Zinc Nitrate Solution Research Articles

Free radical scavenging activity of zinc oxide nanoparticles biosynthesised using Aspergillus carneus

Zinc oxide nanoparticles (ZnO NPs) were confirmed in this work as a good antioxidant source. They were biosynthesised by the preformed biomass of Aspergillus carneus when contacted with 1 mM zinc nitrate solution of pH 9 after 24 h at 150 rpm and 30°C. The biosynthesised NPs were moderately distributed, quasi-spherical in shape with clear edges and the average size of 8–12 nm. The NPs retained full stability at 4°C for at least six months. Their zeta potential was found to be 18.3 mV. Crystalline nature of the ZnO NPs was suggested from diffraction rings appeared as lighted spots on the selected area electron diffraction pattern and confirmed by the X-ray diffraction analysis. High radical scavenging activities (RSA) were found against peroxide ( O 2 2 − ) and 2,2–diphenyl-1-picrylhydrazyl (DPPH). Good activities were also recorded against hydroxyl (OH−) and superoxide ( O 2 − ) radicals. This potential RSA can be rendered to the adsorbed biomolecules on the NPs surface especially the phenolic compounds detected by Fourier transform infrared analysis.

Features of Zinc Modification of a Zeolite Catalyst for Dimethyl Ether Conversion to Synthetic Liquid Hydrocarbons

Liquid hydrocarbons (HCs) with a low aromatic content have been synthesized from dimethyl ether (DME) in a hydrogen medium at a temperature of 340°C and a pressure of 10 MPa in the presence of catalysts based on Zn–HZSM-5 zeolites prepared by impregnation, ion exchange from an aqueous solution of zinc nitrate, and in situ synthesis. It has been shown that zinc modification of zeolite HZSM-5 leads to a decrease in the total number of acid sites with an increase in the fraction of strong Lewis acid sites in the total acidity spectrum. The introduction of Zn into zeolite HZSM-5 by the in situ method leads to an increase in the fraction of mesopores and thereby makes it possible to eliminate diffusion hindrances. These factors can provide a significant increase in the selectivity for liquid HCs and the isoalkane content in their composition and a substantial improvement in the on-stream stability of the in situ synthesized catalyst based on Zn–HZSM-5.

Preparation of silver nanoparticles coated ZnO/Fe3O4 composites using chemical reduction method for sensitive detection of uric acid via surface-enhanced Raman spectroscopy

In this study, silver nanostructures decorated magnetic nanoparticles for surface-enhanced Raman scattering (SERS) measurements were prepared via heat induced catalytic activity of ZnO nanostructures. The ZnO/Fe3O4 composite was first prepared by dispersing pre-formed magnetic nanoparticles into alkaline zinc nitrate solutions. After annealing of the precipitates, the formed ZnO/Fe3O4 composites were successfully decorated with silver nanostructures by dispersing the composites into silver nitrate/ethylene glycol solution at 95 °C in water bath. To find the optimal condition when preparing Ag/ZnO/Fe3O4 composites for SERS measurements, factors such as reaction time and concentration of silver nitrate were studied. Results indicated that the formation of silver nanoparticles (AgNPs) on ZnO/Fe3O4 was significantly improved with the assistance of ZnO. The concentration of silver nitrate and reaction time affected the morphologies and sizes of the formed composites and optimal condition in preparation of the composites for SERS measurement was found using 100 mM of silver nitrate with a reaction time of 20 min. Under optimized conditions, the obtained SERS intensities were highly reproducible. The substrates were applied for quantitative analysis of uric acid in aqueous solution and a linear response for concentrations up to 10 μM was obtained. Successful application of these prepared composites to determine uric acid in urine sample without any pretreatment of the urine sample was done.

