Capturing copper(II) ions using {Cu(tpy)(bpy)} domains

The reaction of 6,6"'-dimethyl-2,2':6',2":6",2'"-quaterpyridine (2) with 2,2':6',2"-terpyridine (tpy) and Cu(NO₃)^·3H₂O leads to the formation of [Cu(tpy)(2)]²⁺ and [Cu₂(tpy)₂(2)]⁴⁺, isolated as the hexafluoridophosphate salts. Single crystal structures of [Cu₂(tpy)₂(2)][PF₆]₄·2H₂O and [Cu(tpy)(2)][PF₆]₂·MeCN are presented and illustrate the special stability of the 5-coordinate {Cu(tpy)(bpy)}²⁺ motif in mono- and dinuclear environments.     

Facile preparation of SiO2 hybrid nanoparticles via Cu2+-amine redox-initiated radical polymerization

The CuSO₄-catalyzed surface-initiated conventional radical graft polymerization of electron-deficient monomers such as N,N-dimethylacryamide (DMAAm) was carried out from amino-functionalized SiO₂ nanoparticles (SiO₂–NH₂) to directly prepare hybrid SiO₂ nanoparticles (SiNPs) chemically grafted with functional poly(N,N-dimethylacryamide) (SiO₂-g-PDMAAm) in aqueous media with trimethyltetradecylammonium chloride (TTAC) added as a surfactant. The optimum reaction conditions were as follows: weight feed ratio CuSO₄·5H₂O:DMAAm:H₂O:SiO₂–NH₂:TTAC of 1:500:5,000:1,000:100 and reaction temperature at 80 °C. Spectroscopy and microscopy confirmed the successful graft polymerization and the formation of hybrid SiNPs with PDMAAm chains. Thermogravimetric analysis indicated the grafting yield could be up to 15.39 wt%. As the active radicals only formed on the SiNP surfaces, there was no free polymer in the reacting mixture. Because of the presence of PDMMAm chains, the hybrid SiO₂-g-PDMAAm nanoparticles exhibited an enhanced dispersion stability in aqueous media over the pristine SiO₂–NH₂, and a thermoresponsive settlement behavior. The parallel experiments with other electron-deficient monomers suggest that the current strategy requires less post-treatment, mild conditions and affords universal applicability.     

Bioactive Chemical Constituents from the Brown Alga Homoeostrichus formosana

A new chromene derivative, 2-(4'',8''-dimethylnona-3''E,7''-dienyl)-8-hydroxy-2,6-dimethyl-2H-chromene (1) together with four known natural products, methylfarnesylquinone (2), isololiolide (3), pheophytin a (4), and β-carotene (5) were isolated from the brown alga Homoeostrichus formosana. The structure of 1 was determined by extensive 1D and 2D spectroscopic analyses. Acetylation of 1 yielded the monoacetylated derivative 2-(4'',8''-dimethylnona-3''E,7''-dienyl)-8-acetyl-2,6-dimethyl-2H-chromene (6). Compounds 1–6 exhibited various levels of cytotoxic, antibacterial, and anti-inflammatory activities. Compound 2 was found to display potent in vitro anti-inflammatory activity by inhibiting the generation of superoxide anion (IC₅₀ 0.22 ± 0.03 μg/mL) and elastase release (IC₅₀ 0.48 ± 0.11 μg/mL) in FMLP/CB-induced human neutrophils.     

Gel-sol synthesis of surface-treated TiO2 nanoparticles and incorporation with waterborne acrylic resin systems for clear UV protective coatings

Visible transparent UV protective coatings were developed by incorporating nano-TiO₂ into waterborne acrylic systems to provide UV protection for UV-sensitive color cool roofing. Water-based high crystalline TiO₂ nanoparticle suspension was prepared via a gel-sol method at a basic pH. The TiO₂ nanoparticles have an average size of 20 nm and are stable against agglomeration. As-prepared TiO₂ nanosuspension is ready to be well dispersed in commercial waterborne acrylic resin system without extra-surface modification. The fabricated TiO₂/acrylic nanocomposite coating achieved a UV cut-off below 350 nm with a visible transmission greater than 85% at 700 nm. It is also demonstrated by using Rhodamine 6G that surface modification of nano-TiO₂ with a SiO₂ insulation layer would suppress the catalytic activity of nano-TiO₂ and improve the UV protection for UV and photocatalysis sensitive dyes.     

