Salicylate Ion Research Articles

Corrosion protection and antibacterial performance of a chitosan/salicylate coating electrogenerated on a magnesium alloy

In this work, chitosan and chitosan/salicylate coatings were prepared by EPD on AZ91D Mg alloy to improve the corrosion resistance of the substrate in a simulated physiological solution. The effect of two concentrations of salicylate on the morphology and anticorrosive behaviour of the coatings was evaluated. The results showed that the addition of 0.50 g/L sodium salicylate to the chitosan formulation decreased the corrosion rate of the chitosan coating from 0.0025 ± 0.0003 to 0.0007 ± 0.0004 mA cm−2. From the results of electrochemical impedance spectroscopy (EIS) and Fourier Transform Infrared (FTIR) analysis, it can be concluded that the presence of salicylate in the coating leads to a self-healing effect that contributes to an improved corrosion protection. In addition, the presence of salicylate in the coating has been shown to increase antibacterial activity against both Gram-positive and Gram-negative bacteria. It has been demonstrated that salicylate can be released from the coating, which has an anti-inflammatory effect. In this way, a novel chitosan/salicylate coating was developed for the first time on a Mg alloy for bactericidal effect, release of salicylate and corrosion protection in simulated physiological solution. So far, chitosan and salicylate have not been investigated as a combination for the development of multifunctional coatings on Mg alloys. In addition, the self-healing effect of salicylate ions in a chitosan coating was established for the first time.

The effect of polarity and hydrogen bonding on the electronic and vibrational structure of the salicylate anion in acetonitrile and water: implicit and explicit solvation approaches.

This study investigates the fluorescence quenching of the salicylate anion in water compared to acetonitrile (ACN) and the stability of its keto structure in ACN using DFT and TD-DFT methods at the 6-311++G(d,p) basis set. Computational simulations in implicit and explicit environments of ACN and water reveal the effects of solvent polarity and hydrogen bonding on enol [Od-H⋯Oa] and keto [Od⋯H-Oa] tautomerization, fluorescence quenching, and the spectral profile of the salicylate anion. Implicit solvation models show a barrier height of approximately 1.9 kcal mol-1 in ACN and 3.6 kcal mol-1 in water for enol-keto tautomerization in the ground state, with no barrier in the excited state, leading to an ESIPT reaction in both solvents, but only ground state proton transfer in ACN. Simulated absorption spectra for both enol and keto forms are similar in both solvents, while the emission spectrum is red-shifted in water. Explicit solvation studies indicate greater stabilization of the salicylate anion in water than in ACN, with a blue shift in absorption and emission spectra and varying oscillator strengths. Solvent molecule positioning affects enol-keto stabilization in the ground state, but only the keto structure is stabilized in the excited state. Simulated IR spectra in water show a blue shift in Od-H stretching frequency and increased water molecule vibrational frequencies, suggesting non-radiative excitation energy transfer from salicylate ions to water molecules via n → σ* intermolecular hydrogen bonding interactions. This mechanism explains the fluorescence quenching observed in water and results align with experimental data, indicating hydrogen-bonded keto form stabilization both in water and ACN.

All-solid-state potentiometric salicylic acid sensor for in-situ measurement of plant.

Using PEDOT as the conductive polymer, an innovative small-scale sensor for directly measuring salicylate ions in plants was developed, which avoided the complicated sample pretreatment of traditional analytical methods and realized the rapid detection of salicylic acid. The results demonstrate that this all-solid-state potentiometric salicylic acid sensor is easy to miniaturize, has a longer lifetime (≥1month), is more robust, and can be directly used for the detection of salicylate ions in real samples without any additional pretreatment. The developed sensor has a good Nernst slope (63.6 ± 0.7mV/decade), the linear range is 10-2 ~ 10-6 M, and the detection limit can reach (2.8 × 10-7M). The selectivity, reproducibility, and stability of the sensor were evaluated. The sensor can perform stable, sensitive, and accurate in situ measurement of salicylic acid in plants, and it is an excellent tool for determining salicylic acid ions in plants in vivo.

