High and Reversible Ammonia Uptake in Mesoporous Azolate Metal–Organic Frameworks with Open Mn, Co, and Ni Sites

A series
of new mesoporous metal–organic frameworks (MOFs)
made from extended bisbenzenetriazolate linkers exhibit coordinatively
unsaturated metal sites that are responsible for high and reversible
uptake of ammonia. Isostructural Mn, Co, and Ni materials adsorb 15.47,
12.00, and 12.02 mmol of NH3/g, respectively, at STP. Importantly,
these near-record capacities are reversible for at least three cycles.
These results demonstrate that azolate MOFs are sufficiently thermally
and chemically stable to find uses in recyclable sorption, storage,
and potentially separation of chemically challenging and/or corrosive
gases, especially when designed to exhibit a high density of open
metal sites.