Magnetothermal properties of (octakis-trifluoromethylphenyltetraazaporphinato)manganese(III) acetate in aqueous suspension

Abstract

The magnetocaloric effect (MCE), heat capacity, and magnetization thermodynamic parameters of the high-spin (octakis-trifluoromethylphenyltetraazaporphinato)manganese(III) acetate, (AcO)MnTAP(3-CF3C6H[Formula: see text], in a 1% aqueous suspension were determined by means of microcalorimetric method at 275–320 K in magnetic fields of 0.1–1.0 T. The conditions are comparable with those used with (octakis(3-tert-butylphenyl)tetraazaporphinato)manganese(III) acetate, (2,3,7,8,12,13,17,18-octaethylporphinato)manganese(III) chloride and (5,10,15,20-tetraphenylporphinato)manganese(III) chloride, acetate or bromide studied earlier. Paramagnetic properties were found in high-disperse particles of complexes, positive MCE values were obtained. As paramagnets, these complexes exhibit a big magnetocaloric effect (up to 0.85 K when the magnetic induction is changed from 0 to 1 T) at temperatures close to room, what could be employed for cooling in home and industrial refrigerators and hyperthermia in cancer diagnostics and therapy. MCE sensitivity to the nature and electronic structure of the aromatic macrocycle was discussed. The specific heat capacity of the complex depended on the temperature was obtained. Effect of magnetic field on the temperature dependence of the specific heat capacity for (AcO)MnTAP(3-CF3C6H[Formula: see text] practically is not visible.