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A novel coumarin derivative ( 5 ) was synthesized and used as a colorimetric and fluorescent probe for selective detection of Cu 2+ ions in the presence of other metal ions, with the detection limits of 5.7 and 4.0 ppb, respectively. Cu 2+ ion reacts with probe 5 to form a 1:1 stoichiometry complex, resulting in a remarkable redshift of absorption maximum from 460 to 510 nm, as well as almost completely quenching fluorescence intensity of probe 5 at the wavelength of 536 nm. These changes can be distinctly observed by naked eyes. In addition, the working pH range of probe 5 is wide and suitable for physiological conditions, thus probe 5 may be used for detection of Cu 2+ ions in living cells. The stable structures of probe 5 and its 1:1 complex with Cu 2+ ion were optimized at the PBE0/6-31+G(d) level of theory. The presence and characteristics of bonds in compounds were studied through atoms in a molecule and natural bond orbital analysis. The formation of the complex led to a strong transfer of electron density from probe 5 as a ligand to Cu 2+ ion, resulting in breaking the π-electron conjugated system, which is the cause of fluorescence quenching and color change of 5- Cu 2+ complex.

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Distichochlamys citrea M.F. Newman (commonly known as “Black Ginger”) is an endemic plant to Vietnam and has been extensively exploited by folk medication for treatments of infection-related diseases and diabetes. In this work, its rhizomes were subjected to fractionated extraction, phytochemical examination, evaluation of antioxidant effect by DDPH free radical neutralization, and inhibitory activity toward α -glucosidase. The compositional components were subjected to in silico screening, including density functional theory calculation, molecular docking simulation, physicochemical analysis, and pharmacokinetic regression. In the trials, EtOAc fraction is found as the bioactive part of most effectiveness, regarding both antioxidant effect (IC 50 = 90.27 µg mL −1 ) and α -glucosidase inhibitory activity (IC 50 = 115.75 μg mL −1 ). Chemical determination reveals there are 13 components of its composition. DFT-based calculations find no abnormal constraints in their structures. Docking-based simulation provides order of inhibitory effectiveness: 3-P53341 > 12-P53341 > 7-P53341 > 4-P53341 > 11-P53341 > 10-P53341 . QSARIS-based investigations implicate their biocompatibility. ADMET-based regressions indicate that all candidates are generally safe for medicinal applications. The findings would contribute to the basis for further studies on the chemical compositions of Distichochlamys citrea and their biological activities. Supplementary Information The online version contains supplementary material available at 10.1007/s11696-022-02273-2.

A benzothiazolium-derived colorimetric and fluorescent chemosensor (L) for detection of mercury ions has been prepared. The detection limits of the colorimetric and fluorescent method for mercury ions are 15.3 and 11.8 ppb, respectively, much lower than the reported chemosensors based on similar derivatives of benzothiazolium. The optimized molecular structures, absorption and fluorescence characteristics of the chemosensor and its complex with mercury ions were carried out using the calculations at the B3LYP/LanL2DZ level of theory, combination with Atoms in Molecules and Natural Bond Orbitals analyses.