Magnetic Properties of One- and Two-Dimensional Functional Materials: Oxygen Molecules Encapsulated in Single-Walled Carbon Nanotubes and Copper Ions Embedded into Phthalocyanine Sheets
Masayuki Hagiwara1, *, Takanori Kida1, Kazuyuki Matsuda2, Haruka Kyakuno2, Yutaka Mniwa3, Zentaro Honda4, Yuya Sakaguchi4, Makoto Tashiro4, Masamichi Sakai4, Takeshi Fukuda4, Norihiko Kamata4, Kouichi Okunishi5
We report on two topics related to one-dimensional (1D)- and two-dimensional (2D) functional materials. Firstly, we describe magnetic properties of oxygen molecules having spin one (S=1) encapsulated in single-walled carbon nanotubes with an inner diameter of ca 0.8 nm.
Materials and Methods:
New functionality is expected to emerge in magnetic ions or molecules confined into nanospaces. This sample is one of such examples and shows magnetic properties of the S=1 1D Heisenberg antiferromagnet, the so-called Haldane magnet. The intrinsic magnetic susceptibility exhibits a broad maximum at around 50 K and decreases steeply with decreasing temperature. Nearly zero magnetization was observed up to the magnetic field of 10 T and then the magnetization increases almost linearly, which agrees well with the magnetization calculated for the S=1 Haldane magnet.
Accordingly, we have succeeded in preparing the Haldane magnet in an artificial manner. Secondly, the synthesis and magnetic properties of highly-ordered poly copper phthalocyanine (PCuPc) are reported. This material was prepared using copper octacyano-phthalocyanine and CuCl2·2H2O. When preparing the material without CuCl2·2H2O, we have found the formation of polymer network that consists of a 2D porous PCuPc sheet, in which the centers of phthalocyanine units are alternately occupied by Cu atom and vacancy.
The formation of half-filling of Cu ions in the polymer network was confirmed by comparing its magnetic properties with those for almost Cu-full-filling polymer. This “half-filling” technique enables us to create alternating arrangements for transition metal centers, paving the way to control magnetic properties of the 2D carbon sheets.
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