AIE active luminous dye with a triphenylamine attached benzothiazole core as a portable polymer film for sensitively detecting CN- ions in food samples

A triphenylamine-based aggregation-induced emission active fluorescent probe for fluorescent ink, fingerprint powder, and visual detection of salmon freshness

BACKGROUND

Multifunctional fluorescent probes have attracted much attention due to their wide range of applications and high utilization. In this study, a multifunctional fluorescent probe (E)-3-(4-(7-(4-(diphenylamino)phenyl)benzo[c] [1,2,5]thiadiazol-4-yl)phenyl)acrylic acid (TBAC) based on triphenylamine was designed and synthesized.

RESULTS

The TBAC probe provided excellent aggregation-induced emission (AIE) performance and could be used as a fluorescent ink for printing. It was also prepared successfully for application as a fingerprint powder, facilitating the visual detection of invisible fingerprints on surfaces such as glass, plastic, tinfoil, metal, aluminum, and resin. The probe exhibited a clear fluorescence response to 12 volatile amines via an AIE-based 'on-off' mechanism in an EtOH/H2O (4/6, v/v) solution. The TBAC/bromocresol green (BCG) indicator label also enabled non-destructive and rapid assessment of salmon freshness through dual-channel colorimetric and fluorescence responses.

CONCLUSION

The versatility of TBAC makes it a promising material for various applications, including fluorescent materials, criminal detection, and food safety. This study provides a new basis for the multifunctional application of fluorescent probes. © 2025 Society of Chemical Industry.

Coumarin Linked Cyanine Dye for the Selective Detection of Cyanide Ion in Environmental Water Sample

A benzoxazole-coumarin-based probe BOC, was synthesized and validated for its anion sensing ability and found to be effective in recognizing cyanide ions. Upon addition of cyanide, a spontaneous color change was observed that was visible to the naked eye. The sensitization process takes place with nucleophilic addition, and the cyanide ion added to the probe disrupts the intra molecular charge transfer transition (ICT) between the donor and acceptor units, causing the pink colored probe to become yellow. Ultraviolet and fluorescence methods were applied to measure the detection limits of probes with added cyanide ions, which were found to be 3.47 µM and 2.48 nM. The stoichiometry of the probe with the cyanide ion was determined by the Job's method, NMR titration, and mass spectrometry and was found to be in a 1:1 ratio. The results obtained from the visual and UV-visible spectral studies are justified by theoretical calculations. The cyanide-loaded probe induced visual changes, which enabled the development of a test strip for field application, and the prepared strip can be used to detect the ppm level of cyanide in water samples. The developed probe, BOC, can be used to detect cyanide ions in various water samples.

Recent Advances in Fluorescent Based Chemical Probes for the Detection of Perchlorate Ions

This review highlights recent advancements and challenges in fluorescence-based chemical sensors for selective and sensitive detection of perchlorate, a persistent environmental pollutant and global concern due to its health and safety implications. Perchlorate is a highly persistent inorganic pollutant found in drinking water, soil, and air, with known endocrine-disruptive properties due to its interference with iodide uptake by the thyroid gland. Human exposure mainly occurs through contaminated water and food. Additionally, perchlorates are prevalent in improvised explosives, causing numerous civilian casualties, making their detection important in a worldwide aspect. Fluorescence-based chemical sensors provide a valuable tool for the selective detection of perchlorate ions due to their simplicity and applicability across various fields, including biology, pharmacology, military, and environmental science. This review article overviews perchlorate chemistry, occurrence, and remediation strategies, compares regulatory limits, and examines fluorescence-based detection mechanisms. It systematically summarizes recent advancements in designing at least a dozen fluorescence-based chemical materials for detecting perchlorate in the environment over the past decade. Key focus areas include the design and molecular architecture of synthetic chemical chromophores for perchlorate sensing and the photochemistry mechanisms driving their effectiveness. The main findings indicate that there has been significant progress in the development of reliable and robust fluorescence-based sensors with higher selectivity and sensitivity for perchlorate detection. However, several challenges remain, such as improving detection limits and sensor stability. The review outlines potential future research directions, emphasizing the need for further innovation in sensor design and development. It aims to enhance understanding and spur advances that could create more efficient and robust chemical scaffolds for perchlorate sensing. By addressing current limitations and identifying opportunities for improvement, the review provides a comprehensive resource for researchers working to develop better detection methods for this significant environmental pollutant.

