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The first chemical synthesis of cellulose derivatives, (1→4)-β-D-glucopyranan derivatives has been accomplished by cationic ring-opening polymerization using 3,6-di-O-benzyl-α-D)-glucopyranose 1,2,4-orthopivalate (1) as a starting monomer, taking into account substituent effects.' Here, three orthoester derivatives as starting materials for the polymerization, 3,6-di-O-benzyl-α-D-glucopyranose 1,2,4-orthopropionate (2), 3,6-di-O-benzyl-α-D-glucopyranose 1,2,4-orthoacetate (3), and 3,6-di-O-benzyl-α-D-glucopyranose 1,2,4-orthobenzoate (4), were selected to investigate the substituent effects of orthoester group on the ring-opening polymerization. These three monomers were polymerized under the same reaction conditions as those of monomer 1, yielding stereoregular (1→4)-β-D-glucopyranan derivatives, previously reported. As the result, monomers 2-4 gave non-regioregular polymers consisting of (1→4)-and (1→2)-β-pyranose units, although they gave high stereoregularity, i.e., β-glucosidic linkage. Thus, it was concluded from the polymerizations of the monomers 1-4 that the orthopivaloyl group of the starting monomer is indispensable for regiospecificity of the polymerization, yielding only the (1-4)-glycosidic bond, not the (1→2)-bond.

A new synthetic method for the preparation of high molecular mass (the highest ; 10 200) condensed tannin has been developed. Polymerization of 3′,4′,5,7-tetrabenzyloxyflavan 3,4-carbonate 2 and subsequent debenzylation gives a condensed tannin having high molecular mass. Molecular mass of the synthetic tannin increases up to a degree of polymerization () of ∼35 with an increase in the reaction time. This high molecular mass condensed tannin, synthesized for the first time, is useful as a model compound for natural condensed tannins with high molecular mass, such as that from Japanese persimmon (Diospyros kaki L.) fruit.

Two homologous series of regio- selectively sub stituted cellulose: 3-O-benzyl-2, 6-di-O-pivaloyl derivatives (Series 1) and 2,3,6-tri-O-acetyl derivatives (Series 2) up to an eicosamer (DP = 20), were synthesized for the first time by elongation of the carbohydrate chain from cellooctaose derivative 5 and subsequent deprotection. Some changing properties of the homologous series with increasing DP were examined. Gel permeation chromatography (GPC) analysis for series 1 and 2 indicated that plots of log M vs retention time gave a straight line. The plots of [M]n/n vs (n − 1)/n (where [M]n is the molecular rotation for an oligomer with DP = n) up to a hexadecamer 9 in series 2 gave straight lines, although the result for the eicosamer 11 deviated somewhat from the line

In contrast to the success in artificial DNA- and peptide-based nanostructures, the ability of polysaccharides to self-assemble into one-, two-, and three-dimensional nanostructures are limited. Here, we describe a strategy for designing and fabricating nanorods using a regioselectively functionalized cellulose derivative at the air–water interface in a stepwise manner. A semisynthetic chlorophyll derivative, pyro-pheophorbide a, was partially introduced into the C-6 position of the cellulose backbone for the design of materials with specific optical properties. Remarkably, controlled formation of cellulose nanorods can be achieved, producing light-harvesting nanorods that display a larger bathochromic shift than their solution counterparts. The results presented here demonstrate that the self-assembly of functionalized polysaccharides on surfaces could lead the nanostructures mimicking the naturally occurring chloroplasts.

O-Benzylation of phloroglucinol, which was difficult due to C-benzylation, was successfully carried out by a method using phloroglucinol triacetate as an intermediate.

