H‑Bonding Interactions Induced Two Isostructural Cd(II) Metal–Organic Frameworks Showing Different Selective Detection of Nitroaromatic Explosives

Two
luminescent Cd­(II) metal–organic frameworks (MOFs) were prepared
from electron-rich π-conjugated fluorescent ligands. They are
isostructural with sql nets. Their strong luminescences
can be quenched by a series of nitroaromatic explosives. Notably, MOF 1 shows highly selective and sensitive detection of 4-nitrophenol
(4-NP), while MOF 2 exhibits good responses toward picric
acid (PA) compared with other nitroaromatic explosives. This different
order of quenching efficiency is because there are H-bonding interactions
between MOF 1 and 4-NP, while MOF 2 lacks
these H-bonding interactions. MOF 1 displays highly selective
and sensitive detection of 4-NP with the high quenching constant (6.74×
104 M–1) and low detection limit (34.48
ppb), which is better than those of known MOFs. MOF 1 and MOF 2 have highly sensitive and selective detection
of 4-NP and PA in the practical application, respectively.