Voltammetric determination of ascorbic acid with zinc oxide modified glassy carbon electrode

Zinc oxide (ZnO) nanostructures electrodeposited from aqueous zinc nitrate solution at 70 °C onto glassy carbon electrode (GCE) were used as electrochemical detectors. The morphology, structure, chemical composition and conductivity of the as-deposited layers were determined using scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and UV–Vis spectroscopy. A highly oriented crystalline ZnO deposit made of a dense array of randomly oriented hexagonal nanorods was obtained without any additives in solution. The electrocatalytic oxidation of ascorbic acid (AA) was studied using cyclic voltammetry in 0.1 M phosphate buffer solution at pH 6.8. Comparing the response for AA oxidation on the bare and modified electrodes, the peak potential was shifted to − 0.45 V on ZnO/GCE with higher current densities and transfer coefficient, due to a simultaneous increase in oxidation rate and surface area. A linear relationship was determined between the anodic peak current and the AA concentration in the range of 0.1–5 mM.

A facile construction of bacterial cellulose/ZnO nanocomposite films and their photocatalytic and antibacterial properties.

Bacterial cellulose (BC) has numerous excellent properties but the absence of antibacterial activity restricts its applications in biomedical field. Therefore, in order to introduce the antibacterial characteristics into BC; herein, a facile method for incorporation of ZnO nanoparticles (ZnO-NPs) is presented. BC films were first immersed in zinc nitrate solution, followed by treating with NaOH solution, the BC loaded ZnO nanocomposite films were dried by a sheet former instrument at 80 °C for 20 min. The obtained BC/ZnO nanocomposites were characterized by different techniques. XRD results showed the hexagonal wurtzite structure of ZnO-NPs while FE-SEM results displayed the particle size of ZnO-NPs was ranging from 70 to 100 nm. Thermogravimetric study revealed the thermal stability of nanocomposite films. The nanocomposite exhibited photocatalytic activity and revealed 91% degradation of methyl orange (MO) under UV-irradiation within 2 h. Moreover, the nanocomposites demonstrated significant UV-blocking properties and showed antibacterial activities against tested Gram-positive and Gram-negative bacterial strains. This work provides a simple and novel method for the synthesis of BC/ZnO nanocomposite as a functional biomaterial.

Poly (vinyl alcohol)/glutaraldehyde/Premna oblongifolia merr extract hydrogel for controlled-release and water absorption application

Fertilizer leaching and water slack are the most problems predominantly found in the agriculture practices. Many efforts have been done by promoting a medium for controlling fertilizer release and water retaining in vicinity of plant and soil. In this work, a biodegradable Premna Oblongifolia Merr (POM) extract/polyvinyl alcohol (PVA) composite based hydrogel for controlled-release and water absorption application has been prepared. The hydrogel composite was successfully synthesized through solution mixing of POM and PVA with an aid of crosslinking agent (glutaraldehyde) at optimum composition in volume ratio of 5:5:9, respectively. In particular, the fertilizer (Zinc nitrate) solution was incorporated into hydrogel matrix for controlled release study. The structural morphology of hydrogel composite was investigated by means of Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. The water absorption capacity and fertilizer-controlled release behaviour of hydrogel composite were evaluated by gravimetric and atomic absorption spectroscopy techniques, respectively. The FTIR spectra showed the evidence of copolymerization of hydrogel precursors, indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp3, C=O, C-N, C-O) as a result of interaction between POM extract and PVA moieties which predominantly occurs through intermolecular hydrogen bonding. In particular, the crosslinking of PVA and POM extract mediated by glutaraldehyde was evidenced by the appearance of new peak for -C-O-C moieties owing to the formation of hemiacetal bridges in between polymer backbones. The insertion of fertilizer into hydrogel matrix was sharpen the peaks of hydrogel moieties and led to new peak appearance at 1384 cm−1 (NO moieties), correspond to the interaction with zinc ions. The X-ray diffraction confirmed the modification of structural morphology of hydrogel with fertilizer insertion as indicated by the slight shift of interlayer distance of polymer matrices. The hydrogel composites showed the large water absorption capacity up to 550 % and could retained water in its matrix for almost 3 weeks. Absorption and released studies indicate that the micronutrient interacts chemically with a surface functional group of hydrogel. The released micronutrient should come from the second and the upper layer where it occurs only at high concentration. These results offer the promising applications for the controlled-release and water absorbent materials.