Benchmarking electrodes modified with bi-doped polypyrrole for sensing applications

Polypyrrole-modified electrodes bi-doped with salicylate and perchlorate anions were synthetized, characterized, and benchmarked according to their ability to meet a set of performance criteria, with the aim of obtaining the best potential candidate for the development of electrochemical sensors. Bi-doped PPy films (PPy-DA) were assessed as compared to those resulting from electropolymerization in solutions providing a single doping anion, namely salicylate (PPy-Sa) or perchlorate (PPy-ClO4−) solutions. Morphological and spectroscopic characteristics of the different polymer films were determined by means of SEM and XPS and Raman spectroscopies. The electrochemical response and electrocatalytic activity of PPy-DA electrodes were characterized by chronoamperometric, voltammetric and electrochemical impedance spectroscopy (EIS) measurements. EIS appeared as a singular tool for determining the conditions where electrochemical response is either dictated by the redox process of the polymer film or governed by a redox couple in solution, and for comparing the electrocatalytic activity of the films without the requirement of knowing the real active electrode area. Comparison was also made among PPy-DA films synthesized by varying dopant concentration in the polymerization bath and electropolymerization time. The presence of salicylate ions favored the formation of films with a three-dimensional tubular structure whereas perchlorate ions contribute to increase their conductivity and electrocatalytic activity. The tubular three-dimensional structure of the electrode surface exhibits an open extended-area pattern that is highly suitable for the electrodeposition of gold nanoparticles (AuNPs), offering new possibilities for developing electrodes for voltammetric sensing. Accordingly, electrodes modified with PPy-DA films decorated with AuNPs were successfully tested for hydrazine determination.

Light-controlled detection of aromatic carboxylate anions using doubly fused naphthopyran derivative

A photochromic naphthopyran derivative, 2,2,11,11-tetraphenyl-2,11-dihydrobenzo[f]pyrano[3,2-h]chromene has been synthesized and its structure was confirmed using various spectroscopic techniques like NMR, infrared spectroscopy (FT-IR), high-resolution mass spectroscopy (HR-MS) and single crystal X-ray diffraction (SCXRD). The synthesized probe has shown a sensitive signal toward salicylic acid and 3,5-diaminobenzoic acid in acetonitrile: water (50:50(v:v)) solvent system at pH 7.6 (1 mM Tris buffer). UV–vis and fluorescence spectroscopic analyses revealed complex formation between these carboxylate anions and the synthesized photochromic probe, with blue shifts in absorption bands & enhancement in fluorescence intensity. Furthermore, photo-switching for the naphthopyran derivative in presence of both carboxylic acids was performed using 365 nm UV light, and results obtained indicated that the release and binding of these carboxylic acids can be controlled using 365 nm UV light. As expected, the fluorescence analysis provided a better limit of detection value as compared to the UV–Vis analysis. Fluorescence spectroscopy yielded a detection limit of 16.29 nM for salicylate ions using the naphthopyran-based probe.

Development of potentiometric sensors based on thiourea derivatives, Gd2O3@rGO and MoO3@rGO for the determination of salicylate in drug tablets and biofluids and DFT studies

Determination of salicylates in pharmaceutical formulations and biofluids is of great importance because of the toxicity of high doses in the blood. However, most analytical methods used for salicylate determination are expensive and time-consuming. In this study, potentiometric sensors based on carbon paste electrodes (CPEs) with the thiourea derivative (TUD1, ionophore) were successfully constructed for the detection of salicylate levels in pharmaceutical formulations and biofluids. Computational studies at the density functional theory (DFT) level were utilized to estimate inter-and intra-molecular interactions between salicylate and TUD1. The sensitivity of the CPEs to salicylate ions was optimized using different plasticizers (2-nitrophenyloctyl ether-NPOE, tricresyl phosphate-TCP, and dibutyl phthalate-DPB), nanomaterials (Gd2O3@rGO and MoO3@rGO), and ion exchanger (tridodecylmethylammonium chloride-TDMAC). The use of nanomaterials (Gd2O3@rGO and MoO3@rGO) improved the sensitivity and response time of the sensor over a wide pH range (4–10). The best sensor achieved a Nernst slope of 60 mV/decade over a dynamic concentration of 10−5 to 10−1 M with a detection limit of 10−5 M and good selectivity to interfering ions (Cl−, F−, Br−, benzoate, uric acid, and ascorbic acid) compared to previous reports. In addition, the sensor exhibited a lifetime of 6 months without any significant change in sensitivity (less than 5 % deviation). The developed sensors were successfully used for the determination of salicylate in tablets (Aspocid®), spiked serum, and spiked urine with high accuracy.

