Four Honeycomb Metal–Organic Frameworks with a Flexible Tripodal Polyaromatic Acid

Reaction
of 4,4′,4″-{[(2,4,6-trimethylbenzene-1,3,5-triyl)­tris­(methylene)]­tris­(oxy)}­tribenzoic
acid (H3TCM) with Mn2+, Cu2+, and
Co2+ salts afforded four interesting metal–organic
frameworks (MOFs), [Mn2(TCM)­Cl­(H2O)3]·3DMF·3CH3OH (1), [Mn4(TCM)2(CH3COO)2(DMF)5]·4CH3OH (2), [Cu2(TCM)­(CH3COO)­(DMF)­(H2O)]·2DMF·3CH3OH
(3) and [Co3(TCM)2(H2O)5]·5DMF·3CH3OH (4).
Single crystal X-ray diffraction analysis revealed that the four structures
based on the flexible TCM tripod consist of honeycomb lattices with
different metal–ligand macrocycles. The assembly of the metal–ligand
macrocycles and framework topologies is dependent on the coordination
geometries of transition metal cations. The two-dimensional coordination
network of 1 was further connected by an auxiliary acetate
ligand to give rise to a three-dimensional honeycomb network of 2. The TCM ligand centered photoluminescences of these compounds
are very sensitive to the coordination modes of the TCM ligands, the
metal secondary building units (SBUs), and their microstructures.
These MOFs also present interesting magnetic behaviors, as revealed
by the study of the magnetic susceptibilities.