Facile synthesis of flake-like dihydrate zinc oxalate particles

Monodispersed dihydrated zinc oxalate (ZnC2O4·2H2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate (Zn(NO3)2) and sodium oxalate (Na2C2O4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(II)-citrate-oxalate-H2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.

Preparation and Electrocatalytic Performance of Nanosphere Array PbO2 Electrode on Stainless Steel-Based Grid-Like ZnO Film

A nanosphere array PbO2 electrode was constructed on as-prepared stainless steel-based grid-like ZnO film via anodic oxidation in lead nitrate solution. The above grid-like ZnO film was prepared in zinc nitrate solution by electrodeposition using polystyrene (PS) microsphere templates. The morphology and composition were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The performance was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) measurements. The results showed that the active layer of the array PbO2 electrode possesses a regular petal-like array structure that consists of many clustered PbO2 nanospheres. The array structure can increase the electrochemical active surface area (ECSA). The total voltammetric charge (qT*) is 2.6 times that of the traditional PbO2 electrode. Additionally, the array electrode shows a larger exchange current density (i0), lower activation energy (Ea) and charge transfer resistance (Rct) during the process of oxygen evolution. In the degradation process of phenol, the degradation rate constant of the array PbO2 electrode is significantly greater than that of a traditional PbO2 electrode. The results demonstrated that the array PbO2 electrode with enhanced electrocatalytic performance is a promising material for degrading organic effluents.

Superhydrophobic Surfaces on 5052 Aluminum Alloy Obtained from LDH Film Modified with Stearic Acid for Enhanced Corrosion Protection

This paper aimed to develop and characterize superhydrophobic surfaces with anticorrosive properties obtained by the chemical modification of the 5052 aluminum alloy with variation of acid etching time, formation of lamellar double hydroxides (LDH) film and immersion in stearic acid. The specimens were etched in HCl (2M) at 5, 10 and 30 min. The aluminum plates were treated with aqueous solution of zinc nitrate (0.1 M) in the presence of ammonia and then immersed in a stearic acid and ethanol solution (1% w/w) to reduce surface energy. Contact angles (CA) were determined. Surface morphology and composition were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersion spectroscopy (EDS), respectively. Linear polarization tests were performed to analyze corrosion resistance. The optimal superhydrophobic performance was obtained with a contact angle of 154º for 30 min of acid etching. This condition also showed higher corrosion resistance, obtaining higher values of Ecorr and lower values of corrosion current density.

311. Preliminary results of the production of Ga-68 with biomedical cyclotron by liquid target

Purpose The aim of this work was to evaluate the feasibility of production of 68Ga via the 68Zn(p,n)68Ga reaction by proton irradiation of enriched zinc nitrate solution using a biomedical cyclotron, an alternative method to the current production through the 68Ge/68Ga generators. Methods The target material was prepared by dissolving metallic 68Zn (enrichment of 99.26%) in HNO3 6 N and then diluting it with HNO3 0.2 N to obtain a 1.7 M solution of 68Zn(NO3)2 [1] . Using the cross-section data (EXFOR database) and the proton stopping power (SRIM software), the 68Ga saturation yield and its impurities were estimated. Irradiation tests were performed using the GE PETtrace cyclotron, located at our Institution. A liquid target was used, with a 25 μm foil of Havar® and a 250 μm foil of Niobium, employed to obtain proper selection of entrance beam energy, to degrade the energy of the beam to 12 MeV in order to minimize the production of 67Ga through the 68Zn(p,2n)67Ga reaction. The modification of the target also allowed us to improve resistance of the foil to acidity of the target material. Irradiations were carried out for 32 ± 1 min at 47 ± 2 μA. The product’s activity was measured using an activity meter calibrated with a standard of 68Ge traceable to NIST, while radionuclidic purity was evaluated by using gamma-ray spectrometry with an HPGe detector. Results The gamma-spectra of the irradiated samples showed the presence of different isotopes of Ga, Cu and Co, as predicted by the theoretical estimates. Radionuclidic purity is within the limits of EU Pharmacopeia up to 3 h after end of bombardment. Separation and recovery up to a yield of 90 ± 9% was obtained. Conclusions In summary, although optimizations and further advances are necessary, the results obtained are very promising and demonstrate the feasibility to produce sufficient activity of 68Ga in cyclotron as a competitive alternative to the 68Ge/68Ga generators.

