Turn-off Fluorescence Research Articles

Facile Synthesis of Phthalazinone/Isoindolinone Substituted Fluorescence Active Indolo[1,2‐a]quinoxaline Derivatives via ANRORC and Fluorescence Turn Off Sensing of Fe2+

AbstractSynthesis of a series of indolo[1,2‐a]quinoxaline derivatives substituted with phthalazinones/isoindolinones/carbonyl benzoylesters at C‐4 position have been accomplished under open air rt/heating conditions following ANRORC (Addition of Nucleophile, Ring Opening and Ring Closure) mechanism. Initially condensation of 2‐(1‐indolyl)‐aniline and ninhydrin generates a spirocyclic intermediate 5′H‐spiro[indene‐2,6′‐indolo[1,2‐a]quinoxaline]‐1,3‐dione, which upon reaction with various nucleophiles like hydrazine/phenylhydrazine, amines and alcohols affords C‐4 substituted indolo[1,2‐a]quinoxalines in high yield (up to ~88 %) via ANRORC. The photophysical investigation shows that the quinoxaline derivatives possess significant fluorescence property with high quantum yield (QY~11.0–17.0). The N‐phenylphthalazinone substituted indolo[1,2‐a]quinoxaline, a molecule structurally similar to 2,2′‐bipyridine system, can efficiently and selectively detect Fe2+ through fluorescence turn off sensing.

Post-functionalization of Fluorinated Dibenzosulfone-based Conjugated Polymer for Smart 'Turn-off' Sensing of Cu2+ Ions.

Post-functionalization of conjugated polymeric backbone with various N-containing heterocycles through nucleophilic aromatic substitution reaction (SNAr) demonstrates crucial tailoring of their photophysical properties. This study explores an approach of post-polymerization modification of a fluorinated dibenzosulfone-based conjugated polymer aiming to incorporate functional groups having coordinating sites to bind metal ions. The resulting polymers, namely BDT-DBTS-IM, BDT-DBTS-TR, and BDT-DBTS-PY, revealed successful substitution reactions with imidazole, triazole, and pyridine respectively, andshowed significant changes in their absorption and emission properties. Notably, BDT-DBTS-IM demonstrated exceptional performance as a chemosensor, exhibiting a dramatic fluorescence turn-off response specifically to copper ions (Cu2+) with the limit of detection of 26 nM and Stern-Volmer quenching constant (KSV) of 8.2×105 Lmol-1. This high selectivity and sensitivity are attributed to the ability of the imidazole group to form a stable complex with Cu2+, resulting in both static and dynamic quenching efficiently. Our findings underscore the potential of post-polymerization modifications to significantly enhance the functionality of conjugated polymers. The ability of BDT-DBTS-IM to detect trace levels of copper ions with high precision highlights its practical utility in environmental and biological monitoring. This research not only demonstrates an approach for post-polymeric modification through SNAr reaction but also opens new avenues for developing sensors.

A novel carbazolyl thiophene-based fluorescent “off-on” probe PCTMF for sequential detection of Cu2+ and cysteine in aqueous

Copper ions and cysteine play a crucial role in pathophysiologic processes in the human body and the environment, so the development of probes with high sensitivity and specificity for continuous detection has become the focus of current research. In the paper, a novel fluorescent compound (named PCTMF) is synthesized with a carbazolyl thiophene group as a fluorescent moiety and formyl hydrazine as a recognition group of Cu2+. In the given DMSO-H2O solvent system, the PCTMF exhibits a highly selective and sensitive turn-off fluorescence response towards Cu2+ with its detection limit (LOD) of 0.14 μM, in the presence of other competing metal ions. The turn-off response mechanism of the probe can be attributed to the formation of complex 2PCTMF-Cu. The 2PCTMF-Cu complex presents good sensing capacity on cysteine (Cys) with a LOD of 52 nM. The molecule designing method provides an “off-on” strategy for sequentially fluorescence detecting metal ions and ligands related.