AIE Active Imidazole-Stilbene Conjugated Fluorescent Probes: Illuminating Latent Fingerprints and Advancing Anticounterfeiting Technologies

Aggregation-induced emission luminogens (AIEgens) are widely used in the realm of latent fingerprint visualization owing to their luminosity and resistance to photobleaching. However, challenges such as significant background interference and limited resolution hinder their rapid advancement. Consequently, there is a pressing need to improve the detailed visualization of latent fingerprint (LFP) imaging, particularly for analyzing level 3 details. To address this, we have designed donor-acceptor (D-A) type AIEgens named MMIMV, DMIMV, and TMIMV. These compounds exhibit robust emissions ranging from 481 to 552 nm and signify positive fluorosolvatochromism. When applied as powder dusting, these derivatives enable the fluorescence imaging of LFPs on various material substrates. The analysis of these imaged LFPs yields intricate details regarding fingerprint ridge patterns. Our results underscore the potential of highly emissive AIEgens MMIMV, DMIMV, and TMIMV as promising candidates for fingerprint visualization, thus offering significant implications for forensic investigations. Furthermore, these derivatives serve as effective fluorescent security inks for writing and drawing, presenting a novel avenue for robust anticounterfeiting applications.

Methoxyquinolone-Benzothiazole Hybrids as New Aggregation-Induced Emission Luminogens and Efficient Fluorescent Chemosensors for Cyanide Ions

This work describes the synthesis and characterization of new quinolone-benzothiazole hybrids, the study of their aggregation-induced emission (AIE) properties, and the use of these systems as efficient fluorescent probes for cyanide ions. These conjugated derivatives are linked through a double bond favoring electronic communication, and together with their planar geometry, can strongly aggregate under solvophobic environments, leading to aggregation and exhibiting significant AIE behavior. The double bond between electroactive units is prone to nucleophilic addition reactions by cyanide ions, selectively, conducive to turning off the fluorescence properties, making this hybrid system an efficient probe for cyanide ions. These studies were theoretically explained using DFT and TD-DFT calculations.

D-π-A-π-D-Configured Imidazole-Tethered Benzothiadiazole-Based Sensor for the Ratiometric Discrimination of Picric Acid: Applications in Latent Fingerprint Imaging

A tetraphenyl imidazole-appended benzothiadiazole-based fluorogenic probe (4,7-bis(4-(1,4,5-triphenyl-1H-imidazol-2-yl)phenyl)benzo[c][1,2,5]thiadiazole (BIPT)) has been successfully synthesized and characterized by NMR and high-resolution mass spectrometry (HRMS) spectral analyses. A low limit of detection (LOD) can be achieved to detect picric acid (PA; 7.89 nM). When benzothiadiazole acceptors are incorporated in the D-A-D probe, it can produce a large Stokes shift (206 nm) as a result. Fascinatingly, the fluorescence signals of BIPT were ratiometrically induced by the interaction with PA and exhibited an apparent emission shift from pink to green. The detection process of BIPT is triggered by an intermolecular charge transfer process, as the charge transfer takes place from the electron-rich imidazole to the electron-deficient PA. Moreover, fluorescence detection of PA has been employed in paper strips. Advantageously, sensor BIPT can potentially be applied to contact mode and real-time detection of PA in environmental water samples. Additionally, the BIPT sensor has been successfully employed for latent fingerprint imaging. The study provides clear insights into the rational design of chemosensors for sensing and real-time applications.

An α-benzithiazolyl 3-pyrrolyl BODIPY probe for ratiometric selective sensing of cyanide ions and bioimaging studies

A simple chromo-fluorogenic chemodosimeter probe, α-benzithiazolyl 3-pyrrolyl BODIPY, was synthesized by reacting α-formyl 3-pyrrolyl BODIPY with 2-aminothiophenol in DMF at reflux under basic conditions. The probe was structurally characterized by X-ray, HR-MS, and 1D & 2D NMR techniques. The X-ray structure revealed that the appended pyrrole was almost in the plane with a small deviation of 12.15° from the 12-atom mean plane of the BF2-dipyrrin core and the benzithiazolyl moiety was also deviated by 18.74° from the BF2-dipyrrin core. The α-benzithiazolyl 3-pyrrolyl BODIPY exhibits one intense absorption band at 608 nm and a less intense band at 412 nm corresponding to the 3-pyrrolyl BODIPY and benzithiazolyl moiety, respectively. The strongly fluorescent probe shows one intense emission band at 637 nm with a quantum yield of 0.48. The probe acted as an exclusive colorimetric and chemodosimetric sensor for CN- ions over other anions with high sensitivity (LOD = 13 nM) and quick response time (10 s) in an aqueous CH3CN medium. The CN- ion attacks the imine group of the benzithiazolyl moiety of 3via a nucleophilic addition reaction and converts the sp2 to sp3 carbon which disrupts the conjugation between the 3-pyrrolyl BODIPY and benzithiazolyl moieties, which is reflected in the clear colour change from red fluorescence to blue fluorescence as well as significant changes in the spectral and electrochemical properties. The detection of cyanide with the probe for biological applications was also performed with plant tissue. DFT/TD-DFT studies were in agreement with the experimental observations.