Application of a novel, efficient and recyclable photo redox catalyst (Zn–Al layered double hydroxide/eosin) for the synthesis of substituted pyridine derivatives under visible light irradiation

Layered double hydroxides (LDHs) are a class of anionic clays with brucite‐like layers and interlayer anions and varying in composition and morphology. LDHs show potential as supports for the immobilization of catalytically active species, to synthesize recyclable catalysts, in which catalytic sites can be preferentially orientated, highly dispersed and stabilized to afford high catalytic efficiency and recyclability in reaction media. Redox active organic dyes such as eosin Y with strong absorption in the visible region of the spectrum have been successfully used. In this work, an intercalated photo redox catalyst (Zn–Al LDH/eosin) was synthesized by co‐precipitation of an aqueous solution of zinc nitrate and aluminium nitrate simultaneously with eosin Y as anionic dye. Zn–Al LDH/eosin as a recyclable catalyst was used in the reaction of various aryl ketones and benzylamines under molecular oxygen and visible light, giving good yields of substituted pyridines at room temperature. Also, the Zn–Al LDH/eosin catalyst could be reused three times without any significant changes in the reaction yields.

Effects of precursor composition used in solution precursor plasma spray on the properties of ZnO coatings for CO2 and UV light sensing

The potential of finely-structured zinc oxide (ZnO) coatings developed via solution precursor plasma spraying (SPPS) as CO2 gas and UV light sensor was explored in this work. The coatings were deposited on stainless steel substrates using aqueous solutions of zinc nitrate and zinc acetate as precursors. The coatings' microstructures were studied in relation to the solution precursors used. Relatively porous coatings were obtained when using acetate as starting precursor compared to the coatings from the nitrate precursor. This was attributed to the different chemical routes of ZnO formation for each precursor droplet upon contact with plasma jet. Phase analysis confirmed the formation of polycrystalline ZnO having wurtzite structure from both precursors. The sprayed ZnO coatings showed good sensitivity and recovery towards UV light. Moreover, the coatings were sensitive towards carbon dioxide (CO2) analyte gas but did not show any good recovery which was attributed to the microstructure of the coatings. These results showed the feasibility of SPPS process for the fabrication of finely-structured ZnO coatings as sensors of CO2 gas and UV light.

Kinetics Modelling of the Adsorption Process of Zinc Ions by Glass Microparticles

The oligodynamic property is a lethal effect which some atoms exert over bacteria, fungi and other microorganisms. The oligodynamic property can be promoted by glass microparticles doped by zinc ionic specimens utilizing the ionic exchange processes. This study is aimed at modelling the behavior of adsorption mechanisms of the zinc ions on glass microparticles absorbent, with potential use as antimicrobial material. Aqueous solutions of zinc nitrate were used as the ionic supplying of zinc ions. The amount of zinc adsorbed on the glass was determined by spectroscopy of atomic absorption and with a mass balance analysis for each adsorption conditions. The experimental data were modeled by three Eq.s employed in adsorption kinetics studies: pseudo first order, pseudo second order and Elovich Eq.. The pseudo second order data model presented the better adjust condition. A sample of zinc glass microparticles, prepared at the finest conditions established by the kinetic model of pseudo second order, was submitted to microbiological analysis: agar diffusion test with Pseudomonas aeruginosa and Staphylococcus aureus and with Candida albicans. The glass doped with ionic zinc inhibited the growth of microorganisms in every conducted analysis.