Nucleation and morphology of crystals in simple and complex silicate glasses R′2O-SiO2, R′2O-R″O-SiO2, (R′ = Li,Na, K; R″ = Ca,Mg) synthesized by the sol-gel method

Sol-gel technology is a promising method not only to obtain the batch of the main composition but also to include low additives in glass. In this work, the batches obtained via the sol-gel method have been used to synthesize silicate glass based on the Li₂O-SiO₂ system with the additives of R′₂O and R″O, (R′ = Na, K; R″ = Ca, Mg). The Li₂O-SiO₂ system without the additives R′ and R″ has been studied by us most completely. It has been determined that the main crystal phase in the glass of Li₂O-SiO₂ system with Li₂O content up to 33 mol % is lithium disilicate, Li₂O · 2SiO₂. In the range of compositions from 33.8 to 40.7 mol % Li₂O, solid solutions based on lithium disilicate are formed; and, starting from 40.7 mol % Li₂O, solid solutions based on lithium metasilicate. The kinetic dependences of the number of nucleating lithium disilicate crystals from the time of heat treatment have been obtained at various temperatures of heat treatment. The temperature dependences of the stationary rate of nucleation of crystals have been studied. The results have been compared for the glass prepared with the use of the conventional and sol-gel method. It has been determined that the complication of the composition of glass based on 26Li₂O · 74SiO₂ (mol %) by the addition of R′ = Na, K; R″ = Ca, Mg affects the morphology of lithium disilicate crystals. The use of the sol-gel method of synthesis of glass leads to a more homogeneous spatial arrangement of crystals in bulk glass, the measure of which (distribution) is the dispersion of the number of traces of crystals per unit area of the section.     

Stable Wollastonite-Cuspidine Glass-Ceramic Using Inexpensive Raw Materials

Transparent glasses within the K₂O-CaO-SiO₂-F composition were prepared. The influence of CaF₂, TiO_2, Li₂O, Li₂O-TiO₂ and CeO₂ additions on the crystallization of the parent glass has been investigated. Crystallization process gave wollastonite and cuspidine as the major phases whereas; xontolite and traces of miserite were developed as subordinate ones. Wollastonite was developed alone in the temperature range of 800 °C-1100 °C in Li₂O-containing the base glass. Wollastonite and cuspidine were stable in the 800-1100 °C range in Li₂O+TiO₂-containing samples and within the 900 °C-1100 °C range in CaF₂ and CeO₂ containing samples. The microstructure of the Li₂O-containing glass-ceramic showed an interlocked needle in nano-scale wollastonite crystals, while fibrous textures were developed in all other crystallized samples at 1000 °C. The thermal expansion coefficient value of the crystallized samples was between 7.596 to 8.708 X10 ^?6 °C^?1 (20-500 °C) and the higher values reflect the increase of crystallization content of cuspidine and even the traces of miserite. This glass-ceramic is thought to be important in dental laboratories.     

A Novel 3-D Nanoporous Ce(III) Metal-Organic Framework with Terephthalic Acid; Thermal,Topology, Porosity and Structural Studies

This study describes the synthesis, crystal structure, porosity, and thermal stability of a new three-dimensional nano-porous metal-organic framework, [Ce₂(tp)₃(DMF)₂(DMSO)₂]_n, 1, (H₂tp = terephthalic acid, DMF = dimethyl formamid, DMSO = dimethyl sulfoxide). Compound 1 was synthesized by the solvothermal reaction of Ce(NO₃)₃·6H₂O and H₂tp and was then characterized by single-crystal X-ray diffraction and infrared spectroscopy. Structural analysis of 1 showed that Ce(III) ion has coordination number nine in a distorted mono-capped square anti-prismatic geometry. Gas sorption studies revealed a relatively reversible type-I isotherm characteristic of a porous material with surface area, pore volume, and average pore size of 179.4 m² g^?1, 0.73 cm³ g^?1, and 3.8 Å, respectively.     

