Complex Ions Research Articles

Influence of multiple detection events on compositional accuracy of TiN coatings in atom probe tomography

The accuracy of composition measurements by atom probe tomography is often dependent on the selected operation mode as well as the applied measurement parameters. The detected hit characteristics, distinguishing between single and multiple events, along with the electric field, are also affected by parameter selection. In this study, atom probe tomography experiments were performed on a stoichiometric TiN coating in voltage as well as in laser-assisted mode with systematically varied laser pulse energies. The observed elemental compositions were compared with complementary ion beam analysis measurements. The influence of multiple detection events was investigated by two approaches: I) A modified local electrode served as a hardware filter, reducing multiple detection events from 78.8 % to 41.9 % and from 40.9 % to 5.6 % using voltage mode and laser-assisted APT (0.6 nJ), respectively, and II) unfiltered datasets were analyzed by data post processing. The latter allowed the study of ion species, particularly of emerging complex molecular ions associated with dissociation processes. Additionally, average electric fields were estimated and spatial considerations were made to investigate the evolution of charge state ratios and hit characteristics during the measurement. Filtering the measurements significantly improved the elemental accuracy. In voltage mode, hardware and software filtering reduced the discrepancy between reference and observed composition from 3.8 at.% to 2.1 at.% and 0.1 at.% within uncertainty limits. In laser-assisted mode, higher laser pulse energy increased the difference between unfiltered data and the reference composition, from 1.4 at.% (0.1 nJ) to 8.1 at.% (2.0 nJ). Ion species analysis of the datasets shows an increasing presence of complex ions (Ti2N) with raising laser pulse energy. Electric field studies reveal a decline from 40 V/nm in voltage mode to 36 V/nm applying a high laser pulse energy of 2.0 nJ, indicating insufficient field strength for neutral nitrogen re-ionization.

Complexation of lanthanide ions with citric acid in aqueous solutions

The stability constants of triply charged lanthanide ions complexes with citric acid of 1:2 stoichiometry weremeasured by potentiometric titration in a wide pH range, and the relationship between the constants and the lanthanide type was analyzed. A mathematical model for the equilibrium in studied solutions was proposed.

Sodium alginate polymer nanoformulation as promising carrier for berberine delivery: Synthesis, morphology and in-vitro evaluation

The present study focused on the fabrication of berberine sodium alginate nanoparticles with a combination approach of conventional nanoprecipitation method with ionic complexation to improve its poor water solubility. The optimization of nanoformulation was done by Central Composite Design and was evaluated for DLS, entrapment efficiency, morphology, FTIR, DSC, antioxidant, anti-inflammatory, antibacterial efficacy and drug release kinetics. The particle size of optimized nanoformulation was in the range of 20 nm to 100 nm with an entrapment efficiency of 94.47%. Antibacterial efficacy of optimized nanoformulation was checked by measuring the zone of inhibition for both gram-positive bacteria and gram-negative bacteria. The optimized nanoformulation showed enhanced antimicrobial activity compared with berberine and control nanoformulation against all bacterial strains. Also, a sustained release of berberine over about 48 h was achieved with nanoformulation and the drug release followed zero-order kinetics. Thus, berberine sodium alginate nanoparticles can potentially increase the oral bioavailability of berberine and can be utilized for controlled delivery thereby reducing the side effects.

Disclosing the Interfacial Electrolyte Structure of Na-Insertion Electrode Materials: Origins of the Desolvation Phenomenon.

Among a variety of promising cathode materials for Na-ion batteries, polyanionic Na-insertion compounds are among the preferred choices due to known fast sodium transfer through the ion channels along their framework structures. The most interesting representatives are Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF), which display large Na+ diffusion coefficients (up to 10-9 m2 s-1 in NVP) and high voltage plateaux (up to 4.2 V for NVPF). While the diffusion in the solid material is well-known to be the rate-limiting step during charging, already being thoroughly discussed in the literature, interfacial transport of sodium ions from the liquid electrolyte toward the electrode was recently shown to be important due to complex ion desolvation effects at the surface. In order to fill the blanks in the description of the electrode/electrolyte interface in Na-ion batteries, we performed a molecular dynamics study of the local nanostructure of a series of carbonate-based sodium electrolytes at the NVP and the NVPF interfaces along with careful examination of the desolvation phenomenon. We show that the tightness of solvent packing at the electrode surface is a major factor determining the height of the free energy barrier associated with desolvation, which explains the differences between the NVP and the NVPF structures. To rationalize and emphasize the remarkable properties of this family of cathode materials, a complementary comparative analysis of the same electrolyte system at the carbon electrode interface was also performed.