Ethylene adsorption onto natural and transition metal modified Chilean zeolite: An operando DRIFTS approach

Abstract Ethylene is a plant growth regulator that induces accelerated softening and ripening of fruits during transport and storage. Among the most applied methods for ethylene control, adsorption appears as a cheap and efficient technique. In this work, the effect of the incorporation of transition metals into natural Chilean zeolite on ethylene adsorption is investigated. Natural zeolite mainly composed of clinoptilotite and mordenite is modified using copper and zinc nitrate solutions and calcined under oxygen flow at 623 K, generating different transition metal modified zeolites. Parent and modified zeolites were characterised by X-ray diffraction, X-ray fluorescence spectroscopy and nitrogen adsorption. Zeolite surface modifications were assessed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Experimental results reveal the incorporation of Cu2+ and Zn2+ as new compensating cations into the zeolite framework. Ethylene adsorption isotherms show an enhancement on the adsorption capacity of Cu-exchanged zeolite. This result is not only associated to the higher micropore surface area of this sample, but also to the higher affinity of ethylene molecules to copper cations incorporated on this zeolite. DRIFTS operando experiments of ethylene adsorption in the absence and in the presence of moisture reveal a competitive mechanism of water and ethylene molecules toward hydroxyl sites. Si-OH-Al and Si-OH sites are rapidly occupied with water, reducing the adsorption of ethylene.

Rapid mussel-inspired synthesis of PDA-Zn-Ag nanofilms on TiO2 nanotubes for optimizing the antibacterial activity and biocompatibility by doping polydopamine with zinc at a higher temperature

Mussel-inspired deposition of polydopamine (PDA) is a green chemical method that has been used to load silver nanoparticles on titanium oxide nanotubes (TiO2 NTs) to kill bacteria. However, a long reaction time is required for both the polymerization of dopamine and the reaction between PDA and silver nitrate. In addition, the deposition of silver nanoparticles is difficult to control, which may increase the risk of cytotoxicity. In this study, a rapid polymerization of dopamine was achieved by performing the reaction in a water bath at 90 °C (PDA-H). Furthermore, the reduction of Ag+ ions was markedly accelerated by the PDA-Zn film that was formed on the surface of TiO2 NTs from a solution of dopamine and zinc nitrate under the same heating conditions. The reaction between the PDA-Zn film and silver nitrate was dramatically reduced to 10 min, and the silver nanoparticles deposited on the PDA-Zn film were more uniform than those by PDA-H film. This PDA-Zn-Ag-TiO2 NTs material exhibited good antibacterial activity, as evidenced by the inhibition zone. The WST-1 assay indicated that the PDA-Zn-Ag film possessed a lower cell cytotoxicity and better biocompatibility than other Ag containing PDA films.

Effect of potential voltages on key functional properties of transparent AZO thin films prepared by electrochemical deposition method for optoelectronic applications

Abstract

Synthesis of zinc oxide microrod arrays and their performance as piezo-generators

ABSTRACTZinc oxide microrods were synthesized by aqueous chemical growth using zinc nitrate and zinc acetate solutions without seed layer. Rod length of around 10 µm was obtained after 5 hr at 95°C. Solution replenishment led to a better alignment normal to the substrate; however, only zinc acetate solution resulted in bigger rods, reaching about 12 µm in length and 5 µm in diameter. X-ray diffraction revealed a pure hexagonal wurtzite structure with high crystallographic texture. Raman spectroscopy showed no evidence of lattice stress. The ZnO microrod arrays were used to fabricate piezoelectric generators, and the largest output was obtained from the generator with the higher density of rods. The use of a piezoelectric polymer in the generators led to an improved performance of at least 200% compared to reports that used a dielectric polymer.

Role of hexamine in ZnO morphologies at different growth temperature with potential application in dye sensitized solar cell

Zinc oxide (ZnO) is a potential semiconductor being investigated for a variety of applications as many are dependent upon its typical shape. Using hydrothermal method, ZnO nanorods are grown using equimolar solutions of Zinc nitrate and Hexamethylenetetramine (HMTA). This study aims to investigate the effects of temperature on morphology of the zinc oxide structures. HMTA beyond acting as a pH buffer, creates a steric interference at lower temperature which gives space for nanorod growth. At higher temperature, this effect is dominated by the excess of ammonia involvement cancelling the non-polar chelation thereby resulting in rice shaped structures. These structures were characterized by SEM, XRD, RAMAN spectroscopy, UV–Vis spectroscopy and photoluminescence. The dye-sensitized solar cell (DSSC) performance is also studied. It is stipulated that though the nanorods show better efficiency, microrice has potential space for improvement.

