Four novel Co(II) metal-organic frameworks based on semi-rigid ligand and their secondary building units transformation

Abstract

Four novel 3D Co(II)-containing metal–organic frameworks (MOFs), namely [Co(ADDA)] (1), [Co(ADDA)(bipy)]·1.5H2O (2), [Co0.5(HADDA)(bipy)0.5] (3) and [Co(ADDA)(bipy)0.5] (4) (H2ADDA = 3,3'-(anthracene-9,10-diyl)diacrylic acid, bipy = 4,4′-bipyridine), have been successfully obtained based on reasonable synthetic strategies. N-donor auxiliary ligand, reaction medium and reaction temperature jointly induce interesting transformation of secondary building unit (SBU), resulting in structure diversities and topology variations. Notably, by increasing the reaction temperature in the mother liquid, 4 with {Co2(COO)4} paddle-wheel SBU can be generated by the single-crystal to single-crystal transformation of 3 with mononuclear {CoO4} SBU. Furthermore, the magnetic properties and electrocatalytic activities of these four Co-MOFs are also investigated in detail.