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.

Development of tissue paper-based chemosensor and demonstration for the selective detection of Cu2+ and Hg2+ ions.

Heavy metals emanate from natural and man-made sources, such as agricultural chemicals including fertilisers and pesticides, medical waste, and chemicals released from industries. Detection and monitoring toxic metal ions is one of the challenges confronting scientists in biological, environmental, and chemical systems. This study describes the design and synthesis of a new imidazole-based fluorescent and colourimetric chemosensor (DPICDT) for highly selective sensing of Hg2+ and Cu2+ ions in aqueous acetonitrile medium. The probe was synthesised by coupling benzil and substituted aldehyde using ethanolic ammonium acetate. The structure of DPICDT was confirmed via IR spectra, NMR, and HR-MS spectra. The DPICDT probe displayed a rapid naked-eye response towards Cu2+ ions from colourless to red-purple and significant fluorescence quenching response towards Hg2+ over other competitive metal ions in both solution and solid support. The binding modes of DPICDT with Cu2+ and Hg2+ ions were found to be at a 1 : 1 ratio as determined using Job plot, ESI HR-MS, and the sensing mechanism was evolved by 1H NMR titrations, HR-MS spectra, and DFT calculations. The lower detection limit was 15.1 nM for Cu2+, eventually far less than the World Health Organization guideline for drinking water (Cu2+ - 31.5 µM) and 1.17 µM for Hg2+ (permissible concentration 2 ppb). Promisingly, the tissue paper-based DPICDT test strips and silica-supported DPICDT were developed and demonstrated for on-site application without resorting to expensive instruments.

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.

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.

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 Zn2+, 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.

A Pyrazolo Imine-based Colorimetric and Turn-on Fluorescent Sensor Probe for Determination of Hg2+ Ion and its Application in Test Paper Strips.

In this work, we synthesized diethylamino substituted pyrazolo imine (3) fluorescent probe for recognition of Hg2+ ion.The sensor probe 3 can detect Hg2+ by colorimetric method, and there is a 10-fold enhancement in fluorescence response. When the fluorescent probe bound with Hg2+ ion, turn-on fluorescence was observed via the coordination. Probe 3 has an excellent selectivity toward Hg2+ in the CH3 CN/H2 O (8:2, v/v) solution with low limit of detection and high binding association constant of 551 parts per billion (ppb) and 6.6067 × 106 m-1 for 3+Hg2+ , respectively. Furthermore, the formation of 3+Hg2+ complex with 1:1 binding mode was evidenced by Job's plot, 1 H NMR spectroscopy and Mass analysis. In addition, probe 3 is a feasible option to detect Hg2+ in various sources of water samples. Bio-imaging experiments have demonstrated that probe 3 can be used to monitor Hg2+ in Escherichia coli bacterial cell. The sensor 3 was also used for paper strip application to detect Hg2+ ion.

A sensitive and selective BINOL based ratiometric fluorescence sensor for the detection of cyanide ions.

A highly selective, novel BINOL based sensor BBCN has been developed for the fluorescent ratiometric detection of cyanide ions (CN-). The optical study revealed that BBCN exhibited unique spectral changes only with cyanide ions in the presence of other competing ions. Besides, an apparent fluorescent colour change from green to blue was observed. A clear linear relationship was observed between the fluorescence ratiometric ratio of BBCN and the concentration of CN- with a reasonably low detection limit (LOD) of 189 nM (507 ppb). The optical response was due to the nucleophilic addition of CN- to the dicyanovinyl group of the sensor, which compromises the probe's intramolecular charge transfer. This mechanism was well confirmed by Job's plot, 1H-NMR and ESI-MS studies. BBCN showed immediate spectral response towards (1 second) CN- and detection could be realized in a broad pH window. Furthermore, the practical utility of BBCN was studied by test paper-based analysis and the detection of CN- in various water resources.

Highly sensitive turn-off fluorescent detection of cyanide in aqueous medium using dicyanovinyl-substituted phenanthridine fluorophore.

Herein, the turn-off fluorescence sensor of 2-((4'-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)-[1,1'-biphenyl]-4-yl)methylene)malanonitrile (7) was developed for the recognition of CN- ions and studied using different spectroscopic techniques. The selective recognition of CN- ions by 7 was investigated via UV-vis spectroscopy and fluorescence studies in acetonitrile solvent, which exhibited an obvious color change from orange to colorless under 365 UV light. The sensor compound 7 possesses a high binding constant (K a) for CN- ions in the order of 5.22 × 106 M-1. The results from the interference studies revealed that probe 7 shows high sensing selectivity and sensitivity for CN- ions over other competitive anions. Probe 7 interacts with cyanide to form a 1 : 1 adduct, and this mechanism was further verified by 1H NMR titration, Job's plot analyses and DFT studies. The sensor probe 7 exhibits advantages such as low limit of detection (LOD) of 39.3 nM, fast response and sensing in a wide pH range of 3 to 11. The practical application of 7 was successfully demonstrated for the determination of CN- ions in test paper strips and various water samples.

