Structural Water Synergistic Hydrogen-Bonded Organic Frameworks: A Fluorescent Sensing Platform Oriented for Intelligent Accessibility

Using
1,3,5-Tris(4-aminophenyl)benzene (TAPB) as the precursor,
we synthesized two single-crystal hydrogen-bonded organic frameworks
(HOFs-T and HOFs-TW). We systematically investigated the impact of
reaction conditions on their structural properties and assessed their
potential as optical sensing materials. In our experiments, HOFs-TW
unexpectedly showed a hexagonal tubular morphology with a stable snowflake-shaped
structural water. These water molecules and TAPB monomers form an
ordered hydrogen-bonding network that reduces aromatic ring dihedral
angles, induces coplanarization, and significantly enhances HOF-TW’s
charge-transfer and photon conversion efficiency (quantum yield 66.56%).
Utilizing the optical properties of HOFs-TW, we incorporated green
carbon quantum dots (CDs) and used molecularly imprinted polymers
(MIPs) as the selective component to develop a ratiometric fluorescence
sensor (CDs@SiO2/HOFs-TW@MIPs). This sensor was designed
for the detection of clofibric acid (CLF) in environmental samples,
exhibiting a linear range of 0–360 μM and a detection
limit of 0.1775 μM. Additionally, we prepared the corresponding
fluorescence test papers and independently developed a smartphone-based
fluorescence-colorimetric sensing application. The test paper’s
fluorescence stabilizes within 1 min 20 s, with three parallel measurements
via an app (relative error 0.205%), completed within 3 min. This study
provides significant theoretical support and insights into the design
and morphological control of single-crystal HOFs. We envision that
this work will further advance the application of fluorescence rapid
detection and optical sensing, expanding its applicability for real-time
monitoring in various scenarios.