Presence Of Ions Research Articles

Hexadecylpyridinium bromides as a new capping agent for improving stability and luminescence of cesium lead bromide perovskites

Because of exception properties, inorganic halide perovskites are promising materials for numerous applications. The efficiency of these materials are evaluated based on their photoluminescence quantum yield, which is the key indicator and proportional to the stability of the perovskite. Hence, to limit the instability of the perovskites, addition of surfactant as ligand has been applied during synthesis of nanoparticle based inorganic perovskite CsPbBr3. As far as we know, only a few researchers have studied the impact of hexadecylpyridinium bromide (CPB) on the stability of the crystal structure of CsPbBr3. In this work, we present a novel approach for lead halide perovskites by incorporating CPB to primarily maintain the perovskite's crystal structure, and later on to enhance the stability of CsPbBr3 NPs while boosting its photoluminescence quantum yield (PLQY). Results showed that CPB enhanced the thermal stability and boosted the PLQY to 90 %. Moreover, CPB had proven its efficiency as a capping agent preventing the exchange of anion between bromide and iodide ions in presence of lead iodide.

An eugenol-sulfonyl based fluorescent probe for recognition of Al3+ in real sample analysis and biological application

The present work describes an eugenol-sulfonyl based fluorescence chemosensor, H4L [H4L=6,6′-((1E,1′E)-((sulfonylbis(6-hydroxy-3,1- phenylene))bis(azanylylidene))bis(methanylylidene))bis(4-allyl-2-methoxyphenol)], which shows maximum emission intensity towards Al3+ ion in presence of other competing metal ions. Upon excitation at 440 nm H4L exhibits a significant rise in fluorescence at 547 nm upon gradual addition of Al3+ ion in the HEPES buffer at pH=7.4 (MeOH:H2O, 4:1, (v/v)). The increasing value of fluorescence is mainly due to chelation enhanced fluorescence effect (CHEF). Complete characterization of the probe (H4L) and metal bound complex (1) have been determined using a range of methods including UV–Vis absorption titration, fluorescence titration, NMR, ESI-mass, etc. Thus 1:2 binding stoichiometry between H4L and metal ion has been also proved. Another important aspect: regeneration and reversibility of H4L are investigated in presence of Na2EDTA. H4L exhibits ∼ 10−6 M order detection limit and significant binding constant (∼106 M−1) for the Al3+ ion, suggesting its potential use in bio-imaging studies. The probe was effectively used in real samples as well as paper strip to locate the Al3+ ion.

Carbon paste based sensor for sensitive Cr(III) ion determination in different water samples and anti-diabetic supplement

A modified carbon paste sensor based on N,N′-(((ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))bis(pyridine-2-amine; BPA Schiff base as Cr(III) selective carrier was fabricated and studied in this work. The proposed sensor homogenization and mechanism of action was studied by infra-red (IR) and scanning electron microscope (SEM) with energy dispersive X-ray (EDX) tools. The sensor covered 1.0 × 10−7–1.0 × 10–1 mol L−1 linear range and a detection limit of 7.22 × 10–8 mol L−1 for Cr(III) with 20.17 ± 0.13 mV decade−1 Nernstian slope. 5 s was the response time of the prepared sensor and it was reproducible and stable for 3 months. The working pH range was 3.3–6.0 and it also works well to determine Cr(III) ion in presence of water miscible solvents up to 12.5% content of the methanol and 17.5% of ethanol. The electrode’s selectivity was studied using separate and mixed solution methods for selectivity coefficients determination and the sensor showed good selectivity relative to a variety of metal ions (selectivity coefficients = 1.01 × 10−5–8.57 × 10−3). In addition, the practical analysis value of the sensor was demonstrated by measurement of Cr(III) quantitatively in mineral water, supplement and also as an indicator electrode in Cr(III) against EDTA potentiometric titration with good reproducibility (RSDs of 0.91–2.15%).