Polymorphism in Ionic Cocrystals Comprising Lithium Salts and l-Proline

The occurrence of polymorphism in ionic cocrystals formed by two lithium salts, lithium salicylate (LIS) and lithium 4-methoxybenzoate (L4M), and l-proline (PRO) has been investigated. The previously reported monoclinic form of the 1:1 cocrystal of LIS and PRO, LISPRO(α), and a new thermodynamically stable orthorhombic polymorph, LISPRO(β), were prepared and characterized. The two polymorphs form square grid, sql, topology coordination networks and differ mainly in the conformation of the salicylate ions and positioning of the sql nets. LISPRO(α) was observed to transform to LISPRO(β) under slurry conditions. The 1:1 ionic cocrystal of L4M and PRO (L4MPRO) was found to form three polymorphs. Apart from the previously reported orthorhombic crystal form, L4MPRO(α), two new monoclinic crystal forms, L4MPRO(β) and L4MPRO(γ), were obtained by modifying crystallization conditions. The new polymorphs were found to be metastable, undergoing transformations to L4MPRO(α) upon exposure to humidity. Experimental conditions that induce transformations between the polymorphs of LISPRO and L4MPRO are detailed, and the structural differences between the polymorphs are discussed in the broader context of polymorphism.

Changing of Electrical Conductivity, Acidity Function Voltage of Potential Difference for Salicylic Acid and Substituted to Study Adsorption Mechanism on Alumina Surface and the Factors Affecting it

In this study and for the first time there are the use of the specific electrical conductivity, acidity function, difference potential for salicylic and acetyl salicylic acids (Aspirin) solution before and after adsorption to describe and elicit adsorption mechanism as followed :-MO¯ + H2O → MOH (first step)MOH + H+ → MOH2+ MOH2+ + Anion L¯ → MOH2+ -------- ¯ L (second step)Mo¯ ( alumina surface ) , ¯ L ( anione )The adsorption mechanism is represented by two steps the first is to change the charge of the alumina surface from the negative polarized charge to the positive polarized charge by adsorption of hydrogen ions and water molecules from the acid solution to the surface of the alumina by adsorption and the second step represented by the adsorption of the negative anion of the acid to the surface. Salicylic acid give (H+) and salicylate ions (anione) and the presence of hydroxyl group on ortho position helps in the stabilization of anion and increase acidity compared with acetyl group. The adsorption process leads to an increase of acidity function by means of the decrease of (H+) ions in the solution by transition from solution to surface of alumina. This is the first step of adsorption and the second step represented by the transition of salicylate ions. This in turn causes decrease of difference potential between the acidic solution and alumina surface. Decrease of (H+) ions in solution causes decrease in electrical conductivity of solution. All these changes clarify mechanism of ions transition and their type from the solution to surface.

The effect of external salts on the aggregation of the multiheaded surfactants: All-atom molecular dynamics studies

Tailoring the molecular design of the surfactants leads to changes in the aggregation properties. The role of external salts on the aggregation properties of the multiheaded surfactants is investigated using molecular dynamics simulations. The multiheaded surfactants show differential aggregation properties on addition of external salts, as reported earlier from experimental studies. We have modelled the multiheaded surfactants to study the effect of external salts (potassium bromide and sodium salicylate) at three different concentrations using the all-atom modelling and explicit solvation. The influence of external salts on the hydration and aggregation propensity, hydrogen bonding, and the structural characteristics of the surfactant aggregates are probed using various analyses across the four groups of multiheaded surfactants. The larger salicylate ion masks the repulsion between the cationic head groups and acts as an effective promoter of aggregation.