To investigate the substituent effects at the 3-O and 6-O positions on ring-opening polymerization, 3,6-di-O-benzyl-α-d-glucopyranose 1,2,4-orthopivalate (1), 3-O-benzyl-6-O-pivaloyl-α-d-glucopyranose 1,2,4-orthopivalate (2), 6-O-benzyl-3-O-pivaloyl-α-d-glucopyranose 1,2,4-orthopivalate (3), and 3,6-di-O-pivaloyl-α-d-glucopyranose 1,2,4-orthopivalate (4) were selected as starting monomers and were polymerized under various reaction conditions. It was concluded from the results of monomer 1 reported previously and from those of monomers 2−4 in our present study that the benzyl group at the 3-O position is indispensable for yielding stereoregular (1→4)-β-d-glucopyranan derivatives, i.e., cellulose derivatives. The mechanisms of ring-opening polymerizations are discussed.

Cellulose, (1→4)-β-d-glucopyranan, was for the first time synthesized by cationic ring-opening polymerization of 3,6-di-O-benzyl-α-d-glucose 1,2,4-orthopivalate (5) into 3,6-di-O-benzyl-2-O-pivaloyl-β-d-glucopyranan (6) and subsequent removal of the protective groups. Polymerization of the orthoester 5 by triphenyl carbenium tetrafluoroborate gave 3,6-di-O-benzyl-2-O-pivaloyl-β-d-glucopyranan with [α]D −37.2° and a number-average molecular weight of 8.3 × 103 ( = 19.3). Removal of the pivaloyl and benzyl groups and subsequent acetylation gave acetylated (1→4)-β-d-glucopyranan which was completely identical with cellulose triacetate (CTA) prepared from low molecular weight cellulose. The synthesized CTA was converted by deacetylation to cellulose, which has the cellulose-II crystal structure.

Methyl 4-O-ethyl-β-D-glucopyranoside was used as a model for cellulose and treated with ozone in distilled water (pH 5.7). Reaction products were analyzed by gas chromatography. The major degradation products were methyl β-D-glucoside and 4-O-ethyl-D-gluconic acid. The minor products were gluconic acid, methyl 4-O-ethyl-glucuronoside, methyl glucuronoside, methyl 4-O-ethyl-2-keto-glucoside, methyl 4-O-ethyl-3-keto-glucoside, methyl 4-O-ethyl-6-aldehyde-glucoside, methyl 6-aldehyde-glucoside, 4-O-ethyl-glucose, glucose, and 3-O-ethyl-arabinose. The oxidation of ring carbons at C4-or C5-positions has little participation in degradation of the glucoside by ozone. The formation of the reaction products could be explained by the insertion of ozone or the radical attack at the carbon-hydrogen bonds in the model compound. The order of relative reactivities of carbons (Cl-C6) of the glucoside toward ozone in distilled water at room temperature was found to be as the following from quantitative analysis of the reaction products : Cl (acetal) >C6 (primary alcohol) >C2. C3 (secondary alcohols) >C4, C5 (ethers). Inhibition of these undesirable reactions is one of the key to the prevention of the viscosity drop in ozone bleaching of kraft pulp.

To investigate the substituent effects at the 2-O, 6-O, and 3-O positions on ring-opening polymerization, 1,4-anhydro-2,3-di-O-benzyl-6-O-pivaloyl-α-d-glucopyranose (1), 1,4-anhydro-3,6-di-O-benzyl...

Methyl 4-O-ethyl-β-D-glucopyranoside (1) was prepared as a model compound for cellulose to investigate the reactions of ozone with polysaccharides during ozone bleaching of kraft pulp. The model compound was converted into authentic carbonyl sugars, methyl 3,6-di-O-acetyl-4-O-ethyl-β-D-arabino-hexopyranosidulose (2), methyl 2,6-di-O-acetyl-4-O-ethyl-β-D-ribo-hexopyranoside-3-ulose (3), methyl 2,3-di-O-acetyl-4-O-ethyl-β-D-gluco-hexodialdo-1,5-pyranoside (4). These carbonyl sugars were converted into O-methyloximes and analyzed by gas chromatography and mass spectrometry.

