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A Schiff base of 4E,10E-4-(2-(4-nitrophenyl)-N-((1H-indol-3-yl)methylene) benzenamine was synthesized and characterized by 1H&13C-NMR, FT-IR, and ESI–MS spectroscopy. UV–visible and fluorescence studies were explored for chemosensor ICPA to detect Ni2+, Fe3+, and Mg2+ by fluorescence chemosensor “turn-on” method in 10 mM HEPES buffer in EtOH/H2O (1:4, v/v) medium. Chemosensor ICPA binds with the selective heavy metal ions and could be proved in very low detection limits. Job’s plot demonstrates 1:1 stoichiometric complexes of ICPA + Ni2+, ICPA + Fe3+, and ICPA + Fe3+ with the calculated mole fraction of 0.5 μM. Binding constant values calculated using the Benesi–Hildebrand method are found to be 3.45 × 108 M−2, 5.63 × 104 M−2, and 8.63 × 103 M−2, respectively. Competitive metal ions tests were also carried out with transition metal ions. Furthermore, HeLa cell activity at different concentrations added with ligand to perform inhibition capability of the probe was also carried out.

A Schiff base compound E-2-(((4-aminophenyl)imino)methyl)-5-(difluoromethoxy)phenol was synthesized and characterized by FT-IR, 1H and 13C NMR, ESI-mass spectroscopy. The synthesized compound also selectively detects Al3+, Fe2+ and Cu2+ without any interference of other metal ions. Fluorescence titrations carried out to find the selectivity of Al3+, Fe2+ and Cu2+ in turn-on system, with binding modes of 2:1 complex, confirmed by Job′s plot. The presence of metal ions Al3+, Fe2+ and Cu2+ with receptor conformed by ESI-MS spectrum, which changed the base value at 298.00 m/z. Moreover, among the binding constant of three metals calculated (20 μM), Al3+ showed a high value of 5.7 × 104 M-1 compared to Fe2+ and Cu2+ metal ions. Prominently, the cytotoxicity activities of probe with HeLa cells were also calculated

A simple and facile synthesis of 1,2-bis((E)-9-anthracenyl)methyleneamino)-9,10-anthraquinone, BAMAAQ (L) has been achieved by the Schiff's base condensation of 1,2-diamino-9,10-anthraquinone (a primary aromatic 1,2-diamine) and anthracene-9-carboxaldehyde (an aldehyde) under reflux condition. The structure of the product obtained from spectra was characterized by FT-IR, 1H and 13C NMR and LC-MS techniques. The UV-absorption and fluorescent emission spectra were carried out for its sensing behavior towards the different metal ions for their “turn-on” and “turn-off” observations. The extraordinary enhancement and extraordinary quenching of the synthesized organic probe (L) by its chemo-sensation were observed for Cu2+ ion and Fe3+ ion, respectively. L-Cu2+ and L-Fe3+ modules were subjected for concentration-dependent (by emission spectra), pH-dependent (by absorption spectra) behaviors and the effective removal of the metal-binding probe by a chelating agent (EDTANa2) making the system attractive by their “on-off” response. FE-SEM with elemental color mapping and EDS analyses were also studied to understand their relative presence of constituted atoms for the subjected modules. The Cytotoxicity and IC50 value measurement were made for the different concentration of the ligand probe, L. And the live cell imaging techniques for the selected two modules were carried out with HepG2 cell line. The computational studies also have been carried out for the better understanding of the ligand probe (L) towards their optimized structure, Mulliken atomic charge (MPA), Natural atomic charge (NPA), surface analysis, Frontier's molecular orbitals (FMOs) and the calculation of molecular descriptors or global reactivity descriptors. The optical property of the ligand probe also investigated theoretically by NLO properties effectively by “polar” energy job.

A Schiff base of E-4-(((1H-indol-3-yl)methylene)amino)-N-(pyrimidin-2-yl)benzene sulfonamide (IMAPB) were synthesized and characterized by FT-IR, 1H & 13C NMR, Mass spectroscopy. Uv-vis spectroscopic measurement probe IMAPB of absorption band 296 nm was observed. The fluorescence intensity at 428 nm was obtained due to turn-on chemosensors for selectivity and sensitivity of Pb2+ ion with the interference of other metal ions. The stoichiometric of 1:1 complex formation of IMAPB+Pb2+ to confirmed association constant value at 2.3×10−4 M−1 (R2=0.94976). The PET mechanism was binding with IMAPB+Pb2+ linked nitrogen and oxygen. Competitive metal ions to select Pb2+ metal ions compared other metal ions. EDTA solution binding of IMAPB+Pb2+ with result fluorescence ON, however, different pH range was used in probe of IMAPB+Pb2+. The cytotoxicity activity of IMAP used different concentration used HeLa cells.

A new simple ‘dual’ chemosensor (3,3’-(1,3-phenylene)bis(quinoxaline-6,3-diyl))bis (phenylmethanone) L14, for distinguishing Al3+ and Cr3+ has been designed, synthesized and characterized. The designed compound revealed certified selectivity and sensitivity among a fluorescence enhancement to Al3+ and quenching to Cr3+ over commonly coexisting cations (such as Cu2+, Hg2+, Fe2+, Pb2+, Ag+, Ni2+, Zr2+, Mn2+, Mg2+, Sr2+, Cd2+, Sn2+, Bi3+ and Zn2+) in DMF-H2O (4/1, v/v). These are reversible with the addition of EDTA. The detection limit for Al3+/Cr3+ by L14 reached the 0.3 μM and 0.5 μM level. The binding process confirmed via UV–Vis, fluorescence measurements, 1H NMR, FE-SEM with EDS and color mapping and DFT calculation. Further, the applicability of the probe was used to the cytotoxic activity, and fluorescent sensors in overseeing intracellular Al3+/Cr3+ in HepG2 cells also demonstrated.

New aldonitrones(1-4) were synthesized and characterized by UV-vis, fluorescence, FT-IR, 1H and 13C NMR spectral analyses. The absorption and fluorescence sensing spectra of the compounds were precise in different polarity of solvent. The solvent polarity parameters have been used to propose a quantitative approach towards the reliable stability of the electronic ground and excited state species. Photochemical behaviors of the compounds were analyzed by applying multi-linear correlation methods. The characterized compounds 1-4 show a chemosensing detection of zinc ion in aqueous solution. Besides, the fluorescence spectroscopic responses were reversible when the Zn2+chelating reagentEDTANa2.The phenomenon proves that these compounds to show a sensitivity “on-off” sensor for Zn2+.Further, to recognize the molecular structure, electronic and optical properties and DFT calculations of the molecules were formed.