RESUMEN

In this study, we propose a promising photoprotective additive that combines the advantages of both organic UV absorbers and inorganic particles without compromising the properties of the paint material. This additive involves the intercalation of a well-known organic UV absorber, 2-phenylbenzimidazole-5-sulfonic acid (PBISA), into zinc-aluminum layered double hydroxide (ZnAl-LDH). Three ZnAl-LDH intercalates with PBISA were prepared using various methods based on either anion exchange or direct synthesis. The intercalates were characterized using powder X-ray diffraction, thermogravimetry, elemental analysis, and IR and UV-Vis spectroscopies. The composition and basal spacings of all three intercalates are very similar. An effective UV protection film was prepared when the ZnAl-PBISA-1 intercalate was incorporated into polyurethane-acrylate lacquer. The resultant UV protective film exhibited stability and uniform distribution of the intercalated fillers. Some minimal particle sedimentation and aggregation were observed on the cured film's underside, but did not compromise the films' UV protective properties. The prepared lacquers with intercalated fillers offer a viable solution for the surface modification of plastic products.

RESUMEN

Raney Al-Ni contains 62% of Ni2Al3 and 38% NiAl3 crystalline phases. Its applicability has been studied within an effective hydrodehalogenation of hardly biodegradable anti-inflammatory drug diclofenac in model aqueous concentrates and, subsequently, even in real hospital wastewater with the aim of transforming them into easily biodegradable products. In model aqueous solution, complete hydrodechlorination of 2 mM aqueous diclofenac solution (0.59 g L-1) yielding the 2-anilinophenylacetate was achieved in less than 50 min at room temperature and ambient pressure using only 9.7 g L-1 of KOH and 1.65 g L-1 of Raney Al-Ni alloy. The dissolving of Al during the hydrodehalogenation process is accompanied by complete consumption of NiAl3 crystalline phase and partial depletion of Ni2Al3. A comparison of the hydrodehalogenation ability of a mixture of diclofenac and other widely used halogenated aromatic or heterocyclic biocides in model aqueous solution using Al-Ni was performed to verify the high hydrodehalogenation activity for each of the used halogenated contaminants. Remarkably, the robustness of Al-Ni-based hydrodehalogenation was demonstrated even for the removal of non-biodegradable diclofenac in real hospital wastewater with high chloride and nitrate content. After removal of the insoluble part of the Al-Ni for subsequent hydrometallurgical recycling, the low quantity of residual Ni was removed together with insoluble Al(OH)3 obtained after neutralization of aqueous filtrate by filtration.

RESUMEN

Classical molecular simulation methods were used for a description of an arrangement of intercalated molecules N-(pyridin-4-yl)pyridin-4-amine (AH) and its derivatives, 3-methyl-N-(pyridin-4-yl)pyridin-4-amine (AMe), and 3-nitro-N-(pyridin-4-yl)pyridin-4-amine (ANO2) within a layered structure of zirconium 4-sulfophenylphosphonate. The intercalated molecules were placed between SO3H groups of the host layers. Their mutual positions and orientations were solved by molecular simulation methods and compared with the presented experimental results. Final calculated data showed differences of partially disordered arrangement of the intercalated molecules between zirconium 4-sulfophenylphosphonate layers. The calculation results revealed a dense net of hydrogen bonds connecting water molecules and the guests in the interlayer space and the sulfo groups of the host layers. We calculated the dipole moments of the AH, AMe and ANO2 guests in the final models in order to illustrate potential use of these materials in non-linear optics.

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RESUMEN

Mixed zirconium 4-sulfophenylphosphonate phenylphosphonates with formulae Zr(HO3SC6H4PO3)1.8(C6H5PO3)0.2·2.6H2O, Zr(HO3SC6H4PO3)1.3(C6H5PO3)0.7·2H2O, and Zr(HO3SC6H4PO3)0.7(C6H5PO3)1.3·3.6H2O (generally, ZrSPhP) were intercalated with a series of amino alcohols, H2N(CH2)nOH, where n = 2 to 6, and triethylamine. It was found that in the case of amino alcohols the basal spacing of the intercalates increases linearly with n. The intercalates prepared can be exfoliated either by sonication or by the action of high-shear forces. The use of a high-shear force disperser is a more efficient exfoliation method, as it provides lamellas with larger lateral dimensions in a much shorter time. It was found that amino alcohols provide roughly the same results regardless of the length of their carbon chain. As follows from atomic force microscopy measurements, triethylamine is the most appropriate exfoliation agent for ZrSPhP as it produces platelets with the largest lateral size and the lowest amount of defects.