Zn(II)/Cd(II) MOFs based on 2,5-thiophenedicarboxylic acid and bis(Imidazole) linkers for highly selective and sensitive detection of Fe3+ and Cr2O72-

Two new MOFs [(Zn2(bib)(tdc)2(H2O)2)]n1 and [Cd(bib)(tdc)(H2O)]n2 [bib = 1,4-bis(imidazole)butane, tdc = 2,5-thiophenedicarboxylic acid] were synthesized by solvothermal method. The synthesized MOFs were characterized by elemental analysis, FT-IR, PXRD, thermal analysis and X-ray single crystallography. Both 1 and 2 are 3D frameworks, in which 1 exhibits 8-fold interpenetrating ths network, whereas 2 shows uninodal 4-connected 3-fold interpenetrating network with lvt topology. Furthermore, 1 and 2 demonstrate selective and sensitive sensing capabilities towards Fe3+ and Cr2O72- ions in presence of various interfering metal ions and inorganic anions. The LOD for Fe3+ using 1 and 2 are 0.085 and 0.167 µM, and for Cr2O72- are 0.037 and 0.045 µM, respectively. The results demonstrate the potential applications of 1 and 2 as a multifunctional fluorescent material for sensing of Fe3+ and Cr2O72- ions.

Ferroelectric Order in the Chiral Coordination Polymers [Ln2(L*)2(ox)2(H2O)2] with Ln=Gd3+ or Dy3+, L*=((S, S)‐1,3‐bis(1‐Carboxylethyl)imidazolium and Ox=Oxalate.

AbstractWe evidence the ferroelectricity of two isostructural magnetic coordination networks obtained from a chiral imidazolium dicarboxylate salt ((S, S)‐1,3‐bis(1‐carboxylethyl)imidazolium or [HL*]) and Gd3+ or Dy3+ ions in presence of oxalic acid (H2ox). The two compounds exhibit a chiral structure P1 and ferroelectric properties. The crystallographic study shows that the Dy based‐compound is isostructural to the Gd analog. The non‐centrosymmetry of the two samples was further checked by means of nonlinear optical spectroscopy. The room temperature ferroelectric character of the compounds has been investigated through by an original method, derived from that used for thin films, made possible by preparing the sample as thin slices of resin containing inclusions of the coordination compounds.

Transition metal complexation assisted stabilization of the deprotonated organic moiety: A strategy for colorimetric and electrochemical recognition of fluoride ion in water medium with organic probe molecules

Excess consumption of fluoride through drinking water causes detrimental effects to human health which has been a serious global concern. This situation demands routine monitoring of fluoride in drinking water in fluoride affected regions around the world. A plethora of organic molecules has been demonstrated as chemosensors based on the fluoride induced deprotonation reaction of the probe molecules. However, most of the probe molecules fail to react with fluoride in aqueous medium which limits their application. Herein, we have demonstrated a metal ion, Ni(II) mediated strategy to retain the reactivity and the sensitivity of the probe molecule towards fluoride ion in aqueous medium with the help of two benzothiazole based probe molecules (R and P). Both the probe molecules showed retention of the affinity towards fluoride ion in aqueous medium in presence of Cu2+ ion but the colorimetric response is not upto the mark. On the other hand, the probe molecule P showed excellent affinity and colorimetric response towards aqueous fluoride ion in presence of Ni2+ ion. The methodology is validated with UV–Vis spectroscopy and Differential pulse voltammetry (DPV) technique. Probe molecule P in presence of Ni2+ ion showed limit of detection values 0.60 ppm and 0.57 ppm w.r.t. UV–Visible spectroscopy and DPV technique respectively. Furthermore, the efficiency of the methodology w.r.t. P was tested with real samples collected from the fluoride affected areas of Assam, India and found that the data corroborates well with the results of ion selective electrode. This methodology can provide a new dimension in the development of a low cost method for routine sensing of fluoride ion with organic probe molecules in drinking water for low resource world.