Theory of Liquids for Studying the Conformational Flexibility of Biomolecules with Reference Interaction Site Model Approximation

The theory of fluids is used to modify the integral equations of the reference interaction site model (RISM) approximation. Its applicability to the study of biomolecules solvation is evaluated. Unlike traditional RISM applications, the new integral equation contains an intramolecular correlation matrix that only needs to be calculated once. This allows us to bypass the effort of repeatedly solving RISM equations and the time-consuming averaging of values obtained for each time point of a molecular trajectory. The new approach allows for the assessment of the conformational transience of dissolved molecules while taking into account the effects of solvation. The free energy of oxytocin, which is a peptide hormone, as well as self-assembled ionic peptide complexes calculated using both the traditional RISM and the new RISM with average matrix (RISM-AM) approach are estimated. The free energy of oxytocin calculated using RISM-AM shows that the statistical error does not exceed the error obtained by standard averaging of solutions in the RISM equation. Despite the somewhat ambiguous results obtained for ionic peptide self-assembly using RISM-AM with Lennard–Jones repulsion correction, this method can still be considered applicable for fast molecular dynamics analysis. Since the required computational power can be reduced by at least two orders of magnitude, the medium-matrix RISM is indeed a highly applicable tool for studying macromolecular conformations as well as corresponding solvation effects.

Simultaneous removal of Methylene blue and Cadmium from aqueous solution by a novel sulfonated material: Characterization, mechanism and application

Remediation of water bodies contaminated by organic or inorganic pollution has attracted widespread attention, only a few research focused on the remediation of organic-inorganic combined water pollution. In this study, a novel sulfonated material (HMFA), modified from coal fly ash (CFA) through alkali fusion and hydrothermal methods, was synthesized for the simultaneous removal of Methylene blue (MB) and Cadmium (Cd(II)) from wastewater, achieving the waste-control-waste strategy. Characterization results showed that functional groups such as hydroxyl and sulfonic acid groups are favorable for adsorption. The environmental factors exerted influence on the adsorption, with the presence of competing ions producing the most significant inhibitory effect. Under optimal conditions, the adsorption amounts of MB and Cd(II) were 116.69 and 93.53 mg g-1 in single system and 100.23 and 85.49 mg g-1 in binary system, respectively. The results of model fitting showed that the removal of MB and Cd(II) by HMFA in single system was consistent with pseudo-second-order kinetic model and Langmuir model. Apart from electrostatic attraction, the primary adsorption mechanisms on HMFA include hydrogen bonding for MB, as well as ion exchange and complexation for Cd(II), quantitative calculations have been carried out. HMFA remained favorable recyclability, and had higher selectivity on MB in natural water bodies. In conclusion, as a low-cost and efficient adsorbent material, HMFA has great potential for dye and heavy metal pollution control, which can provide more reference and theoretical support for solid waste resource utilization and dye/heavy metal removal in wastewater.

Protomer of Imipramine Captured in Cucurbit[7]uril.

Small molecules possessing multiple proton-accessible sites are important not only to many biological systems but also to host-guest chemistry; their protonation states are causal to boosting or hindering specific host-guest interactions. However, determining the protonation site is not trivial. Herein, we conduct electrospray ionization ion mobility spectrometry-mass spectrometry to imipramine, a known molecule with two protonation sites, based on the introduction of cucurbit[7]uril as a host molecule. For protonated imipramine, the proposed strategy allows clear distinction of the two protomers as host-guest complex ions and can be leveraged to capture the energetically less preferable protomer of the protonated imipramine.

A unified viscoelastic constitutive model for studying the mechanical behaviors of polyelectrolyte complex hydrogels with different crosslinker degrees

Bio-based hydrogels formed by the chemically or physically cross-links are promising materials in the biological system. In this paper, we propose a constitutive model within the framework of finite-strain viscoelasticity to investigate the mechanical behaviors of bio-based polyelectrolyte complex (PEC) hydrogels from the ionic complexation of sodium hyaluronate (HA)/chitosan with and without chemical crosslinkers. The structure of the viscoelastic constitutive model consists of a spring and a Kelvin element, in which two softening factors are adopted to represent the states of ionic bonds and bridges in the hydrogels. Based on some constitutive assumptions and through the conventional approach of thermodynamics, the constitutive equation system of the model is derived. Corresponding to the hydrogels with different crosslinker concentrations, the values of material parameters in the model are identified. To show the validity of the model, it is applied to simulate the mechanical behaviors of the hydrogel samples in the uniaxial tensile tests and cyclic loading–unloading tests. It is found that the model predictions can fit the experimental data quite well. Based on the modeling results, some further analyses regarding the effects of softening factors on the response of HA/chitosan hydrogels have also been conducted.

