Functionalization of Cyclodextrins with N-Hydroxyphthalimide Moiety: A New Class of Supramolecular Pro-Oxidant Organocatalysts

N-hydroxyphthalimide (NHPI) is an organocatalyst for free-radical processes able to promote the aerobic oxidation of a wide range of organic substrates. In particular, NHPI can catalyze the hydroperoxidation of polyunsaturated fatty acids (PUFA). This property could be of interest for biological applications. This work reports the synthesis of two β-cyclodextrin derivatives (CD5 and CD6) having a different degree of methylation and bearing a NHPI moiety. These compounds, having different solubility in water, have been successfully tested for the hydroperoxidation of methyl linoleate, chosen as the PUFA model molecule

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

Following an optimized multicomponent procedure, an aryl amine, a ketone, and a cyclic ether or an alcohol molecule are assembled in a one-pot synthesis by nucleophilic radical addition of ketyl radicals to ketimines generated in situ. The reaction occurs under mild conditions by mediation of the TiCl4/Zn/t-BuOOH system, leading to the formation of quaternary β-amino-ethers and -alcohols. The new reaction conditions guarantee good selectivity by preventing the formation of secondary products. The secondary products are possibly derived from a competitive domino reaction, which involves further oxidation of the ketyl radicals

Adsorbent sponges from TEMPO-oxidized cellulose cross-linked with branched-PEI for water remediation

A new class of cellular solids with macro and micro porosity have been synthesized by the combination of cellulose nanofibers from TEMPO-NaClO mediated oxidation (TOCNF) [1] and branched polyethyleneimine, via formation of amide-bonds (TOCNF-bPEI copolymer). The sponge-like materials obtained in this way have chelating amino groups as basic sites in the nano-porous structure, showing high performances in removing heavy metal ions and phenolic pollutants from contaminated water

Nanostructured Cellulose-Based Sorbent Materials for Water Decontamination from Organic Dyes

Nanostructured materials have been recently proposed in the field of environmental remediation. The use of nanomaterials as building blocks for the design of nano-porous micro-dimensional systems is particularly promising since it can overcome the (eco-)toxicological risks associated with the use of nano-sized technologies. Following this approach, we report here the application of a nanostructured cellulose-based material as sorbent for effective removal of organic dyes from water. It consists of a micro- and nano-porous sponge-like system derived by thermal cross-linking among (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF), branched polyethylenimine 25 kDa (bPEI), and citric acid (CA). The sorbent efficiency was tested for four different organic dyes commonly used for fabric printing (Naphthol Blue Black, Orange II Sodium Salt, Brilliant Blue R, Cibacron Brilliant Yellow), by conducting both thermodynamic and kinetic studies. The material performance was compared with that of an activated carbon, commonly used for this application, in order to highlight the potentialities and limits of this biomass-based new material. The possibility of regeneration and reuse of the sorbent was also investigated

TEMPO-Oxidized Cellulose Cross-Linked with Branched Polyethyleneimine: Nanostructured Adsorbent Sponges for Water Remediation

Adsorbent sponges for water remediation were prepared using TEMPO-oxidized cellulose nanofibers (TOCNFs) as three-dimensional scaffolds, and branched polyethyleneimine (bPEI, 25 KDa) as the cross-linking agent. TOCNFs were suspended in aqueous solution in the presence of variable amounts of bPEI. The mixtures were first freeze-dried and then thermally treated (from 60 to 102 °C over 10 h) promoting the formation of amide bonds between the carboxylic groups of TOCNF and the primary amines of bPEI. The resulting materials, which were characterized by FTIR and 13C CP-MAS NMR spectroscopy, scanning electron microscopy, and elemental analysis, showed higher chemical and mechanical stability in water than non-reticulated cellulose composites. The high adsorption capability of the new sponges was verified for different organic pollutants (p-nitrophenol, 2,4,5-trichlorophenol, and amoxicillin), and heavy metal ion pollutants (Cu, Co, Ni, Cd), indicating their potential for water decontamination