The N-hydroxyphthalimide (NHPI)-mediated indirect electro-oxidation of non-phenolic lignin model compounds has been investigated for selective Cα-carbonylation of lignin. A cyclic voltammogram of NHPI in 0.1 M LiClO4/CH3CN with 2,6-lutidine interpreted that NHPI can act as a mediator in the indicated process in the range 0.5–0.8 V vs. Ag/Ag+. The corresponding Cα-carbonyl compounds was obtained in high yields (85–97%) in the case of the monomer 1-(4-ethoxy-3-methoxyphenyl) ethanol in 0.1 M LiClO4/CH3CN or 0.1 M LiClO4/(CH3CN/H2O=7/3) with a small amount of 2,6-lutidine at 0.7 V vs. Ag/Ag+. The processing of the dimeric lignin model compound (4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether) also gave the corresponding Cα-carbonyl compound in high yield (88–92%). The reaction proceeds through hydrogen atom transfer in the NHPI-mediated electro-oxidation. On the other hand, the direct electro-oxidation and indirect electro-oxidation mediated by ABTS [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate)] of the dimeric compound preferentially gave the corresponding Cα-Cβ cleavage product in low or moderate yields (5–40%). The conclusion is that NHPI is an excellent mediator for selective Cα-carbonylation of non-phenolic β-O-4 structures in lignin in electronic mediator system.

The so-called γ-TTSA method has been developed for the cleavage of β-O-4 linkages in lignin. It consists of four steps: (1) γ-tosylation, (2) thioetherification (substitution reaction with 1-dodecanethiol to γ-thioether), (3) sulfonylation (oxidation from γ-thioether to γ-sulfone), and (4) mild alkali degradation of γ-sulfone. The method was tested on non-phenolic dimeric β-O-4 lignin model compounds: 1G (4-benzyloxy-3-methoxyphenylglycerol-β-guaiacyl ether), 1S (4-benzyloxy-3,5-dimethoxyphenylglycerol-β-syringyl ether), and 1H (4-benzyloxyphenylglycerol-β-phenyl ether). It is demonstrated that the mild alkali degradation of the γ-sulfone group proceeds efficiently, i.e., the electron-withdrawing sulfone group at γ-position contributes to the cleavage of β-O-4 linkages. The γ-TTSA method may be especially useful for the elucidation of lignin-carbohydrate complex structures containing benzylether bonds.

The influence of initiator, solvent, monomer concentration, and temperature on the ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-6-O-pivaloyl-α-D-glucopyranose (1) and 1,4-anhydro-3,6-di-O-benzyl-2-O-pivaloyl-α-D-glucopyranose (2) was investigated. Polymerization of 1 gave non-stereoregular polymers consisting of mainly (1→5)-α-glucofuranosidic units with an [α] D value of ca. +84°. Polymerization of 2 with PF 5 catalyst produced new stereoregular polysaccharide derivatives, 3,6-di-O-benzyl-2-O-pivaloyl-(1→5)-β-D-glucofuranans, with an [α] D value of ca.-66°. Debenzylation and depivaloylation of the substituted polymers afforded unsubstituted (1→5)-β-glucofuranan

Synthese d'-1-O-allyl-3-O-benzyl-2,4,6-tri-O-acetyl (ou 1-O-allyl-tetra-O-acetyl) glucopyranoside a partir d'3-O-benzyl-tetra-O-acetyl (ou per-O-acetyl) glucopyranose, d'ethyle ether-trifluoroborane et de prop-2-en-1-ol

O-Benzylation of phloroglucinol, which was difficult due to C-benzylation, was successfully carried out by a method using phloroglucinol triacetate as an intermediate.

In this chapter, we show how cello-oligosaccharide synthesis can play an important role on understanding physical properties of industrially produced cellulose derivatives. As one example, a synthetic strategy for cello-oligosaccharide derivatives related to methylcellulose (MC) is discussed in detail. The physical properties of MC are attributed to its block-like chemical structure. Thus, blockwise methylated cello-oligosaccharides were synthesized as models of the structural units of MC. An aqueous solution of the blockwise methylated cello-oligosaccharides showed higher surface activity than that of industrially produced MC. Namely, it was confirmed that the synthesized cello-oligosaccharide derivatives have surface activity superior to that of MC due to controlling the block structure of substituents along the molecular backbone. Furthermore, blockwise methylated cello-oligosaccharides self-assembled to form ellipsoidal nano particles in water. These new findings are of importance not only for the investigation on phase separation phenomenon of MC but also for the development of new applications of cello-oligosaccharide derivatives.