Synthesis, Characterization and Spectral Studies of Some Metal Ions Complexes with New Schiff Base Ligand Derived From 6- Amino Penicillanic Acid And Biological Screening Study For The Pt(II) Complex.

The complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg (II) and Pt(II)were prepared from the complexation reaction between the new Schiff base ligand and Selected Metal Ions. Ligand was derived from the condensation reaction of Oxo(4-(pyridin-2-yl)phenyl) methyline, 4-amino antipyrine, and 6-amino pencillic acid ). The ligand and its complexes were characterized by C.H.N elemental analysis, Uv-Vis, FT-IR, and molar conductivity, Atomic absorption, magnetic moment measurements and mass spectra studies. The results of this studies show the coordination sites for the ligand with the metal ion were to be through oxygen, nitrogen atoms of 6-amino pencillic acid, and the nitrogen atom of 4-amino antipyrine. The complexes were found to have the general formula [(M)(L)2]Cl2 where M = Co(II), Ni(II), Cu(II), Zn(II), Hg(II), and Cd(II), except the [Pt(L)Cl]Cl. The electronic spectral and magnetic measurement data indicated that the complexes exhibited octahedral geometry, except the Pt(II) complex suggested a square planar geometry around the central metal ion. The ligand forms shape as natural tridentate manner. The biological activity results showed the inhibitory effect for platinum(II) the complex. In this study the cytotoxicity of Pt(II) complex on human colon cancer cell line LS 174 T CRC was investigated and African green monkey kidney cells normal cells were MTT assay. The metal complexes showed selective cytotoxicity against colorectal, this metal Complex excelled in halting proliferation of LS 174 T CRC cancer cells line with median inhibitory concentration (IC50) values of Pt(II) complex. The results indicate undoubtedly the possibility of using them as antitumor drugs in the field of pharmacy colon cancer.

Nutrient-rich hydrothermal carbon production by exogenous nutrients combined with seaweed internal water

As a product of hydrothermal carbonization (HTC) technology, hydrothermal carbon has shown excellent application potential in soil improvement, greenhouse gas reduction and pollution remediation. Since a large amount of water and biomass are directly used as reaction media, hydrothermal carbon produced by traditional HTC possesses poor nutrient properties and accompanied by the generation of toxic and hazardous wastewater. Here, a versatile and easily scalable strategy has been demonstrated for the one-step production of industrial nutrient-rich hydrothermal carbon (NRHC) by combining the exogenous nutrients with seaweed internal water. During the reaction process, exogenous nutrients (NH4H2PO3, KNO3, CO(NH2)2) participated in the HTC reaction and were uniformly distributed on the surface of hydrothermal carbon through surface complexation precipitation, ion exchange, and electrostatic interactions. Simulations based on density functional theory revealed that NRHC produced in presence of exogenous nutrients possessed more active sites and surface charges. Moreover, the adsorbent and adsorbate were simultaneously affected by intermolecular forces, electrostatic forces, and internal energy of the system, and the thermodynamics of adsorption process was more stable. Compared with no exogenous nutrient involvement, NRHC produced by exogenous nutrients showed 2.12, 18.56, and 25.69 times increase in the N, P, and K content. The length of the seed germination root system increased by 4.3–5.9 times, which met the standards set for agricultural fertilizer. Due to increased yield per unit volume and reduced wastewater generation, the cost of NRHC production reduced by 47.83–58.23 per cent and profit enhanced by 1.56–1.68 times, as compared to traditional HTC. This low-cost streamlined process provides a new strategy for large-scale production and direct application of hydrothermal carbon.

A paper-based ratiometric fluorescent sensor for NH3 detection in gaseous phase: Real-time monitoring of chilled chicken freshness

A ratiometric fluorescence sensor platform with easy-to-use and accurate is nanoengineered for NH3 quantitative detection and visual real-time monitoring of chicken freshness using smartphones. The ratiometric fluorescent probe formed by combining the zinc ion complex and carbon dots has a double-emitted fluorescence peak. The fluorescence intensity of the complex changed can be clearly observed with the increase of the concentration of ammonia solution under 365 nm wavelength excitation. In order to detect NH3 concentration in gaseous phase, a portable paper-based sensor was designed. The sensor had a good linear relationship with NH3 concentration ranging from 10.0 to 90.0 μmol/L and the LOD value was 288 nM. This fluorescent paper-based sensor was used to check the freshness of chicken breast refrigerated at 4 °C, revealed observable shifts from blue to green. The fluorescent paper-based sensor can detect NH3 concentration in real time and simplify the monitoring process of meat freshness while ensuring accuracy and stability.

