Cp/mas 13c nmr and Electron Diffraction Study of Bacterial Cellulose Structure Affected by Cell Wall Polysaccharides

Acetobacter xylinum was cultured in Schramm–Hestrin medium containing pectin (pectin medium), xylan (xylan medium), or glucomannan (mannan medium). X-ray diffractometry revealed that xylan and glucomannan affected the size of the cellulose crystals and their d-spacing values. Solid-state cross polarization magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy indicated that the ratio of cellulose I was reduced by the addition of polysaccharides. These effects were more remarkable on the cellulose in the mannan medium than that in the xylan medium, and were scarcely observed in the pectin medium. Electron diffraction analysis revealed that these effects on hemicelluloses along cellulose microfibrils are continuous in the mannan medium and discontinuous in the xylan medium. These findings suggest that the uronic acid in the polysaccharides prevents interactions with cellulose leading to alterations of the structure of the cellulose crystal.     

Extraction and Mutual Separation of Actinide(III), (IV), (V) and (VI) Ions by N,N′-Dimethyl-N,N′-Dihexyl-3-Oxapentanediamide and Thenoyltrifluoroacetone

Actinide(III), (IV), (V) and (VI) ions were extracted by N,N-dimethyl-N,N-dihexyl-3-oxapentanediamide (DMDHOPDA) and thenoyltrifluoroacetone (HTTA). The extraction behaviors suggested the possibility of the mutual separation, and the convenient separation method of actinide ions (III), (IV), (V) and (VI) without reducing and oxidizing agents was studied. Th(IV) was extracted from the aqueous phase by HTTA (5 mM in toluene) in the first step. The Am(III) and U(VI) ions can be extracted by 1 and 20 mM DMDHOPDA in toluene, and the Np(V) ion can be extracted into nitrobenzene with 100 mM DMDHOPDA in the last step. The residual activities in the aqueous phase were much lower than the initial activities. These activities in the fractions were confirmed by the gamma- and the alpha-spectrometry. The one-through and rough separation is advanced, and in case of the fine isolation of actinide elements, each fraction should be purified in more detail.     

Extraction behaviors of Eu,Th, U and Am with diamides+thenoyltrifluoroacetone

N,N-dimethyl-N,N-dihexyl-3-oxapentanediamide, DMDHOPDA, N,N-dihexyl-3-thiopentanediamide, DHTPDA and N,N-dihexyl-3-oxapentanediamide, DHOPDA were synthesized and tested for the synergistic extraction of Eu³⁺, Th⁴⁺, UO ₂ ²⁺ , NpO ₂ ⁺ and Am³⁺ with thenoyltrifluoroacetone (HTTA). Although Eu³⁺, Th⁴⁺, UO ₂ ²⁺ and Am³⁺ were not extracted by DHTPDA or DHOPDA alone, they were extracted synergistically when combined with HTTA. Analysis of the dependency of extraction on pH and extractant concentration indicated that the dominant extracted species were Eu(TTA)₃(A), Th(TTA)₃(A)(X), UO₂(TTA)₂(A) and Am(TTA)₃(A) (where A is diamide, and X is chloroacetate or ClO ₄ ^– ).     

Structure,stability, and electronic and NMR properties of various oxo- and nitrido-derivatives of [L(Salen)Mn(III)]+, where L = none and imidazole. A density functional study

Structure, stability, and electronic and NMR properties of [(Salen)Mn(III)](+)-derived intermediates/reactants in the epoxidation/amination of unfunctionalized olefins, namely [(Salen)Mn(V)O](+) (1-oxo), [(Salen)Mn(IV)O] (2-oxo), and [(Salen)Mn(V)N] (3), have been studied with the B3LYP density functional method. It has been shown that the (1)A, (3)A, and (5)A states of cationic 1-oxo species are virtually degenerate, while for the neutral 2-oxo species the ground (4)A state lies 6.4 kcal/mol lower than (2)A. In the nitrido species 3, the (1)A state has been shown to be the ground state in agreement with experiment. We have investigated isomerization of 1-oxo and 2-oxo species into unusual [(OSalen)Mn(III)](+) (1-N-oxo and 1-peroxo) and [(OSalen)Mn(II)] (2-N-oxo and 2-peroxo) species, respectively. For cationic species 1, the 1-N-oxo isomers are more stable (by 10-12 kcal/mol) than the 1-oxo isomer and are separated from the latter by 21-22 kcal/mol barriers. On the other hand, 1-peroxo isomers are calculated to be 14-16 kcal/mol higher than the 1-oxo isomer. For neutral species 2, however, both 2-N-oxo and 2-peroxo isomers lie significantly higher in energy than the 2-oxo isomer. It has been shown that coordination of axial imidazole ligand alters relative energies of spin states for 1- and 2-oxo species, destabilizing low-spin states. For singlet states of H(2)Salen, 1-oxo, and 3, we have calculated (1)H, (13)C, (15)N, and (17)O NMR chemical shifts using the gauge-independent-atomic orbital (GIAO) approach.     

Ferrocene-containing polymers. I. Radiation-induced polymerization of ferrocenylmethyl methacrylate

γ-Ray-induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low-molecular-weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose-rate dependence of the polymerization rates were different between the two states. Wide-line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ-irradiated FMMA and 1,1′-ferrocenyl-di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.