  Metal-organic frameworks (MOFs) stand as one of the most promising materials
for the development of advanced technologies owing to their unique combination
of properties. The conventional synthesis of MOFs involves a direct reaction of
the organic linkers and metal salts, however, their post-synthetic modification
is a sophisticated route to produce new materials or to confer novel properties
that cannot be attained through traditional methods. This work describes the
post-synthetic MOF-to-MOF transformation of a non-luminescent MOF (Zn-based
OX-1) into a highly luminescent framework (Ag-based OX-2) by a simple immersion
of the former in a silver salt solution. The conversion mechanism exploits the
uncoordinated oxygen atoms of terephthalate linkers found in OX-1, instead of
the unsaturated metal sites commonly employed, making the reaction much faster.
The materials derived from the OX-1 to OX-2 transformation are highly
luminescent and exhibit a selective response to acetone, turning them into a
promising candidate for manufacturing fluorometric sensors for the diagnosis
and monitoring of diabetes mellitus. Our methodology can be extended to other
metals such as lead (Pb). The fabrication of a polymer mixed-matrix membrane
containing OX-1 is used as a proof-of-concept for capturing Pb ions (as
pollutants) from water. This research instigates the exploration of alternative
methodologies to confer MOFs with special aptitudes for photochemical sensing
or for environmental applications such as water purification.
