Synthesizing New Hybrid Zeolitic Imidazolate Frameworks by Controlled Demolition and Reconstruction

A synthesis
method to obtain new zeolite imidazolate framework
(ZIF) materials that are otherwise difficult to synthesize by known
techniques such as direct crystallization or solvent-assisted linker
exchange, is demonstrated. Treatment of an easily synthesized “template”
ZIF (such as ZIF-8) with an acid gas (humid SO2) allows
controlled demolition of metal-linker coordination bonds, while preserving
overall crystal topology. The partially demolished crystals are then
reconstructed into highly crystalline mixed-linker ZIFs with unique
characteristics by insertion of different linkers that displace the
damaged linkers. One illustration shows the synthesis of a series
of mixed-linker ZIFs containing benzimidazole linkers that show entirely
different gate-opening and diffusion characteristics from ZIFs of
the same composition prepared by direct crystallization. Also shown
is the synthesis of new mixed-linker SOD-topology ZIFs containing
bulky halobenzimidazole and alkylbenzimidazole linkers, which are
very difficult to synthesize by other methods. The present method
is seen to considerably reduce thermodynamic or kinetic barriers for
replacement and insertion of linkers into ZIF topologies.