Streamlined turn-off fluorescence sensing of Donepezil: Enhancing evaluation in pharmaceutical formulations, quality control labs, and biological fluids at nano levels

Donepezil (DPZ) is used to treat Alzheimer’s disease by increasing acetylcholine in the brain, necessitating precise analytical methods for its evaluation. This study aims to develop and validate a new turn-off fluorescence sensing method for quantifying DPZ, enhancing its evaluation in pharmaceutical formulations, quality control laboratories, and biological fluids. By leveraging the fluorescence-quenching interplay between DPZ and tetrabromofluorescein, the assay parameters were fine-tuned to enhance the development of an ion-associated complex. The developed method demonstrated a measurement range from 40 to 800 ng/mL, with detection and quantification limits of 12.6 ng/mL and 38 ng/mL, respectively. However, the successful application of the method to commercial DPZ tablets and plasma samples confirmed its effectiveness for both quality control labs and clinical research settings. It ensured accurate content uniformity and high precision, making it ideal for routine DPZ monitoring. In contrast to previous methods, this approach emphasizes environmental sustainability, evaluated using advanced tools like the Eco score scale, AGREE, RGB12, and BAGI. These tools facilitated a thorough assessment of the method’s ecological impact and sustainability, underscoring its advantage over traditional methods in terms of environmental responsibility.

Selective Detection of Picric Acid by Benzodiazepine Containing Enaminone Core as Receptor and Its Application to Real Water Sample Analysis.

Nitroaromatic compounds are highly explosive and illegitimate substances. Over a decade, chemists have been affianced in extensive research on the selective and sensitive detection of these nitroaromatic explosives for homeland security and environmental protection. The benzodiazepine-based enaminone (BDE) receptor has been synthesized by aqueous extract of onion catalyzed three-component reaction between o-phenylenediamine, dimedone with an aldehyde. The BDE probe is well analyzed and applied to a sensor that selectively detects picric acid (PA). UV-Vis and fluorescence spectroscopy were used to investigate the photophysical responses of the receptor (BDE). From the observed results BDE found turn-off fluorescence with the addition of picric acid and the lowest limit of detection and limit of quantification was achieved about 24.6 nM and 73.8 nM. The fluorescence quantum yield was attained about 0.28. The BDE-PA adduct formation was confirmed by 1H NMR titration analysis. The Job's plot analysis was performed through 1H NMR titrations and established the binding stoichiometry ratio of the BDE-PA adduct as 1:1 ratio. Further, DFT calculations supported the observed photophysical responses of BDE-PA adduct to confirm the molecular level interactions. The receptor was effectively applied to approximate level of picric acid in real water sample analysis.

Two new Cd(II)-based coordination polymers derived from flexible linker: Highly sensitive and selective “turn off-on” fluorescent sensors for ferric and dichromate ions

Coordination polymers (CPs) are peculiar multidimensional materials that find utility as luminescent sensors for ions and molecules existing in wastewater discharge. Herein, two new Cd(II)-based CPs with formula [Cd(L)(phen)]·0.5H2O (1) and [Cd(L)(2,2'-bipy)] (2) (H2L = 3,3'-((1,2-phenylenebis(methylene))bis(oxy))dibenzoic acid, phen = 1,10-phenanthroline and 2,2'-bipy = 2,2'-bipyridine) have been synthesized and characterized. The single crystal X-ray analysis for 1 reveals that, Cd(II)-based centre adopts an octahedral geometry and is coordinated to four carboxyl O atoms from three L2- ligands and two N atoms from phen molecules. While, in CP 2, the Cd(II) centre is seven coordinated, which is completed by five carboxylate O atoms from two distinct L2− ligands and two N atoms from the 2,2-bipy ligand. Both 1 and 2 have been used as turn-off fluorescence sensor for selective and sensitive detection of Fe3+ and Cr2O72-. The CP 1 exhibited superior selectivity and sensitivity than 2 with limit of detection (LOD) 1.732×10-5 M and 5.996×10-6 M against Fe3+ and Cr2O72- respectively. Interestingly, the emissive behaviour of 1 get restored on adding 2-hydroxybenzoic acid (2-hyd acid) (turn on) due to the competitive formation of 2-hyd acid @Fe3+ or 2-hyd acid@Cr2O72- and concomitant release of 1. The fluorescence recovery selectivity of 2-hyd acid over other antioxidants has been attributed to the synergistic effect of high EHOMO value and a small space steric hindrance. The sensing properties of the MOF have been addressed with the help of Hirshfeld surface and density functional theory analyses.

Fluorescent Iron-Doped Polymer Dot Nanozyme-Based Cascade System for Dual-Mode Detection of Acetylcholinesterase Activity and Its Inhibitors.