The effect of loading on sintering and catalytic activity of Pt/SiO2 hybrid catalyst powders synthesized via spray pyrolysis

Platinum (Pt) is commonly used as a heterogeneous catalyst to effectively convert carbon monoxide (CO) from automobile exhaust gas into carbon dioxide (CO₂). Platinum/silica (Pt/SiO₂) hybrid catalyst powders with varying Pt content were synthesized via a spray pyrolysis process. The average particle size and specific surface area of the Pt nanoparticles on the Pt/SiO₂ hybrid catalyst powders were characterized as-prepared and after heat treatment. As the Pt loading increased, the Pt nanoparticles grew on the surface of the SiO₂ as a result of sintering, and the catalytic efficiency decreased. This work demonstrates that the Pt/SiO₂ (4 wt% Pt) hybrid catalyst powder is suitable as a hightemperature automobile exhaust catalyst, compared with the Pt/SiO₂ hybrid catalyst powder with high Pt loading (14 wt% Pt), indicating that metal nanoparticle loading is a key factor for determining catalytic activity.     

Self-assembled HPW/silica–alumina mesoporous nanocomposite as catalysts for oxidative desulfurization of fuel oil

Mesoporous silica–alumina–polyoxometalate (HPW/SiO₂–Al₂O₃) nanocomposite materials with silica–aluminum molar ratios of 10–80 have been successfully synthesized by evaporation induced self-assembly method with non-ionic surfactant P123 as template agent. The surface areas and pore sizes of the obtained HPW/SiO₂–Al₂O₃ materials are in the range of 509–623 m² g^?1 and 3.6–3.8 nm, respectively, with different silica–aluminum molar ratios. The incorporated polyoxometalate clusters preserve their intact Keggin structure into the mesoporous frameworks. The Py–FTIR investigations indicate that the surface acidity of catalysts gradually increases with an increase in the percentage of aluminium, and the Lewis acidity sites are predominant. The nanocomposites were used as catalysts, and H₂O₂ as oxidant for oxidative desulfurization (ODS) of model fuel, which was composed of benzothiophene (BT), petroleum ether and benzene. The results show that the adsorption capacity and ODS performance of catalysts have close relationship with their surface acidity. An appropriate amount of Lewis acidity sites can contribute to the selective oxidation of the BT due to the preferential adsorption of BT on the catalyst surface, while the Brönsted acidity sites have a negative impact on the selective oxidation of the BT. As a result, the mesoporous HPW/SiO₂–Al₂O₃ with silica–aluminum molar ratio of 50 shows the highest selectivity for BT oxidation in the presence of benzene and has achieved the goal of desulfurization. In addition, the catalyst shows excellent reusing ability, which makes it a promising catalyst in ODS process.     

Adsorption and photodegradation of methylene blue on TiO2-halloysite adsorbents

TiO₂-halloysite (TiO₂-HNT) composites were fabricated by depositing anatase TiO₂ on the halloysite (HNT) surfaces with calcination treatment at 100, 200, 300 and 500 °C. The obtained composites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD). HNT was attached with TiO₂ particles or clusters in sizes of 10–30 nm. With the increasing of calcination temperature, the crystalline of anatase became more perfect, but the structure of HNT could be destroyed at 500 °C. The adsorption and photodegradation of methylene blue (MB) by TiO₂-HNTs were investigated. The kinetic adsorption fit the pseudo second-order, and the isotherm data followed the Langmuir model. The maximum adsorption capacities of MB were in the range of 38.57 to 54.29 mg/g. TiO₂-HNTs exhibited an efficient photocatalytic activity in the decomposition of MB. For TiO₂-HNT calcined at 300 °C, 81.6% MB were degraded after 4 h treatment of UV irradiation.     

