Toward a Green SPPS: The Use of an Innovative Mesoporous pDVB Support for Environmentally Friendly Solvents.

This study explores the use of a novel polymeric mesoporous support (pDVB) for solid-phase peptide synthesis (SPPS), with the aim of improving the efficiency and sustainability of the process. The pDVB support, functionalized with the Fmoc-Rink amide linker, offers advantages over conventional supports based on gel-type, lightly crosslinked polymer skeletons, particularly with regard to reduced reliance on swelling capacity, which allows the use of a wider range of solvents. The work focuses on greener and eco-friendly solvents such as TEP, ACN, IPA, and their mixtures with DMSO to replace toxic solvents such as DMF.

Structural Rearrangement Followed by Entrapment of Subnanometer Building Blocks of Iron Oxyhydroxide in Aqueous Iron Chloride Solutions.

Iron oxyhydroxide, a natural nanophase of iron found in the environment, plays a crucial role in regulating surface and groundwater composition. Recent research proposes that within the nonclassical prenucleation cluster growth model, subnanometer-sized clusters (olation clusters/Fe δ-Keggin oxolation clusters) might act as the prenucleation clusters (PNCs) of ferrihydrite or iron oxyhydroxide solid phase. However, these clusters are difficult to characterize as they are only observable momentarily in low-pH, high-Fe concentration solutions before agglomerating into extended solids, keeping the controversy over the true nature of the PNCs alive.

Synthesis of Ion-Exchange Catalysts by Introduction of Fluorinated Ponytails into Novel Mesoporous Polymers.

A novel synthetic procedure for the functionalisation of styrenic cross-linked polymers with perfluorinated acyl chains has been reported. The effective significant grafting of the fluorinated moieties is supported by {H}-C and {F}-C NMR characterisations. This kind of polymer appears promising as catalytic support for a variety of reactions requiring a highly lipophilic catalyst.

Cross-Linked Polymers as Scaffolds for the Low-Temperature Preparation of Nanostructured Metal Oxides.

The current state of the art of the use of cross-linked organic polymers, both insoluble (resins or gels) and soluble (micro- and nanogels), as aids for the low-temperature preparation of stable metal oxide nanoparticles or nanostructured metal oxides is reviewed herein. Synthetic strategies for inorganic oxide nanomaterials of this kind can greatly benefit from the use of cross-linked polymers, which may act as scaffolds/exotemplates during inorganic nanoparticle synthesis, or as stabilizers following post-synthetic modification of the nanoparticles. Furthermore, the peculiar properties of the organic cross-linked polymers add to those of the inorganic oxide nanoparticles, producing materials with combined properties.

Effect of the Sulfonation on the Swollen State Morphology of Styrenic Cross-Linked Polymers.

The chemical structure and morphology of a set of sulfonic gel-type poly(styrene-divinylbenzene) resins (2 mol% DVB) prepared with different synthetic approaches were investigated by solid state NMR, Inverse Size Exclusion Chromatography (ISEC), FT-IR and elemental analysis to compare their swollen state structure. FT-IR and solid state NMR clearly show that the sulfonation mainly occurs in the para- position with respect the main polymer chain. Sensible proportions of sulfone bridges were found in the materials obtained with oleum and chlorosulfonic acid.

Pd Metal Catalysts for Cross-Couplings and Related Reactions in the 21st Century: A Critical Review.

Cross-couplings and related reactions are a class of highly efficient synthetic protocols that are generally promoted by molecular Pd species as catalysts. However, catalysts based on more or less highly dispersed Pd metal have been also employed for this purpose, and their use, which was largely limited to the Heck reaction until the turn of the century, has been extended in recent years to most reactions of this class. This review provides a critical overview on these recent applications of Pd metal catalysts.

Synthesis of nanocomposites from Pd(0) and a hyper-cross-linked functional resin obtained from a conventional gel-type precursor.

Hyper-cross-linked resins stemming from a gel-type poly-chloromethylated poly(styrene-co-divinylbenzene) resin (GT) have been investigated by a multi-methodological approach based on elemental analysis, scanning electron microscopy, X-ray microanalysis, and solvent absorption. The hyper-cross-linking of the parent resin was accomplished by Friedel-Crafts alkylation of the phenyl rings of the resins with the chloromethyl groups. This produced a permanent pore system comprising both micropores (<2.

Highly hydrophilic copolymers of N,N-dimethylacrylamide, acrylamido-2-methylpropanesulfonic acid, and ethylenedimethacrylate: nanoscale morphology in the swollen state and use as exotemplates for synthesis of nanostructured ferric oxide.

The polymer framework of water-swollen copolymers of N,N-dimethylacrylamide, acrylamido-2-methylpropanesulfonic acid, and ethylenedimethacrylate (nominal cross-linking degrees of 4, 8, and 20 mol %) is composed of highly expanded domains, with "pores" not less than 6 nm in diameter. When the 4% cross-linked copolymer (DAE 26-4) is swollen with a 10(-4) M solution of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) in water, MeOH, EtOH, or nBuOH, the molecules of the paramagnetic probe rotate rapidly (τ<1000 ps) and as fast as in the bulk liquid in the case of water. The swelling degree of DAE 26-4 is related to the Hansen solubility parameters of a number of liquids, including linear alcohols up to n-octanol.

Characterisation of solute mobility in hypercross-linked resins in solvents of different polarity: two promising supports for catalysis.

Two hypercross-linked resins stemming from a gel-type poly-chloromethylated styrene-divinylbenzene resin (GT) in beaded form are investigated with a combination of spectroscopic techniques (EPR and time-domain (TD)-NMR spectroscopy) to evaluate their use as supports for the development of operationally flexible heterogeneous metal catalysts, suitable to be employed in liquid and gas phase. The first resin (HGT) is the direct product of the hypercross-linking reaction, whereas the second one (HGS) is the sulphonated analogue of HGT obtained by exchanging approximately 3 wt % of the chloromethyl groups with sulphonic groups. HGT and HGS absorb both polar and apolar solvents in the permanent nanoporosity created by the hypercross-linking, and NMR data highlight that the pore size is not affected by the different properties of the investigated liquid media.

Synthesis and catalytic activity of metal nanoclusters inside functional resins: an endeavour lasting 15 years.

Cross-linked functional polymers (functional resins) are versatile, designable and useful supports for metal nanoclusters that are able to provide reasonably thermally and mechanically stable multi-functional metal catalysts characterized by good activity and selectivity. The paper reviews authors' contributions to the field from the early 1990s to the present.