Bulky Schiff-base ligand supported Co(ii) single-ion magnets with zero-field slow magnetic relaxation.

Two mononuclear Co(ii) complexes with tetrahedral coordination geometry have been constructed from different bulky Schiff-base ligands. Both complexes exhibit slow magnetic relaxation without a static field and their relaxation behaviors can be tuned by ligand substitution. Clear magnetic hysteresis loops were observed for both complexes at 2 K.