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Boron chemistry has raised much interest because, despite the difference between necessities and toxicity being very narrow, it is still widely used in industrial processes. In a previous work we reported an adsorbent for boron extraction from water by the functionalisation of a UVM-7 mesoporous silica matrix with gluconamide moieties. The ability of this material to adsorb boron is based on its well-known affinity for coordinating the cis-diols present in attached saccharide. Although much research on the formation of boron esters with sugars and sugar derivatives in solution has been done, very few reports have dealt with the adsorption mechanism of boron onto functionalised materials in the solid state. Hence an in-depth study of the adsorption process was conducted in this paper. For this purpose, several solids with increasing boron contents were prepared from the gluconamide-functionalised UVM-7 material and an isothermal boron adsorption curve was obtained. The 11 B and 13 C MAS NMR techniques were used to characterise the obtained solids, and the simulation of the boron NMR and isothermal adsorption combined data was accomplished to enlighten the boron adsorption process. A model with three different coordination environments, two possible adsorption sites and the presence of oligomeric boron species allowed us to reproduce not only the isothermal boron adsorption curve, but also the evolution of the integrated areas for the signals in the 11 B MAS NMR spectra obtained for the different boron-containing gluconamide-functionalised UVM-7 materials. [ABSTRACT FROM AUTHOR]

In this work we present a synthesis strategy for the preparation of Stöber-type mesoporous particles functionalized with inorganic species. The procedure is based on a combination of the Atrane and the Stöber methods. Both as a source of silicon and of the incorporated heteroelements (Fe, Zn, Al, Ti) the corresponding atrane complexes are used as hydrolytic reagents. These complexes are easily formed by reaction with triethanolamine. Mesoporosity is achieved using surfactant micelles as templates. Obtaining uniform spherical particles is achieved by optimizing the amount of water-ethanol in the reaction medium. The particle sizes have been modulated by controlling simple parameters such as reaction time or temperature. The incorporation of inorganic species is on many occasions incompatible with the preservation of spherical morphology, resulting in heterogeneous particles in shape and size and even phase segregation for high functionalization degrees. The methodology that we propose makes it possible to achieve a high concentration of highly dispersed heteroelements (even at molecular level), maintaining, to a large extent, both sphericity and particle size homogeneity. The Si/M molar ratios achieved are significantly lower (greater functionalization) than those usually reported in the literature. The strategy is generalizable for the incorporation of a great variety of elements, and specially for first row transition elements. [Display omitted] • A reproducible "one pot" method to obtain mesoporous Stöber type particles is described by using atrane complexes as hydrolytic precursors • The particle size can be easily modulated (100–300 nm) through simple parameters as t and T reaction. • We achieved relatively high heteroelement incorporations in the 10 ≤ Si/M ≤ 14. • The inorganic functionalization occurs without loss of the spherical shape and porosity. • The heteroelements result highly dispersed as isolated sites or small clusters without phase segregation. [ABSTRACT FROM AUTHOR]

Silica-based UVM-7-type bimodal mesoporous materials with high gadolinium content (∞ ≥ Si/Gd ≥ 13) have been synthesized through a one-pot surfactant-assisted procedure from hydroalcoholic solution using a cationic surfactant as template, and starting from atrane complexes of Gd and Si as inorganic precursors. The novel synthetic pathway developed in the study preserves the UVM-7-type architecture while optimizing the dispersion of the Gd-guest species at the nanoscale and even at atomic level. It has been determined that the number of Gd atoms forming clusters is always less than 10. The behaviour under exposure to ultra-high magnetic fields reveals a significant increase in the transversal relaxivity value when compared with related materials in the bibliography. Their activity as T2 instead of T1 contrast agents is discussed and explained considering the high Gd-dispersion and concentration, nature of the materials as well as due to the high magnetic fields used, typical of MRM studies. The absence of toxicity has been confirmed in preliminary cell cultures "in vitro" and the degradation of the solids studied under biological conditions. Results suggest that the atrane route could be a suitable synthesis approach for the preparation of Gd containing contrast agents. [Display omitted] • Very high Gd-containing (Si/Gd = 11–13) hierarchical bimodal porous silicas have been synthesized. • The materials are monophasic samples without segregation of Gd 2 O 3 nanodomains. • The Gd centres result highly dispersed in the form of Gd n clusters (n < 10). • The high Gd concentration and dispersion confers these materials interest as contrast agents. • A remarkable increase of the T2 relaxivity when working under ultra-high magnetic fields is observed. [ABSTRACT FROM AUTHOR]

