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Updated: Jul 12, 2026
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in
Mami Yamada1, Takuya Sato, Mikio Miyake
1Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan. m-yamada@cc.tuat.ac.jp
Abstract:
Nanometer-size metal coordination polymers are fascinating to explore, since their unique properties are controlled by a large ratio of surface atoms, which is an entirely different effect from that in a bulk crystal. In this report, we have demonstrated the reaction time-induced structural conversion of nanometer-sized metal coordination nano-polymers (MCNPs). The MCNP selected here was a Prussian blue analogue, cobalt hexacyanoferrate (Fe-CN-Co) with ca. 3 nm. When Fe-CN-Co MCNPs were synthesized in reverse micelles of cationic surfactants, cetyltrimethylammonium halides [CTAX, X=B (bromide), C (chloride)], their color dramatically changed from red to green with increasing the reaction time. We investigated the mechanism of this characteristic color change using XRD, FT-IR, UV-vis spectra, CHN elemental analyses, ICP, and TGA, which indicated that the coordination geometry of Co(II) ions was changed from a 6-coordinate octahedral (Oh) to a 4-coordinate tetrahedral (Td) with clear crystal distortion. The magnetic behavior of the prepared Fe-CN-Co MCNPs was also reaction-time dependent, as illustrated by SQUID and 57Fe Mössbauer spectra.
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