Nanosized Vanadium, Tungsten and Molybdenum Oxide Clusters Grown in Porous Chitosan Microspheres as Promising Hybrid Materials for Selective Alcohol Oxidation

Abstract

The ability of chitosan biopolymer to coordinate vanadium, tungsten and molybdenum metallic species and to control their mineralisation growth provides a new family of surface-reactive organic-inorganic hybrid microspheres. Drying the resulting materials under supercritical conditions allowed the gel network dispersion to be retained, thereby leading to a macroporous catalyst with surface areas ranging from 253 to 278 m(2) g(-1). On account of the open framework structure of these microspheres, the redox species entangled within the fibrillar network of the polysaccharide aerogels were found to be active, selective and reusable catalysts for cinamylalcohol oxidations.

Pd embedded in chitosan microspheres as tunable soft-materials for Sonogashira cross-coupling in water–ethanol mixture

“…This has been confirmed by DRIFT where the typical signal of primary amine at 1592 cm -1 significantly 10 decreases at the expense of new band at 1638 cm -1 due to (C=N) vibration (S3, SI). 13 C MAS NMR spectroscopy reveals the existence of additional peaks with respect to those of native chitosan (signals around 27.9, 43.6 and 96.7 ppm can be respectively attributed to central CH2-CH2-CH2, the CH2-CH2- 15 HC=N and the carbon directly attached to nitrogen atom (C=N)) (S4, SI).…”

“…In sharp contrast, Pd-CS-Glu microspheres features two palladium species; the most abundant one being Pd 0 with its binding 5 energy at 337 eV and 343 eV and those of Pd +2 at 340 and 346 eV for 3d5/2 and 3d3/2 respectively (S7, SI). 18,19 At this point, three Pd-hosted alcogel-and aerogel-based materials with similarities in their intrinsic textural properties of the support (macroporous fibrillar network and millimetric 10 dimension of the microspheres), but with different metalsupport coordination strength (weakly coordinated Pd in CS, incarcerated Pd nanoparticles in CS-Glu and strongly coordinated Pd 2+ in CS-SH) were prepared. Beside our motivation to elucidate -for the first time -the difference on 15 the performance of support in catalysis between CS alcogels and aerogels, a second important point is to determine how CS functionalization influences the catalytic activity and if there is a borderline between efficient scavenger and efficient catalyst.…”

“…Mild and sustainable reaction conditions (copper-free, ethanol-water as solvent, 65 °C) enable Sonogashira cross-coupling catalysis to be performed with quantitative yields, low metal contamination, easy work up and good recyclability. This 5 straightforward and sustainable chemistry affords versatile ecoefficient catalysts bearing many useful properties: their gentle reducing conditions to produce metal nanoparticles (without using toxic reducing agents neither hydrogen treatment) and their easy recovery from the reaction medium whereas 10 heterogeneous system needs specific filters are among their most illustrative advantages over the existing Pd-supported catalysts. The metal scavenging ability of these microspheres can be interesting for the synthesis of active pharmaceutical ingredients, specifically those for which the metal 15 contamination has to be reduced to few ppb.…”

Chitosan-MgO Nanocomposite: One Pot Preparation and Its Utility as an Ecofriendly Biocatalyst in the Synthesis of Thiazoles and [1,3,4]thiadiazoles

“…Moreover, only small acceptable shift in the bands of chitosan-MgO nanocomposite was attributed to the influence of the incorporation of MgO nanoparticles. This shift in bands was familiar as result of chitosan with metal oxides [21]. The latter shifts are shown, especially at bands of NH and OH groups, which is evidence for the H-bonding interaction of these group with MgO molecules.…”

Copper Nanoparticles Stabilized in a Porous Chitosan Aerogel as a Heterogeneous Catalyst for C−S Cross‐coupling

“…In addition, chitin, from which chitosan is extracted, is the most abundant waste residue in the fishery industry. Chitosan has proven its efficiency for metal ion removal from polluted media and as an insoluble support for transition‐metal complexes and active noble MNPs …”