Co/Fe pseudomorphic overlayers were grown on the Fe(0 0 1) surface. Results confirms the PED nature of LMDAD modulations, which can be used as an estimate of the bulk sensitivity of the experiment.     

Interaction of Co with an Fe(111) surface

Adsorption of CO on Fe(111) below 300 K causes the appearance of three different non-dissociated species as distinguished by their CO stretch frequencies of about 1530 cm^-1 (a), 1800 cm^-1 (b), and 2000 cm^-1 (c). At T ? 220 K the b-state is first filled up and saturates after 1.5 L exposure; upon increasing the temperature it partly desorbs around 400 K and partly dissociates. Recombination of the C and O atoms followed by CO desorption takes place at about 800 K. Above 1.5 L exposure the a- and c-states are occupied simultaneously; in the thermal desorption spectrum in turn they show up as a relatively broad shoulder at ～ 340 K, which indicates similar adsorption energies for these two species. Saturation of the surface is reached after about 6 L exposure, which is paralleled by a continuous work function increase of up to Δφ = 1.6 eV. A high background intensity in the LEED pattern suggests substantial disorder in the adlayer. Evaluation of the TDS data yields about 2:1 population of the b- and (c + a)-states. The unusual low CO frequency of the a-state finds its analogues in reports on CO adsorption at stepped surfaces, as well as with complex compounds where the π-orbitals of the ligand directly interact with a neighboring metal atom. This species is therefore identified with adsorption in the “deep hollow” sites on the rather open Fe(111) surface. The b-state is tentatively attributed to the “shallow hollow” sites, and the c-state to adsorption on the “on top” sites.     

Vibration Spectra of Coprecipitated Fe(III)-Ni(II) and Fe(III)-Cu(II) Hydroxides and of the Products of Their Thermolysis

A range of coprecipitated Fe(III)-Me(II) (Me(II) = Ni, Cu) hydroxides and of the products of their thermolysis have been investigated by the IR spectroscopy method. The basic absorption bands has been assigned, and the chemistry of the process of formation of coprecipitated hydroxides has been discussed from the standpoint of generation of heteronuclear hydrococomplexes.     

Site symmetry of Mn(II) and Co(II) in zinc phosphate glass

Optical absorption and EPR spectra of Mn(II) and Co(II) doped zinc phosphate glasses have been investigated. Crystal filed parameters and g values are determined. For Mn(II) doped glass the values are Dq=850, B=850, and g values are around 2 at room temperature (RT). For Co(II) doped glass, Dq=890, B=700, and g=4.45 and 2.06 at liquid nitrogen temperature. The optical and EPR data has been correlated.     

A quantitative atom-probe field-ion microscope study of the compositions of dilute Co(Nb) and Co(Fe) alloys

The compositions of Co-1.0at%Nb and Co-1.0at%Fe alloys have been measured using the atom-probe field-ion microscope. The main purpose of this experimental work was to find a set of optimum conditions which gives the correct solute concentrations in these alloys. This information was necessary for measuring the absolute compositions, in our extensive investigations of solute atom segregation effects to individual stacking faults in these alloys. The dependence of each alloy's composition on the following parameters was investigated: (1) the specimen temperature; (2) the pulse fraction; (3) the field-evaporation rate; (4) the crystallographic plane; (5) the effect of the presence of hydrogen in the atom-probe on the measured Nb composition in a Co-1.0at%Nb alloy. It is shown that the composition determined by the atom-probe FIM is very sensitive to some of the parameters listed above. The effects of these experimental parameters on the measured Nb and Fe concentrations are discussed in terms of possible field-evaporation models. Under certain experimental conditions drastically different behavior has been observed in these alloys; preferential field-evaporation of solute atoms in a Co-1.0at%Fe alloy and preferential retention of solute atoms in a Co-1.0at%Nb alloy was observed. Correct solute concentrations were obtained by using the following experimental parameters: (1) a specimen temperature of less than or equal to 60 K; (2) a pulse fraction of greater than or equal to 0.10.     

Hg(II) Selective Complexation by Chromoionophoric Calix[4]arene Derivative

The present article describes an exploration regarding Hg(II) selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4). The binding affinity of 4 toward selected transition metal ions such as Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) have been investigated by UV-visible and fluorescence spectroscopies. From the results it has been noticed that 4 confers a pronounced preference for Hg(II) in complexation phenomenon even in the presence of other metal ions. The results of Job's plot analysis reveal 1:1 host-guest complex formation between Hg(II) and 4. The FT-IR spectroscopy also supports the complexation affinity of 4 for Hg(II).     

利用二阶方向导数极大值检测红外小目标

为提高复杂环境下红外小目标的检测率,提出了基于二阶方向导数极大值的红外小目标检测算法。该算法首先对二阶方向导数的性质进行了分析,对极大值进行阈值翻转操作,将背景中的平坦成分和边缘成分剔除。接着,根据小面模型对背景进行预测,并以预测误差为权值进一步增强小目标区域。以上2个步骤的计算可通过4个卷积实现,加快了检测速度。最后,对少量候选小目标计算局部对比度,降低了虚警率。实验结果表明：该检测算法在6种复杂背景下平均信杂比增益为78.413 0,平均背景抑制因子为35.079 6,具有较强的鲁棒性和较高的检测率。     

Detection of DNA Bases Using Fe Atoms and Graphene

The adsorption of DNA bases on a magnetic probe composed of Fe atoms and graphene is studied by using firstprinciples calculations.The stability of geometry,the electronic structure and magnetic property are investigated.The results indicate that four DNA bases,i.e.,adenine,thymine,cytosine and guanine,can all be adsorbed on the probe solidly.However,the magnetic moments of the composite structure can be observed only when adenine adsorbs on the probe.In the cases of the adsorption of the other three bases,the magnetic moments of the composite structure are zero.Based on the significant change of magnetic moment of the composite structure,adenine can be distinguished conveniently from thymine,cytosine and guanine.This work may provide a new way to detect DNA bases.     

Room Temperature Ferromagnetism in Graphene/SiC(0001) System Intercalated by Fe and Co

The utilization of graphene on silicon carbide (SiC) substrates holds substantial promise for advancements in spintronics and nanoelectronics. Furthermore, incorporating magnetic metals provides an optimal framework for probing fundamental physical phenomena. The approach to developing such systems is in situ intercalation of graphene with magnetic metals. Herein, the electronic structure is analyzed and the magnetic properties of the system are synthesized by the thermal decomposition of 6H-SiC(0001) surface and subsequent intercalation of graphene with cobalt (Co) and iron (Fe) atoms. X-ray photoemission spectroscopy and low-energy electron diffraction are employed to control the synthesis and metal intercalation processes. The morphological characteristics of the synthesized system are studied by means of atomic force microscopy. The findings derived from magneto-optic Kerr effect measurements reveal a homogeneous ferromagnetic ordering at room temperature. Angle-resolved photoemission spectroscopy is used to ascertain the impact of intercalation on graphene's electronic structure. The results of this study are essential for the development of graphene-based spintronics and nanoelectronic devices as well as for fundamental studies in magnetic graphene systems.