Isothermal compressibility, internal pressure studies of aqueous rare earth nitrate solutions at 298.15 K: An attempt to estimate ionic radii and understand inner– and outer–sphere exchange water structural interactions

In this communication, we report our analysis and results concerning the determination of ionic radii in aqueous solution phase for Lanthanum (La+3), Neodymium (Nd+3), Erbium (Er+3) and Ytterbium (Yb+3) ions in presence of nitrate (NO3-) anion at 298.15 K. The literature data for density, adiabatic compressibility, and specific heat capacity of solutions at constant pressure have been used to compute isothermal compressibility, internal pressure of solutions in limiting concentration range. The apparent molar isothermal compressibility of electrolytes and hydration numbers have been obtained. The electrostriction for rare earth cations and intrinsic volumes have been calculated using thermodynamic equations. The ionic radii of cations have been obtained using the ionic partial molar volume data of NO3- ions and the results are compared with those obtained for rare earth chlorides. The two series affect is also observed for ionic radii and internal pressure. The results have been explained on the basis of water structural effects due to electrostatic field and water dipole interaction between the inner– and outer–sphere water exchange reaction.

A comprehensive assessment of interfacial and bulk properties of sodium dodecylsulfate via addition of competitive Hofmeister ions in presence of Cosolvent: A combined experimental and theoretical study

The synergistic interaction of sodium dodecyl sulphate (SDS) and added electrolyte in presence of cosolvent is investigated by determining the critical micelle concentration of SDS. The present system is carried out with two different types of counterions from Hofmeister series where Hofmeister chaotropic ion i.e. NH4+ is attracted more towards the negatively charged chaotropic dodecyl sulphate headgroup of SDS than the kosmotropic ion. To understand the thermodynamic behavior of SDS micelle, counterion binding constant values are measured using the well-established Corrin-Harkins or modified Corrin-Harkins equations. Various assessments of aggregation and adsorption phenomena of SDS micelle are established from both experimental and theoretical concepts. The exchange of counterion i.e. Na+ ion by NH4+ ions can occur at a particular electrolyte concentration where SDS micelle leads to the formation of ammonium dodecyl sulphate (AmDS) in the present cosolvent media. Therefore, the Hofmeister chaotropic ion (NH4+) is found to be a competitive ion. In addition to that, solvophobicity of the cosolvent mixture is another important parameter which could influence SDS micellization differently.

A facile and highly selective fluorimetric chemosensor 1,2,4-Aminonaphthol sulfonic acid for detection of copper ions in aqueous medium

1,2,4-Aminonaphthol sulfonic acid (H) shows strong fluorimetric properties which can be utilized for recognition behavior of cation identification. Sensor (H) has selective complexing ability towards Cu2+ ions in presence of other metal ions in aqueous medium. Study of Stern-Volmer plot confirmed static as well as dynamic quenching mechanisms. The Job's plot exhibited stoichiometric ratio between metal ions and receptor as 1:1. Benesi Hildebrand equation was used to calculate association constant Ka (1.43 × 103 M-1) for Cu2+ ions. Fluorescence study revealed that the sensor (H) is capable to detect Cu2+ ions efficiently in aqueous medium without the bar of maintaining pH of the solution.

Selective and sensitive sensing of mercuric ions by natural compound qingyangshengenin

Mercuric ion (Hg2+) is acknowledged as one of the most dangerous contaminants, originating from a range of natural sources and industrial wastes. Hence, it is very important to design and develop highly selective and sensitive probes for the quick detection of Hg2+ in aquatic environments. In view of this, in the presented study a biocompatible C21-steroidal aglycone, qingyangshengenin (1), has been isolated from 95% ethanol extracts of the roots of Cynanchum otophyllum Schneid and characterized by NMR spectroscopy and mass spectrometry. The obtained natural product had been used as photoluminescent sensor for selective and sensitive detection of mercuric cation with limit of detection of 1.61 ppm and KSV value of 7.46 × 102 M−1. Also, interference experiments revealed that 1 can selectively detect Hg2+ ion in presence of other metal cations. Further, theoretical calculations have been done to assess the reason for selectivity of this steroid against the mercuric ion. The integrated experimental and theoretical studies reveals that the plausible reason for the selectively and sensitivity of qingyangshengenin to detect Hg2+ was accredited to the better interaction between Hg2+ and qingyangshengenin.

