ABSTRACTThe reaction of a wide variety of cyanometalate complexes of the general
form [M(CN)x]n- (where M= a transition metal ion) with
square planar [PdCl4]2- in aqueous solution leads to
the formation of linear polymers. Polymerization occurs via substitution of
chloride ligands on the Pd(II) centers, by the nitrogen end of the cyanide
ligand to generate extended bridging cyanide structures. Upon generation at
room temperature polymer solutions of this type under go a sol-gel
transition to generate robust hydrogels having water content in excess of
95%. In the case of the cyanocobaltate/tetrachloropalladate gel, pyrolysis
at 900°C produces ferromagnetic Pd/Co metallic alloys having novel
morphological character. Materials formed with a hydrogel having a 2:1 Pd to
Co stoichiometry are found to be “sponge-like”. When placed in water, the
metallic matrix swells becoming pliable and holding up to seven equivalents
of water per metal site. The conductivity and magnetic properties of this
material are maintained in the swollen state. Sintering of the Pd/Co
hydrogel in air generates the layered oxide, PbCoO2 having a
delafossite structure.
Diblock/Triblock Structural Transition and Sol-Gel Transition of Peptide/PEG Diblock Copolymer Having a Terminal Terpyridine Group Induced by Complexation with Metal Ion