A thiophene-linked terpyridine based phenanthridine chemoreceptor for Cd2+ and Cr3+ selective ratiometric fluorescence detection in environmental water and rice samples

BACKGROUND

The studied materials, Cadmium (Cd2+) and Chromium (Cr3+) are highly toxic, and it focuses on investigating various environmental sources, such as industrial processes and waste water. When quantities of Cr3+ and Cd2+ exceed the allowable limit, biological toxicity and hazardous environmental pollution are unavoidable. In order to address this problem, we introduce 5-(5-(4-([2,2':6',2″-terpyridin]-4'-yl) phenyl) thiophen-2-yl)-7,8,13,14-tetrahydrodibenzo [a,i] phenanthridine (TPTP), a dual-emission response chemosensor that employs a colorimetric and fluorescence turn-on approach for the rapid, sensitive, and discriminate detection of Cr3+ and Cd2+ ions.

RESULTS

We created a newly designed luminous TPTP sensor based on intramolecular charge transfer (ICT). TPTP sensor probe specifically determined Cr3+ and Cd2+ ions with an immediate colour shift from cyan to green and orange in CH3CN: H2O (6:4) solvent solution. The permissible level set by the Environmental Protection Agency (EPA) of the United States for the presence of Cr3+ and Cd2+ ions in drinking water was higher than the detection level of 3.5 and 9.7 nM, by this sensor respectively. NMR titrations, HRMS, and theoretical calculation methods were employed to examine the accurate sensing processes of TPTP and complexes.

SIGNIFICANCE

This is an effective method of detecting Cr3+ and Cd2+ ions in an environmental system using a ratiometric methodology. In addition, TPTP was used to determine the concentration of Cr3+ and Cd2+ ions in natural water and food samples. Fluorescent bio-imaging studies revealed that the present sensor TPTP could identify Cr3+ and Cd2+ ions inside living HeLa cells. A paper kit analysis has been done on TPTP, which has a time-to-result of less than 1 s and offers a cost-effective assay. As a result, the platform offers portability.

Fluorescence-based ratiometric sensors as emerging tools for CN- detection: Chemical structures, sensing mechanisms and applications

Hazardous cyanide anions (CN-) are increasingly threatening the environment and human health due to their widespread use in industry and many other fields. Over the past three decades, a large number of probes have been reported to sensitively and selectively detect this toxic anion, while a rather limited number of ratiometric fluorescent probes have been developed. The ratiometric probes have significant potential in bio-imaging and biomedical applications because of the ability to detect CN- in a quick, convenient and affordable way. In this review, we introduce 42 ratiometric fluorescent probes reported in the past 6 years (2018-2023) for CN- detection. Our description includes the chemical structures, photo-physical properties, CN- sensing mechanisms, solution color changes, limits of detection (LODs) and/or various applications of these chemical probes. This review provides guidelines for design and development of a new ratiometric probe for effective CN- detection.

The catalyst free synthesis of dibenzo[a,j]acridine and its applications in bioimaging of BF3 in HeLa cells

In this paper, we discuss how tetrahydrodibenzo[a,j]acridine (4-HA) loses its hydrogen, which makes dibenzo[a,j]acridine (ARM) and also how 4-HA can be synthesized effectively using 2-tetralone in high yield. Dehydrogenative condensation and dehydrogenation are the two processes that make up the overall reaction of this synthetic approach. In addition, the presence of BF3 caused a remarkable fluorescence shift in ARM. Test paper analysis was used for examining the practical usefulness of ARM, which can be seen under UV light, resulting in this unique phenomenon. The fluorescent bio imaging experiment demonstrates that the sensor ARM has the capability to detect BF3 in living HeLa cells.