Surface functionalization of cellulose with poly(3-hexylthiophene) via novel oxidative polymerization.

Surface functionalization of cellulose with poly(3-hexylthiophene) (P3HT) was conducted with FeCl3 as an oxidant in three different solvents: acetonitrile, chloroform, and hexane. Of these three solvents, hexane best promoted the grafting P3HT to cellulose with a high grafting ratio and molecular weight. The maxima of the UV-vis absorption and fluorescent spectra, observed at around 500 and 600nm, respectively, represented the build-up of the conjugated chain length formed by the grafting of P3HT onto the cellulose surface. The HOMO level of cellulose as determined by photoemission yield spectroscopy decreased from 4.83 to 4.67eV after modification with P3HT. Grafting P3HT onto the surface of cellulose provided super-hydrophobic property with a lotus effect. The conductivity of cellulose also improved significantly, from 10-9 to 10-6S/cm when P3HT was present on the surface. The thermal stability and crystallinity of cellulose decreased slightly upon graft polymerization with P3HT.

Fluorescence control of chitin and chitosan fabricated via surface functionalization using direct oxidative polymerization.

The copolymer of 3-hexylthiophene (3HT) and fluorene (F) was directly grafted onto chitin and chitosan using FeCl3 as an oxidant. The properties of the grafted chitin/chitosan were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-Vis spectroscopy, fluorescence spectroscopy, X-ray diffraction analysis, thermogravimetric analysis (TGA), transmission electron microscopy-energy dispersive X-ray spectroscopy, and quantum yield measurements. The UV-Vis absorption peaks of the chitin/chitosan grafted with 3-hexylthiophene and fluorene copolymer were increasingly blue-shifted upon increasing the fluorene content and the red-shifted emission of the grafted chitin/chitosan were controlled by varying the monomers feed of the 3HT/F units. The hypsochromic and bathochromic shifts of chitin/chitosan were ascribed to the (3HT/F) moieties grafted to their surface. The quantum yield of grafted chitin/chitosan increased upon increasing the fluorene content. The TGA and XRD analysis revealed that the thermal stability and crystallinity of chitin/chitosan decreased upon grafting the copolymer of fluorene and 3-hexylthiophene. This article represents a simple route towards the surface modification of chitin and chitosan using conducting copolymers, providing multicolor chitin and chitosan via a one-step reaction.

Photoluminescence Control of Cellulose via Surface Functionalization Using Oxidative Polymerization.

Control of the photoluminescence properties of cellulose is conducted by introduction of conducting polymers including fluorene (F) and 3-hexylthiophene (3HT) on cellulose surface through FeCl3 oxidative polymerization. The UV-vis absorption peak of cellulose grafted with the 3-hexylthiophene and fluorene copolymer was increasingly blue-shifted with increasing fluorene content and the shift in the peak position in photoluminescence spectra depend on the initial 3HT:F ratio of the copolymer. The crystallinity and thermal stability of cellulose decreased slightly upon graft polymerization with PF and P3HT, while the quantum yield, determined using absolute methods, increased from 3.1 to 9.7% with increasing fluorene content. The roles of the 3HT and F copolymers in improving the properties of cellulose were thoroughly studied by FT-IR, UV-vis, fluorescence, X-ray diffraction (XRD), thermogravimetric (TG), transmission electron microscopy-energy dispersive X-ray (TEM-EDX), and quantum yield measurements. Mechanistic insight into the grafting reaction is also provided.

Revisiting dimerization of acetoacetamide leading to 4,6-dimethyl-2-pyridone-5-carboxamide.

A commercially purchased acetoacetamide was found to dimerize during storage for several months to afford 4,6-dimethyl-2-pyridone-5-carboxamide. We successfully achieved the quantitative dimerization of acetoacetamide by using an acid catalyst. It was also found that the pyridone formed served as a self-catalyst of the dimerization.

Enantiopure O-ethyl phenylphosphonothioic acid: a solvating agent for the determination of enantiomeric excesses.

An improved method, which is highly reproducible, was developed for the enantioseparation of racemic O-ethyl phenylphosphonothioic acid (1a) with brucine by introducing seeding to a supersaturated solution of the diastereomeric salt mixture. The present method gave both diastereomeric salts in high yields with a diastereomeric ratio of >99.5:0.5 upon choosing the crystallization solvent (MeOH for the (R)-1a salt and MeOH/H2 O for the (S)-1a salt). The enantiopure acid showed a good chirality recognition ability for not only strong bases, such as amines and amino alcohols, but also weakly basic alcohols and was applicable as a solvating agent to the (1) H NMR determination of the enantiomeric excess of chiral amines, amino alcohols, and alcohols, including aliphatic substrates.