Abstract: We report herein the development of a new optoelectronic nose composed of seven sensing materials prepared by the incorporation of pH indicators and chromogenic reagents selective to metabolites into inorganic materials (UVM-7 and alumina). The nose has been applied to monitor fresh pork sausage ageing. Sausages were packaged together with the disposable array in a modified packaging atmosphere (30% CO2, 70% N2) and colour changes were measured at seven day intervals. Simultaneously, microbiological and sensory analyses were performed. Colour modulations of the chromogenic array were processed with standard analytical tools, including principal component analysis (PCA) and partial least squares (PLS). According to the PCA, the array was able to monitor the sausage spoilage process and to distinguish between each sampled day. Moreover, the PLS statistical analysis of the chromogenic data displayed a linear correlation between the predicted and measured values of the storage days, mesophilic bacteria (cfu g−1) and the sensory score with regression coefficients of 0.9300, 0.9472 and 0.9381, respectively. [Copyright &y& Elsevier]

Abstract: Porous silicas with pore sizes at two length scales (meso and large meso/macroporous) have been prepared through a one-pot surfactant assisted procedure by using a simple template agent and starting from silicon atrane complexes as hydrolytic inorganic precursors. The special organization of these bimodal porous silicas can be related to the nanometric character of their constituent mesoporous particles. Whereas the small intra-particle mesopore system is generated by the templating effect of the surfactant, the large pore system is defined by inter-particle voids. We have studied the effect of different procedural parameters on the small pore system and also on the nucleation and growth of the nanoparticles. The formation of these hierarchical materials is explained on the basis of kinetic (hydrolysis and condensation reaction rates) and thermodynamic (silica solubility) concepts. [Copyright &y& Elsevier]

[Display omitted] • Highly active green catalyst for the reduction of nitroarenes. • Control of interfacial deposition of Pd nanoparticles assisted by polidopamanine. • Effect of inorganic core morphology on catalytic activity. • Comparison of catalytic activity based on corrected turn-over frequency. • Multi-curve resolution factorial analysis applied to the study of the catalytic activity of a multi-step reaction. Two green catalysts based on Pd(0) nanoparticles (Pd NPs) anchored through PDA on porous silica and magnetite have been synthesized using a generalized simple and reproducible "two-step" methodology. Both catalysts were tested for a model reaction, the hydrogenation of 4-nitrophenol using NaBH 4 as the hydrogenating agent, and especially good activity has been achieved in the case of the catalysts containing magnetite as inorganic core (Pd NPs-PDA@Fe 3 O 4). We analyzed the effect associated with the catalyst separation method (centrifugation or magnetically) that affect to the distribution and aggregation degree of the Pd NPs. In addition, we also correlate the final catalyst morphology with the activity and its relationship with the nature of the inorganic supports: porous (UVM-7 type silica) or massive, although on a nanoscale, typical of the Fe 3 O 4 particles used. We have also studied the activity of the catalysts in the hydrogenation of nitroarenes, that follows the Haber multistep mechanism through various intermediates. In order to understand not only the process as a whole, but also the importance of each step and the intermediates involved, we have applied the multivariate curve resolution (MCR) factorial methodology. This approach, that normally is not used in the catalysis works, makes it possible to quantitatively determine the rate limiting step, and allow to extract complete information from a multistep catalytic process. [ABSTRACT FROM AUTHOR]