Covalently immobilized porphyrins as photooxidation catalysts

Porphyrins covalently linked to aminomethylated Merrifield polymers, by chlorosulfonation activation of the porphyrin nucleus, are able to generate singlet oxygen with an efficiency which is related to the spacer between porphyrin and the polymer backbone. Juglone and ascaridole are efficiently produced in the presence of these supported catalysts.http://www.sciencedirect.com/science/article/B6THR-4NTRT0M-7/1/c9bc37705a3639162941e23c9c85343

Silica grafted polyethylenimine as heterogeneous catalyst for condensation reactions

Primary amine groups were attached to a silica surface by using α,ω-diamines derivatives and (3-glycidyloxypropyl)-trimethoxysilane activation. The same activation was used to graft polyethylenimine, which also contains secondary and tertiary amine groups. These silica aminated structures were tested as heterogeneous catalysts in nitroaldol condensation with nitromethane, the derivative with the polyethylenimine moiety being the more active catalyst. This catalyst also showed efficiency in the Knoevenagel condensation of benzaldehydes with ethyl cyanoacetate under very mild reaction conditions and showed much the same efficiency when used in consecutive reaction runs. A reaction mechanism with participation of the several amine groups of the catalysts is discussed

Cymbeline

Quite high count of congestions between scenes, but most of them minimal or minimised

Low temperature matrix-isolation and solid state vibrational spectra of 5-chlorotetrazole

The vibrational spectra of 5-chlorotetrazole (CN4HCl) isolated in an argon matrix (T ¼ 8.5 K) and in the solid state (at room temperature) were studied. The infrared spectrum of monomers of 5-chlorotetrazole isolated in an argon matrix agrees well with the spectrum predicted theoretically (DFT(B3LYP)/6-31G*) for the 2Htautomer of the compound. The bands assigned to the 1H-tautomer appear in the experimental spectrum as very low intensity features. Based on the relative intensities of the bands in the spectra of the 1H- and 2Htautomers, the relative amount of the first tautomer in this matrix can be estimated as 1%. Three matrixes were deposited with different nozzle temperatures and the enthalpy difference between the tautomers DH ¼ 8.0 kJ mol 1 was estimated using the Van’t Hoff relation. The internal energy difference between the two tautomers was predicted theoretically (DFT B3LYP/6-31G*) as 12.6 kJ mol 1. This is in reasonable agreement with experimental observations. In the crystalline phase, this compound exists in its 1H-tautomeric form. Accordingly, the IR spectrum of polycrystalline 5-chlorotetrazole is well reproduced by the spectrum predicted theoretically for the 1H- tautomer

Influence of feeding regimens on rat gut fluids and colonic metabolism of diclofenac-β-cyclodextrin

Feeding states may affect the performance of colonic prodrugs. The aim is to investigate the influence of feeding regimen in Wistar rats on: (i) distribution and pH contents along the gut and (ii) metabolism of two colonic prodrugs, diclofenac-β-cyclodextrin and a commercially available control, sulfasalazine, within the caecal and colonic contents. Male Wistar rats were subject to four different feeding regimens, the gut contents characterized (mass and pH) and the metabolism of prodrugs investigated. The feeding regimen affects gut contents (mass and pH), more specifically in the stomach and lower intestine, and affects the rate of metabolism of diclofenac-β-cyclodextrin, but not that of sulfasalazine. The latter's degradation is much faster than that of diclofenac-β-cyclodextrin while the metabolism of both prodrugs is faster in colonic (versus caecal) contents. Fasting results in most rapid degradation of diclofenac-β-cyclodextrin, possibly due to lack of competition (absence of food) for microbial enzymatic activity

Immobilised porphyrins in monoterpene photooxidations

Porphyrins were covalently linked to modified Merrifield polymers by chlorosulphonation activation of the porphyrin nucleus. These supported porphyrins were used as photosensitizers to promote singlet oxygen oxidation of monoterpenes with an efficiency that depends on porphyrin structure and the spacer used to link it to the polymer structure. The performance of these photosensitizers was studied. Citronellol and [alpha]-terpinene gave the expected singlet oxygen ene addition products. [alpha]-Pinene and [beta]-pinene also gave products from non-ene reactions, which is explained by the existence of an alternative radical pathway.http://www.sciencedirect.com/science/article/B6WHJ-4SG556B-1/1/0455044852b08c2b9832fda1d111135

Covalently immobilized porphyrins as photooxidation catalysts

Porphyrins covalently linked to aminomethylated Merrifield polymers, by chlorosulfonation activation of the porphyrin nucleus, are able to generate singlet oxygen with an efficiency which is related to the spacer between porphyrin and the polymer backbone. Juglone and ascaridole are efficiently produced in the presence of these supported catalysts.http://www.sciencedirect.com/science/article/B6THR-4NTRT0M-7/1/c9bc37705a3639162941e23c9c85343

Immobilised porphyrins in monoterpene photooxidations

Porphyrins were covalently linked to modified Merrifield polymers by chlorosulphonation activation of the porphyrin nucleus. These supported porphyrins were used as photosensitizers to promote singlet oxygen oxidation of monoterpenes with an efficiency that depends on porphyrin structure and the spacer used to link it to the polymer structure. The performance of these photosensitizers was studied. Citronellol and α-terpinene gave the expected singlet oxygen ene addition products. α-Pinene and β-pinene also gave products from non-ene reactions, which is explained by the existence of an alternative radical pathway

Glycopolymer Brushes by Reversible Deactivation Radical Polymerization: Preparation, Applications, and Future Challenges

The cellular surface contains specific proteins, also known as lectins, that are carbohydrates receptors involved in different biological events, such as cell-cell adhesion, cell recognition and cell differentiation. The synthesis of well-defined polymers containing carbohydrate units, known as glycopolymers, by reversible deactivation radical polymerization (RDRP) methods allows the development of tailor-made materials with high affinity for lectins because of their multivalent interaction. These polymers are promising candidates for the biomedical field, namely as novel diagnostic disease markers, biosensors, or carriers for tumor-targeted therapy. Although linear glycopolymers are extensively studied for lectin recognition, branched glycopolymeric structures, such as polymer brushes can establish stronger interactions with lectins. This specific glycopolymer topology can be synthesized in a bottlebrush form or grafted to/from surfaces by using RDRP methods, allowing a precise control over molecular weight, grafting density, and brush thickness. Here, the preparation and application of glycopolymer brushes is critically discussed and future research directions on this topic are suggested

The Impact of the Addition of Compatibilizers on Poly (lactic acid) (PLA) Properties after Extrusion Process

Poly (lactic acid) (PLA), due to its biodegradability, biocompatibility, and renewability, is one of the most promising biobased polymers for replacing some of the petrol-based materials. Low flexibility of PLA is overcome, by blending it with olefin-based polymers, such as polypropylene (PP). However, the use of compatibilizing agents is required to attain final materials with suitable mechanical properties. Such agents, although essential, can affect PLA structure and, consequently, the mechanical properties of the PLA. To the best of our knowledge, this issue was never studied, and the results can contribute to achieving the best formulations of PLA-based blends according to their final applications. The thermal and mechanical properties of the extruded PLA, with three different commercial compatibilizing agents, were evaluated with the purpose of demonstrating how the compatibilizers can introduce structural differences into the PLA chain during the extrusion process. The combination of crystallinity, molecular weight, and the morphology of the samples after extrusion determines the final mechanical properties of PLA. Despite being a fundamental study, it is our aim to contribute to the sustainability of PLA-based industries. The addition of a 2.5% concentration of C1 compatibilizer seems to have less influence on the final morphology and mechanical properties of the blends