Regularities of Magnetocaloric Effect and Determination of Some Thermodynamic Parameters for (Octaethylporphynato)chloro-manganese(III)

Abstract

chloromanganese(III) (6% suspension in water) were measured by microcalorimetric method in the dependence of temperature (298-353 K) and magnetic field (0-0.7 T). It is found that the MCE has positive value which increases with growth of the magnetic field induction at all the temperatures and decreases with the temperature growth at all the magnetic fields. Breaking the magnetic field leads to adiabatic demagnetizing. The dependence of specific heat capacity of the studied system from the value of magnetic field induction has maximum at 0.2-0.3 T at all the temperatures. When the induction value is higher than 0.6 T the specific heat capacity value is less than that in zero field. The temperature growth leads to the increase of the specific heat capacity in all the magnetic fields. On the base of the experimental data on the magnetocaloric effect and specific heat capacity of the manganese complex the dependencies of enthalpy, of the magnetic components of molar heat capacity and entropy from the temperature and magnetic induction are calculated.

Effect of peripheral modification of manganese(III) porphyrazine on its reactivity in the coordination of imidazole

“…Comparison of the electronic absorption spectra of porphyrazine complexes I and II with those of Mn(III) complexes with octaethylporphyrin [20] [CHCl 3 , λ max , nm (log ε): 428 (4.17), 473 (4.68), 590 (3.76)] showed the same relation as that reported in [21] for analogous iron(III) complexes. Replacement of the -CH= groups by -N= is accompanied by red shift of the long-wave absorption maxima (bands I and II) and blue shift of the short-wave absorption band (III).…”

Recent progress in organometallic porphyrin‐based molecular materials for optical sensing, light conversion, and magnetic cooling

“…All results were obtained by a microcalorimetry method described in the works. [165,166] That is the direct method of MCE determination, in which adiabaticity of magnetization is maintained by rapid changes of a magnetic field. MCE related to the completely thermostatic calorimetric cell with solid paramagnets and water above it were observed in the first works.…”

Magnetocaloric Effect in Carbon-Containing Compounds

“…The work was devoted to the studies of the structure, synthesis, composition, magnetic properties and applicability of magnetic 3d, 3d-4f and 4f-coolants in different spheres of activity. Homometallic gadolinium compounds were studied in different clusters where the values of the magnetic component of the entropy change -∆S m , which is a measure of MCE, reached about 27 J/kg at 5 K and changes of magnetic field from 0 to 1 T. Thus, studying zero-sized lanthanides(III) "built" into the coordination sphere of the tetrapyrrole macrocycle is a new field of research with only a small number of studies which include, in addition to the works on SMMs that were partially quoted in the previous section, our research into magnetocaloric properties of paramagnetic metalloporphyrins/metal phthalocyanines [30][31][32][33][34][35][36][37][38][39][40].…”

“…An example of their formula is given below (Fig. 4.1) at the temperature of 270-350 K and magnetic induction 0 -1 T [30][31][32][33][34][35][36][37][38][39][40]41].…”

“…It means that the magnetocaloric effect is influenced by the nature of the substituent in the macrocycle, while the acetate ligand nature has a less significant effect. The MCE reaction to the nature of the complex is explained by the differences in the mutual position of the energy of the d-orbitals in the field of the ligands [37].…”