Chemosensory rhodamine-immobilized mesoporous silica material for extracting mercury ion in water with improved sensitivity

Mesoporous silica material, SBA-15, is an excellent support for constructing fluorescent surface sensor. In this paper, we reported a three-step surface reaction involved strategy to construct efficient fluorescent surface sensor for mercury ion by clicking rhodamine fluoroionophores onto APES-functionalized SBA-15, which is fully characterized by IR spectra, TGA analysis, elemental analysis, nitrogen adsorption experiment and TEM. Our experimental results indicated that such a strategy exhibits an obviously higher loading efficiency within SBA-15 than a previously reported strategy. The Hg²⁺ extracting efficiency for SBAIR was found to be enhanced (ca. 89%). In addition to the high selectivity, the current chemosensor shows improved sensitivity and can respond to Hg²⁺ as low as ppb level (1.0 × 10⁻⁸ M, 2 ppb) in water.     

Anisotropy of the spectroscopy properties of the wurtz-stannite Cu2ZnGeS4 single crystals

In this study, the near band edge anisotropic optical properties of wurtz-stannite (WS) Cu₂ZnGeS₄ single crystals were characterized using polarization-dependent transmittance and electrolyte electroreflectance (EER) techniques. Single crystals of Cu₂ZnGeS₄ were grown by chemical vapor transport method using iodine as a transport agent. Analysis of absorption spectra revealed indirect allowed transitions for Cu₂ZnGeS₄ with the band gaps of 2.02 (2.07) and 2.08 (2.14) eV for E‖b and Е‖a polarization configurations at 300 (10) K. The room-temperature EER spectra in the vicinity of the direct band edge showed anisotropic transitions at around 2.38, 2.44 and 2.45 eV for E‖b, Е‖a and Е‖c polarizations, respectively. Based on the experimental observations and recent band-structure calculations a plausible band diagram near band edge of WS-Cu₂ZnGeS₄ was constructed.     

Colorimetric and fluorescent sensing of transition metal ions in aqueous medium by salicylaldimine based chemosensor

The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine (receptor 1) was studied by visual observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe³⁺, Co²⁺, Ni²⁺ and Cu²⁺. Binding affinity toward Cu²⁺ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe³⁺, Co²⁺ Ni²⁺ and Cu²⁺ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism.     

Synthesis and characterization of Cu3N-WC nanocomposite films prepared by direct current magnetron sputtering

Cu₃N-WC films were synthesized on an arc ion plated TiN_x interlayer by direct current magnetron sputtering. The Cu₃N-WC films, composed of columnar WC crystals 3-5 nm in size and amorphous Cu₃N phases, were grown using the layer-plus-island mode. Deposition rate of Cu₃N-WC films declined from 11.7 to 7.5 nm/min when the WC target power increased from 200 to 400 W because the Cu target was poisoned by the diffusion of WC molecules. Nano-indentation testing results showed that the highest measure of hardness of Cu₃N-WC films was up to ∼ 41 GPa and the H³/E^?2 value of the Cu₃N-WC_47.4 was around 0.41 GPa, indicating the excellent plastic deformation resistance of the film. Incorporation of the soft lubricant Cu₃N phase and the uniform distribution of WC hard phases resulted in significant improvements in friction coefficient and wear resistance. As such, Cu₃N-WC films have a good potential in future wear applications.     

