A Novel Fluorescent Sensor for Detecting Ag and Hg ions: A Combination of Theoretical and Experimental Studies.

A new fluorescent sensor based on diethylaminosalicylaldehyde-thiosemicarbazide (DST) was studied using a combination of density functional theory calculations and experimental investigations. DST was able to detect the metal ions Ag and Hg in the presence of various competing metal ions and anions, with detection limits of 0.45 and 0.

Radical Scavenging Activity of Natural Anthraquinones: a Theoretical Insight.

Anthraquinones (ANQs) isolated from plants are known to have antidiarrheal, antitussive, anthelmintic, analgesic, anti-inflammatory, antihyperlipidemic, antihyperglycaemic, and antimicrobial activities. The antioxidant properties were also noted but not confirmed thus far. In this study, the superoxide and hydroperoxide radical scavenging activities of six ANQs were evaluated using a computational approach.

Substituent Effects on the N-H Bond Dissociation Enthalpies, Ionization Energies, Acidities, and Radical Scavenging Behavior of 3,7-Disubstituted Phenoxazines and 3,7-Disubstituted Phenothiazines.

The substituent effects on the N-H bond dissociation enthalpies (BDE), ionization energies (IE), acidities (proton affinity, PA), and radical scavenging behavior of 3,7-disubstituted phenoxazines (PhozNHs) and 3,7-disubstituted phenothiazines (PhtzNHs) were determined using density functional theory, with the M05-2X functional in conjunction with the 6-311++G(d,p) basis set. These thermochemical parameters calculated in both gas phase and benzene solution with respect to the changes in several different substituents including halogen, electron-withdrawing, and electron-donating groups at both 3 and 7 positions in both PhozNHs and PhtzNHs systems were analyzed in terms of the inherent relationships between them with some quantitative substituent effect parameters. The kinetic rate constants of hydrogen-atom exchange reactions between PhozNH and PhtzNH derivatives with the HOO radical were also calculated, and the effects of the substituents on the kinetic behaviors of these reactions were thereby quantitatively evaluated.

A coumarin derivative-Cu complex-based fluorescent chemosensor for detection of biothiols.

Herein, a novel fluorescent sensor has been developed for the detection of biothiols based on theoretical calculations of the stability constant of the complex between a Cu ion and ()-3-((2-(benzo[]thiazol-2-yl)hydrazono)methyl)-7-(diethylamino) coumarin (BDC) as a fluorescent ligand. In this study, on the basis of density functional theory method, the Gibbs free energy of ligand-exchange reaction and the solvation model were carried out using thermodynamic cycles. The obtained results are in good agreement with the experimental data.

Coumarin-Based Dual Chemosensor for Colorimetric and Fluorescent Detection of Cu in Water Media.

A novel coumarin derivative () was synthesized and used as a colorimetric and fluorescent probe for selective detection of Cu ions in the presence of other metal ions, with the detection limits of 5.7 and 4.0 ppb, respectively.

Theoretical Study on the Antioxidant Activity of Natural Depsidones.

Depsidones are secondary metabolites in lichens with a range of potential health benefits. Among others, these compounds are believed to exhibit high hydroxyl radical and superoxide scavenging abilities, warranting a detailed investigation of their antioxidant properties. In this study, the radical scavenging activity of natural depsidones from lichenized fungi was investigated in silico.

Hg-Promoted Spirolactam Hydrolysis Reaction: A Design Strategy for the Highly Selective Sensing of Hg over other Metal Ions in Aqueous Media.

A mercury sensor (-(rhodamine-6G)lactam-ethylenediamine-4-dimethylamino-cinnamaldehyde-RLED) based on the Hg-promoted hydrolysis reaction has been designed and developed with a combination of theoretical calculations and experimental investigations. The interaction between RLED and Hg goes through a fast-initial stage with formation of a 1:1 complex, followed by a slow hydrolysis process. The formation of durable intermediate complexes is due to quite a long hydrolysis reaction time.

A new rhodamine-based fluorescent chemodosimeter for mercuric ions in water media.

A new rhodamine-ethylenediamine-nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg(2+) ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF-ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn(2+) , Cu(2+) , Cd(2+) , Pb(2+) , Ag(+) , Fe(2+) , Cr(3+) , Co(3+) , Ni(2+) , Ca(2+) , Mg(2+) , K(+) and Na(+) . The sensing results and the molecular structure suggested that a Hg(2+) -induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring-opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn-on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg(2+) ions in aqueous solution.

A new fluorescent chemosensor for Hg2+ in aqueous solution.

We prepared an aminothiourea-derived Schiff base (DA) as a fluorescent chemosensor for Hg(2+) ions. Addition of 1 equiv of Hg(2+) ions to the aqueous solution of DA gave rise to an obvious fluorescence enhancement and the subsequent addition of more Hg(2+) induced gradual fluorescence quenching. Other competing ions, including Pb(2+), Cd(2+), Cr(3+), Zn(2+), Fe(2+), Co(3+), Ni(2+), Ca(2+), Mg(2+), K(+) and Na(+) , did not induce any distinct fluorescence changes, indicating that DA can selectively detect Hg(2+) ions in aqueous solution.