Copper(II)-selective fluorimetric bulk optode membrane based on a 1-hydroxy-9,10-anthraquinone derivative having two propenyl arms as a neutral fluorogenic ionophore

DFT/TDDFT investigation on the UV-vis absorption and fluorescence properties of alizarin dye

Potential energy curve for the ESIPT. Top inset: vibrationally resolved emission spectra computed for both tautomers. Bottom insets: main vibrational modes.

An efficient and selective flourescent chemical sensor based on 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as a new fluoroionophore for determination of iron(III) ions. A novel probe for iron speciation

A novel fluorescent chemical sensor for the highly sensitive and selective determination of Fe(3+) ions in aqueous solutions is prepared. The iron sensing system was prepared by incorporating 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a neutral Fe(3+)-selective fluoroionophore in the plasticized PVC membrane containing sodium tetraphenylborate as a liphophilic anionic additive. The response of the sensor is based on the strong fluorescence quenching of L by Fe(3+) ions. At pH 5.5, the proposed sensor displays a calibration curve over a wide concentration range from 6.0 × 10(-4) to 1.0 × 10(-7) M, with a relatively fast response time of less than 2 min. In addition to a high stability and reproducibility, the sensor shows a unique selectivity toward Fe(3+) ion with respect to common coexisting cations. The proposed fluorescence optode was applied to the determination of iron(III) content of straw of rice, spinach and different water samples. The fluorescent sensor was also used as a novel probe for Fe(3+)/Fe(2+) speciation in aqueous solution.

Determination of terbium in phosphate rock by Tb3+-selective fluorimetric optode based on dansyl derivative as a neutral fluorogenic ionophore

For the first time a highly sensitive and selective fluorimetric optode membrane was prepared for determination of trace amounts of Tb(III) ions in phosphate rock samples. The Tb(III) sensing system was constructed by incorporating 5-(dimethylamino)-N'-(2-hydroxy-1-naphthoyl) naphthalene-1-sulfonohydrazine (L) as a neutral Tb(III)-selective fluoroionophore, in the plasticized PVC membrane containing sodium tetraphenyl borate as a liphophilic anionic additive. The response of the optode is based on the strong fluorescence quenching of L by Tb(3+) ions. At a pH value of 5.0, the optode displays a wide concentration range of 1.0 x 10(-7) to 1.0 x 10(-2)M, with a relatively fast response time of less than 45 s. In addition, to high stability and reproducibility, the sensor shows a unique selectivity towards Tb(3+) ion with respect to common cations. The optode was applied successfully to the trace determination of terbium ion in binary mixture and water samples and the determination of Tb(3+) in phosphate rock samples.

Ab initio tools for the accurate prediction of the visible spectra of anthraquinones

The UV/vis absorption spectra of 101 anthraquinones solvated in two protic solvents (methanol and ethanol) has been theoretically predicted using the time-dependent density functional theory (TD-DFT) for the excited state calculations and the polarizable continuum model (PCM) for evaluating bulk solvent effects. Two functionals (B3LYP and PBE0) have been used and they provide similar mean absolute deviations (approximately 0.09 eV) but mean signed errors presenting opposite signs. The errors can be minimized by using simple or multiple linear regression, the latter combining the results of both functionals to reach an optimal estimation of the lambda(max) (mean absolute error 0.06 eV). Specific fittings for the two media have been performed and it turned out that our approach is even more efficient for anthraquinones solvated in ethanol.