Structures and magnetic properties of a trinuclear angular [Ni3] and a heptanuclear wheel-like [Ni7] complexes with a Schiff base ligand

The presence of large magnetic anisotropy with nickel(II) ions facilitates the single-molecule magnet (SMM) behavior in multimetallic nickel(II) complexes. Herein syntheses under ambient conditions, characterizations, crystal structures, and experimental magnetic analyses of an angular [NiII3L4] and a wheel-like [NiII7L6] complexes of general formula [Ni3L2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Ni7(μ-L)6(μ-OMe)6]Cl2·6H2O (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol) have been reported. The angular core of trimetallic neutral complex 1 is assembled using four L−, two bridging water molecules, and two bound trifluoroacetate anions. In contrast, the heptanuclear complex 2 features a planar wheel-like arrangement with a central NiII enclosed by a {NiII6} hexagon bound to six MeO− and six L−. The isolation of these two aggregates of varying nuclearity and metal ion: ligand anion ratio indicated the importance of reaction conditions and crystallization to follow the bottom-up assembly processes. Experimental magnetic studies showed antiferromagnetic interactions between the central and terminal NiII ions in complex 1 and competing ferro- and antiferromagnetic interactions in the wheel-like complex 2.

Synthesis and Characterization of a Novel Azo-Dye Schiff Base and Its Metal Ion Complexes Based on 1,2,4-Triazole Derivatives

The study focused on producing and examining the properties of the 2-(((3-mercapto-5-(4-nitrophenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)-4-(((4-mercaptophenyl) diazenyl)phenol) ligand (L) and its complexes with three transition metal ions, namely Ni(II), Co(II), and Cu(II). The ligand was formed through diazotization and coupling reactions between 4-aminobenzenethiol and a coupling Schiff base derived from 1,2,4-triazole. The characterization of the ligand and its metal ion complexes was carried out using analytical techniques such as FTIR, 1H- and 13C-NMR, UV-visible spectroscopy, and thermal analysis (TGA and DTG). Various physical methods were employed to synthesize and analyze the properties of the three mononuclear Co(II), Ni(II), and Cu(II) complexes with the azo-dye Schiff's base ligand. Based on the microanalysis and spectroscopic results, it was determined that the coordination between the azo Schiff base ligand and the central metal ion occurred through the NOS-donating atoms of the ligand. The analysis of the electronic spectra revealed that the synthesized Co(II) and Ni(II) complexes exhibited an octahedral geometry, while the Cu(II) complex had a distorted octahedral geometry. The implications of the finding regarding the octahedral and distorted-octahedral geometries include expanding the structural diversity in coordination chemistry, providing insights into ligand-metal interactions, and understanding the influence of geometry on properties.

Determination of Tissue Phantom Ratios of High Energy Photon Beams Using Monte Carlo Code

Monte Carlo codes are veritable tools in radiotherapy to understand the transport mechanism, dose distributions, and energy depositions of ionizing radiations traversing in different media. In some beam calibration protocols, a tissue-phantom-ratio at depths 20 cm and 10 cm (TPR20,10) in a phantom is used to determine the beam-quality conversion factor for different ion chambers. Thus, this study aims to evaluate the efficiency of Monte Carlo code in the determination of beam quality of high radiation energy beams similar to what is expected in clinical settings. Electron Gamma Shower National Research Council in Canada (EGSnrc) Monte Carlo Code was used to design complex ion chamber geometries according to the manufacturer’s specifications. Phase space files were used as x-ray beam radiation sources. Two set-ups (SAD and SSD) methods were used for the determination of TPR20,10 to conform to the accepted clinical procedures. Beam collimation was 10 cm by 10 cm field size with an ionization chamber placed at 20 cm and 10 cm in the water phantom to obtain doses at two points respectively. The TPR20,10 of each energy was obtained using the appropriate equations. The obtained results showed no significant difference between the measured and available TPR 20,10 data (p = 0.995). Ion chamber configurations and specifications were also found not to have a significant effect (p = 0.33) on the TPR 20,10 obtained values. The results obtained in this study are in agreement with the recommended standard values. The findings of this study show that the Monte Carlo codes can be used as a tool in determining x-ray beam quality indices of designed clinical linear accelerator (Linac) machines.