Synthesis, characterization, luminescence and NLO properties of heterotrinuclear MII-RuII-MII (M=Ni/Zn) complexes composed of coordination and organometallic sites

A new series of heterotrinuclear complexes of the type [Ru(dppm)2((CCC6H4CCC6H3 (O)HCNC6H4X)Ni(L'))2] (1a-c) and [Ru(dppm)2((CCC6H4CCC6H3(O)HCNC6H4X)Zn(L'))2] (2a-c) were prepared by the reaction of trans-[Ru(dppm)2(CCC6H4CCC6H3(OH)HCNC6H4X)2] with Ni(II)/Zn(II) ions in presence of 8-hydroxyquinoline. (where, X= Cl, Br, I; L'= 8-hydroxyquinoline) All the complexes were characterized by elemental analysis, FT-IR, 1H NMR, ESI-MS, UV–visible and thermogravimetric studies. The electrochemical properties of all the complexes indicate quasireversible redox behaviour corresponding to Ru(II)-Ru(III) and Ni(II)/ Ni(III) for 1a-c and Ru(II)/Ru(III) for 2a-c and are susceptible to variation of substituent group on ligand. All complexes show room temperature luminescence corresponding to π→π* intraligand charge transfer (ILCT) transition. The emission wavelength of the complexes is finely tuned by increasing π-conjugation and variation of substituent groups in the complexes. The second harmonic generation (SHG) efficiency of the complexes was measured by Kurtz-powder technique indicating that all complexes displayed the second harmonic generation (SHG) property.

Selective and sensitive sensing of copper(II) by natural compound C-21 steroid caudatin

Selective and sensitive sensing of varied analytes is playing important role in assessing the concentration of different pollutants in aquatic system. In view of this, in the presented study a biocompatible C-21 steroid caudatin (1) has been isolated from C. otophyllum, characterized using multinuclear NMR spectroscopy and mass spectrometry. The obtained natural product had been used as photoluminescent sensor for selective and sensitive detection of cupric cation with limit of detection of 1.93 ppm and KSV value of 3.45 × 103 M−1. Also, interference experiments revealed that 1 can selectively detect Cu2+ ion in presence of other metal cations. Further, theoretical calculations have been done to assess the reason for selectivity of this steroid against the copper cation. The integrated experimental and theoretical studies reveals that the plausible reason for the selectively and sensitivity of caudatin to detect Cu2+ was accredited to the better interaction between Cu2+ and caudatin as well as competitive absorption light due to UV–Vis spectral overlap operates between Cu2+ and caudatin that are collectively responsible for the quenching in emission of caudatin.

Selective determination of cuprous ion in copper dissolving solution based on bathocuproine-modified expanded graphite electrode.

The presence of cuprous ions in the copper-dissolving solution significantly affects the microstructure of copper plated surface. Fewer quantitative analyses of cuprous ions in the copper foil productive process had rarely been involved so far. In the present work, a novel electrochemical sensor of the bathocuproine (BCP) modified expanded graphite (EG) electrode was developed for the selective determination of cuprous ions. EG has a large surface area, good adsorption, and excellent electrochemical performance which remarkably promoted analytical sensitivity. Meanwhile, the selective determination of the BCP-EG electrode for cuprous ions in the coexistence of ten thousand times of copper ions have been achieved on the benefit of the special coordination of BCP to cuprous ions. In the coexistence of 50g/L copper ions, the analytical performance of the BCP-EG electrode for the determination of cuprous ions had been examined. The results represented a wide detection range of cuprous ions in the range of 1.0μg/L-5.0mg/L, with a low detection limit of 0.18μg/L (S/N = 3) and the BCP-EG electrode has great selectivity to cuprous ions in presence of various interferences. The analytical selectively for cuprous ions supported by the proposed electrode would be a potential analytical tool for quality improvement in electrolytic copper foil manufacturing.