In order to synthesize ( 1 → 5)-β- d -galactofuranan by rig-opening polymerization, 3,6-di-O-benzyl-α- d -galactofuranose 1,2,5-orthopivalate (9) the most appropriate monomer was synthesized from d -galactose via 10 reaction steps. Novel intramolecular orthoesterification, which is a key reaction for sythesizing compound 9, was accomplished by treatment of 5-O-monocholoacetyl-2,3,6-tri-O-pivaloyl- d -galactofuranosyl chloride (6) with thiourea in pyridine at 80 °C to give the expected orthoester (7) in good yield without any side reactions.

Two novel methods for the syntheses of 1,4-anhydro-3- O -benzyl-2- O -pivaloyl- ( 1 ) and 2- O -acetyl-1,4-anhydro-3- O -benzyl- α - d -xylopyranose ( 2 ), starting materials for synthesizing stereoregular β -( 1 → 5)-xylofuranan by ring-opening polymerization are reported. Both synthetic routes start from d -xylopyranose, involve nine reaction steps, and give approximately 30–35% overall yields. The key reaction in the novel synthetic routes is the intramolecular nucleophilic attack of C-1 oxyanion on the C-5 position of 3- O -benzyl-5- O -( p -toluenesulfonyl)- α - d -xylofuranose ( 10 ), resulting in 1,5-acetal bond formation in high yield. The present synthetic routes enable us to prepare 1,4-anhydro- α - d -xylopyranose derivatives having different substituents at the 2- O - and the 3- O -positions.

Regioselectively ethylated celluloses, 2-O- (1), 3-O- (2), and 6-O-ethyl- (3) celluloses were synthesized via ring-opening polymerization of glucopyranose orthopivalate derivatives. The number-average degrees of polymerization (DP(n)s) of compounds 1 and 2 were calculated to be 10.6 and 49.4, respectively. Three kinds of compound 3 with different DP(n)s were prepared: DP(n)s = 12.9 (3-1), 60.3 (3-2), and 36.1 (3-3). The 2-O-, 3-O-, and 6-O-ethylcelluloses were soluble in water, confirmed by NMR analysis. Furthermore, the 3-O- (2), and 6-O-ethyl- (3-2) celluloses showed thermo-responsive aggregation behavior and had a lower critical solution temperature (LCST) at about 40 degrees C and 70 degrees C, respectively, based on the results from turbidity tests and DSC measurements. The 6-O-ethyl-cellulose (3-3) with DP(n) = 36.1 and DP(w) = 54.6 showed gelation behavior over approx 70 degrees C, whereas the 6-O-ethyl-celluloses 3-1 and 3-2 with lower and higher molecular weight, such as DP(n)s 12.9 and 60.3, did not show gelation behavior at this temperature. It was revealed that the position of ethyl group affected the phase transition temperature. According to our experiments, the 3-O-ethyl and 6-O-ethyl groups along the cellulose chains caused the thermo-responsive property of their aqueous solutions. The appropriate DP of the regioselective 6-O-ethyl-cellulose existed for gelation of the aqueous solution.

Horseradish peroxidase (HRP)-catalyzed dehydrogenative polymerization of guaiacyl (G) and syringyl (S)-type monolignol γ-O-glucosides, isoconiferin (iso-G) and isosyringin (iso-S), which contain a hydrophilic glucosyl unit on γ-position of coniferyl alcohol and sinapyl alcohol, respectively, was monitored by gel permeation chromatography coupled with photodiode array detection (GPC-PDA). Contrary to the conventional dehydrogenative polymerization of monolignols, the polymerization of the glycosides produces water-soluble synthetic lignins (DHPs) in a homogeneous aqueous phase. Taking advantage of this unique reaction system, the method was developed to follow the changes of molecular weights in the course of DHP formations. Moreover, PDA detection permits determination of oligomeric S-type quinone methide intermediates (QMs) formed as stable transient compounds during polymerization of iso-S. A detailed comparison of the polymerization profiles revealed entirely different behaviors of G- and S-type monomers. The data strongly support the view that the low reactivity of oligomeric S-type QMs impedes the formation of DHPs from S-type monomers. In copolymerization of G- and S-type monomers, it is conceivable that G-type phenolic hydroxyl groups serve as good nucleophilic reactants to scavenge S-type QMs resulting in efficient production of DHPs. As a consequence, the present approach can be a powerful tool to study the in vitro dehydrogenative polymerization providing further mechanistic insights into lignin polymerization in vivo.

