Lipase-catalyzed resolution of anti-substituted 1,3-dioxepan-5-ols

Several anti-6-substituted 1,3-dioxepan-5-ols were kinetically resolved using an immobilized lipase (Amano PS–C II) in toluene in the presence of vinyl acetate at 30 C. This approach provided, in some cases, the alcohol and the acetate in high enantiomeric purity, depending on the nature of the substituent (R = N3, SePh, I, OBn) and the acetal group (unsubstituted or dimethyl). The role of the size of substituents is also discussed. Enantiopure anti-6-substituted 1,3-dioxepan-5-ols are useful building blocks.

Cyclodextrins: Heterocyclic molecules able to perform chiral recognition (part i)

Photostability assessment of natural pyrethrins using halloysite nanotube carrier system

Natural pyrethrins are one of the most used pesticides and insect repellents employed for domestic or agronomic use. However, they are highly hydrophobic and suffer from insolubility in water media and ready decomposition by photochemical, and oxidative actions. These aspects hamper their long-term storage and applicability. Herein, we report the synthesis and characterization of a nanomaterial based on the loading of pyrethrum extract (PE) into natural, low-cost, and eco-compatible halloysite nanotubes (Hal). The Hal/PE nanomaterial was thoroughly characterized, and the morphology was imaged by TEM and SEM investigations. Release experiments showed a slow release of pyrethrins from the car…

Covalently Modified Halloysite Clay Nanotubes: Smart Nanomaterials for Drug Delivery Applications

Halloysite nanoclays (HNTs) are promising nanomaterials because of their versatile properties, such as hollow tubular morphology and tunable surface chemistry. HNTs are biocompatible, no toxic and abundantly available at low cost. Due to these characteristics HNTs are suitable for development of hybrid sustainable materials, which are perspective for polymeric matrices reinforcement, active food packaging and drug delivery. HNTs are quite polydisperse in size with a length of ca. 1 m, while the external diameter and the lumen range between 50-80 nm and 10-15 nm, respectively. Chemically, halloysite is composed of gibbsite octahedral sheet (Al-OH) groups on the inner surface and siloxane (S…