A new method to construct hierarchical ZSM-5 zeolites with excellent catalytic activity

Desilicication and dealuminzation with weak alkaline solution and acid liquor is an effective way to construct hierarchically mesoporous without damaging its crystallinity and preserving its acidity in ZSM-5 zeolites. We investigated the influence of the concentration of NaAlO₂, treatment time, temperature and the concentration of HCl on the crystallinity of ZSM-5 and characterized the products with XRD, SEM, XRF, BET, NH₃-TPD, etc. The results showed that the appropriate concentration of NaAlO₂ solutions extract selectively silicon from the framework of the zeolites while a small portion of aluminum would patch some parts of vacancies produced by the removal of silicon, then the HCl would dealuminize to maintain the SiO₂/Al₂O₃ ratios, which preserved the crystallinity of ZSM-5 perfectly. Furthermore, the micro-reaction activity tests displayed that the obtained products had higher catalytic than the parent zeolites because of their optimized hierarchical micro-mesoporous.     

Urothermal Synthesis of a New Cd(II)-Terephthalate: Synthesis,Structure, CO2 Adsorption and Luminescent Properties

A new Cd(II) compound, namely [Cd(pbdc)(e-urea)]_n (1 H₂pbdc = terephthalic acid, e-urea = ethyleneurea), has been synthesized by urothermal reactions of Cd(NO₃)₂, and H₂pbdc. Single crystal X-ray analysis reveals that it features a three-dimensional framework based on Cd(II)-carboxylate inorganic chains. The coordinated e-urea molecules are filled in the rhombic channels. Thermal analysis reveals that it can be stable up to 350 °C. The CO₂ adsorption and luminescent properties of compound 1 were also investigated.     

Composition and pH dependence on aggregation of SiO2–PVA suspension for the synthesis of porous SiO2–PVA nanocomposite

Porous monolithic SiO₂–poly(vinyl alcohol) (PVA) nanocomposites were fabricated by drying an SiO₂–PVA suspension. Depending on the amount of added PVA and pH value of the suspension, the Brunauer–Emmett–Teller surface areas, total pore volumes, and mean pore radii of the (100 ? x)SiO₂–xPVA (x = 0, 10, 20, 30 wt%) nanocomposites were 102–313 m² g^?1, 0.61–1.42 cm³ g^?1, and 8.1–14.7 nm, respectively. Some cracks were observed in the monolithic SiO₂–PVA nanocomposite, affected by the pore size. To elucidate crack generation, the correlation between the dispersion/aggregation in the SiO₂–PVA suspension and the pore size distribution of the nanocomposite was evaluated in terms of the added PVA amount and pH value. At x = 20 and pH 3, the SiO₂ particles and PVA aggregated in the suspension. The preparation of crack-free monolithic SiO₂–PVA nanocomposites was possible using the aggregated suspension owing to the low capillary force during drying because of the relatively large pores.     

Preparation and Characterization of Polysiloxane@CeO2@PMMA Hybrid Nano/Microspheres via In Situ One-Pot Process

In this study, polysiloxane@CeO₂@PMMA microspheres were successfully synthesized by controllable one-pot process, in which CeO₂ nanoparticles were stabilized in the surface of PMMA nano/microsphere using an in situ precipitation method. The core–shell structure of the synthesized product were confirmed by FT-IR, XRD and electronic microscope analysis. The size of polysiloxane@CeO₂@PMMA nano/microspheres were about 550 nm via microscopy analysis. Moreover, the novel hybrid nanocomposites eliminated the yellowish coloration problem of CeO₂ and had good dispersibility. In addition, the transmittance of the multifunctional films based on polysiloxane@CeO₂@PMMA microspheres owned good transmittance of visible light and can block harmful UV rays, which can be attributed to nano-CeO₂ accession. Hence, such green synthesized route can be considered as a simple common method for preparing UV-shielding multifunctional materials.     

