EXAFS Studies of Organic Molecular Ferromagnets Based on Cobalt Phthalocyanine: Na_2.8CoPc

Abstract

<jats:p> Cobalt phthalocyanine ( Na <jats:sub>2.8</jats:sub> CoPc ) organic molecular ferromagnets with a Curie temperature higher than room temperature were synthesized. By means of EXAFS spectroscopy the nearest coordinational environment of the Co ion was examined in both Na <jats:sub>2.8</jats:sub> CoPc and pristine β- CoPc as well as in standard substances containing metallic cobalt. The nearest coordinational environment of the Co ion in ferromagnetic Na <jats:sub>2.8</jats:sub> CoPc is shown to remain virtually invariable as compared with that in pristine β- CoPc . This environment is conditioned by the nitric and carbonic coordination spheres of the phthalocyanine and differs essentially from the nearest coordinational environment of Co in metallic cobalt. The results of EXAFS studies serve as direct structural evidence that the nature of the ferromagnetism in Na <jats:sub>2.8</jats:sub> CoPc is conditioned by the organic matrix, namely by ( CoPc )<jats:sup>2−</jats:sup> and ( CoPc )<jats:sup>3−</jats:sup> anions with unpaired π-electrons in the 7 e <jats:sub> g </jats:sub> doubly degenerate MO of the conjugated phthalocyanine macro-ring. </jats:p>

Docking MOF crystals on graphene support for highly selective electrocatalytic peroxide production

“…2(f). These explicitly showed that the electronic density of Co(II) was dispersed by the nitrogen doped graphene supports [75][76][77][78][79]. Such finding was further supported by the downshift of graphitic and pyrrolic peaks in MOF@NG and MOF@NG' compared to those of NG and NG' in the N 1s spectra (Fig.…”

High temperature molecular magnetism caused by π-electrons: copper phthalocyanine doped with alkaline metals

“…A number of phthalocyanine-based charge-transfer compounds have been obtained and studied, using this technology. The alkaline-metal doped metal phthalocyanines A x MPc (at x>1.5) stand out of this group because of their unusual magnetic properties [12][13][14][15][16][17]. The most significant feature of A x MPc magnets is their high value of T C that sometimes exceeds the room temperature.…”

Formation of nickel nanoparticles and magnetic matrix in nickel phthalocyanine by doping with potassium

“…Nickel nanoparticles were produced by intercalation of heated up to 300 °C potassium vapor in the polycrystalline powder of NiPc. This method of gas-phase doping of phthalocyanines has been described in detail previously [8][9][10].…”

“…The delocalization of an "extra" electron between adjacent molecular anions leads to their ferromagnetic ordering. It should be noted that stabilization of the ferromagnetic state due to the double exchange is much stronger than the Heisenberg stabilization [29,8,10].…”

“…The formation of nickel nanoparticles in phthalocyanine matrix was studied in [7] synthesized by codeposition of metal and phthalocyanine vapors, but the obtained nanoparticles were oxidized after ten days exposition to air. Magnetic properties of metal-phthalocyanines doped with alkaline metals were investigated also earlier in papers [8][9][10]. It was shown that in some cases metal nanoparticles in MPc were formed depending on the doping conditions.…”