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.

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.

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

Aggregation-induced emission (AIE) active 3-(3-(benzo[d]thiazol-2-yl)-2-hydroxyphenyl)-2-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)acrylonitrile (BTPA) has been designed and synthesized herein, with the goal of detecting CN^- ions at a low-level in semi-aqueous medium. The deliberate addition of the electron-deficient alkene BTPA increased its sensitivity and selectivity to CN^- ions, with a better detection limit of 6.4 nM, unveiling the next-generation approach to creating sophisticated CN^- ions selective chemosensors. The ESI-MS and NMR spectra analyses provided strong support for the structures of the chemosensors, while the UV-Vis, photoluminescence, and ¹H-NMR titration experiments provided support for the sensing efficiencies. Subsequently, PVDF/BTPA electrospun nanofibers have been effectively produced as functional films. These nanofiber films exhibit outstanding mechanical strength, photo/thermal stability, and optical responsiveness to CN^- ions, making them a potential choice for on-field emerging contaminant detection.

A novel phenanthridine and terpyridine based D-π-A fluorescent probe for the ratiometric detection of Cd2+ in environmental water samples and living cells

A "turn-on" Donor-π-Acceptor (D-π-A) containing phenanthridine-functionalized extended π-conjugate terpyridine, 5-(4'-([2,2':6',2''-terpyridin]-4'-yl)-[1,1'-biphenyl]4-yl)7,8,13,14-tetrahydrodibenzo [a, i] phenanthridine (TBTP) was synthesised. It shows strong selectivity for the detection of toxic Cd²⁺ without interference from other metal ions. In the presence of Cd²⁺, the absorption of the TBTP changes dramatically along with the fluorescent emission with the large Stokes shift of 6300 cm^-1. When the compound TBTP is exposed to UV light, its colour changes from blue to orange over the addition of Cd²⁺. Adding other transition metal ions has no effect. This is based on the mechanism of intramolecular charge transfer. The detection limit for Cd²⁺ was found to be around 1.181 × 10^-8 M. An investigation of the sensing mechanism includes job plot, NMR titration, DFT calculation, and HRMS analyses. Excitingly, the recognition of Cd²⁺ in CH₃CN: H₂O (8:2, v/v) medium is quantitative without interference from Zn^2+, which is a common interferent for Cd²⁺. Furthermore, the probe was used for detecting Cd²⁺ in real water samples and cell imaging in living cells was also performed.

Benzothiazole appended 2,2'-(1,4-phenylene)diacetonitrile for the colorimetric and fluorescence detection of cyanide ions

A benzothiazole appended 2,2'-(1,4-phenylene)diacetonitrile derivative (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(3-(benzo[d]thiazol-2-yl)-4-hydroxyphenyl)acrylonitrile) (PDBT) has been synthesized and investigated as a novel sensor, capable of showing high selectivity and sensitivity towards CN^- over a wide range of other interfering anions. After reaction with CN^-, PDBT shows a new absorption peak at 451 nm with a color transformation from colorless to reddish-brown. When yellow fluorescent PDBT is exposed to CN^-, it displays a significant increase in fluorescence at 445 nm, resulting in strong sky-blue fluorescence emission. The nucleophilic addition reaction of CN^- plays a role in the sensing mechanism of PDBT to CN^-. PDBT can distinguish between a broad variety of interfering anions and CN^- with remarkable selectivity and sensitivity. Furthermore, the detection limit of the PDBT probe for CN^- is 0.62 μM, which is significantly lower than the WHO standard of 1.9 μM for drinking water. Density functional theory simulations corroborated the observed fluorescence changes and the internal charge transfer process that occurs after cyanide ion addition. In addition, real-time applications of PDBT, such as cell imaging investigations and the detection of CN^- in water samples, were successfully carried out.

Zinc ion detection using a benzothiazole-based highly selective fluorescence "turn-on" chemosensor and its real-time application

A new photochromic fluorescence chemosensor was devised and effectively synthesized using benzothiazole and imidazopyridine derivatives. A "turn-on" fluorescence sensor BIPP for Zn²⁺ detection was developed and has a quick response, excellent sensitivity, and remarkable selectivity over other metal ions. When Zn²⁺ was added to the BIPP solution, a new strong fluorescence emission peak at 542 nm formed with a considerable increase in intensity. The fluorescence color of the BIPP solution changed from blue to bright green. The binding ratio 8 : 2 was found between BIPP and Zn²⁺ by the results of Job's plot, HRMS and ¹H-NMR. The detection limit (LOD) of BIPP towards Zn²⁺ was determined to be 2.36 × 10^-8, which is remarkably low. The ability to detect Zn²⁺ in real water samples demonstrates that BIPP may also be used in environmental systems. Additionally, BIPP can be used to measure Zn²⁺ levels in living cells.

A benzothiazole-based new fluorogenic chemosensor for the detection of CN− and its real-time application in environmental water samples and living cells

Since the cyanide ion is used in a wide range of industries and is harmful to both human health and the environment, a number of research efforts are dedicated to creating fluorescence sensors for the detection of cyanide (CN⁻). Herein, for the fluorescence detection of CN⁻, a new highly selective and sensitive sensor 2-(3-(benzo[d]thiazol-2-yl)-4-hydroxybenzylidene)-1H-indene-1,3(2H)-dione (BID) was created by conjugating a benzothiazole moiety with 1H-indene-1,3(2H)-dione. The donor and acceptor components of this hybrid receptor were covalently connected through a double bond. The nucleophilic addition of a cyanide anion to the BID inhibits the intramolecular charge transfer (ICT) transition, resulting in spectral and colour alterations in the receptor. When the solvent polarity was increased from n-hexane to methanol, this molecule exhibited a bathochromic shift in the emission wavelength (610 to 632 nm), suggesting the presence of a solvatochromic action. The sensor BID has shown strong specificity towards CN⁻ by interrupting its internal charge transfer (ICT), resulting in a significant change in the UV-vis spectrum and a notable blue shift in the fluorescence emission spectrum. The cyanide anion (CN⁻) is responsible for the optical alterations observed by BID, as opposed to the other anions examined. The detection limit was 5.97 nM, significantly less than the WHO's permitted amount of CN⁻ in drinking water. The experimental findings indicate that BID's fluorescence response to CN⁻ is pH insensitive throughout a wide pH range of 6.0 to 12.0. The interaction mechanism between the BID and CN⁻ ions has been studied by HRMS, ¹H-NMR titration experiments, FT-IR, and DFT, which confirmed the nucleophilic addition of CN⁻ on vinylidene and subsequent disturbance of ICT. Additionally, we demonstrated the real-time detection application of CN⁻ in environmental water samples and live-cell imaging.

Since the cyanide ion is used in a wide range of industries and is harmful to both human health and the environment, a number of research efforts are dedicated to creating fluorescence sensors for the detection of cyanide (CN⁻).

A phenanthridine-based probe for selective detection of hypochlorite ions

A novel oxime-based fluorescent chemosensor (E)-2-(4′-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)-[1,1′-biphenyl]-4-yl)ethen-1-ol (PBO) has been developed for the fluorimetric detection of hypochlorite ion (OCl−).