Preparation and Characterization of Chitosan-Blended Multiwalled Carbon Nanotubes

Composites comprised of chitosan (CS) and multiwalled carbon nanotubes (MWCNTs) were fabricated by milling and ultrasonication dispersion methods. Scanning electron microscopy images showed homogeneous dispersion of MWCNTs throughout the CS matrix for samples prepared by either ultrasonication or milling methods. Further, the crystallinity of the CS component was found to decrease with the addition of MWCNTs, although the decomposition temperature and the storage modulus (E′) of the samples were improved. The decomposition temperature for the composite prepared by milling was 7°C higher than that by the ultrasonication. Meanwhile, the E′ decreased relatively slowly with temperature in the dynamic mechanical analysis measurements. In addition, IR analysis implied an interaction between CS and MWCNTs, which likely originated from hydrogen bonds between the amino, hydroxyl, and carboxyl groups of the two components. Compared with the ultrasonication, milling was more effective to promote the formation of the hydrogen bonds between CS and the MWCNTs and thus enhance the thermal stability of CS.     

Preparative access to medicinal chemistry related chiral alcohols using carbonyl reductase technology

Libraries of highly enantioenriched secondary alcohols in both enantiomeric forms were synthesised by enzymatic reduction of their parent ketones using selectAZyme? carbonyl reductase (CRED) technology. Commercially available CREDs were able to reduce a range of substrate classes efficiently and with very high enantioselectivity. Matching substrate classes to small subsets of CREDs enabled the fast development of preparative bioreductions and the rapid generation of 100–1500 mg samples of chiral alcohols in typically >95% ee and the majority in ?99.0% ee. The conditions for small scale synthesis were then scaled up to 0.5 kg to deliver one of the chiral alcohols, (S)-1-(4-bromophenyl)-2-chloroethanol, in 99.8% ee and 91% isolated yield.     

Synthesis of peptide dendrimers with polyhedral oligomeric silsesquioxane cores via click chemistry

Inorganic polyhedral oligomeric silsesquioxane (POSS) was used as the core for the synthesis of poly(Llysine) peptide dendrimer via copper-catalyzed azide-alkyne click chemistry. The inorganic/organic composite dendrimer was characterized by MS, 1H NMR, FTIR, GPC and DLS.     

Hexagonal columnar mesophases of polycatenar para-phenylene connected bis-oxadiazole-based liquid crystals

In this article polycatenar liquid crystals containing two 1,3,4-oxadiazoles interconnected by a para-substituted benzene ring as the central linking unit and three alkoxy chains at each terminal have been synthesised, and investigated by polarising microscopy, DSC and XRD scattering. Molecules with medium chain length form exclusively hexagonal columnar liquid crystalline phases.     

Studies on Carbohydrates X. A New Method for the Preparation of Isopropylidene Saccharides

Cabohydrates reacting with acetone in the presence of molecular sieve and p—toluene sulfonic acid provided a simple, convenient, high yield and good selective process for preparation of isopropylidene carbohydrates.     

Synthesis of the melatonin receptor agonist Ramelteon using a tandem C–H activation–alkylation/Heck reaction and subsequent asymmetric Michael addition

An asymmetric synthesis of the melatonin receptor agonist Ramelteon 1 has been achieved, which involved a tandem C–H activation–alkylation/Heck reaction and subsequent highly diastereoselective asymmetric Michael addition to generate the corresponding chiral intermediate, which was readily converted into Ramelteon 1 in 19% overall yield in 15 linear steps.