Phthalocyaninato lanthanide(iii) acetates as a new class of molecular paramagnets with large magnetocaloric effect

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

“…[167][168][169][170][171] A paramagnet heat capacity observed in the same experiment as for MCE values and calculated according to Equation (10 was evaluated as a difference (Equation (11). In the subsequent works, [34,166,[172][173][174][175][176][177] a new method based on using Equation (12 had allowed to eliminate the influence of a cell without a paramagnet and to determine the paramagnet true MCE. In the same time, the heat capacity of a paramagnet was independently observed by a direct differential scanning calorimetry method.…”

“…In the first case, the MCE value depends not only from the spin state of a central ion but also from an electronic and chemical structure of bonded axial groups (Figure 13 created by using the works [166,167,[169][170][171][172][173]175,177,178] ), which ultimately leads to spin density delocalization or to ferromagnetic coupling with an additional spin carrier in a molecule structure. To give insight into the nature of spin distribution, they resort to comparative analysis of paramagnet UV-vis spectra or to computational calculations.…”

“…Both the electron and lattice contribution in the (Cl)YbP (4-t BuPh) 4 MCE value result in the horizontal part on the MCE temperature dependence (Figure 16 created from the data [176] ). [172] Finally, the important role in the formation of the porphyrin/phthalocyanine-based paramagnet spin state belongs to the antiferromagnetic coupling if the one is possible. MCE of 0.47 K at 278 K when the magnetic field is changed from 0 to 1 T in (AcO)GdPc decreases almost an order of magnitude by the transition to the sandwich analog, GdPc 2…”

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].…”