Assembly, Disassembly, and Reassembly: Conversion of Homometallic Coordination Networks into Mixed Metal–Organic Frameworks

A strategy for the conversion of
homometallic coordination networks into mixed metal–organic
frameworks (MM′MOFs) is proposed. Ni­(II) complexes of dipyrrin
(dpm) ligands bearing peripheral pyridyl or imidazolyl units have
been shown to self-assemble into coordination polymers with the metal
cation in an octahedral environment coordinated to two bis-pyrrolic
chelates and two neutral monodentate coordinating units such as pyridyl
or imidazolyl moieties. Taking advantage of the chelate effect, the
two monodentate units may be replaced by a diimine ligand leading
to the disassembly of the networks by the formation of discrete soluble
complexes. The latter can be employed as metallatectons for the construction
of heterometallic architectures upon reaction with a secondary metal
salt. This approach was applied using either 1,10-phenanthroline (phen)
or 2,2′-bipyrimidine (bpm) as chelates leading to a series
of mono- and binuclear metallatectons of the (phen)­Ni­(dpm)2 and (bpm)­[Ni­(dpm)2]2 type. Subsequent assembly
with CdCl2 afforded either interpenetrated 2D grid-type
architectures or 3D MM′MOFs.