A New Reactive 1,8-Naphthalimide Derivative for Highly Selective and Sensitive Detection of Hg<Superscript>2+</Superscript>

A 1,8-naphthalimide derivative with a reactive aliphatic hydroxyl was designed and synthesized as a fluorescent probe. Its structure was characterized by IR, ¹H NMR, ¹³C NMR, LC-MS and HPLC. The probe showed high selectivity and sensitivity to Hg²⁺ over other metal ions such as Pb²⁺, Na⁺, K⁺, Cd²⁺, Cr³⁺, Zn²⁺, Cu²⁺, Ni²⁺, Ca²⁺, Fe³⁺, Fe²⁺, Co²⁺, Mn²⁺ and Mg²⁺ in MeCN/H₂O (15/85, v/v). The increase in fluorescence intensity was linearly proportional to the concentration of Hg²⁺ in the range of 18–40 μM with a detection limit of 1.38 × 10^?7 mol/L. The probe could work in a pH span of 4.3–9.0 and respond to Hg²⁺ quickly with strong anti-interference ability. Job’s plot suggested a 1:2 complex of the probe and Hg²⁺.     

Synthesis and microstructure of Co/Ni: MgGa<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles

This report discusses the preparation and microstructure of Co/Ni co-doped MgGa₂O₄ nanoparticles. The nanoparticles with the size of 20–55 nm were synthesized by sol-gel method. The phase and crystallinity were confirmed by X-ray powder diffraction (XRD) pattern. The particle size was estimated according to XRD data and transmission electron microscopy. The electronic structure was studied using X-ray photoelectron spectroscopy (XPS). The XPS studies showed that Ga³⁺ ions possess tetrahedral and octahedral sites of spinel structure and the inverse degree (two times of the fraction of tetrahedral Ga³⁺ ions) has increased with the increase of the doping concentration of Co²⁺ and Ni²⁺ ions. For Co/Ni co-doped MgGa₂O₄, two broad absorption bands of 350~500 and 550~700 nm were observed in the absorption spectra. The broad band at 350~500 nm was assigned to the combination of the absorption of octahedral Co²⁺ and Ni²⁺ ions, whereas the absorption band at 550~700 nm is mainly due to tetrahedrally coordinated Co²⁺ ions and octahedrally coordinated Ni²⁺ ions.     

A Rhodamine Derivative Based Chemosensor with High Selectivity and Quick Respond to Cr<Superscript>3+</Superscript> in Aqueous Solution

In this paper, a new kind of colorimetric chemsensor aiming at detecting Cr³⁺ has been synthesized, and it is based on the “Off-On” effect of a rhodamine derivative. Comparing with other metal irons (Na⁺, K⁺, Ni²⁺, Hg²⁺, Fe³⁺, Mn²⁺, Co²⁺, Cd²⁺, Cu²⁺, Pb²⁺, Zn²⁺, Mg²⁺, Ba²⁺, Ag⁺, Fe²⁺, Ce³⁺), the chemsensor has a quick and accurate response to Cr³⁺ in H₂O-EtOH solution (4/1, v/v). There is an obvious change in color, from colorless to bright pink when Cr³⁺ is detected. According to the fitting curve based on Benesi-Hildebrand equation and working curve of absorption strength in UV-vis spectrum, the binding pattern of Cr³⁺ and the rhodamine derivative follows a 1:1 stoichiometry. The chemsensor shows great potential in monitoring Cr³⁺ in the aqueous medium with high efficiency, which is supposed to complete the recognition in the minimum as 5.2?×?10^?7 mol/L within 5 min.     