RESUMEN

The use of nanosheets of layered calcium phenylphosphonate as a filler in a polymeric matrix was investigated. Layered calcium phenylphosphonate (CaPhP), with chemical formula CaC6H5PO3∙2H2O, is a hybrid organic-inorganic material that exhibits a hydrophobic character due to the presence of phenyl groups on the surface of the layers. In this paper, various CaPhP synthesis methods were studied with the aim of obtaining a product most suitable for its subsequent exfoliation. The liquid-based approach was used for the exfoliation. It was found that the most promising technique for the exfoliation of CaPhP in an amount sufficient for incorporation into polymers involved using propan-2-ol with a strong shear force generated in a high-shear disperser. The filler was tested both in its unexfoliated and exfoliated forms for the preparation of polymer composites, for which a low molecular weight epoxy resin based on bisphenol A was used as a polymer matrix. The prepared samples were characterized by powder X-ray diffraction, atomic force microscopy, optical and scanning electron microscopy, and dynamic mechanical analysis. Flammability and gas permeation tests were also performed. The addition of the nanofiller was found to influence the composite properties - the exfoliated particles were found to have a higher impact on the properties of the prepared composites than the unexfoliated particles of the same loading.

RESUMEN

Two binary boron hydrides (NH4)2B10H10 and Na2B12H12 and mono- and dicarboxy p- and m-carboranes (namely, 1-(COOH)-closo-1,7-C2B10H11, 1,12-(COOH)2-closo-1,12-C2B10H10 and 1,7-(COOH)2-closo-1,7-C2B10H10) were intercalated into ZnAl-layered double hydroxides (ZnAl-LDH) and into Zn5(OH)8(NO3)2·2H2O. The formed compounds were characterized using elemental analysis, thermogravimetry analysis, X-ray powder diffraction, infrared spectroscopy and solid state NMR. All the intercalated boron compounds are present in the interlayer space of the layered hosts as anions. It is presumed that in the case of B10H102-, B12H122- and 1,12-(COO)2-closo-1,12-C2B10H102-, the guest molecules form a monolayer, whereas in the case of 1-(COO)-closo-1,7-C2B10H111- and 1,7-(COO)2-closo-1,7-C2B10H102- a bilayer arrangement is more probable. In the case of 1,7-(COO)2-closo-1,7-C2B10H102-, the guest molecules are strongly interdigitated resulting in lowering of the interlayer distance. Two different modes of binding were found. Whereas the carboxylate derivatives of p- and m-carboranes are bonded through classical hydrogen bonds, the corresponding parent borane anions interact with the host structures by mainly dihydrogen bonding. In effect, both kinds of hydrogen bonding are mainly of an electrostatic nature. The dihydrogen bond is detected, e.g. in crystal engineering, and represents a driving force for interactions of boranes with biomolecules. Since the latter dicarboxylic acids were found to be superacids, their interactions with the host structures should be stronger than in the case of the benzoic and terephthalic acid intercalates.

RESUMEN

Studies have been focused on the synthesis of N→Ga-coordinated organogallium selenides and tellurides [L1 Ga(µ-Se)]2 (1), [L2 Ga(µ-Se)]2 (2) and [L1 Ga(µ-Te)]2 (3), respectively, containing either N,C,N- or C,N-chelating ligands L1, 2 (L1 is {2,6-(Me2 NCH2 )2 C6 H3 }- and L2 is {2-(Et2 NCH2 )-4,6-tBu2 -C6 H2 }- ) having Ga/E (E=Se or Te) atoms in 1/1 ratio. To change the Ga/E ratio, an unusual N→Ga-coordinated organogallium tetraselenide L1 Ga(κ2 -Se4 ) (4) was prepared. An unprecedented complex (L1 Ga)2 (µ-Te2 )(µ-Te) (5), as the result of the non-stability of 3, was also isolated. Compound 2 is a suitable single-source precursor for the preparation of amorphous GaSe thin films by the spin coating. Moreover, simple heating of an octadecylamine solution of 2 provided, after work up, monoclinic Ga2 Se3 crystals with different crystallinity according to conditions used. Therefore, compound 2 may be also used as a source of Ga2 Se3 in the low-temperature doping process of Bi2 Se3 .