Different effects of Zn and Cu ions incorporated on TiO2 photoelectrodes on the back electron transfer in solar cells

ABSTRACTZinc and copper ions were incorporated on the surface of TiO2 films via a dipping process, and the resulting films were used as the photoelectrodes of dye-sensitized solar cells (DSSCs). The DSSC with Zn2+(30)-TiO2/FTO electrode, prepared by soaking bare TiO2/FTO in a zinc nitrate solution for 30 min, showed an improvement in power conversion efficiency, due to an enhancement in both open circuit voltage (Voc) and short circuit current (Jsc), compared to those of reference cell with bare TiO2/FTO. It was revealed that the Zn2+ incorporation on the TiO2 surface led to a retardation of the back electron transfer, inducing a prolonged electron lifetime of photo-injected electrons, and thereby increasing the Voc and Jsc. On the contrary, the back electron transfer was scarcely delayed in the device with Zn2+(30)-TiO2/FTO electrode.

Novel heat-resistant and soluble poly(amide–ether)/zinc oxide nanocomposites: synthesis, characterization and computational study

Novel heat-resistant poly(amide–ether)/zinc oxide nanocomposites containing two different types of ZnO nanoparticles were successfully prepared by a solution intercalation technique. A new poly(amide–ether) (PAE) as a source of polymeric matrix was synthesized by direct polycondensation reaction of new diamine containing 1,3,4-oxadiazole and biphenyl groups with 4,4′-(butane-1,4-diylbis(oxy))dibenzoic acid in a medium consisting of N-methyl-2-pyrrolidone,triphenyl phosphite, calcium chloride, and pyridine. Fourier-transform infrared (FTIR), nuclear magnetic resonance (1H NMR), and UV–Vis technique were used for characterization of as-synthesized PAE. The synthesized PAE revealed good solubility in dipolar aprotic solvents at room temperature and the inherent viscosity of the PAE in DMF at a concentration of 0.01 g dL−1 at 25 °C was 0.34 dL/g. Improved solubility was attributed to the presence of flexible ether linkage in the polyamide backbones that reduce the chain–chain interaction and enhance solubility by penetrating solvent molecules into the polyamide chains. The structural and electronic properties of PAE units were studied by ab initio density functional theory method using the B3LYP/6-31G (d) level of theory. Due to incorporation of biphenyl group as an electron donor on the 1,3,4-oxadiazole ring in the structure of PAE, the highest occupied molecular orbitals (HOMO) are localized mainly on biphenyl group. The calculated absorption spectrum of the studied PAE exhibited the maximum absorption wavelength which corresponds to the electronic transition from the HOMO-1 to LUMO with 92% contribution. Zinc oxide nanoparticles were synthesized by a direct precipitation method from zinc nitrate solution and were modified with 1-methyl-3-(trimethoxysilylpropyl) imidazolium chloride. The PAE/ZnO nanocomposite films were prepared by simple dissolution technique using 3 wt% of ZnO nanoparticles and modified ZnO nanoparticles. The morphology, crystalline phase, and thermal stability of the resultant materials were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), thermal gravimetric analysis (TGA), and FTIR techniques. The FE-SEM analysis showed better dispersion of ZnO@ImCl nanoparticles within the poly(amide–ether) matrix in comparison with ZnO nanoparticles, which arises from high interactions between ZnO@ImCl and the PAE chains. Thermogravimetric analysis results indicated improving on thermal properties of the poly(amide–ether) nanocomposites as compared with the neat poly(amide–ether). The incorporation of functional ZnO@ImCl nanoparticles could further improve the thermal properties of poly(amide–ether). The high interaction between poly(amide–ether) and ZnO@ImCl nanoparticles, the presence of oxadiazole, ether, amide and imidazole content of the ZnO@ImCl nanoparticles seem to be responsible for the improvement of the thermal properties. Furthermore, the presence of oxadiazole, ether, amide and bulky biphenyl groups in the poly(amide–ether) backbone increased the solubility in organic solvents.