Fluorescent and Chromogenic Receptor Bearing Amine and Hydroxyl Functionality for Iron (III) Detection in Aqueous Solution

The noncyclic 2,2′-[ethane-1,2-diylbis (iminomethanediyl)]diphenol (4) fluorescent receptor bearing two amine and hydroxyl groups have been designed and investigated for their binding properties towards various cations. The fluorescent spectral measurements revealed that receptor 4 is a selective fluorescent sensor for Fe³⁺ ions but not for metal ions such as Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ and Bi³⁺. The binding ability was confirmed with spectroscopic methods and density functional theory calculation (DFT). This straightforward and cost effective receptor provides rapid detection of Fe³⁺ ions at concentrations as low as 2.5 μM and expected to be useful to design efficient chemically and biological sensor.     

Investigation of the structural and electrochemical performance of Li<Subscript>1.2</Subscript>Ni<Subscript>0.2</Subscript>Mn<Subscript>0.6</Subscript>O<Subscript>2</Subscript> with Cr doping

Cr-doped layered oxides Li[Li_0.2Ni_0.2???x Mn_0.6???x Cr_2x ]O₂ (x?=?0, 0.02, 0.04, 0.06) were synthesized by co-precipitation and high-temperature solid-state reaction. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TRTEM), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). XRD patterns and HRTEM results indicate that the pristine and Cr-doped Li_1.2Ni_0.2Mn_0.6O₂ show the layered phase. The Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂ shows the best electrochemical properties. The first discharge specific capacity of Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂ is 249.6 mA h g^?1 at 0.1 C, while that of Li_1.2Ni_0.2Mn_0.6O₂ is 230.4 mA h g^?1. The capacity retaining ratio of Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂ is 97.9% compared with 93.9% for Li_1.2Ni_0.2Mn_0.6O₂ after 80 cycles at 0.2 C. The discharge capacity of Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂ is 126.2 mA h g^?1 at 5.0 C, while that of the pristine Li_1.2Ni_0.2Mn_0.6O₂ is about 94.5 mA h g^?1. XPS results show that the content of Mn³⁺ in the Li_1.2Ni_0.2Mn_0.6O₂ can be restrained after Cr doping during the cycling, which results in restraining formation of spinel-like structure and better midpoint voltages. The lithium-ion diffusion coefficient and electronic conductivity of Li_1.2Ni_0.2Mn_0.6O₂ are enhanced after Cr doping, which is responsible for the improved rate performance of Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂.     

Urea Based Dipodal Fluorescence Receptor for Sensing of Fe3+ Ion in Semi-Aqueous Medium

Urea based fluorescent chemosensor 1 was synthesized. Receptor 1 shows unique selectivity for the Fe³⁺ion and no such significant response was noticed with other metal ions (Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ and Bi³⁺) in DMSO/H₂O (50:50,v/v) semi-aqueous solution. The binding features have been established by absorption and fluorescence spectroscopic methods. The binding constant (K) values obtained from Benesi-Hildebrand, Scatchard and Connor plot for receptor 1 is (8.3?±?0.3) × 10³ M^?1 and has good detection limit 0.7?μM. The stoichiometry of 1.Fe³⁺ complex was confirmed by mass spectroscopy and Job’s plot.

Anthranilic acid-formaldehyde polymers

Poly(anthranilic acid-formaldehyde)s (AFs) were prepared and characterized by IR spectroscopy, M^– _n, viscosity, and TGA. Polymeric metal chelates of AF samples with Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺, and Cr²⁺ ions have been prepared and characterized. The electrical conductivity of polymeric chelates and iodine-doped polymeric chelates was studied over a temperature range of 35° to 100°C. From the electrical conductivity of these polymers, activation energies (E_a ) of electrical conduction were evaluated, and the electrical conductivity data of undoped and iodine-doped polymers were compared.     