Solvent-free synthesis of halloysite-layered double hydroxide composites containing salicylate as novel, active fillers

Solvent-free syntheses provide an alternative path that reduces the use of hazardous substances. In this work, a sustainable synthesis of nanometric layered double hydroxide particles grafted over halloysite nanotubes ([email protected]) is reported using a mechanochemical technique. Samples loaded with different LDH percentage (100%, 50%, 40%, 30%, 20%, 10% with respect to the HNT content) were prepared and characterized. Spectroscopic and morphological characterizations allowed to select the sample with 20% by weight of LDH as the best composite ([email protected]), wherein no LDH phase segregation was observed and the nanosheets were homogeneously grafted throughout the surface of the halloysite nanotubes. The combination of cationic and anionic clays in one filler enables the preparation of a composite which can be easily dispersed in a polymer and release active molecules. To this end, salicylate ions were incorporated into the layered double hydroxide nanoflakes of [email protected] and three intercalation strategies, comprising both solvent-free and traditional intercalating routes, were tested. Results of salicylate release tests indicate that the intercalating route used affects the amount of species hosted, the strength of the salicylate-LDH interactions and the drug release time, thus offering the possibility of selecting the most suitable method of drug incorporation to tune the salicylate content depending on a specific aim.

Studies of high-nuclearity lanthanide-titanium oxo clusters: Structure and properties

Three new lanthanide-titanium oxo clusters (LnTOCs), namely, Ti4Gd2, Ti13Gd2 and Ti14Gd4 were synthesized by reactions of different lanthanide salts with salicylic acid (H2sal) in different solvents. Crystallographic studies reveal that both Ti4Gd2 and Ti13Gd2 are composed by a oxo-centred triangular motif {Ti2Gd(μ3-O)}, while Ti14Gd4 has a heart-shaped heterometallic core {Ti12Gd2O13(OH)6}, which represents the second highest nuclearity LnTOC reported to date. In addition, these compounds exhibit a strong absorption in visible light region and a fast photocurrent response owing to the existence of salicylate ions.

Fundaments of Toxicology-Approach to the Poisoned Patient.

Management of the poisoned patient begins with supportive care, assessment of organ function and dysfunction, and consideration of known or suspected poisons. The possibility of multiple ingestions should be considered with intentional exposures or suicide attempts. Enteric decontamination involves treatment to prevent the absorption of toxins from the gastrointestinal system and includes the use of activated charcoal. Poisoned patients may benefit from the use if antidotes are available, or enhanced elimination as with salicylate ion trapping during urinary alkalinization. The use of intravenous lipid therapy is of clinical benefit in poisoning from bupivacaine, amitriptyline, and bupropion. Hemodialysis is the most inexpensive, widely available, and most commonly used method of extracorporeal drug removal in the treatment of poisoning. Chelators with different chemical properties can bind toxic metals, providing an essential mechanism for detoxification, and may be used in combination with extracorporeal therapies such as DFO with HD for aluminum or iron, and DMSA or DMPS with HD to treat arsenic or mercury intoxication. The use of displacers with hemodialysis can be considered to augment clearance of protein-bound toxins.