A Phenolic Schiff Based AIE‐Active Quinoxaline‐Based Receptor for Selective Sensing of Fluoride Ions

AbstractAnions play very important role in various physiological, biological process and essential in various medical diagnosis. Amongst, anionic species fluoride is considered an essential component, however, the excess amount of fluoride may cause issues with various organs of the body such as kidney and nervous system. Herein we developed a new fluorescent chemosensor based on quinoxaline receptor 1 for rapid sensitive detection of fluoride ion. The receptor contains the free hydroxy proton which easily undergoes deprotonation occurs the OH− to give phenoxide ion via hydrogen bond interaction with fluoride ions. The deprotonation reaction on the aromatic system. The receptor 1 showed good selectivity towards F− ion in presence over another anion. The absorption and emission studies, naked eye detection and test strip application was performed for fluoride ion detection. The binding constant for the receptor was calculated by Benesi Hildebrand method and was found to be 8.76×104 M−1. While the limit of detection was observed to be 3.1 μM which much lower than the permissible limit of 270 μM given by United State Environmental Protection Agency (EPA). Thus, we believe this new derivative may be used in future for real world application for fluoride ion detection.

Kinetic study of L-lysine and L-arginine by hexacyanoferrate (III) ion in presence of Os (VIII)

Amino acids and their metal complexes have vital role in functioning the metabolism of all living system. Amino acids can undergo many types of reactions in acidic as well as in alkaline medium. The reactions of L-lysine and L-arginine amino acids have been selected in alkaline medium for the present study. The kinetics of oxidation of L-lysine and L-arginine by alkaline Os (VIII), which was continuously regenerated by hexacyanoferrate (III) ion, was studied in the 0.01- 0.10 M and 298 K – 318 K temperature range. The rate of reaction was found to be zero with respect to [Fe(CN6)]3- and one with respect to Os (VIII).

Salicylaldehyde based Schiff base as a selective and sensitive chemosensor for Cd2+ and Ni2+ ions

A new salicylaldehyde-based sensor N'-(5-bromo-2-hydroxybenzylidene)-4-methylbenzohydrazide (P4) was designed, and its sensing ability towards various metal ions was assessed using UV-visible spectroscopy. The structure of P4 was spectroscopically characterized by UV-Visible, Infrared, 1H-NMR, 13C-NMR spectroscopy and mass spectrometry. UV-Visible absorption spectral study showed selective sensing ability of P4 for Cd2+ and Ni2+ ions in presence of diverse transition metal ions. The results revealed that the detection limit for Cd2+ and Ni2+ was 3.14 µM and 0.92 µM, respectively. Moreover, the compound P4 was fully implemented for detection of Cd2+ and Ni2+ in simulated samples.

Ni-sinapic acid nanocomposite in the selective sensing of permanganate ions

A polyphenolic acid assisted synthesis of Ni nano particles for absorption spectrophotometric sensing of MnO4- ions in micro molar range is reported here. The synthesis was carried out using a green approach where sinapic acid acts as a capping agent. The synthesized nano particle was then characterized using UV–Vis spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, powder X-ray diffraction analysis, X-ray photoelectron spectroscopy. The particle size is around 5 to 10 nm with the presence of both porosity and nano crystallinity as obtained from the transmission electron microscopic analysis. This nano particle can selectively sense permanganate ions in presence of different co-existing ions with the limit of detection (LOD) 0.413 µM. The sensing mechanism was examined with the isothermal titration calorimetry (ITC) and X-ray photoelectron spectroscopy (XPS). Isothermal titration calorimetric data suggests that the interaction between permanganate and the nano particle is enthalpy driven process with ΔH and ΔG values are −80 kcal/mol and −5.72 kcal/mol respectively. XPS data confirmed the presence of Ni(II) ions in the Ni-SA NPs and the atomic percentage of the same differed in presence of KMnO4. There was no significant interference from the contemporary ions and even in the presence of Mn2+ ion. The method has also been applied for the natural water samples and for vegetable. ∼ 88 to 108 % of the added KMnO4 could be recovered from the tap water sample using our prepared methodology. The limit of detection and the present technique are compared with the previously reported literature and have been found to be comparable, even in solvent-free conditions and using simple instrumentation.