Metal Complexation Properties of Schiff Bases Containing 1,3,5-Triazine Derived from 2-Hydroxy-1-Naphthaldehyde in Solution. A Simple Spectrofluorimetric Method to Determine Mercury (II)

Four new Schiff base ligands carrying naphthalene groups were prepared from the reaction of 2,4-diamino-6-methyl-1,3,5-triazine and 2,4-diamino-6-undecyl-1,3,5-triazine with 2-hydroxy-1-naphthaldehyde. The influence of a series of metal ions including Cu²⁺, Co²⁺, Hg²⁺, Al³⁺, Cr³⁺, Fe³⁺, Pb²⁺, Ni²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Ag⁺, Ba²⁺, Ca²⁺ and Mg²⁺ on the spectroscopic properties of the ligands was investigated by means of absorption and emission spectrometry. The results of spectrophotometric and spectrofluorimetric titrations disclosed the complexation stoichiometry and complex stability constant of the ligands with metal ions. A simple spectrofluorimetric method was developed using the Schiff base derived from 2,4-diamino-6-undecyl-1,3,5-triazine to determine Hg²⁺ ion. No cleanup or enrichment of the tap water sample was required. A modified standard addition method was used to eliminate matrix effect. The standard addition graph was linear between 0.2 and 2.6 mg/L in determination of Hg²⁺. Detection and quantification limits were 0.08 and 0.23 mg/L, respectively. The simple and cost-effective method can be applied to water samples.     

A New Fluorescent Chemosensor Detecting Co<Superscript>2+</Superscript> and K<Superscript>+</Superscript> in DMF Buffered Solution

A new fluorescent chemosensor 2-(2-thiophene)imidazo [4,5,f]-1,10-phenanthroline (L) was prepared and characterized. By adding univalent or divalent metal ions such as Na⁺, K⁺, Mg²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Zn²⁺, Cd²⁺ and Hg²⁺ ions into the solution of L in DMF under buffered conditions with the working pH ranging from 7.0 to 8.0, we found that L could be used to detect K⁺ ratiometricly and it could also be applied to sense Co²⁺ with the phenomenon of fluorescence quenching of L. While the response behavior of L was not discernibly affected by other examined metal ions.     

Enhancement of up-conversion luminescence in Zn2SiO4:Yb3+, Er3+ by co-doping with Li+ or Bi3+

Yb³⁺/Er³⁺ co-doped Zn₂SiO₄ ceramics are rapidly synthesized by the microwave radiation method. Green and red up-conversion emissions are observed in Zn₂SiO₄: Yb³⁺, Er³⁺ ceramics under 980 nm excitation. The influence of co-doped Li⁺ or Bi³⁺ ion on luminescence intensity for the phosphors has been investigated. At Li⁺ or Bi³⁺ doping concentration of 1 mol%, up-converted green emission can be increased by 6 times and 20 times, respectively. It is believed that co-doped Li⁺ or Bi³⁺ ion results in the local distortion of Er³⁺ in Zn₂SiO₄, increasing the intra-4f transitions of Er³⁺ ions. The local distortion is proved by spectral probing method with Eu³⁺.     

Tuning the bandgap of ZnO by substitution with Mn, Co and Ni

ZnO doped with Mn²⁺, Co²⁺ and Ni²⁺ have been prepared by the decomposition of acetate solid solutions. Electronic absorption spectroscopy has been used to measure the bandgaps of the doped ZnO samples and the variation of the bandgap with dopant concentration has been examined.     

A Novel Hg<Superscript>2+</Superscript> Selective Ratiometric Fluorescent Chemodosimeter Based on an Intramolecular FRET Mechanism

A irreversible Hg²⁺ selective ratiometric fluorescence probe FR, a fluorescein fluorophore linked to a rhodamine B hydrazide by a thiourea spacer, was designed and synthesized. The developed probe FR exhibited great ratiometric fluorescence enhancement and remarkable yellow-magenta color change toward Hg²⁺ with excellent selectivity in aqueous acetone solution, and the ratiometric fluorescence response to Hg²⁺ was not interfered by other metal cations including Fe³⁺, Co²⁺, Ni²⁺, Cr³⁺, Zn²⁺, Pb²⁺, Cd²⁺, Ca²⁺, Mg²⁺, Ba²⁺ and Mn²⁺. The linear range and the detection limit of this supposed ratiometric fluorescence method for Hg²⁺ were 0.0–10.0 × 10⁻⁶ and 5 × 10⁻⁸ M, respectively.     