Synthesis and Structure of the Np(VII) Complex with Guanidinium,Li[C(NH<Subscript>2</Subscript>)<Subscript>3</Subscript>]<Subscript>2</Subscript>[NpO<Subscript>4</Subscript>(OH)<Subscript>2</Subscript>]·6H<Subscript>2</Subscript>O

The previously unknown Np(VII) compound Li[C(NH₂)₃]₂[NpO₄(OH)₂]·6H₂O (I), containing organic cations, was synthesized and studied by single crystal X-ray diffraction. In contrast to the relatively numerous structurally characterized salts of [NpO₄(OH)₂]^3– anions with Na⁺, K⁺, Rb⁺, and Cs⁺ cations, which were prepared only from strongly alkaline media, crystals of I were isolated from solutions with a very low concentration of OH^– ions (about 0.1 M). The compound is relatively stable in storage in the dry form, but is strongly hygroscopic. In the structure of I, there are two independent Np(VII) atoms with the oxygen surrounding in the form of tetragonal bipyramids. In contrast to the other salts of the [NpO₄(OH)₂]^3– anions with singlecharged alkali metal cations, the C(NH₂) ₃ ⁺ ions and hydrated Li⁺ ions in I interact with the oxygen surrounding of Np(VII) only via hydrogen bonds of types O_w–H···O and N–H···O with the formation of a three-dimensional H-bond network.     

The influence of transition metal ions on collagen mineralization

The ions in body fluid play an important role in bone formation besides being a synthesizing material. Transition metal ions Co^2 +, Ni^2 +, Zn^2 +, Fe^3 +, Mn^2 +, Cu^2 +, Cd^2 + and Hg^2 + doped hydroxyapatite (HAP)/collagen composites were synthesized successfully in the presence of collagen traces at mild acidic pH for the first time. However, the amount of doped Hg^2 + and Cd^2 + was relatively low. Meanwhile, through soaking the collagen sponge as a template in simulated body fluid (SBF) which contains different transition metal ions (Mn^2 +, Cu^2 +, Ni^2 +, Co^2 +, Cd^2 +, Hg^2 +), bone-like HAP/collagen composites were synthesized. Hg^2 + had a certain inhibitory effect on the formation of HAP crystals on the surface of the collagen sponge while Co^2 + can promote the formation of HAP on the collagen sponge. For both HAP/collagen composites and HAP/collagen sponge, it was found that transition metal ions Mn^2 + had a significant effect on the morphology of HAP particles and could induce to form floc-like HAP particle aggregates.     

Novel Holmium (Ho) and Praseodymium (Pr) ternary complexes with fluorinated-ligand and 4,5-diazafluoren-9-one

Four ternary complexes Ln1 and Ln2 (Ln=Ho and Pr) were synthesized, with 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dione and 4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-(naphthalen-2-yl)decane-1,3-dione served as main sensitizers, respectively. Their elemental analyses, Fourier Transform Infrared spectra, and luminescent properties were investigated. The complexes all show the characteristic near-infrared luminescence of corresponding Ln³⁺ ions, via an antenna effect. Furthermore, the influence of ligands structure on the luminescence behavior of complexes is discussed and it is believed that the fluorinated alkyl chains of ligands affect the energy transfer in complexes.     

Synthesis of diketopyrrolopyrrole (DPP)-based small molecule donors containing thiophene or furan for photovoltaic applications

Two π-conjugated small molecules based on diketopyrrolopyrrole (DPP), DPP4T and DPP2F2T, were synthesized using the Suzuki coupling reaction. DPP4T and DPP2F2T contained furan and thiophene, respectively, next to a DPP core. Organic photovoltaic cells (OPVs) were fabricated using two DPP-based oligothiophenes as donors. DPP4T showed higher power conversion efficiency (PCE) (1.44%) than DPP2F2T (0.85%). The short-circuit current (J_SC) of DPP4T (4.38 mA cm⁻²) was nearly twice that of DPP2F2T (2.49 mA cm⁻²). The improved photovoltaic properties of DPP4T could be explained by the optical properties and the film morphology.     