The interaction of selenite and ferrous ions in presence or absence of granite

The interaction of selenite and ferrous ions in presence or absence of granite

A mono-nuclear Cu(II) complex of an unsymmetrical Schiff base ligand and its use to synthesise trinuclear CuII2MnII complexes showing anion dependent SMM behaviour

The effort for synthesis complexes of unsymmetrical Schiff base ligands derived from 2,2-dimethyl-1,3-propanediamine, o-hydroxyacetophenone and salicylaldehyde by modified Edler's method resulted in the isolation of mononuclear [CuL]·CH3OH (1), where H2L = N-(α-methylsalicylidene)-N′-(salicylidene)-2,2-dimethyl-1,3-propanediamine. Complex 1 on reaction with Mn(II) ion in presence of ClO4−, N(CN)2−, or N3− yielded three tri-nuclear complexes [(CuL)2Mn(CH3OH)2](ClO4)2·3H2O (2) [(CuL)2Mn(N(CN)2)2] (3) and [(CuL)2Mn(N3)2]∙2H2O (4), respectively. X-ray crystallography revealed square planar geometry of Cu(II) and distorted octahedral geometry of Mn(II) in the complexes. Temperature dependent molar magnetic susceptibility measurements illustrated overall anti-ferromagnetic coupling between the Cu(II) and Mn(II) centres in complexes 2–4 with exchange coupling parameters, J = −16.82 cm−1 and g = 2.06 for 2, J = −19.40 cm−1 and g = 2.10 for 3 and J = −18.98 cm−1 and g = 2.11 for 4. Among these hetero-metallic complexes only the azide derivative (4) presented prominent ac signals under an applied dc bias field. Cyclic voltammetry measurements showed reversible Cu(II)/Cu(I) couple for complex 1 whereas complexes 2–4 showed irreversible reduction of Cu(II).

An asymmetric MnO2|activated carbon supercapacitor with highly soluble choline nitrate-based aqueous electrolyte for sub-zero temperatures

• Eutectic of choline nitrate and water maintains liquid state down to -100°C. • MnO 2 /carbon supercapacitor at 1.8 V operates down to -40°C. • Charge compensation in MnO 2 by the nitrate ions in presence of bulky choline cations. MnO 2 |activated carbon supercapacitors are attractive power devices that rival the electric double-layer capacitors (EDLCs) due to high reachable voltage. However, they greatly suffer from performance loss at low temperature as most of aqueous electrolytes freeze below ca. -10°C. Here, a concentrated choline nitrate-based (5 mol/L aqueous ChNO 3 ) electrolyte is applied to extend the working temperature range due to its eutectic-like properties. In such electrolyte, water acts as hydrogen bond donor for nitrate anion and low hydration energy for large choline cations favors ionic transport. The MnO 2 /CNT composite electrode with a hierarchical structure has been synthesized by hydrothermal process. The presence of CNTs as core component facilitates the electron conduction, while the two-dimensional MnO 2 flakes grown on the surface provide electrolyte transport pathways and improve the interfacial processes (pseudocapacitive charge/discharge). Thanks to the low hydration of choline cation, the individual activated carbon (AC, negative) and MnO 2 /CNT (positive) electrodes are charged symmetrically up to a cell voltage of 1.8 V. Overall, due to the wide electrochemical stability window (∼2.0 V) and anti-freezing properties of ChNO 3 -based aqueous electrolyte and the hierarchical design of the MnO 2 /CNT composite, the asymmetric supercapacitor operates down to -40 °C and displays excellent energy and coulombic efficiency with no loss of performance after several thousand cycles. This work provides a new possibility on the low temperature application of high voltage supercapacitors.