Potentiometric study on the composition and stability of acetylacetoneanthranilic acid (SCHIFF's base) Complexes of Zinc (II) and Palladium (II)

The condensation of acetylacetone with anthranilic acid in presence of piperidine as the condensing agent gives acetylacetoneanthranilic acid SCHIFF 'S base (H₂AA) which forms complexes with Zinc (II) and Palladium (II). The dissociation constants of H₂AA have been determined by interpolation at half n̄ values and also by algebraic method which give the values 4.85 and 8.25 at 30° ± 1 °C for the dissociation constants. The stability constants of Zinc (II) and Palladium (II) complexes have been determined adopting CALVIN and MELCHIOR 'S extension of BJERRUM 'S method and the values of log k₁ are found to be 2.92 and 3.97 respectively at 30° ± 1 °C. In these complexes 1:1 metal-ligand stoichiometry is observed.     

Synthesis,characterization, and cell viability of bifunctional medical-grade polyurethane nanofiber: Functionalization by bone inducing and bacteria ablating materials

There is an extensive possibility of improving characteristics of fibers used in hard tissue engineering, being hydrophobic and less osteoconductive, resulting in the dynamic growth of new tissues. The current work focuses on the fabrication of nanofibers incorporated with titanium dioxide (TiO₂) ''as osteoconductive'' and silver (Ag) ''as self-healing'' nanoparticles (NPs). The incorporation of AgNO₃ by in situ method not only helped to impart the antibacterial activity but also changed the contact angle from 81 ± 03° in the case of pristine nanofibers to 74 ± 03°, 61 ± 03°, 50 ± 08°, and 39 ± 1.1°, in the composite scaffolds containing 0.01, 0.03, 0.05, and 0.07 M of Ag salts. The incubation in simulated body fluid at 37°C to induce mineralization on nanofiber scaffolds indicated Ca and P crystals' formation. The antibacterial activity showed significantly more toxicity toward E. coli (8.3 ± 0.9 mm) than S. aureus (1.2 ± 0.1 mm). Biocompatibility studies using MTT assay on the pre-osteoblasts showed that both TiO₂ and Ag NPs present in the nanofibers are non-toxic to the bone-like cells. However, results show that a higher concentration of Ag NPs (i.e., 0.07 M) is toxic to cells growing. Finally, all the results suggest that the nanofiber scaffolds have considerable scope for future bone tissue engineering materials.     

Reaction of fatty acids with 3,3′-iminobis-propylamine to produce soil hydrophobic agents

The reaction between two moles of fatty acid and one of 3,3′-iminobis-propylamine (DPTA) is somewhat analogous to the reaction between fatty acid and diethylenetriamine (DETA) that we had reported previously, but there are significant differences. Conversion to the diamide HN(CH₂CH₂CH₂NHCOR)₂ proceeds much more rapidly but less efficiently than does the reaction of fatty acid with DETA. The former diamide is obtained in only about a 70% yield and byproducts are obtained, whereas the reaction with DETA yields the diamide almost quantitatively. Cyclization to the pyrimidine $$RCONHCH_2 CH_2 CH_2 NCH_2 CH_2 CH_2 N = CR$$ is extremely slow and incomplete. The analogous cyclization of α,ω-diamides of DETA produces high yields of imidazolines. The AOCs wet method for amine titration gave erroneous structural information when the test was applied to the diamides of DPTA, as was the case for the DETA-diamide. The water repellency of soils treated with a homologous series of fatty iminobis-propylamine (DPTA)-diamides was studied, and the following observations were made: 1) the fatty DPTA-diamides were slightly more hydrophobic than the fatty DETA-diamides, which we ascribe to the additional methylene groups of the former; 2) hydrophobicity intensified with increasing molecular weight of the saturated fatty acids; and 3) unsaturation, as in the oleic derivative, enhanced hydrophilicity.     

