No abstract

A crude cellulase preparation from Aspergillus niger was used to depolymerize chitosan. The depolymerization process was followed by measuring the apparent viscocity and the intrinsic viscosity. The optimum conditions for enzymatic hydrolysis were investigated. On the selected optimum conditions (pH 5.0, temperature 50°C, and an enzyme to substrate ratio of 1:5), chitosan was hydrolyzed for 1, 4, 8, and 24 h, its viscosity-average molecular weights were 3.49×10 4 , 1.18×10 4 , 5.83×10 3 , and 1.13×10 3 , respectively. Compared with chitosan having viscosity-average molecular weight of 5.18× 10 5 before enzymatic hydrolysis, the crude cellulase preparation had rather apparent effect on depolymerization of chitosan. Through the comparison of different origin of cellulases, the prepared cellulase has good ability of enzymatic hydrolysis. The reproducibility and reversibility for enzymatic hydrolysis was appraised. The data are of value for the production of low-molecular weight chitosans and chitooligomers of medical and biotechnological interest.

In the crystal structure of the title organic salt, C3H10NO+·IO4 −·C12H24O6, the protonated 2-meth­oxy­ethanaminium (CH3OC2H4—NH3 +) cation forms a 1:1 supra­molecular rotator–stator complex with the 18-crown-6 mol­ecule via N—H⋯O hydrogen bonds. The (CH3OC2H4—NH3 +) group is attached from the convex side of the bowl-shaped crown, in contrast to similar ammonium cations that nest in the curvature of the bowl. The cations are associated via N—H⋯O inter­actions, while the cations and anions are linked by weak C—H⋯O hydrogen bonds, forming cation–crown–anion chains parallel to [010].

In the title compound, [FePt(C5H5)(C24H19NP)Cl2]·0.5CH2Cl2, the PtII atom adopts a distorted square-planar geometry defined by one P atom and one N atom from the bidentate [2-(diphenyl­phosphino)phenyl­imino­meth­yl]ferro­cene ligand and two Cl atoms. Two disordered dichloro­methane solvent mol­ecules are each 0.25-occupied on a twofold rotation axis.