Direct immersion single-drop microextraction combined with fluorescence detection using an optical probe. Application for highly sensitive determination of rhodamine 6G

The use of an optical probe for fluorescence detection combined with direct immersion single-drop microextraction has been demonstrated as an innovative approach. The optical probe served both as a drop holder for extractant and as a measuring device which made it possible to eliminate the use of cuvettes. A laser and a light emitting diode (LED) were tested as possible light sources. Both of them showed comparable results. However, given the much smaller half-band width of the laser radiation, its use has proven to be preferable since background correction can be eliminated. Direct immersion single-drop microextraction of an ionic association complex of rhodamine 6G with picric acid with subsequent fluorescent detection (λex was 532 nm and 525 nm for laser and LED, respectively; λem was 560 nm for both laser and LED) was used a model system to evaluate the new approach. The extractant phase was a 55 μL amyl acetate microdrop fixed in the optical part of the probe. LOD, LOQ and linear calibration range were found as 0.14, 0.48 and 0.5–10 nmol L−1, and 0.15, 0.50 and 0.5–5 nmol L−1 for laser and LED light sources, respectively. The accuracy of the method was assessed by analyzing real water samples.

Degree of complexation of microelement ions by biodegradable IDHA chelator in water and simulated fertilization environment

Abstract The degree of complexation of microelement ions by the biodegradable chelating agent - IDHA was examined in the work. The tests were carried out in water and in a simulated fertilizer environment. In order to compare the obtained results, tests were also carried out for the commonly used EDTA. The performed analyzes allow to determine the influence of the presence of compounds containing macroelements on the degree of binding of microelement ions by the biodegradable IDHA and EDTA chelators. The obtained results make it possible to determine the optimal conditions for the chelation of cations by IDHA, which in the future may be used in the production of micronutrient fertilizers on a large scale.

Synthesis, Crystal Structure, and Thermal Behavior of the [Fe(bpy)3]2[Ba(NO3)6] Ionic Complex

Synthesis, Crystal Structure, and Thermal Behavior of the [Fe(bpy)3]2[Ba(NO3)6] Ionic Complex

Complexation of Lanthanide Ions with Citric Acid in Aqueous Solutions

Complexation of Lanthanide Ions with Citric Acid in Aqueous Solutions

Synergistic Effect of Composite Complex Agent on BTA Removal in Post-Cu-CMP: Experimental and Theoretical Analysis

Nowadays the development of nanoscale-interconnected integrated circuit chips makes the chemical mechanical polishing (CMP) and post-CMP cleaning more challenging. In general, organic residues such as benzotriazole (BTA) can adsorb on the wafer surface after CMP process and form thin films to prevent the contact between cleaning solution and the wafer surface, which thus can seriously affect the post-CMP cleaning process. And the efficient removal of BTA remains problematic due to the potential introduction of additional impurities. Therefore, a new alkaline cleaning solution based on citric acid (CA) was proposed to improve the removal efficiency of BTA. Results exhibit that the cleaning efficiency of BTA residues can reach 98.86% with 400 ppm tetraethyl ammonium hydroxide (TEAH) and 0.6 wt% CA (pH = 10.5). X-ray photoelectron spectroscopy (XPS) measurements show that the cleaning solution can coordinate with copper ions to break the ionization balance of Cu-BTA. In addition, the electronic properties and reaction sites on copper surface were determined by quantum chemical calculation and density functional theory (DFT). The theoretical analysis indicates that CA has hydroxyl and carboxyl functional groups, and its presence with TEAH can promote the complexation of Cu ions, which accelerates the breakage of Cu-BTA and the desorption of BTA from the copper surface.

The use of Clitoria ternatea as sustainable detection tool for Ni (II) and Cu (II) ions in simple paper-based analytical device

Clitoria ternatea plants was growth widely in Indonesia. It was used as natural coloring in food or supplements. In this study, the C. ternatea flower was extracted using ethanol 70% and used for detection of metal ions (Ni, Cu) in aqueous medium. The ability of anthocyanins in C. ternatea extract to react with metal ions was studied using UV-Visible spectroscopy. It was found that the complex of metal ions with C. ternatea flower extract making the hypsocromic effect to the spectra of C. ternatea pure extract. Furthermore, simple paper based analytical device attached with C. ternatea extract was used as test spot to detect the metal ions. It reveals that the color of C. ternatea extract was changed and the calibration curve was obtained. The limit of detection (LOD) in the optimum pH for Ni (II) and Cu (II) was 8.89 ppm, and 4.49 ppm, respectively. Thus, this study showed that C. ternatea flower extract provides sustainable color detection for metal ions with economic and environmental benefits.