Effects of in situ and ex situ formations of silica nanoparticles on polyethersulfone membranes

This study deals with the observed changes in the structure and performance of polyethersulfone (PES) membranes due to in situ formation and ex situ addition of silica particles (SiO₂). Hydrolysis and condensation of tetraethyl orthosilicate (TEOS) inside the PES polymer matrix and the reaction of TEOS with ammonium hydroxide were chosen to form in situ and ex situ SiO₂ formations, respectively. The resultant structure confirmed by X-ray diffraction for the composite PES membranes showed the retention of the amorphous nature even after the addition of SiO₂. The FTIR study revealed the functional groups corresponding to silica networks with enhanced OH signatures on the surface of the composite membranes. Field emission scanning electron microscopic images showed the variation in the surface and cross-sectional structures for the pure and composite membranes. Considerable reduction in the thickness of the skin, difference in the pore structure and ‘finger-like’ cross-sectional morphology with the presence of SiO₂ was observed in PES membranes. Both SiO₂/PES composite membranes were showed a minor change in their glass transition temperature (T _g). The ex situ methodically formed composite membrane displayed an increase in the pure water flux and decrease in bovine serum albumin rejection as compared to in situ and pure PES membranes. These kinds of composite membranes can be utilized for water treatment applications demanding higher water flux.     

Preparation and characterization of equimolar SiO2–Al2O3–TiO2 ternary aerogel beads

Crack-free mesoporous equimolar SiO₂–Al₂O₃–TiO₂ ternary aerogel beads have been synthesized and characterized. Silica sol, alumina sol, and titania sol were synthesized individually to prevent the formation of inhomogeneous structure due to the different hydrolization and polymerization rate of individual precursor. After mixing these three types of acidic sols, SiO₂–Al₂O₃–TiO₂ ternary beads were prepared by the ball dropping method. The ternary aerogel beads were typically mesoporous, showing high surface area (305 m² g^?1), large pore volume (1.32 cm³ g^?1), and high surface acid amount (0.884 mmol NH₃ g^?1). Moreover, the acid sites of the ternary aerogel beads showed higher thermal stability than those of binary aerogel beads. Gradient drying (GD), supercritical drying (SD), ambient drying (AD), extended aging (EA) and hydrophobic modifying drying (HM) have been employed to investigate the effects of drying method on the characteristics of the aerogel beads. The surface areas of the ternary aerogel beads obtained by different drying methods decrease in the sequence EA > HM > GD > SD > AD. The ternary aerogel beads have been characterized by scanning electron microscopy, nitrogen adsorption, X-ray powder diffraction, Fourier-transform infrared spectroscopy (FTIR), solid-state NMR, temperature-programmed desorption measurements, pyridine adsorption FTIR, and differential scanning calorimetry.     

EXTRACTION OF IRON(II) BY 2-(2'-THIAZOLYLAZO)-4,6-DIMETHYLPHENOL AND 2-(4',5'-DIMETHYL-2'-THIAZOLYLAZO)-4,6-DIMETHYLPHENOL

The extraction of Fe(II) from 0.1M NaClO₄. by 2-(2'-thiazolylazo)-4,6-dimethylphenol (TADMP) and 2-(4 ', 5'-dimethy1-2’-thiazolylazo)-4,6-dimethylphenol (DMTADMP) dissolved in chloroform has been studied by distribution methods. The experimental data, treated by both graphical and numerical methods, may be explained by assuming the formation of the species FeRClO₄. (logK₁₀₁₁ = 7.58±0.09 and 9.58±0.10) and FeR₂ logK₁₀₂₀. = 14.31±0.22 and 15.32±0.18) for Fe(II)-TADMP and Fefll)-DMTADMP systems, respectively.