Dual Functional sp² Carbon-Conjugated Nanoporous Covalent Organic Framework as a Janus Fluorescence Sensor for the Detection of Hazardous Substances

Abstract

Constructing a luminescent covalent organic framework (LCOF) via an ultrasound-assisted one-step reaction used for “one to many” recognition of targets is a challenge. In this work, we report a fluorescent sp2c-covalent organic framework (COF) (TzDA–BTAN–COF) containing a regular nanoporous structure, uninterrupted π-electron delocalization, and an electron-deficient unit. We explore the use of the TzDA–BTAN–COF for the visual inspection and fluorescent quantitative analyses of hazardous substances. The TzDA–BTAN–COF, as a Janus sensor, exhibited double nature with different fluorescence properties: “turn-on” and “turn-off.” Fluorescence enhancement was exhibited in the presence of electron-rich ofloxacin (OFLX) and fluorescence quenching in the presence of electron-deficient picric acid (PA) and aristolochic acid (AAS). The fluorescence-on and -off sensing mechanism might be attributed to the photoinduced electron transfer by the electron transfer from the donor to the acceptor based on theoretical calculations. In addition, the TzDA–BTAN–COF has been used for the highly sensitive fluorescence detection of PA, AAS, and OFLX. It exhibited good linearity toward PA, AAS, and OFLX over the range from 0.1 to 80, 0.01 to 100, and 0.01 to 1 μg mL–1 with a limited detection of 32.1, 3.3, and 3.0 ng mL–1, respectively. Meanwhile, the real samples were measured, with satisfactory recoveries (95.0–105.5%) and reliable analytical results. The TzDA–BTAN–COF is the first nanoporous COF Janus fluorescence sensor for the “one to many” recognition and fluorescence detection of different hazardous substances by dual functional fluorescence-on and -off sensing.

A Halogen‐Bonded Organic Framework (XOF) Emissive Cocrystal for Acid Vapor and Explosive Sensing, and Iodine Capture

“…Stern–Volmer plot of relative luminescent intensity versus picric acid concentration until 15 µ m afforded a quenching constant ( Ksv ) of 1.33 × 10 5 m −1 and limit of detection (LoD) of 12 n m (Figure S64, Supporting Information), which is on par with the best MOF and COF materials (Table S10, Supporting Information). [ 61,78–82 ] We attribute this remarkable feature to the fluorescent quenching caused by photo induced electron transfer, which is a common mechanism for AIEgen‐based sensors to detect picric acid (Figure S67, Supporting Information). Moreover, TIEPE‐DABCO is available for reversible picric acid sensing upon washing off with ethanol (Figure S65, Supporting Information).…”

Carboxyl-Functionalized Covalent Organic Polymer for Removal of Tobramycin and Ofloxacin from Water

“…TFPT-BTAN-COP-CN was synthesized under the reported method with slight modification. 28 The mixture of BTAN (23 mg, 0.16 mmol), TFPT (89 mg, 0.12 mmol), and 1,2-dichlorobenzene (5 mL) in a 25 mL ampule bottle was sonicated for 5 min. Then, 0.5 mL of NaOH solution (4 M) was added to the mixture, followed by sonication for another 5 min.…”

Z-scheme charge transfer between a conjugated polymer and α-Fe2O3 for simultaneous photocatalytic H2 evolution and ofloxacin degradation

“…Therefore, they can also be used as an electron donor to inject electrons into an electron acceptor. 46,47 PEB-DBT with thiophene sulfone units can serve as electron acceptors, thereby its Fermi level can be uplied by the surface-absorbed OFL. However, as MB and RhB contain N atoms the electron-withdrawing group in the benzene ring, they always serve as the electron acceptor.…”