RESUMEN

The intercalation chemistry of layered alkaline-earth metal phenylphosphonates with the general formula MeC6H5PO3·2H2O (Ca, Sr, Ba) is reviewed. The preparation of the host materials is described and their behavior in dependence on the relative humidity and pH of the reaction medium is discussed. Mutual relationships between MeC6H5PO3·2H2O and Me(C6H5PO3H)2 were investigated using a method of computer-controlled addition of reagents. The MeC6H5PO3·2H2O compounds are able to intercalate species having a free electron pair through the so-called coordination intercalation. In this way, 1-alkylamines, 1-alkanols, 1,n-diols and 1,2-diols were intercalated. In the case of the ethanol and methanol intercalates of strontium phenylphosphonate we were able to determine the structure of the host part by single-crystal X-ray diffraction. By combination of the data obtained from the diffraction with molecular modeling we suggested the arrangement of the host molecules in the interlayer space of the host. The arrangement of the shorter diols in the interlayer space of strontium phenylphosphonate was also proposed on the basis of molecular modeling calculations. These models help us to understand the structure of the prepared intercalates.

RESUMEN

Classical molecular simulation methods were used for a detailed structural description of zirconium 4-sulfophenylphosphonate and zirconium phenylphosphonate 4-sulfophenylphosphonates with general formula Zr(HO3SC6H4PO3) x (C6H5PO3)2-x ·yH2O (x = 0.7-2; y = 0 or 2). First, models describing the structure of zirconium 4-sulfophenylphosphonate (x = 2) were calculated for the hydrated (y = 2) and dehydrated (y = 0) compounds. Subsequently, models for two mixed zirconium phenylphosphonate 4-sulfophenylphosphonates (x = 1.3 and 0.7) were calculated. Optimized models suggest that the presence of water molecules between sulfo groups creates a water-sulfonate layer with a system of hydrogen bonds. We suppose that this arrangement is the reason for a higher proton conductivity of the hydrated samples compared to dehydrated samples. When the water molecules are removed, a small decrease in the basal spacing (around 0.06 Å) is observed. This behavior is confirmed by the simulated models, where no significant changes in the structure on dehydration were observed except the absence of the water molecules and a lower number of hydrogen bonds between two adjacent sulfonate sheets. Due to the good crystallinity of the samples and the presence of sharp non-basal peaks in their X-ray diffraction patterns, Miller indices of the non-basal peaks in the diffraction patterns calculated from the models can be compared with those found in the experimental data. This allowed us to precisely describe for example (15 5-2) planes, from which mutual distances of the phenyl rings were determined to be 2.62 Å. Graphical Abstract Detailed ball and stick view into the interlayer structure of ZrSPhP1.3.

RESUMEN

Eight new barium methylphosphonates were prepared and described. In dependence on pH, either barium hydrogen methylphosphonates or barium methylphosphonates can be formed. In the case of barium methylphosphonates, BaCH3PO3·3H2O crystallizes from the solution at room temperature and BaCH3PO3·H2O at a temperature above 65 °C. On heating, these hydrates form two anhydrous barium methylphosphonates (α-BaCH3PO3 and ß-BaCH3PO3) with the same composition but with a different structure. In a basic environment, barium hydrogen methylphosphonate monohydrate, Ba(CH3PO3H)2·H2O, transforms to BaCH3PO3·3H2O through an intermediate with the formula Ba2(CH3PO3H)2(CH3PO3)·4H2O. The reverse reaction, that is the reaction of BaCH3PO3·3H2O with methylphosphonic acid, proceeds to the intermediate only and hydrogen methylphosphonate is not formed. Acidic Ba(CH3PO3H)2·H2O is able to interact with basic amines and form stable intercalates with them. Structures of ß-BaCH3PO3 (P21/c, a = 8.4501(6) Å, b = 7.2555(7) Å, c = 7.4604(8) Å, ß = 99.837(8)°, Z = 4) and BaCH3PO3·H2O (P21/c, a = 20.5077(5) Å, b = 7.2175(2) Å, c = 7.4909(3) Å, ß = 95.522(3)°, Z = 8) were solved from powder X-ray diffraction data. Both compounds are layered, and the layers are formed of two sheets of Ba atoms connected through oxygen atoms of the phosphonate groups. The methyl groups point towards the interlayer space. In the case of BaCH3PO3·H2O, the molecules of water are coordinated to the Ba atoms and are placed in the interlayer space among the methyl groups.

RESUMEN

We report on a very significant enhancement of the thermal, chemical, and mechanical stability of self-organized TiO2 nanotubes layers, provided by thin Al2O3 coatings of different thicknesses prepared by atomic layer deposition (ALD). TiO2 nanotube layers coated with Al2O3 coatings exhibit significantly improved thermal stability as illustrated by the preservation of the nanotubular structure upon annealing treatment at high temperatures (870 °C). In addition, a high anatase content is preserved in the nanotube layers against expectation of the total rutile conversion at such a high temperature. Hardness of the resulting nanotube layers is investigated by nanoindentation measurements and shows strongly improved values compared to uncoated counterparts. Finally, it is demonstrated that Al2O3 coatings guarantee unprecedented chemical stability of TiO2 nanotube layers in harsh environments of concentrated H3PO4 solutions.