The advancement of acetylcholinesterase (AChE) activity and its inhibitor assays is crucial for clinical diagnosis, drug screening, and environmental monitoring. A nanozyme-mediated cascade reaction system could offer promising prospects for a wide range of applications in such biosensing; however, the creation of nanozyme catalysts with diverse functionalities remains a significant challenge. Herein, we have proposed a multifunctional iron-doped polymer dots (Fe-PDs) nanozyme possessing excellent fluorescence and peroxidase (POD)-mimicking activity. Notably, the Fe-PDs nanozyme is capable of catalyzing H2O2 to produce a series of reactive oxygen species, which can simultaneously quench the fluorescence of Fe-PDs and induce a chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB), enabling the dual-mode detection of H2O2 through both fluorescence turn-off and absorbance turn-on signals. Furthermore, by integrating acetylcholine (ACh) and choline oxidase (ChOx), we have developed a three-enzyme (AChE-ChOx-POD) cascade-based fluorometric and colorimetric dual-mode sensing platform for monitoring AChE activity and its inhibitors. The sensitive and convenient dual-mode sensor has achieved low limits of detection with 0.5 mU/mL (fluorometry) and 0.014 mU/mL (colorimetry) for AChE, respectively, which are superior to the traditional Ellman's assay. More significantly, this sensor can also be extended to detect the reversible and irreversible inhibitors of AChE, such as tacrine (IC50 = 23.3 nM) and carbaryl (LOD = 0.8 nM). We firmly believe that this innovative dual-mode nanozyme-involved multienzyme cascade system-based sensing strategy will stimulate further exploration and serve as a versatile and practical tool for biochemical sensing applications.

A Visible-Light-Responsive Fluorescent Diarylethene Having a Betaine Structure.

As a new molecular scaffold of photoswitchable fluorophore, we developed a photochromic diarylethene containing a betaine structure based on pyridinium N-enolate. A facile reaction of a pyridyl-substituted dithienylperfluorocyclopentene derivative with octafluorocyclopentene constructed the betaine structure. The introduction of the betaine moiety provided the diarylethene molecule with bathochromically shifted optical absorption and fluorescing ability, thus enabling the molecule to function as a visible-light-sensitive turn-off mode photoswitchable fluorophore. The molecule in the open-ring form emitted bright blueish green fluorescence. Upon irradiation with 405 nm light, the molecule underwent cyclization isomerization to form the closed-ring isomer and the fluorescence intensity significantly decreased. The turn-off mode fluorescence photoswitching was observed not only in solution but also in polymer films.

Click Chemistry Derived Hexa-ferrocenylated 1,3,5-Triphenylbenzene for the Detection of Divalent Transition Metal Cations.

The 1,3-dipolar cycloaddition reaction (click chemistry approach) was employed to create a hexa-ferrocenylated 1,3,5-triphenylbenzene derivative. Leveraging the presence of metal-chelating sites associated with 1,2,3-triazole moieties and 1,4-dinitrogen systems (ethylenediamine-like), as well as tridentate chelating sites (1,4,7-trinitrogen, diethylene triamine-like) systems, the application of this molecule as a chemosensor for divalent transition metal cations was investigated. The interactions were probed voltammetrically and spectrofluorimetrically against seven selected cations: iron(II) (Fe2+), cobalt(II) (Co2+), nickel(II) (Ni2+), copper(II) (Cu2+), zinc(II) (Zn2+), cadmium(II) (Cd2+), and manganese(II) (Mn2+). Electrochemical assays revealed good detection properties, with very low limits of detection (LOD), for Co2+, Cu2+, and Cd2+ in aqueous solution (0.03-0.09 μM). Emission spectroscopy experiments demonstrated that the title compound exhibited versatile detection properties in solution, specifically turn-off fluorescence behavior upon the addition of each tested transition metal cation. The systems were characterized by satisfactory Stern-Volmer constant values (105-106 M-1) and low LOD, especially for Zn2+ and Co2+ (at the nanomolar concentration level).