STUDY OF ANION EXCHANGE EXTRACTION OF SOME ANIONIC COMPLEXES OF IRON (III) BY ORGANIC SOLUTIONS OF QUARTERLY AMMONIUM SALTS

The anion-exchange extraction of salicylate, thiosulphate and thiocyanate iron (III) complexes by solutions of chlorides of quaternary ammonium salts (QAS) in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, nitrobenzene) was studied. The composition of the iron (III) anionic complexes was established by the analysis of the calibration curves E = f(pCFe (III)) constructed from iron (III) solutions against the background of various contents of thiocyanate, thiosulphate and salicylate ions and the steepness of the electrode function. As an indicator electrode the ion-selective electrode was used with a membrane, which based on a nitrobenzene solution of tetradecylammonium bromide. The solution containing of alkyldimethylbenzylammonium chloride and alkyldimethylethylbenzylammonium chloride and the corresponding organic solvent were mixed in a ratio of 1:1. An organic layer containing the QAS was selected. The anion-exchange extraction was provided in contact with aqueoses solutions of Fe(III) anionic complexes. The extraction process is estimated quantitatively using a distribution coefficient (D). The value of D is calculated taking into account the iron (III) concentration in the aqueous phase before and after extraction. The content of iron (III) in solutions is determined spectrophotometrically (λ = 440 nm). It is established that the value of the distribution coefficient depends on the permittivity (ε) of the organic solvent. In the row toluene - carbon tetrachloride - ethyl acetate - isobutyl alcohol - nitrobenzene, the permittivity increases. In the same sequence, D increases for all studied complex iron(III) ions. Moreover, a decrease in the concentration of the extracted particle leads to an insignificant decrease in the value of the distribution coefficient. The composition and stability of the complex iron (III) ion have a significant effect on the extraction activity.

The distribution of complexes 69mZnL1Cl2, [69mZn(L2)2]Cl2, and [69mZn(L2)2]Sal2 (L1 is N-(5,6-dihydro-4H-1,3-thiazin-2-yl)benzamide, L2 is 2-aminopyrimidine, Sal is a salicylate ion) in vivo in mice

The distribution of complexes of thiazine and pyrimidine derivatives possessing antileukemic activity and labeled with radionuclide 69mZn in the organs of mice and its rate of excretion were studied. A solution of ZnCl2 was used for comparison. An increase in the time of excretion of the drug from the body and a decrease of its penetration into the brain in the presence of a salicylate ion were observed.

Catalytic effects of cationic nanoparticle (CTABr/NaX/H2O, X = Cl, Br) for the piperidinolysis of phenyl salicylate ions

The expression of pseudo-second-order rate constants (k X) for cationic nanoparticle (CN) [CTABr/NaX/H2O, X = Br, Cl, CTABr = cetyltrimethylammonium bromide] catalyzed piperidinolysis-ionized phenyl salicylate (PSa–), at constant [CTABr]T, 0.1 M piperidine (Pip), and 35°C, were calculated from the relationship: k obs = (k 0 + k X[NaX])/(1 + K X/S[NaX]), in which k 0, k X, and K X/S are constant kinetic parameters and k obs represents the pseudo-first-order rate constant for Pip reaction with phenyl salicylate ion in the presence of CN. The source of the large catalytic effect of CN catalyst was shown to be due to the transfer of PSa– from pseudo-phase of the CNs to the bulk aqueous phase through X–/PSa– ion exchange at the surface of the CNs.

Effects of Hydrotropic Salt on the Nanoscopic Dynamics of DTAB Micelles.

Effects of a hydrotropic salt, sodium salicylate (NaSal), on the dynamic behavior of cationic dodecyltrimethylammonium bromide (DTAB) micelles as studied using dynamic light scattering (DLS) and quasielastic neutron scattering (QENS) techniques are reported here. DLS study showed that the addition of NaSal leads to a decrease in the apparent diffusion coefficient of the whole micelle indicating micellar growth. QENS data analysis suggested that observed dynamics involves two distinct motions, lateral motion of the surfactant over the curved micellar surface and localized segmental motion of the surfactant. It is found that the addition of NaSal slows down the lateral motion of DTAB while the localized segmental motion of the DTAB chain is not affected much. An atomistic molecular dynamics (MD) simulation was performed to gain further insight into the underlying phenomena. MD simulation results are found to be consistent with the experimental observations. MD simulation revealed that location of the salicylate ions on the micellar surface and their strong electrostatic association with their oppositely charged surfactant headgroup are the major factors in slowing down the lateral motion of the DTAB molecule. In the present work, a quantitative description of the effects of NaSal on the nanoscopic dynamics of DTAB micelles and its correlation with the microstructure of the micelle is provided.

