Structural, electronic and magnetic properties of 8-hydroxyquinoline-based small molecules TMQx (TM=Cr, Mn, Fe, Co, Ni, Cu, Zn, and x=2 or 3)

•The properties of 8-hydroxyquinoline-based small molecules are systemically studied.•The TMQ2 molecules have more symmetrical structures than the TMQ3 molecules.•The magnetic moment adopts integer number for all TMQ2 and TMQ3 molecules.•The magnetism can be explained by the crystal field theory.

The structural, electronic and magnetic properties of 8-hydroxyquinoline-based small molecules TMQx (TM=Cr, Mn, Fe, Co, Ni, Cu and Zn, and x=2 or 3) are systemically studied from first principles. These small molecules are spin-polarized semiconductors except for NiQ2, ZnQ2, and CoQ3. For TMQ2, the magnetic moments can be expressed as 8-nµB (n is the number of 3d electrons of TM ions. For Mn, Fe, Co, and Ni, n=5, 6, 7, and 8 respectively) and 10-nµB (n=9 and 10 for Cu and Zn, respectively). For TMQ3, the magnetic moments can be expressed as 6-nµB (n=3, 4, 5, 6 for Cr, Mn, Fe, and Co, respectively). The magnetism can be explained by the spin-polarized filling of splitting d orbitals on the basis of the crystal field theory. This provides theoretical insight for better understanding of 8-hydorquinoline-based complexes (TMQx).

Graphical abstractThe magnetic moments for all 8-hydroxyquinoline-based small molecules adopt integer numbers; this can be explained in a simple framework on the basis of the crystal field theory.Figure optionsDownload full-size imageDownload as PowerPoint slide