Dehydro acetic acid analogue Schiff base as multimode fluorescence chemosensors for Th4+ and Ni2+ ions and its application to in-vivo bioimaging

Dehydroacetic acid analogue (DHA) and 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide (COM) Schiff base ligand (COM-DHA)as dual-mode fluorescence chemosensorwas synthesized and structurally characterised by using elemental analysis, FTIR, NMR, and Mass analysis. The free probe COM-DHA shows distinct fluorescence emission at 476 nm, upon interaction with Ni2+ the emission intensity was quenched and with Th4+ the emission intensity was redshirted to 500 nm. Further, the ratiometric fluorescence change (I500/I476) was used to detect Th4+, and a turn-off fluorescence probe COM-DHA at 476 nm was used to detect Ni2+ ions. The COM-DHA forms a 2:1 stoichiometric complex with both Ni2+/Th4+ ions with an estimated association constant of 4.84 × 104 and 6.68 × 104 M−2 respectively. A further probe COM-DHA is that it has a wide working pH range (5 to 10) with a short response time (2 to 3 min). The detection limit of COM-DHA towards Ni2+ and Th4+ was found to be 77.8and 48.7 nM, respectively. The, DFT/TD-DFT calculations and FTIR analysis were used to study the binding mechanism between COM-DAH and Ni2+/Th4+ ions. Furthermore, the proposed probe COM-DHAhas successfully quantified trace amounts of Ni2+ and Th4+in real samples and applied them to the in-vivo bioimaging of Th4+ in C. elegans model.

Design and synthesis of high quantum yield doped carbon nano probe derived from household sources for sensing of the anti-GERD drug pantoprazole

This contribution aims to design and validate a new green, cheap, and fast approach for determining the anti-GERD drug pantoprazole in different matrices. New S and N-doped carbon nanomaterials (S,N-CNMs) have been prepared via microwave irradiation of a mixture of widely available household sources. Remarkably, the utilization of a blend of carbamide and thiocarbamide with table sugar yields S,N-CNMs exhibiting the utmost quantum yield (54 %), hydrophilicity, as well as stable, homogeneous, and diminutive particle size distribution. Fourier transform infrared spectroscopy, transmission electron microscopy, spectrophotometry, and fluorescence spectroscopy were applied to characterize the S,N-CNMs. The S,N-CNMs have been used as a turn-off fluorescence probe to determine pantoprazole via a synergism of the inner filter effect and static quenching mechanisms. The fluorescence quenching is linearly correlated to pantoprazole concentration over the range of 1.0–25.0 µg/mL with a detection limit of 0.16 µg/mL. The developed probe exhibited good selectivity for pantoprazole in the presence of variability of substances. Therefore, it was applied for quality control of pantoprazole in pharmaceutical tablets and vials with an average recovery % of 100.10 ± 0.77 % and 100.33 ± 0.92 %, respectively. Moreover, it was successfully implemented to examine the content uniformity of pantoprazole in tablets. Furthermore, the prepared S,N-CNMs have been successfully used for the analysis of pantoprazole in human plasma after a simple protein precipitation step with a recovery % of 97.88 ± 5.72 %. The greenness and blueness of the developed method have been positively assessed by recent tools showing the eco-friendliness and applicability of the developed method.

A Highly Efficient Fluorescent Turn-Off Nanosensor for Quantitative Detection of Teicoplanin Antibiotic from Humans, Food, and Water Based on the Electron Transfer between Imprinted Quantum Dots and the Five-Membered Cyclic Boronate Esters.

Teicoplanin has been banned in the veterinary field due to the drug resistance of antibiotics. However, teicoplanin residue from the antibiotic abuse of humans and animals poses a threat to people's health. Therefore, it is necessary to develop an efficient way for the highly accurate and reliable detection of teicoplanin from humans, food, and water. In this study, novel imprinted quantum dots of teicoplanin were prepared based on boronate affinity-based precisely controlled surface imprinting. The imprinting factor (IF) for teicoplanin was evaluated and reached a high value of 6.51. The results showed excellent sensitivity and selectivity towards teicoplanin. The relative fluorescence intensity was inversely proportional to the concentration of teicoplanin, in the range of 1.0-17 μM. And its limit of detection (LOD) was obtained as 0.714 μM. The fluorescence quenching process was mainly controlled by a static quenching mechanism via the non-radiative electron-transfer process between QDs and the five-membered cyclic boronate esters. The recoveries for the spiked urine, milk, and water samples ranged from 95.33 to 104.17%, 91.83 to 97.33, and 94.22 to 106.67%, respectively.