Metal ion interaction with ribosomal RNA

Summary We have used UV differential spectroscopy in order to detect small modifications in the ribosomal RNA absorption spectrum due to the binding of rRNA molecules with the metal ions Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, Co²⁺ and Ni²⁺. Our data show that all the ions, investigated are involved in ion-type bond with the phosphate groups of rRNA and cause a refolding of the molecules with an overall increase in basebase ?stacking? interactions. Besides this ion-type binding with phosphate groups, transition metal ions Mn²⁺, Co²⁺, and Ni²⁺ are also able to bond directly to the bases To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Measurement of the proton NMR field shift in aqueous solutions containing Cu2+, Cr3+, Fe3+ and Mn2+ ions

There are presented measurements of the NMR field shifts for aqueous protons in aqueous solutions containing paramagnetic inorganic compounds of Cu²⁺, Cr³⁺, Fe³⁺ and Mn²⁺ ions. The measurements have been performed on samples in the form of transversally magnetized long cylinders using both the internal and external NMR standards. The experimentally determined shifts are related to the NMR field position of protons in pure water. The results for demagnetizing shifts are compared with the data which were computed from the magnetic susceptibility values (measured by magnetostatic method), the chemical shifts are compared with the results of other authors. Results of measurements indicate a small chemical shift of internal standards in some solutions.     

A Novel Naphthalene-Immobilized Nanoporous SBA-15 as a Highly Selective Optical Sensor for Detection of Fe<Superscript>3+</Superscript> in Water

A novel organic-inorganic hybrid optical sensor (SBA-NCO) was designed and synthesized through immobilization of isocyanatopropyl-triethoxysilane and 1-amino-naphthalene onto the surface of SBA-15 by post-grafting method. The characterization of materials using XRD, TEM, N₂ adsorption-desorption, and FT-IR techniques confirmed the successful attachment of organic moieties and preserving original structure of SBA-15 after modification step. Fluorescence experiments demonstrated that SBA-NCO was a highly selective optical sensor for the detection of Fe³⁺ directly in water over a wide range of metal cations including Na⁺, Mg²⁺, Al³⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ in a wide pH values.     

A Highly Selective Turn on Fluorescence Sensor for Hg2+ Based on Rhodamine Derivative

A novel fluorescent rhodamine based chemosensor (E)-3′,6′-bis(diethylamino)-2-((2-(pyridin-2-ylmethoxy)benzylidene)amino)spiro[isoindoline-1,9′-xanthen]-3-one, RSP, had been successfully developed and well characterized by NMR, FT-IR and Mass spectroscopy. The chemosensor exhibits high selectivity for Hg²⁺ over other ions (Ag⁺, Pb²⁺, Cu²⁺, Ni²⁺, Fe³⁺, Co²⁺, Zn²⁺ and Cd²⁺) with fluorescence enhancement in ethanol solution. More over the detection limit of the sensor is in the 10^?6 M level. The binding ratio of RSP-Hg²⁺ complex was determined to be 1:1 according to the Job plot. Test strips based on RSP were fabricated, which showed the application of the sensor for detection of mercuric ions in water by naked eyes.     