The solvent pH effect in the horseradish peroxidase (HRP)-catalyzed polymerization of sinapyl alcohol (S-alc) and analogously, sinapyl alcohol γ-O-glucoside (isosyringin, iso-S) was investigated particularly focusing on the behavior of syringyl-type quinone methide intermediates (S-type QMs) under acidic conditions. At first, the HRP-catalyzed polymerization of iso-S at pH 6.5–2.5, which produces water-soluble dehydrogenation polymer (DHP) intermediates in a homogeneous phase, was monitored by UV spectroscopy and gel permeation chromatography with photodiode array detection (GPC-PDA). Under acidic conditions at pH below 4.5, unstablilized S-type QMs from iso-S are rapidly quenched resulting in efficient productions of DHPs, although substantial loss of HRP activity and the resulting insufficient polymerization were inevitable at pH below 3.5. In addition, it was found that a small addition of guaiacyl-type comonomer (isoconiferin, iso-G) effectively promotes the polymerization of iso-S under acidic conditions, in which the comonomer serves as a radical mediator to facilitate the HRP-catalyzed oxidations of iso-S. Next, the HRP-catalyzed polymerization of S-alc at various pH values was conducted and the resulting DHPs were characterized by GPC and NMR measurements. The yields of isolated DHPs significantly increased as solvent pH decreased below 4.5. The structural analyses of the DHPs demonstrated that reaction selectivity of S-type QMs during the polymerization drastically changed at pH below 4.5: they react efficiently with water molecules as solvent leading to the formation of benzyl alcohol type β-O-4 substructures preferentially to the formation of α-O-aryl type substructures. Consequently, the data in this study demonstrated that acidic conditions at pH below 4.5 are favored in the dehydrogenative polymerization of S-alc from the viewpoint of the reactivity of S-type QMs.

A series of condensed tannin derivatives with non-, mono-, di- and tri-hydroxylated B-rings were synthesized starting from phloroglucinol and benzaldehyde derivatives. The protein-precipitating capacity of these condensed tannin derivatives showed 1) A condensed tannin with only a 4′-hydroxylated B-ring has almost the same protein-precipitating capacity as that of a condensed tannin with 3′,4′-dihydroxylated or 3′,4′,5′-trihydroxylated B-rings. 2) The complexing ability of phenolic hydroxyl groups in the B-ring are effective in the order of p- > m- > o-positions.

Four regiospecifically methylated condensed tannin derivatives were synthesized by the condensation of regiospecifically methylated flavan-3, 4-diols protected by benzyl groups, and subsequent debenzylation. The monomeric flavan-3,4-diols were obtained via four reaction steps starting from phloroacetophenone derivatives and protocatechualdehyde derivatives. Protein—precipitating capacity of these synthetic condensed tannin derivatives was tested and a comparision of these capacity suggests the following results: 1) Phenolic hydroxyl groups in tannins are essential sites for protein precipitation. 2) Although the A-ring has been considered not to be important for tannin—protein interactions, it was proved that the A-ring also plays an important role together with the B-ring. 3) Both hydroxyl groups of A- and B-rings may synergistically interact with proteins.