Sensing features, on-site detection and bio-imaging application of a tripodal tris(hydroxycoumarin) based probe towards Cu2+/His

A new tripodal tris(hydroxycoumarin) based Schiff base, HCTN was synthesized and characterized by FT-IR, 1H NMR, 13C NMR and ESI-HRMS. The probe, HCTN exhibits cyan emission in DMSO/HEPES buffer (9:1, v/v) which selectively detects Cu2+ ion via turn-off fluorescence. The quenching of the fluorescence was due to the binding of the probe, HCTN towards paramagnetic Cu2+ ion resulting in chelation enhanced quenching effect (CHEQ). From the spectroscopic results, the limit of detection of Cu2+ ion was obtained as very low as 0.40 × 10−9 M. The complexation of the metal ion, Cu2+ towards the probe HCTN was confirmed by the ESI-HRMS and Job’s plot analysis which supports 1:1 binding stochiometric ratio. In order to validate the affinity of Cu2+ ion towards histidine, the HCTN+Cu2+ system was utilized for the detection of histidine via turn-on mode by the metal displacement approach. The detection limit of His was found to be 7.31 × 10−10 M. In addition to the above, the probe was utilized for various detection applications such as paper strips, cotton swabs, logic gates and thin film applications. The probe, HCTN extends its application to the confocal bioimaging to sense the Cu2+ and Histidine intracellularly.

A 1,8-Naphthalimide-based Tripodal Fluorescent Chemosensor to Selectively Detect Copper Ions.

A 1,8-naphthalimide-based tripodal fluorescent ligand (L3) was synthesized through the copper (I) catalyzed Huisgen azide-alkyne cycloaddition reaction of 2-(2-azidoethyl)-6-morpholino-1H-benzo[de]isoquinoline-1,3(2H)-dione with triproparagylamine. Naphthalimide acts as the fluorophore while the triazole and amine nitrogens chelate the metal ion. L3 showed a selective fluorescence turn-off for Cu(II) over other metal ions in aqueous acetonitrile solution. A Job's plot, Benesi-Hildbrand plot and high-resolution mass spectrometry data confirm a 1:1 binding stoichiometry with a binding constant of 7.8 х105 M- 1 while addition of disodium EDTA demonstrates its reversibility. The structure and stability of the complex was supported by theoretical calculations. The limit of detection for Cu(II) was calculated to be 0.3 µM which is considerably lower than WHO recommended Cu(II) limit in drinking water.

Fluorescent Turn-off Probe of Ni2+ Based Nitrogen-Doped Carbon Dots

ABSTRACT: An effective and facile method of generating nitrogen-doped carbon dots (N-CD) by microwave irradiation is presented in this study. A precursor, succinic acid (SA), and a nitrogen source, bis-(3-aminopropyl)-amine (BAPA), were used to obtain N-CD. A precious quantum yield (QY) of 49.0% was obtained from the preparation of N-CD, which was well-soluble in water. The N-CD material was highly selective and sensitive for the detection of nickel ion (Ni2+), with a detection limit of 0.26 μM and a linear concentration range of 5-175 μM. The quenching of the N-CD by the presence of Ni2+ was referred to formation of complexes because of the interaction of Ni2+ on the N-CD. Hence, the proposed study has great promise regarding Ni2+ detection in broad applications. Keywords: Microwave, Ni2+, nitrogen-doped carbon dots.

Green synthesis of copper nanoclusters using Cissus quadrangularis leaves extract and cysteine as cooperative ligands for the detection of Fe3+ ion and 2,6-dipicolinic acid in biofluids via fluorescence turn off–on mechanism

An off–on fluorescent sensor is devised by using greenish-blue light-emitting Cissusquadrangularis-cysteine-CuNCs (C. quadrangularis-Cys-CuNCs) for the rapid, precise, and recognition ofFe3+ ion and 2,6-dipicolinic acid (DPA). The structure, size, surface functionalities and oxidation state of the elements present in C. quadrangularis-Cys-CuNCs are confirmed by high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopic and X-Ray diffraction (XRD) techniques. The as-synthesized C. quadrangularis-Cys-CuNCs exhibited λEm/Ex at491/370 nm. The fluorescence intensity ofC. quadrangularis-Cys-CuNCs was reduced selectively to 63 % by Fe3+, however it was restored with the addition of DPA. This method exhibited the limits of detection (LODs) of 0.125 and 0.38 μM for Fe3+ and DPA, respectively. The C. quadrangularis-Cys-CuNCs based fluorescence turn-off–on sensing platform showed remarkable performance for the analyses of Fe3+ ion and DPA in real samples, revealing great potentiality of the method for practical applications.

