Urea Metal–Organic Frameworks for Nitro-Substituted Compounds Sensing

Urea
groups are known to form strong hydrogen bonds with molecules containing
atom(s) that can act as hydrogen bond acceptor(s). Thus, urea is a
particularly interesting building block for designing receptors for
neutral or charged guests. In the quest for new sensors with enhanced
performance for the detection of nitro-substituted compounds, two
pillared metal–organic frameworks containing urea functional
groups were synthesized and structurally characterized. The sensing
properties of these frameworks toward nitro-analytes were investigated
and compared to each other. The study clearly reveals the importance
of urea groups orientation inside the pore cavity of MOFs, as well
as the supramolecular interactions between the interpenetrated networks.
This work is interesting as it represents the first example of urea-functionalized
MOFs for nitro-analytes recognition.