The metal complexes using organic ligands with photo-excited high-spin states

In this work, 4-pyridyl-phenylanthracene-iminonitroxide radical 2 was synthesized, which can make the coordination to metal ions. It was confirmed by the time-resolved ESR experiments that 2 has a photo-excited quartet (S = 3/2) high-spin state. Cu(II)(hfac)2(2)2 and Mn(II)(hfac)2(2)2 were synthesized by using 2 as a ligand. Their magnetic properties on the ground states were analyzed by three-spincluster model S1 − SM − S2 (S1 = S2 = SM = 1/2 for Cu(II)(hfac)2(2)2 and S1 = S2 = 1/2, SM = 5/2 for Mn(II)(hfac)2(2)2). The exchange interactions (J/kB) between 2 and the metal ions were very weak (J/kBs were ferromagnetic for Cu(II)(hfac)2(2)2 and antiferromagnetic for Mn(II)(hfac)2(2)2). The molecular orbital calculations of 2 have suggested the strong interaction between the paramagnetic center of the metal ions and the photo-excited quartet high-spin state.

Graphical abstract4-Pyridinyl substituted phenyl-anthracene-iminonitroxide radical 2, the metal complexes Cu(II)(hfac)2(2)2 and Mn(II) (hfac)2(2)2 were synthesized. The photo-excited quartet high-spin state of 2 was proved by time-resolved ESR. The magnetic properties and molecular structures of the metal complexes in the ground states were also investigated by magnetic susceptibility measurements and X-ray analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide