화학공학소재연구정보센터
Inorganic Chemistry, Vol.58, No.14, 9187-9194, 2019
Pressure-Controlled Migration of Paramagnetic Centers in a Heterospin Crystal
A study of the single-crystal-to-single-crystal transformation induced by temperature variation for the chain polymer Cu(II) complex with nitronyl nitroxide showed that an increase in the hydrostatic pressure of up to similar to 0.07 GPa completely changes the intracrystalline displacements of molecules relative to one another. This, in turn, significantly affects the interaction energy of the unpaired electrons of the paramagnetic centers and hence the form of the temperature dependence of the magnetic susceptibility AfT. The cooling of crystals under normal conditions causes a rearrangement of the intrachain exchange clusters {>N-center dot O-Cu(II)-O center dot N<} accompanied by a shortening of the distances between the paramagnetic centers. This changes the character of exchange interactions and generates multistage spin transitions. An increase in the hydrostatic pressure leads to a drastic change in the O center dot center dot center dot O distances between the nitroxyl fragments of adjacent chains, an increase in the antiferromagnetic exchange between them, and complete suppression of spin transitions.