Doped ions (Co2+, Fe3+) tuning morphologies and magnetic properties of indium oxide nanoparticles

Transition-metal ion-doped indium oxide was potentially used in spintronic devices. In this article, 10 at.% Co²⁺- and Fe³⁺-doped indium oxide nanocrystals were, respectively, prepared by direct solvothermal method. The influences of doped ions on their morphologies and magnetic properties of indium oxide nanocrystals were investigated. It was found that the doped ions could tune the microscopic morphologies and crystalline structures of indium oxide nanoparticles. Co²⁺-doped samples were polycrystalline nanoflowers aggregated by about 5 nm nanocrystals while Fe³⁺-doped specimens were single-crystalline nanocubes with crystalline sizes of about 16 nm. Meanwhile, the magnetic transition from diamagnetism to paramagnetism was also realized by doping Co²⁺ or Fe³⁺ ions into the indium oxide host matrices. In addition, their magnetic properties were further demonstrated to be intrinsic and not caused by impurities.     

8-Hydroxyquinoline Functionalized Graphene Oxide: an Efficient Fluorescent Nanosensor for Zn<Superscript>2+</Superscript> in Aqueous Media

A nanosensor, based on 8-hydroxyquinoline functionalized graphene oxide, was developed for the fluorescence detection of Zn²⁺. It showed high selectivity and sensitivity for Zn²⁺ion in aqueous solution over other metal ions such as Li⁺, Na⁺, Ca²⁺, Mg²⁺, Al³⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Ni²⁺, Pb²⁺, Fe²⁺, Fe³⁺and Cr³⁺. Due to the linearity of the emission intensity toward Zn²⁺ concentration, fluorescent technique could be used for the detection of Zn²⁺ ion even at very low concentrations.     

Fluorescence Sensors for Selective Detection of Hg2+ Ion Using a Water-Soluble Poly(vinyl alcohol) Bearing Rhodamine B Moieties

The novel water-soluble poly(vinyl alcohol) with pendant rhodamine B moiety as colorimetric and fluorescene chemosensor for Hg²⁺ ions was prepared by grafting poly(vinyl alcohol) using rhodamine B hydrazide and hexamethylenediisocyanate as fluorescent dye and coupling agent, respectively. Because of their good water-solubility, the polymers binding rhodamine B can be used as chemosensors in aqueous media. With the addition of Hg²⁺ ions into the aqueous solution, visual color changes and fluorescence enhancements were detected. In addition, we also noticed that other metal ions such as Ag⁺, Cd²⁺, Co²⁺, Cu²⁺, K⁺, Mg²⁺, Ba²⁺, Fe²⁺, Ni²⁺, Pb²⁺, Cr³⁺, Fe³⁺ and Zn²⁺ cannot induce obvious changes to the fluorescence spectra of the polymer chemosensors. The combination of water solubility and positive fluorescence response as well as color change are hence particularly promising for the practical utility of the sensors.     

Magnetic properties of transition metal substituted La0.85Ag0.15Mn1−yMyO3 compounds (M=Co, Cr and Al)

In this paper we report a systematic study of Mn-site substitution by M=Co, Cr and Al in La_0.85Ag_0.15MnO₃ series to understand the magnetic interactions between Mn and other transition metals. The long-range ferromagnetic (FM) ordering of the parent compound was significantly affected by Mn-site substitution. The measured magnetic properties of Co-doped samples have been explained on the basis of FM interactions in Mn³⁺-O-Mn⁴⁺, Co²⁺-O-Mn⁴⁺, Co³⁺-O-Mn⁴⁺ networks and simultaneous antiferromagnetic (AFM) interactions in Mn⁴⁺-O-Mn⁴⁺, Co²⁺-O-Mn³⁺ networks. The magnetic properties of Cr-doped compounds could be understood on the basis of double exchange FM interactions in Mn³⁺-O²⁻-Mn⁴⁺ networks and competing AFM in Cr³⁺-O-Mn⁴⁺, Mn⁴⁺-O-Mn⁴⁺, Cr³⁺-O-Mn³⁺ networks. However, it is found that the doping of Al ions play a role of magnetic dilution, without contributing any other competing magnetic interaction. The field variations of magnetization of all the above three series could be analysed by fitting to Brillouin function model and the effective spin contribution for FM has been determined. The measured saturation magnetization has been explained quantitatively.