Aggregation of silver nanoplates in the presence of L‐cysteine and the application for separation

A facile method was investigated to fabricate the aggregated silver nanoplates as products for separation materials. Initially, ageing of L‐cysteine capped silver nanoplates in ethanol solvent led to fast aggregation. Then, the as‐formed aggregates were easily prepared as powder due to the highly volatile properties of ethanol. Interestingly, the aggregated powder would be soluble again after the dispersion in water and the re‐dispersed nanoplates could be obtained. Furthermore, the heavy metal ions such as Cu²⁺, Pb²⁺ and Hg²⁺ would soon accelerate the aggregation of the dispersed silver nanoplates again. The reversible aggregation process could be employed for separation applications in the future.Inspec keywords: silver, nanoparticles, aggregation, nanofabrication, organic compounds, separation, dissolving, copper, lead, mercury (metal)Other keywords: aggregation, L‐cysteine, separation materials, ageing, L‐cysteine capped silver nanoplates, ethanol solvent, aggregated powder, heavy metal ions, Ag, Cu, Pb, Hg     

Divalent ion uptake of heavy metal cations by (aluminum + alkali metals) – substituted synthetic 1.1 nm-tobermorites

The reactions of Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Cd²⁺ or Hg²⁺ synthetic (Al + alkali metal) – substituted tobermorites were studied. Among these cations, Mn²⁺, Fe²⁺, Cu²⁺, Zn²⁺, pb²⁺ and Hg²⁺ appears to exchange with outer planar surface of Ca²⁺ of tobermorites due to the break down of structural Ca-O bonds, in addition to the substituted alkali metals in the structure. But it is difficult to delineate the extent of this reaction from the precipitation of the concerned ions as carbonates, hydroxy carbonates, hydroxy nitrates or hydroxides. The uptake of metal ions by these solids led to their amorphization in many cases due to the partial exchange and the acidic nature of metal solutions, and hence their reactions are not strictly analogous to cation exchange in zeolites and clays. The order of ion uptake has been found in the following order: Fe²⁺ > Ni²⁺ > Co²⁺ > Zn²⁺ > Cu²⁺ > Mn²⁺ > Hg²⁺ > Cd²⁺ > pb²⁺.     

Synthesis and Structure of Mixed-Cation Salts with [PuO<Subscript>4</Subscript>(OH)<Subscript>2</Subscript>]<Superscript>3–</Superscript> Anions

Mixed-cation salts of the composition NaM₂[PuO₄(OH)₂]·4H₂O, where M = Rb (I) and Cs (III), and NaRb₅[PuO₄(OH)₂]₂·6H₂O (II) were synthesized and structurally characterized. The central Pu atom in [PuO₄(OH)₂]^3– anions has oxygen surrounding in the form of a tetragonal bipyramid with oxygen atoms of hydroxide ions in apical positions. The hydrated Na⁺ cations have oxygen surrounding in the form of a distorted octahedron. In the structure of I, there are two independent Rb⁺ cations with 10- and 12-vertex coordination polyhedra (CPs), and in the structure of II, three independent Rb⁺ cations with the 12-, 11-, and 13-vertex CPs. In the structure of III, the Cs⁺ cation has a 12-vertex CP. Frameworks of large Rb⁺ or Cs⁺ cations can be distinguished in the structure. The CPs of the Pu and Na atoms (I, III) sharing a common edge or the isolated CPs of the Pu and Na atoms (II) are incorporated in these frameworks. Hydrogen bonds influence the crystal packing and the geometric characteristics of the [PuO₄(OH)₂]^3– anions.     

Fine-tuning supramolecular assemblies of fullerenes bearing long alkyl chains

Fine-tuning of the supramolecularly organized nanometer scale architectures of fullerene derivatives, fulleropyrrolidines substituted with a mono-, di-, or tri(n-hexadecyloxy)phenyl group is described. These synthetic fullerene derivatives possess one- (1), two- (2), or three- (3) long alkyl chains. The correlation between the number of alkyl chain multiplicity and the self-organized bilayer structures as the fundamental subunit as well as the superstructures formed in different solvents were investigated using microscopic and spectroscopic techniques. The fullerene derivatives studied formed interdigitated lamellar bilayer structures whose d spacing values, estimated by X-ray diffraction patterns, are 2.63 nm for 1, 3.50 nm for 2, and 4.28 nm for 3, respectively. There are the two differing intermolecular forces present due to C₆₀ (sp²-carbons) or alkyl chains (sp³-carbons). Fullerene moieties always exhibit strong π-π interactions, while van der Waals interactions between alkyl chains can be altered by variation of their multiplicity. Substitution of three alkyl chains at the fullerene moiety (3) was the most effective method for stimulating polymorphism in its derivatives in different solvents.     