Effects of some 5-anilino-1,2,4-thiadiazole derivatives onto leukemic cells

The antileukemic activities of some thiadiazole derivatives in the forms of hydrochlorides and salicylates have been determined. The insertion of salicylate ion in the compound increases the therapeutic index, mainly due to the reduction of cytotoxicity against healthy cells.

Counterion Effect on Krafft Temperature and Related Properties of Octadecyltrimethylammonium Bromide

AbstractIn the present work, we have investigated the effect of some counterions on the Krafft temperature (TK) and the micelle formation of octadecyltrimethylammonium bromide (OTAB) in aqueous solution. The results showed that the ions with more chaotropic nature increase the TK while those with a kosmotropic, hydrotropic and less chaotropic nature lower the TK of the surfactant. More chaotropic SCN− and I−, being weakly hydrated, form contact ion pairs with the octadecyltrimethylammonium ion and reduce the electrostatic repulsion between the surfactant molecules. As a result, these ions exhibit salting out behavior and raise the TK of the surfactant. On the other hand, less chaotropic Cl− and NO3−, kosmotropic SO42− and F− and hydrotropic benzoate and salicylate ions increase the solubility of the surfactant, with a consequent decrease in the TK. SO42−, F−, benzoate and salicylate cannot form contact ion pairs with the weakly hydrated cationic part of OTAB. Rather, being extensively hydrated and kosmotropic in nature, these ions do not show any tendency to shed their hydrated water molecules to form contact ion pairs with the weakly hydrated octadecyltrimethylammonium ion and therefore, stay apart. As a result, the TK of the surfactant decreases significantly in the presence of these ions. The critical micelle concentration (CMC) of the surfactant decreases significantly in the presence of these ions due to screening of the micelle surface charge by the added counterions. Consequently, the surfactant molecules attain better packing because of substantial reduction in the electrostatic repulsion between the charged head‐groups, showing a significant decrease in the CMC.

Towards stabilization of the potential response of Mn(III) tetraphenylporphyrin-based solid-state electrodes with selectivity for salicylate ions

We report a new type of solid-state electrode (type I) of a simple design with polyvinyl chloride membranes based on Mn(III) tetraphenylporphyrin and with graphite as the electronically conducting substrate. Enlargement of the membrane/graphite contact area by soaking graphite in the plasticizer with subsequent conditioning of the electrode at 30 °C allowed us to shorten the time required to achieve steady potential values of the sensors to just 3 days. These electrodes do not require a specially added RedOx system in the transducer layer. Stabilization of the EMF response of type I electrodes is compared to type II electrodes which contain a Cu0/Cu2+ RedOx couple in the transducer layer. Type I sensors are suitable for measuring the salicylate ion concentration in the clinically important concentration range down to 2.5 × 10−4 M with a sensitivity to salicylate ion of −59.0 mV decade−1 in solutions with a high constant background of chloride ions of 0.12 M at pH = 5.3, making this a promising technique for an effective design of solid-contact ion-selective electrodes with polymeric sensing membranes.

Determination of Relative Counterion Binding Constant to Cationic Micelles.

The efficiency of counterion affinity towards ionic micelles is often described in terms of the degree of counterion binding (β X ) to ionic micelles or the conventional ion-exchange constant ([Formula: see text]) or relative binding constant ([Formula: see text]) of X - and Br- counterions. This review describes the use of ionized phenyl salicylate ions, PSa-, as a new probe to determine [Formula: see text] values using a semiempirical spectrophotometric method. The value of [Formula: see text] is found to be comparable to reported values obtained using different probes by the semiempirical kinetic method as well as different physical methods. Application of semiempirical methods for calculation of [Formula: see text] or [Formula: see text] values involves an inherent assumption that these values are independent of the physicochemical characteristics of the probe molecule.