The results of X-ray photoelectron spectroscopy (XPS) analyses indicated that palladium chloride was adsorbed on a plastic surface coated with a chitosan-containing paint (C-Paint), and was completely reduced to Pd(0) after reduction with dimethylamine-borane. To improve the stability and hardening properties of C-Paint, UV-curable chitosan derivatives, such as N -[3-methoxy-4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]methylated chitosan and N -(3-methoxy-4-methacryloyloxyphenyl)methylated chitosan, were synthesized. The derivatives showed better affinity for organic solvents. After UV irradiation for 20 s, an acidic solution of these derivatives was transformed to a gel, and the dried films exhibited good palladium(II) adsorption at pH 1.1.

A novel cellulose derivative, 6-O-dihydrophytylcellulose (DHPC), was first synthesized via a ring-opening polymerization and allowed to self-assemble onto an air-water interface. Langmuir-Blodgett (LB) films were characterized with atomic force microscope (AFM), UV-vis spectroscopy, and Fourier transform infrared spectroscopy. The surface pressure-area (pi-A) isotherms for DHPC and beta-carotene (betaC) mixture indicated strong interaction between these compounds to pack well. Thus, DHPC has the ability to anchor betaC in the monolayer. It was proved that a betaC-DHPC monolayer was transferred successfully onto a substrate, yielding Y-type LB films by UV spectroscopic analysis. The transmission and reflection-absorption IR spectra (RAS) indicated that the dihydrophytyl chains had almost trans-zigzag conformation and were oriented nearly perpendicular to the substrate. AFM section analysis revealed the thickness per layer to be 2.32 nm. Consequently, DHPC was found to be an appropriate matrix to fabricate the mixed LB films containing betaC.

UV-curable chitosans (UVCC-7-10) were synthesized using less-toxic agents. The UVCC-7 was completely cured by UV spot irradiation for 4 s. The UVCC-7 was implanted into murine subcutaneous tissues, and the response to the implantation was observed by histological examination at 7 days after implantation. In the histological findings, the implant was surrounded by thin fibrous granulating tissue with no inflammatory cellular infiltration. Fibroblasts infiltrate between the cured implant. The novel synthesized UVCC-7 showed good biocompatibility.

3- O -Benzyl-α- d -xylopyranose 1,2,4-orthopivalate ( 1 ) was newly synthesized and polymerized under cationic polymerization reaction conditions in order to synthesize stereoregular (1→4)-β- d -xylopyranan. Although the polymerization of orthopivalate 1 was carried out under various reaction conditions, a non-stereoregular polymer, but mainly consisting of (1→4)-β-xylopyranose units, was obtained. Comparing these results with those of glucose 1,2,4-orthopivalates, it was revealed that not only the substituents in the C-2 and C-3 positions, but also the CH 2 OR group in glucose 1,2,4-orthopivalate, largely contribute to (1→4)-β-glucosidic bond formation by the ring-opening polymerization.

Analysis of insoluble complexes between tetragalloylglucose and proteins following a series of successive washes with buffer indicated (1) heterogeneity of binding between galloylglucose and protein and (2) irreversible denaturation of protein during interaction with galloylglucose. Relatively large amounts of tetragalloylglucose were removed by initial washes, indicating weak, low affinity binding, whereas smaller amounts removed by subsequent washes suggest bonds with a higher affinity. Although the maximum number of bindings sites, calculated per 10,000 M(r) of protein, was similar for BSA, myoglobin and lysozyme, the proportion of these sites that appeared to have high affinity, varied from 8 to 29%. The low proportion of strongly binding sites in lysozyme explains its relatively low tannin-complexing ability. Solubility decrease in protein during successive washing and decrease in the beta-glucosidase activity indicate that irreversible denaturation of protein occurs, which progresses with an increase in the incubation time with galloylglucose and galloylglucose/protein molar ratio in the mixture. Relative affinity of galloylglucose is directly related to the ability to cause irreversible denaturation.