Computational Approaches to Develop Isoquinoline Based Antibiotics through DNA Gyrase Inhibition Mechanisms Unveiled through Antibacterial Evaluation and Molecular Docking.

Developing a new antibacterial drug by using (Z/E)-4-(4-substituted-benzylidene)-2-isoquinoline-1,3(2H,4H)-diones (5a-h) via DNA gyrase inhibition mechanism is the main aim of this study. DNA gyrase inhibition assay was executed to confirm the DNA gyrase inhibition potentials of 5a-h. DNA gyrase inhibitory potentials were further validated through molecular docking. Docking study was also intended to get more insight into the binding mode of 5a-h into the active site of DNA gyrase A. Agar well diffusion method antimicrobial activity on Gram-ve bacteria Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424), and Gram+ve bacteria (Staphylococcus aureus (MTCC 96) and Streptococcus pyogenes (MTCC 442) was evaluated. Excellent DNA gyrase inhibition was exhibited by the compound 5c, IC50 0.55±0.12 µM; 5d, IC50 0.65±0.075 µg/mL; 5e, IC50 0.45±0.035 µM; 5f, IC50 0.58±0.025 µM; 5h, IC50 0.25±0.015 µM while Clorobiocin (standard) showed IC50 0.5±0.05 µM. Apart from all the in vitro studies, a plausible mechanism of DNA gyrase inhibition was also proposed through the in silico validations that are including molecular docking, predicted SAR, functional group availability, pharmacokinetic, and ADMET properties. These predictions are well supported to confirm the druggability possibility of the most potent compounds among (Z/E)-4-(4-substituted-benzylidene)-2-isoquinoline-1,3(2H,4H) -diones (5a-h).

Iodine catalyzed three component synthesis of 1-((2-hydroxy naphthalen-1-yl)(phenyl)(methyl))pyrrolidin-2-one derivatives: Rationale as potent PI3K inhibitors and anticancer agents.

A series of 1-((2-hydroxynaphthalen-1-yl)(phenyl)(methyl))pyrrolidin-2-one derivatives by an efficient iodine catalyzed domino reaction involving various aromatic aldehydes, 2-pyrrolidinone and ß-naphthol was achieved and the structures were elucidated by FTIR 1H NMR, 13C NMR, and HRMS. Subsequently they were evaluated for cytotoxicity against breast cancer (MCF-7), colon cancer (HCT116) cell lines. In the cytotoxicity, the relative inhibition activity was remarkably found to be high in MCF-7 cell lines as 79% (4c), 83% (4f) and the IC50values were 1.03µM (4c), 0.98µM (4f). Compounds 4a, 4e, 4k-m, and 4q were found to be inactive and rest showed a moderate activity. In order to get more insight into the binding mode and inhibitor binding affinity, compounds (4a-q) were docked into the active site phosphoinositide 3-kinase (PI3K) (PDB ID: 4JPS) which is a crucial regulator of apoptosis or programmed cell death. Results suggested that the hydrophobic interactions in the binding pockets of PI3K exploited affinity of the most favourable binding ligands (4c and 4f: inhibitory constant (ki)=66.22nM and 107.39nM). The SAR studies demonstrated that the most potent compounds are 4c and 4f and can be developed into precise PI3K inhibitors with the capability to treat various cancers.

Novel phenanthridine (PHE-4i) derivative inhibits carrageenan-induced rat hind paw oedema through suppression of hydrogen sulfide.

This study was conducted to assess the anti-inflammatory effect of a novel synthesized phenanthridine alkaloid (PHE-4i) and to examine the possible involvement of hydrogen sulfide (H2S) in anti-inflammatory mechanism. The synthesized phenanthridine derivative PHE-4i (2, 5, and 10 mg/kg) was administered intraperitoneally to rats. One hour following treatment, inflammation was induced by intraplantar injection of carrageenan (1 %), in the hind paw. Paw volume as the index of inflammation was measured before and after carrageenan injection. Neutrophil sequestration into the hind paw was quantified by measuring tissue myeloperoxidase (MPO) activity and was compared for the inhibition of H2S production. Pretreatment with PHE-4i significantly reduced carrageenan-induced hind paw weight, MPO activity, leukocyte infiltration, and H2S production in a dose-dependent manner (p < 0.001). These results indicate that the anti-inflammatory effect of PHE-4i on carrageenan-induced rat paw oedema could be via the inhibition of the gaseous mediator H2S.