RESUMEN

Our studies have been focused on the synthesis of N→Ga coordinated organogallium sulfides [L1 Ga(µ-S)]3 (1) and [L2 Ga(µ-S)]2 (2) containing either N,C,N- or C,N-chelating ligands L1 or L2 (L1 is {2,6-(Me2 NCH2 )2 C6 H3 }- and L2 is {2-(Et2 NCH2 )-4,6-tBu2 -C6 H2 }- ). As the result of the different ligands, compounds 1 and 2 differ mutually in their structure. To change the Ga/S ratio, unusually N→Ga coordinated organogallium tetrasulfide L1 Ga(κ2 -S4 ) (3) was prepared and the unprecedented complex [{2-[CH{(CH2 )3 CH3 }(µ-OH)]-6-CH2 NMe2 }C6 H3 ]GaS (4) was also isolated as the minor by-product of the reaction. Compounds 1-3 were further studied as potential single-source precursors for amorphous GaS thin film deposition by spin-coating.

RESUMEN

Strontium phenylphosphonate intercalates with 1,2-diols (from 1,2-ethanediol to 1,2-hexanediol) were synthesized and characterized by X-ray diffraction, thermogravimetry, chemical analysis, and molecular simulation methods. Prepared samples exhibit a very good stability at ambient conditions. Structural arrangement calculated by simulation methods suggested formation of cavities surrounded by six benzene rings. Each cavity contained one molecule of diol and one molecule of water for the 1,2-ethanediol to 1,2-butanediol intercalates. In the case of 1,2-pentanediol two types of cavities alternated: one with diol molecules and another one with two water molecules. In the 1,2-hexanediol intercalate the benzene rings created two types of cavities containing one or two diol molecules, respectively, and this conformational variability led to a more disordered arrangement with respect to the models with shorter alkyl chains. Coordination of the oxygen atoms of the diols to the strontium atoms of the host follows the same pattern for all 1,2-diol intercalates except the 1,2-hexanediol intercalate, where these oxygen atoms can be mutually exchanged at their positions. The calculated basal spacings and structural models are in good agreement with experimental basal spacings obtained from X-ray powder diffraction and with other experimental results.

RESUMEN

The aim of the study was to prepare PLGA microparticles for prolonged release of mirtazapine by o/w solvent evaporation method and to evaluate effects of PVA concentration and organic solvent choice on microparticles characteristics (encapsulation efficiency, drug loading, burst effect, microparticle morphology). Also in vitro drug release tests were performed and the results were correlated with kinetic model equations to approximate drug release mechanism. It was found that dichloromethane provided microparticles with better qualities (encapsulation efficiency 64.2%, yield 79.7%). Interaction between organic solvent effect and effect of PVA concentration was revealed. The prepared samples released the drug for 5 days with kinetics very close to that of zero order (R(2 )= 0.9549 - 0.9816). According to the correlations, the drug was probably released by a combination of diffusion and surface erosion, enhanced by polymer swelling and chain relaxation.

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RESUMEN

Strontium phenylphosphonate intercalates with 1,n diols (n=2-4, 6-8) having general formula SrC6H5PO3⋅x(HO(CH2)nOH)⋅yH2O were prepared by precipitation from strontium phenylphosphonate solution and the corresponding diols. Prepared compounds exhibit a very good stability at ambient conditions. The intercalates were characterized by X-ray diffraction, thermogravimetry and elemental analysis. Thanks to the existence of free spaces among the benzene rings the diols exhibit a peculiar intercalation behavior. This behavior is explained on the basis of molecular simulation, which facilitated to elucidate the arrangement of the diol (guest) molecules in the specifically shaped space between the layers of the host material. From the structural point of view the intercalates can be divided into two subgroups: (i) intercalates with 1,2- to 1,4-diols and (ii) intercalates with 1,6- to 1,8-diols. The alkanediols of the first group are immersed in the free spaces among the benzene groups, their molecules adopt a horseshoe shape meaning cis conformation and are bonded by both of their OH groups to one host layer. The longer alkanediol chains of the second group allow anchoring to both neighboring layers of the host forming a kind of pillared structure in the interlayer space. The diol molecules are in this case bonded to the host layers by their OH groups to the oxygen atoms of the host layers and to water molecules present in the interlayer space through hydrogen bonds. The values of the basal spacing obtained from the experimental powder X-ray patterns are in a very good agreement with the basal spacing values calculated from the models. The molecular simulation of a 1,5-pentanediol intercalate, which we were not be able to synthesize, explained why this intercalate cannot be stable.

