Studies on the Silk-Palladium Catalyst. III. Physicochemical Characterization

Abstract 1. From the infrared absorption measurements of silk fibroin, silk fibroin-PdCl2 complex, and silk-palladium catalyst, it was concluded that the NH, OH, COOH and CONH groups of the fibroin participate in the chelate formation with palladous chloride. On reduction of the chelate with hydrogen, the chelate bonds are broken and the fibroin restores its original form. 2. X-ray diffraction pictures of the above-mentioned samples and of the corresponding preparations of the 6-Nylon series suggest that a part of the palladium atoms in the silk-palladium catalyst is assembled in fine crystaline particles and the other part of the palladium probably becomes regularly arranged in the micelle structures of the fibers. However, the possibility that certain regular structures have emerged in the carrier protein itself can not be excluded. 3. Part of the palladium in silk fibroin-PdCl2 complex can be readily released with p-nitrosodimethylaniline, while the rest appears to be strongly kept in the fiber structure.