Determination of the modulated structure of the misfit layer compound (LaS)1.196VS2

Single crystal X-ray diffraction was used to determine the modulated structure of the misfit layer compound (LaS)_1.196VS₂. This compound crystallizes in the triclinic system with cell parameters: a_s = 3.410 (1) Å, b_s = 5.845(1) Å, c_s = 11.191(2) Å, α ≈ 95.15(4), β ≈ 84.79(2)°, and γ ≈ 89.98(2)°, q = 0.5978(4)a_s^* − 0.002(1)b_s^* + 0.004(2)c_s^*, and V_s = 221.2(1) Å³. A (3 + 1)D superspace group, X(α,β,γ), was used to analyze the complete structure (X is referring to a pseudo C centering). The largest modulation amplitudes are observed for La-S (between La (subsystem 2) and S (subsystem 1)), as well as V-V distances. In connection with the large V-V modulation, we observed the formation of “linear vanadium clusters” that may impact on the transport properties.     

Ion exchange and electrochemical evaluation of the microporous phosphate Li9Fe7(PO4)10

A new lithium iron(III) phosphate, Li₉Fe₇(PO₄)₁₀, has been synthesized and is currently under electrochemical evaluation as an anode material for rechargeable lithium-ion battery applications. The sample was prepared via the ion exchange reaction of Cs₅K₄Fe₇(PO₄)₁₀1 in the 1 M LiNO₃ solution under hydrothermal conditions at 200 °C. The fully Li⁺-exchanged sample Li₉Fe₇(PO₄)₁₀2 cannot yet be synthesized by conventional high-temperature, solid-state methods. The parent compound 1 is a member of the Cs_9−xK_xFe₇(PO₄)₁₀ series that was previously isolated from a high-temperature (750 °C) reaction employing the eutectic CsCl/KCl molten salt. The polycrystalline solid 1 was first prepared in a stoichiometric reaction via conventional solid-state method then followed by ion exchange giving rise to 2. Both compounds adopt three-dimensional structures that consist of orthogonally interconnected channels where electropositive ions reside. It has been demonstrated that the Cs_9−xK_xFe₇(PO₄)₁₀ series possesses versatile ion exchange capabilities with all the monovalent alkali metal and silver cations due to its facile pathways for ion transport. 1 and 2 were subject to electrochemical analysis and preliminary results suggest that the latter can be considered as an anode material. Electrochemical results indicate that Li₉Fe₇(PO₄)₁₀ is reduced below 1 V (vs. Li) to most likely form a Fe(0)/Li₃PO₄ composite material, which can subsequently be cycled reversibly at relatively low potential. An initial capacity of 250 mAh/g was measured, which is equivalent to the insertion of thirteen Li atoms per Li_9+xFe₇(PO₄)₁₀ (x = 13) during the charge/discharge process (Fe²⁺ + 2e → Fe⁰). Furthermore, 2 shows a lower reduction potential (0.9 V), by approximately 200 mV, and much better electrochemical reversibility than iron(III) phosphate, FePO₄, highlighting the value of improving the ionic conductivity of the sample.     