RESUMEN

Two new intercalates of tris[4-(pyridin-4-yl)phenyl]amine (TPPA) with zirconium hydrogen phosphate and zirconium 4-sulfophenylphosphonate having formulae Zr(HPO4)2·0.21(C33H24N4)·2.5H2O and Zr(HO3SC6H4PO3)(1.3)(C6H5PO3)(0.7)·0.35(C33H24N4)·2.5H2O were prepared and characterized by thermogravimetry, IR spectroscopy, and powder X-ray diffraction. The TPPA molecule has been selected as a model tripodal push-pull system with three peripheral basic centers that may undergo protonation. Their protonation/quaternization afforded HTPPA/MeTPPA molecules with enhanced intramolecular charge-transfer (ICT), which has been documented by electrochemical measurements, UV-Vis spectra and calculated properties such as the HOMO/LUMO levels and the first and second hyperpolarizabilities. Intercalation of TPPA into layered zirconium hydrogen phosphate and zirconium 4-sulfophenylphosphonate led to its significant organization and protonation as shown by the IR spectra. From the powder X-ray data we can deduce that the TPPA molecules are placed in the interlayer space of both hosts by anchoring two peripheral nitrogen atoms to one host layer and the opposite pyridine-4-yl terminus to the other neighboring host layer. In zirconium 4-sulfophenylphosphonate, the TPPA molecules are oriented perpendicularly, while in zirconium phosphate these molecules are slanted with respect to the layers of the host. On dehydration by heating, the interlayer distance of the intercalate decreases, which indicates a further slanting of the TPPA molecules. It follows from the UV-Vis spectra that TPPA is present in both intercalates in an equilibrium of protonated and non-protonated forms. The described materials represent the first case when a tripodal push-pull system was incorporated into a system with restricted geometry with the aim to influence its optical properties.

RESUMEN

The Letter describes the preparation and characterization of a conjugate of isoniazid (INH) with magnetic nanoparticles Fe3O4@SiO2 115±60 nm in size. The INH molecules were attached to the surface of nanoparticles by a covalent pH-sensitive amidine bond. The conjugate was characterized by X-ray diffraction, SEM, dynamic light scattering, IR spectroscopy and microanalysis. The conjugate released isoniazid under in vitro conditions (pH=4; 37 °C; t1/2≈115 s). In addition, the cytotoxicity of the Fe3O4@SiO2-INH conjugate was evaluated in SK-BR-3 cells using the xCELLigence system.

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Put the right spin on it: Mixed monomeric organotin(IV) chalcogenides of the general formula L(2)Sn(2)EX(2) containing two terminal Sn-X (X = Se, Te) bonds were prepared and were tested as potential single-source precursors for the deposition of semiconducting thin films. Spin-coating deposition of [{2,6-(Me(2)NCH(2))(2)C(6)H(3)}SnSe](2)(µ-S), as the useful single-source precursor, provided amorphous Sn-S-Se semiconducting thin films.

RESUMEN

The present paper deals with the preparation and characterization of a conjugate of isoniazid (INH) with the block copolymer methoxypoly(ethylene glycol)-b-poly(L-lysine) (mPEG-b-PLL). The structure of the conjugate (mPEG-b-PLL-INH) was verified by means of (1)H NMR, GPC, infrared spectroscopy, elemental analysis and powder X-ray diffraction. The conjugate contains six l-lysine units with five INH molecules, which are attached by means of pH-sensitive amidine bond. Under in vitro conditions, the conjugate is hydrolyzed and isoniazid is released (pH 4; 37 °C; t(1/2) ≈ 10 h).

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The application of green chemistry in the nano-science and technology is very important in the area of the preparation of various materials. In this work, an eco-friendly chemical method was successfully used for the preparation of hyaluronan fibers containing silver nanoparticles (AgNPs). Thus, hyaluronic acid (HA) was dissolved in an aqueous solution of sodium hydroxide to prepare a transparent solution, which was used for the preparation of fibers by a wet-spinning technique. Consequently, silver nanoparticles inside the fiber were prepared. Different parameters affecting the preparation of final product, such as concentration of silver nitrate, hyaluronan fiber concentration, time and temperature of the reaction, pH of the reaction mixture, were studied. AgNPs were confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), two-dimensional X-ray scattering (2D SWAXS), UV/Vis spectroscopy, inductively coupled plasma optical emission spectrometry (ICP OES) and scan electron microscopy (SEM). Mechanical properties of prepared fibers were also measured.

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