The design of sustainable procedures for the preparation of cobalt/carbon-based materials as an anode for hydrogen fuel production through electrocatalytic water splitting has attracted much interest in the last few years. Herein, a novel environmentally friendly approach for the development of stable and active catalysts for the oxygen evolution reaction (OER) is reported. In detail, the methodology aimed at developing a sequence of composites having a low cobalt loading (<4%_wt) using polyphenols extracted from green tea as metal stabilizers and activated carbon derived from pinecones as a metal-support as well as a co-active material. The approach exploited ultrasound (US), microwave (MW) and combined US/MW-assisted techniques with the purpose of enhancing the final electrocatalytic activity of these new composites, replacing conventional high-temperature approaches. The results indicated that the so-produced electrocatalytic materials followed the order of activity US > MW/US > MW > conventional heating, with the best sample requiring an overpotential of 365 mV to deliver a current density of 10 mA cm⁻² and a Tafel slope of 58 mV dec⁻¹.

Silica-supported metallic species have emerged as valuable green-chemistry catalysts because their high efficiency enables a wide range of applications, even at industrial scales. As a consequence, the preparation of these systems needs to be finely controlled in order to achieve the desired activity. The present work presents a detailed investigation of an ultrasound-promoted synthetic protocol for the grafting of β-cyclodextrin (β-CD) onto silica. Truly, ultrasound irradiation has emerged as a fast technique for promoting efficient derivatization of a silica surface with organic moieties at low temperature. Three different β-CD silica-grafted derivatives have been obtained, and the ability of β-CD to direct and bind Cu when CD is bonded to silica has been studied. A detailed characterization has been performed using TGA, phenolphthalein titration, FT-IR, diffuse reflectance (DR), DR UV-Vis, as well as the inductively-coupled plasma (ICP) of the β-CD silica-grafted systems and the relative Cu-supported catalysts. Spectroscopic characterization monitored the different steps of the reaction, highlighting qualitative differences in the properties of amino-derivatized precursors and final products. In order to ensure that the Cu-β-CD silica catalyst is efficient and robust, its applicability in Cu(II)-catalyzed alkyne azide reactions in the absence of a reducing agent has been explored. The presence of β-CD and an amino spacer has been shown to be crucial for the reactivity of Cu(II), when supported.

This work presents a proof of concept for a green cyclodextrin derivatisation method that uses low-boiling epoxide reagents in a high-energy ball mill (HEBM). The simplified preparation and purification of low substitution-degree common (2-hydroxy)propylated β- and γ-cyclodextrins (β/γ-CDs) has been realised. The intelligent use of propylene oxide has also facilitated the more effective synthesis of highly substituted γ-CD. Epichlorohydrin-crosslinked CD-polymers (CDPs) have also been effectively prepared in the ball mill. The unoptimised preparations of soluble and insoluble CDPs displayed very small particle size distributions, while the prepared polymers currently have different complexation properties to those of their classically prepared analogues.

This work presents a group of high-quality hydrophilic and negatively charged coated, iron oxide magnetic nanoparticles (MNPs) that have been prepared using a microwave-ultrasound-assisted protocol, and demonstrates the great impact that the synthetic strategy has on the resulting MNPs. The different coatings tested, including citric acid, carboxymethyl dextran and β-cyclodextrin (βCD)/citric acid have been compared and have shown good dispersibility and stability. The ability of βCD to maintain the inclusive properties of the coated MNPs has been proven as well as their cytocompatibility. An amino citrate-modified βCD is proposed and its capabilities as a flexible amphoteric adsorbing device have been studied. The NMR relaxometric properties of the coated MNPs have been investigated using field-cycling nuclear magnetic relaxation dispersion profiles. For the amino citrate-modified βCD system, the order of magnitude of the Néel relaxation time is in the typical range for superparamagnetic systems' reversal times, i.e., 10⁻¹⁰–10⁻⁷ s. The r_d value corresponds to the physical radius of the magnetic core, suggesting that, in this particular case, the coating does not prevent the diffusive motion of water molecules, which provide the basis for potential future magnetic resonance imaging (MRI) applications.

The development of new strategies for spatially controllable immobilization has encouraged the preparation of novel catalysts based on the organic-inorganic hybrid concept. In the present paper, a Cu-based multi-structured silica catalyst has been prepared and fully characterized. The inclusion of Cu(II) in β-cyclodextrins has been exploited with the double aim to stabilize the metal and to act as a source of Cu(I) catalytic sites. Multi-technique characterization by infrared, UV-visible, electron microscopy and X-ray absorption spectroscopies of the fresh and exhaust catalysts provided information on the local structure, redox properties and stability of the investigated hybrid systems. The catalytic system showed that copper nanospecies were dispersed on the support and hardly affected by the catalytic tests, confirming the stabilizing effect of β-CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Overall, we demonstrate a feasible approach to efficiently anchor Cu(II) species and to obtain a reusable single-site hybrid catalyst well suited for Cu(I)-catalyzed alkyne-azide cycloaddition.