Fluorescent and colorimetric dual-mode chemosensor for easy detection of Cu2+: Practical and smartphone-based application to test strip and water sample

A fluorescent and colorimetric dual-mode chemosensor HNHQ, based on the julolidine and naphthol moieties, was synthesized. Compound HNHQ exhibited unique photophysical properties of an intense fluorescence with a high quantum yield (Φ = 0.363) and a light yellow color through the ICT mechanism. HNHQ could detect Cu2+ through both a fluorescence turn-off and a colorimetry variation of light yellow to yellowish brown. HNHQ reacted with Cu2+ with a binding ratio of 1:1. The detection limit for Cu2+ was analyzed to be 1.60 μM for fluorescence and 1.32 μM for UV–vis, considerably below the safe value of 31.5 μM established by the World Health Organization (WHO). HNHQ analyzed Cu2+ in the pH range of 6–8 and reversibly identified Cu2+ by using ethylenediaminetetraacetic acid (EDTA). Moreover, HNHQ could effectively detect Cu2+ in mineral and tap water samples, in addition to test strips through fluorescent and colorimetric changes. As a portable probe, HNHQ was successfully applied to a smartphone-based RGB analysis for the quantitative examination of Cu2+. The detection mechanism of HNHQ for Cu2+ was illustrated by 1H NMR titration, ESI-MS analysis, and density functional theory (DFT) calculations.

L-tryptophan-assisted anthracene functionalization for copper-induced fluorescence Turn-off and controlled supramolecular nano-assembly

A fluorescent chemosensor, l-Tryptophan-assisted Anthracene conjugate (1), has been designed and developed. 1 is highly selective and sensitive for detecting Cu(II) ions through a fluorescence "turn-off" mechanism, even in a competing environment with a high detection limit of 9.4 × 10−6 M. The smaller spherical nano-assembly transforms into larger spherical nano-assembly upon incubation with Cu(II) ions, highlighting the metal-induced morphological transformation of nano-assemblies.

N-rich carbon nanosphere as fluorescent nanoprobe for intracellular iron

Nitrogen rich carbon nanoparticles are known to provide higher fluorescence stokes shift, and thereby are potential candidates for fluorescent sensors. Herein, a facile one-step hydrothermal synthesis is reported for N-rich carbon nanospheres (G-CNS) from caffeine and o-phenylenediamine as precursors. The as-synthesized G-CNS showed high fluorescence with λem at 509 nm, with a highly selective fluorescence turn-off response towards Fe2+/Fe3+, rendering these carbon nanospheres as potential candidates to detect intracellular labile iron pool in live cells. The intracellular labile iron pool in iron-overloaded cells was sensed using the synthesized G-CNS. Mechanistically, the fluorescence quenching via dynamic pathway involves the formation of an excited state charge transfer process, which undergoes non-radiative decay.

Fluorescent detection of nitrofuran antibiotics with a recordly brilliant covalent organic framework

The antibiotic residues in the water have serious effects on ecological security despite its importance for human in countering bacterium infection. The effective detection of antibiotics in drinking water could give fast, accurate diagnostic evidence, and help prevent antibiotic contamination. Herein, we report a novel fluorescent covalent organic framework (TAPA-BTD-COF) for the highly effective detection of nitrofuran antibiotics. TAPA-BTD-COF is synthesized by condensation of benzothiadiazole and tris(4-aminophenyl) amine. It exhibits an extremely strong blue fluorescence and has a record absolute fluorescence quantum yield (PLQY) in organic solvents. Besides, the COF had strong light-absorption. These properties rendered it very brilliant fluorescence, which is convenient for achieving fluorescent sensing applications. TAPA-BTD-COF exhibited efficient turn-off fluorescence response to four different kinds of nitrofuran antibiotics. Moreover, TAPA-BTD-COF fluorescence sensor exhibited a fast response to nitrofuran antibiotics with a wide detection range and linear relationship, with satisfactory LOD of 0.10 μM. And the rapid response can be achieved within 10 s. Real samples of three kinds of different water and three different kinds of meat were analyzed by adding standard recovery test. The experimental results indicated that the fluorescent sensor exhibited paralleled excellent recovery in comparison with ISO standard liquid-chromatography method. Besides, IR and XPS experiments were conducted to investigate the underlying mechanism for this efficient fluorescence sensing. The results revealed a static quenching mechanism by forming electron donor–acceptor adducts between COF sensor electron-rich triphenylamine group and nitrofuran antibiotics electron-deficient nitrofuran groups.