Smart Stimulation Response of a Pyrene-Based Lanthanide(III) MOF: Fluorescence Enhancement to HX (F and Cl) or R‑COOH and Artificial Applicable Film on HCl Vapor Sensing

Toxic acids produced by industries are major hazards
to the environment
and human health, and luminescent pyrene-based crystalline metal–organic
frameworks (MOFs) demonstrate promising performance in the detection
of toxic acids. Herein, two novel isostructural 3D porous lanthanide
MOFs, H3O·[Ln3(TBAPy)2(μ2-H2O)2(OH)2]·2DMA·2Diox·6.5H2O (Ln = Pr (1) and Ce (2); H4TBAPy (1,3,6,8-tetrakis(p-benzoic acid)pyrene);
and DMA: N,N-dimethylacetamide)
were synthesized, which showed alb topology. Based
on the protonation and hydrogen bond mechanism, complex 1 could be used as a fluorescence recognition sensor for HX (X = F,
Cl, Br, and I) acid solutions with different luminescence behaviors.
It is worth noting that complex 1 exhibited high sensitivity
in the fluorescence enhancement sensing of hydrofluoric acid, oxalic
acid, and trichloroacetic acid. In particular, complex 1 had a low limit of detection (LOD) for OA (0.1 μM) and was
applied to real monitoring of orange fruit samples. In addition, the
PVA@1 film could selectively, sensitively, and quantitatively
respond to hydrochloric acid (HCl) vapor through fluorescent quenching;
due to its protonation and adsorption capacity, the LOD was 0.18 ppm.
Therefore, the portable optical device, the PVA@1 film,
can detect HCl gas in trace amounts, achieving the ultimate goal of
real-time and rapid detection, which has potential application value
for industrial production safety.