The first chemical synthesis of cellooctaose by a convergent synthetic method is described. A challenging glycosylation between cellotetraosyl donor 5 and acceptor 7 proceeded in a one-step reaction using a high-vacuum system for anhydrous glycosylation and minimizing imidate side reactions such as hydrolysis and glycosyl fluoride formation. Pivaloyl, allyl, and benzyl protecting groups of cellooctaose derivative 8 were completely removed with SeO 2 -AcOH, NaOMe-MeOH, and H 2 /Pd(OH) 2 -C, respectively. The acetylation after each deprotection step finally led to cellooctaose hexacosaacetate ( 20 ), which is useful for purification and structural identification. Finally, the acetyl derivative 20 was deacetylated with 1,8-diazabicyclo[5.4.0.]undec-7-ene (DBU) in 20% MeOH-CH 2 Cl 2 to give pure cellooctaose ( 21 ). The analogous synthetic route to the present convergent synthetic design of cellooctaose may be a most promising one that enables us to synthesize cellulose with a defined degree of polymerization (dp).

Co-precipitation of a series of galloylglucoses (hydrolysable tannins) with bovine serum albumin (BSA) was studied stoichiometrically by analysing both galloylglucoses and BSA in the precipitates using HPLC. BSA-precipitating ability increased mainly with an increase in the number of galloyl groups in a galloylglucose molecule but was also affected by the position of the galloyl group (penta- > tetra- > 2,3,6-tri- > 2,3,4-tri- >> di- >> monogalloylglucose). The precipitated BSA increased linearly with an increase in the number of galloyl groups bound to a BSA molecule. BSA-precipitating abilities of the galloylglucoses were closely related to their relative affinities for BSA. These results suggest a two-stage mechanism: initial complexation of galloylglucose with BSA and subsequent precipitation, as a mechanism of the co-precipitation.

Right-handedness derived from bisporphyrins attached to a cellotriose backbone at O-6 and O''-6 positions is revealed for the first time. This cellotriose is proposed as a model of alternatingly functionalized cellulosics, which have promising properties for applications in optoelectronics and molecular receptors owing to the chirality and rigid backbone effects.

The authors studied acetylation of bacterial cellulose (BC) nanofibers to widen the applications of BC nanocomposites in optoelectronic devices. The slight acetylation of BC nanofibers significantly reduces the hygroscopicity of BC nanocomposites, while maintaining their high optical transparency and thermal stability. Furthermore, the degradation in optical transparency at elevated temperature (200°C) was significantly reduced by acetylation treatment. Therefore, the acetylation of bionanofibers has an extraordinary potential as treatment for property enhancement of bionanofiber composites.

Cellulose was reacted with a series of 4-alkoxytrityl chlorides (C(n)TCl, n: number of carbon atoms in a saturated alkyl chain) under homogeneous reaction conditions in LiCl-N,N-dimethyl acetoamide to give a series of 6-O-(4-alkoxytrityl)celluloses (C(n)TC) with a high degree of substitution (DS), from 0.94 to 0.99, and with high regioselectivity at the 6-O position. Solubility of the C(n)TC in nonpolar solvents depended on the alkyl chain length: as the alkyl chain lengthens, cellulose derivatives become more hydrophobic and are readily soluble in nonpolar solvents, but not in polar solvents. Acetates of the C(4)-C(18)TC (C(4)-C(18)TCAc) showed anisotropic structures over melting temperatures (T(m)) examined under a polarized optical microscope (POM). Over isotropization temperatures (T(i)), flow birefringence were detected for C(12)-C(18)TCAc. The T(m) and T(i) decreased linearly with an increasing number of carbon atoms in the alkyl substituent. Wide-angle X-ray scattering (WAXS) studies of C(n)TC indicated that the fully extended side chains were perpendicular to the polymer backbone and interdigitated. These C(n)TC with the improved solubility may be used as starting materials for further derivatization focused on the secondary hydroxyl groups at the C-2 and C-3 positions.

Synthese d'-1-O-allyl-3-O-benzyl-2,4,6-tri-O-acetyl (ou 1-O-allyl-tetra-O-acetyl) glucopyranoside a partir d'3-O-benzyl-tetra-O-acetyl (ou per-O-acetyl) glucopyranose, d'ethyle ether-trifluoroborane et de prop-2-en-1-ol