Effect of salting-out agents on nitric acid distribution between liquid and vapor in the course of evaporation of nitric acid radioactive waste

The database on the influence of concentrations of salting-out agents with different cation valence (Li⁺, Na⁺, K⁺, Cs⁺, NH₄⁺, Mg2+, Ca²⁺, Cu²⁺, Zn²⁺, Al³⁺, Fe³⁺, La³⁺, Pu⁴⁺, UO₂²⁺ nitrates) and of H₂SO₄ on the HNO₃ distribution between liquid and vapor at atmospheric pressure was verified and expanded by performing equilibrium evaporation experiments in an evaporator without reflux with circulation of the bottoms. This equilibrium can be described by the equation \(\log {\kern 1pt} {\alpha _H} = - 2.35 + 2\log \;{X_{\Sigma N{O_3}}}\) (where \({X_{\Sigma N{O_3}}}\) is the total concentration of nitrate ions in aqueous solution), taking into account partial binding of water due to hydration of the salting-out agent and apparent hydrolysis of polyvalent cations, and also incomplete dissociation of sulfuric acid. The suggested model is valid at \({X_{\Sigma N{O_3}}}\) from 3 to 16 M (azeotrope); at \({X_{\Sigma N{O_3}}}{\text{ < }}\;3\), Raoult’s law is observed (α_H = const), which is confirmed by a number of examples. In this model, the additivity of the properties of the salting- out agents, taking into account the concentration of “free” water, is assumed, which allows calculation of the composition of the bottoms and distillate when evaporating waste of any composition from radiochemical plants.     

Removal of radionuclides,macrocomponent metal ions,and organic compounds from solutions by nanofiltration

Removal of Mg²⁺, Сa²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Fe³⁺, and Pr³⁺ ions, tracer amounts of ¹³⁷Cs, ⁸⁵Sr, and ⁶⁰Co radionuclides, and oxalate and ethylenediaminetetraacetate ions from solutions using a polymeric nanofiltration (NF) membrane produced by RM Nanotekh (Russia) was studied. The selectivity (S) of the NF membrane to multicharged metal cations is considerably higher than to single-charged cations. The NF membrane exhibits the highest selectivity (S = 94–97%) to triple-charged Fe³⁺ and Pr³⁺ ions and double-charged Cu²⁺ ions. The selectivity to double-charged Mg²⁺ and Zn²⁺ ions is somewhat lower (90–94% on the average). Among doublecharged cations, the NF membrane exhibits the lowest selectivity (80–88%) to Ni²⁺ and Cа²⁺ ions. The NF membrane shows high performance in retention of tracer amounts of Sr (S = 95%) and Co (S > 99%) radionuclides, and also of oxalate (S = 94.5%) and ethylenediaminetetraacetate (S = 97.5%) ions. Examples of using the nanofiltration method for removing ⁶⁰Co from a model solution simulating NPP bottom residue and for removing transition metal impurities from a LiCl solution are presented.     

Transformation of Dion-Jacobson phase to Aurivillius phase: synthesis of (PbBiO2)MNb2O7 (M = La, Bi)

We describe transformations of the Dion-Jacobson (D-J) phases, KLaNb₂O₇ and RbBiNb₂O₇, to the Aurivillius (A) phases, (PbBiO₂)LaNb₂O₇ (1) and (PbBiO₂)BiNb₂O₇ (2), in a metathesis reaction with PbBiO₂Cl. Oxide 1 adopts centrosymmetric tetragonal structure (a = 3.905(1) Å, c = 25.66(1) Å), whereas oxide 2 crystallizes in a noncentrosymmetric orthorhombic (A2₁am) (a = 5.489(1) Å, b = 5.496(2) Å, c = 25.53(1) Å) structure. Oxide 2 shows a distinct SHG response towards 1064 nm laser radiation. The role of La³⁺ versus Bi³⁺ in the perovskite slabs for the occurrence of noncentrosymmetric structure/ferroic property in these materials is pointed out.     

