Performance of 4,5-diphenyl-1H-imidazole derived highly selective 'Turn-Off' fluorescent chemosensor for iron(III) ions detection and biological applications.

Two fluorescent chemosensors, denoted as chemosensor 1 and chemosensor 2, were synthesized and subjected to comprehensive characterization using various techniques. The characterization techniques employed were Fourier-transform infrared (FTIR), proton (1 H)- and carbon-13 (13 C)-nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization (ESI) mass spectrometry, and single crystal X-ray diffraction analysis. Chemosensor 1 is composed of a 1H-imidazole core with specific substituents, including a 4-(2-(4,5-c-2-yl)naphthalene-3-yloxy)butoxy)naphthalene-1-yl moiety. However, chemosensor 2 features a 1H-imidazole core with distinct substituents, such as 4-methyl-2-(4,5-diphenyl-1H-imidazole-2-yl)phenoxy)butoxy)-5-methylphenyl. Chemosensor 1 crystallizes in the monoclinic space group C2/c. Both chemosensors 1 and 2 exhibit a discernible fluorescence quenching response selectively toward iron(III) ion (Fe3+ ) at 435 and 390 nm, respectively, in dimethylformamide (DMF) solutions, distinguishing them from other tested cations. This fluorescence quenching is attributed to the established mechanism of chelation quenched fluorescence (CHQF). The binding constants for the formation of the 1 + Fe3+ and 2 + Fe3+ complexes were determined using the modified Benesi-Hildebrand equation, yielding values of approximately 2.2 × 103 and 1.3 × 104 M-1 , respectively. The calculated average fluorescence lifetimes for 1 and 1 + Fe3+ were 2.51 and 1.17 ns, respectively, while for 2 and 2 + Fe3+ , the lifetimes were 1.13 and 0.63 ns, respectively. Additionally, the applicability of chemosensors 1 and 2 in detecting Fe3+ in live cells was demonstrated, with negligible observed cell toxicity.

A new 5-bromoindolehydrazone anchored diiodosalicylaldehyde derivative as efficient fluoro and chromophore for selective and sensitive detection of tryptamine and F- ions: Applications in live cell imaging.

A novel indole hydrazone tagged moiety, 2-((5-bromo-1H-indol-2-yl) methylene) hydrazono) methyl)-4, 6-diiodophenol (BHDL) has been developed for the selective and sensitive detection of biogenic tryptamine and F- ions. The binding dexterity of probe BHDL towards F-/tryptamine (TryptA) has been investigated by UV-visible/fluorescence spectroscopy. In the presence of TryptA, probe exhibits strong enhancement in the emission band at 433 nm and the band at 555 nm underwent a blue shift accompanied by a decrease in intensity by the inhibition of Excited State Intramolecular Proton Transfer (ESIPT) on BHDL. Excitingly, complexation with F- ions as well triggers an enhancement in a fluorescence band at 430 nm with the concomitant disappearance of the emission band at 555 nm due to the inhibition of ESIPT and deprotonation process initiated by the hydrogen bonding complex formation. Further, Density Functional Theoretical (DFT) calculations have been performed to support the mechanism functioned on the probe BHDL in the presence of TryptA/F-.

A novel pyrazole bearing imidazole frame as ratiometric fluorescent chemosensor for Al3+/Fe3+ ions and its application in HeLa cell imaging.

New pyrazole bearing imidazole derivative was successfully synthesized and thoroughly characterized by various spectroanalytical techniques. The sensor DIBI shows a highly selective and sensitive fluorescent response with the addition of Al3+/Fe3+ ions in acetonitrile-water mixture. The strong fluorescent molecule exhibits a notable ratiometric emissions at 462 nm and 470 nm for Al3+ and Fe3+ ions, respectively (λex = 280 nm). Job's plot studies conclude that the coordination between DIBI with Al3+/Fe3+ was 1:1 binding stoichiometry. The limit of detection of DIBI with Al3+/Fe3+ was calculated as 2.12 × 10-7 M and 1.73 × 10-6 M, respectively. The TD-DFT calculations further supported the photonics performances of the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al3+/Fe3+ in cancer cells via fluorescence microscopy.

Novel Furan Coupled Quinoline Diamide Hybrid Scaffolds as Potent Antitubercular Agents: Design, Synthesis and Molecular Modelling.

BACKGROUND: A novel series of 2-[(2-{[2-(furan-2-yl) quinolin-4-yl] carbonyl} hydrazinyl) carbonyl] benzoic acid, -4-oxobut-2-enoic acid and -4-oxobutanoic acids were synthesized and screened for in vitro antitubercular activity. OBJECTIVES: In the present investigation, we describe the synthesis and biological screening of furan C-2 quinoline coupled diamides for antitubercular activity. METHODS: The mycobacterium tuberculai testing was carried out by MABA method and molecular docking studies were done by open-source molecular docking program, Autovina, using Pyrx 0.8 interface. RESULTS: The results revealed that the compounds inhibited the growth of H37Rv strain at concentrations as low as 1.6 to 12 µg/ml. Molecular binding of furan, quinoline and diamide (FQD) derivatives on five targets was good and these compounds fit very well within the binding domain of the target protein. CONCLUSION: The synthesized FQD derivatives exhibited moderate to good inhibition activity especially compounds 5f, 5b and 8a exhibited very good inhibition activity due to the presence of three different scaffolds, such as INH, phenyl ketobutyric acid and fluoroquinolines. Hybridized molecules might have multiple modes of action / inhibit more than one tubercular target and could pave way for novel drug discovery in the field of tuberculosis.

Execution of julolidine based derivative as bifunctional chemosensor for Zn2+ and Cu2+ ions: Applications in bio-imaging and molecular logic gate.

A simple julolidine based chemosensor (JT) was designed and synthesized by single condensation step. JT displayed excellent selectivity and sensitivity with on-off responses towards Zn2+ and Cu2+ over other biologically relevant metal ions in aqueous media. Upon addition of Zn2+ ions, JT exhibited a significant blue shift in emission followed by turn-on enhancement while with Cu2+, the fluorescence intensity of JT was completely vanished. The 1:1 binding affinity between JT and Zn2+/Cu2+ was proposed by Job's plot analysis. The detection limit for Zn2+ and Cu2+ ions reached at 3.5 × 10-8 M and 1.46 × 10-6 M, respectively. The sensing mechanism of JT with Zn2+/Cu2+ was supported by DFT calculations. Based on photophysical studies and its reversibility environment with EDTA, molecular logic gates were fabricated. Furthermore, JT was successfully established to detect intracellular Zn2+ ions in live cells by turn-on response.