Dual-Color 2D Lead–Organic Framework with Two-Fold Interlocking Structures for the Detection of Nitrofuran Antibiotics and 2,6-Dichloro-4-nitroaniline

The
misuse of organic pollutants such as nitrofuran antibiotics
(NFAs) and 2,6-dichloro-4-nitroaniline (DCN) has become a hot topic
of global concern, and developing rapid, efficient, and accurate techniques
for detecting NFAs and pesticides in water is a major challenge. Here,
we designed a novel lead-based anion 2D metal–organic framework
(MOF){[(CH3)2NH2]2[Pb(TCBPE)(H2O)2]}n (F3) with interlocking structures, in which TCBPE stands for 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene.
Powder X-ray diffraction and thermogravimetric analysis revealed that F3 has excellent chemical and solvent stability. It is worth
noting that F3 has a grinding discoloration effect. The
solvent-protected grinding approach achieved F3B with
a high quantum yield (QY = 73.77%) and blue fluorescence, while the
direct grinding method produced F3Y with a high quantum
yield (QY = 37.27%) and yellow–green fluorescence. Importantly, F3B can detect NFAs in water rapidly and sensitively while
remaining unaffected by other antibiotics. F3Y can identify
DCN in water quickly and selectively while remaining unchanged by
other pesticides. F3B demonstrated high selectivity and
rapid response to NFAs at a limit of detection (LOD) as low as 0.26
μM, while F3Y indicated high selectivity and responded
quickly to DCN in water at an LOD as low as 0.14 μM. The method
was successfully applied to detect NFAs in actual water samples of
the fish tanks and ponds as well as the pesticide DCN in soil samples.
The recovery rates were 97.0–105.15% and 102.2–106.48%,
and the relative standard deviations were 0.63–1.45% and 0.29–1.69%,
respectively. In addition, F3B and F3Y can
be made into fluorescent test papers for the visual detection of NFAs
and DCN, respectively. Combined with experiments and density functional
theory calculations, the mechanism of fluorescence quenching of MOFs
by target analytes was also revealed.