Metal clusters and nanoparticles assembled in zeolites: an example of stable materials with controllable particle size

An ion-exchangeable zeolite (mordenite) is used to control the formation of nanoparticles and clusters within the solid matrix by the hydrogen reduction of metal ions (Ag⁺, Cu²⁺, and Ni²⁺). SiO₂/Al₂O₃ molar ratio in mordenite appears to be an efficient tool to manage the reducibility of the metal ions. Few-atomic silver clusters in line with the larger silver nanoparticles were observed with DRS for the reduced Ag⁺-exchanged mordenites. Cu²⁺-exchanged ones produce the copper nanoparticles with different optical appearance, and Ni²⁺-exchanged mordenites are reduced up to complicated species with no explicit assignment of metal particles under the conditions studied.     

Crystal structure,nonlinear optical and photophysical properties of a novel chromophore constructed with terpyridine,triphenylamine and ethyl cyanocaetate functional moieties

A novel chromophore (Z)-ethyl-3-(4-((4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl) (phenyl) amino)phenyl)-2-cyanoacrylate(3), constructed with triphenylamine moiety as the electron donor (D), 2, 2: 6, 2-terpyridine moiety as an electron acceptor (A), and ethyl cyanocaetate group as an auxiliary electron acceptor (A′), has been designed and synthesized. The crystal structures of 3 and its mediator 2 (4″-(4′-(4-(Diphenylamino) phenyl) aldehyde)-2,2′:6′,2″-Terpyridine), have been determined by single crystal X-ray diffraction analysis. The linear and nonlinear spectra of these chromophores were investigated on the basis of experimental and calculation methods. The two-photon absorption (TPA) cross-sections of 1–3 were determined by a femtosecond open-aperture Z-scan technique. The maximum value of the TPA cross-section (σ) for 3 is 7938.3 GM in DMF solution. However, much weaker two-photon absorption responses were observed at the same condition for chromophore 1 and 2, respectively. The results of the work indicate that, the photophysical properties of the D–A configuration group are influenced largely by the auxiliary moiety (A′) attached.     

Complexes of An(VI) with Cyclobutanecarboxylic Acid Anions and Outer-Sphere Alkali Metal Cations

New complexes of hexavalent actinides with cyclobutanecarboxylic acid (Hcbc) anions, Na₄[NpO₂· (cbc)₃]₄·H₂O (I), K[NpO₂(cbc)₃] (II), Cs[NpO₂(cbc)₃] (III), and Cs[PuO₂(cbc)₃] (IV), cbc = C₄H₇(COO)^–, were synthesized and studied by single crystal X-ray diffraction. The structures of I–IV are based on the anionic complexes [AnO₂(cbc)₃]^– surrounded by alkali metal cations. The AnO ₂ ²⁺ cation in the anionic complex is bonded with three chelating C₄H₇COO^– anions, and the coordination polyhedron (CP) of An is a hexagonal bipyramid with the O atoms of the AnO ₂ ²⁺ cations in apical positions. The coordination number (CN) of the alkali metal cations in the structures of II–IV is the same and equal to 6; the coordination surrounding of the K⁺ and Cs⁺ cations is constituted by the O atoms of six C₄H₇COO^– anions. The crystal structures of II–IV are examples of cubic 3-connected networks (10,3) built of alkali metal and actinide cations. In the structure of I, there are four kinds of crystallographically different NpO ₂ ²⁺ and Na⁺ cations. The coordination surrounding of the NpO ₂ ²⁺ cations differs only in the conformational characteristics of the C₄H₇COO^– ligands. Four independent Na⁺ cations differ from each other in the structure of the coordination surrounding. The CPs of the Na(1) and Na(4) atoms can be described as distorted octahedra (CN 6); that of Na(3), as a trigonal prism (CN 6); and that of Na(2), as a tetragonal pyramid (CN 5) with one of the basal vertices occupied by the Ow(1) atom of a water molecule. In the structure of I, the configuration of the network formed by the Na and Np cations differs from the cubic 3-connected network found in the structures of II–IV.