Substituent effect in the magnetocaloric properties of (ethoxy)(oxo){5,10,15,20-tetra[(4-trifluoromethyl)phenyl] porphinato}molybdenum(V)

The problem of increasing the magnetocaloric effect (MCE) magnitude meets the requirements of such areas as magnetic refrigeration, hyperthermia in medicine and robotics. One of the three known factors controlling the molecular magnets based on porphyrin and phthalocyanine complexes, the spin density exchange between the spin carrier ion and the organic environment remains the least studied. To understand its contribution to the magnetocaloric properties of paramagnetic metalloporphyrins, we have modified the (ethoxy)(oxo)(5,10,15,20-tetraphenylporphinato)molybdenum(V) (O[Formula: see text]Mo(OEt)TPP) structure by introducing CF 3 substituents exhibiting strong electronic effects in organic compounds. Paramagnetic O[Formula: see text]Mo(OEt)TPP and O[Formula: see text]Mo(OEt)T(4-CF[Formula: see text]PP were synthesized and characterized by spectral UV–vis, IR, 1 H NMR, MALDI TOF, EDS methods, SEM, and X-ray phase analysis. Thermodynamic magnetization parameters, MCE over the temperature range of 285–335 K in magnetic fields from zero to 1 T, and the heat capacities in the temperature range from 270 to 418 Ê in zero fields were obtained using the microcalorimetry and DSC methods. The spin density distribution in paramagnets was studied computationally using DFT (UB3LYP*[Formula: see text]D3BJ/6-31G[Formula: see text]LanL2DZ level). The practically crucial 8.6-fold increase in MCE with the O[Formula: see text]Mo(OEt)TPP substitution by –CF 3 groups is due to the change in the contribution of the lattice subsystem during magnetization.