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[EN] Three fluorescent probes (1–3) for the selective and sensitive detection of hydrogen sulfide have been synthesized and characterized. Probe 1 is a coumarin derivative functionalized with an azide moiety whereas 2 contain the azide reactive group into a naphthalene fluorophore backbone. Probe 3 is composed also by a naphthalene fluorophore but, in this case, functionalized with a sulfonylazide reactive moiety. Probes 1 and 3 are non-fluorescent whereas 2 is weakly emissive in HEPES (10 mM, pH 7.4)–DMSO 99:1 (v/v). The emission behavior of the three probes was tested against selected anions, bio-thiols and oxidant molecules. Of all the chemical species tested, only HS− is able to induce an enhancement in the emission intensity (50, 11 and 20-fold for 1, 2 and 3, respectively). The observed emission in the presence of hydrogen sulfide is ascribed, in the case of probes 1 and 2, to an azide–amine reduction induced by HS− anion, whereas for probe 3 the sensing mechanism is related with a sulfonylazide–sulfonamide conversion. The three probes are very sensitive to HS− anion with limits of detection of 0.17, 0.20 and 0.40 mM for 1, 2 and 3 respectively. Cell viability studies demonstrated that 1–3 probes are essentially non-toxic at concentrations 10–50 μM and are well suited for in vivo studies. Finally, probe 1 was used for the detection on intracellular HS− anion in HeLa cells by means of confocal microscopy. ; Financial support from the Spanish Government (Project MAT2012-38429-004-01) and the Generalitat Valenciana (Project PROMETEO/2009/016) is gratefully acknowledged. S.E. is grateful to the Generalitat Valenciana for his Santiago Grisolia fellow. C.T. also thanks the Ministerio de Ciencia e Innovacion for her FPU grant. L.E.S.F. thanks the Carolina Foundation and UPNFM-Honduras for his doctoral grant. ; El Sayed Shehata Nasr, S.; De La Torre Paredes, C.; Santos Figueroa, LE.; Marín Hernández, C.; Martínez Mañez, R.; Sancenón Galarza, F.; Costero Nieto, AM. (2015). Azide and sulfonylazide functionalized ...

A family of heterocyclic thiosemicarbazone dyes (3a-f and 4) containing furyl groups was synthesized in good yields, characterized and their response in acetonitrile in the presence of selected anions was studied. Acetonitrile solutions of 3a-f and 4 showed absorption bands in the 335-396 nm range which are modulated by the electron donor or acceptor strength of the heterocyclic systems appended to the thiosemicarbazone moiety. Fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulphate, nitrate, acetate and cyanide anions were used in recognition studies. From these anions, only sensing features were seen for fluoride, cyanide, acetate and dihydrogen phosphate. Two clearly different chromo-fluorogenic behaviours were observed: (i) a small shift of the absorption band due to the coordination of the anions with the thiourea protons and (ii) the appearance of a new red shifted band due to deprotonation. For the latter effect, a change in the colour of solution from pale yellow to purple was observed. Fluorescence studies were also in agreement with the different effects observed in the UV/Vis titrations. In this case, hydrogen bonding interactions were visible through the enhancement of the emission band, whereas deprotonation induced the appearance of a new red-shifted emission. Logarithms of stability constants for the two processes (complex formation + deprotonation) for receptors 3a-f in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec V1.1.18 program. Semi-empirical calculations to evaluate the hydrogen-donating ability of the receptors and a prospective electrochemical characterization of compound 3b in the presence of fluoride were also performed. © 2012 The Royal Society of Chemistry. ; We thank the Spanish Government (project MAT2009-14564-C04-01) and the Generalitat Valenciana (project PROMETEO/2009/016) for support. We are also grateful to the Fundacao para a Ciencia e Tecnologia (Portugal) and FEDER-COMPETE for financial ...

A family of heterocyclic thiosemicarbazone dyes (3a-d) containing thienyl groups has been synthesized, characterized, and their chromo-fluorogenic response in acetonitrile in the presence of selected anions was studied. Acetonitrile solutions of 3a-d show absorption bands in the 338-425 nm range, which are modulated by the groups attached to the thiosemicarbazone moiety. The fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulfate, nitrate, acetate, and cyanide anions were used in the recognition studies. Only sensing features were observed for fluoride, cyanide, acetate, and dihydrogen phosphate anions. Two different chromogenic responses were found, (i) a small shift of the absorption band due to coordination of the anions with the thiourea protons and (ii) the appearance of a new red-shifted band due to deprotonation of the receptor. For the latter process changes in the color solutions from pale-yellow to orange-red were observed. Fluorescence studies showed a different emission behavior according to the number of thienyl rings in the pi-conjugated bridges. Stability constants for the two processes (complex formation+deprotonation) for receptors 3a-d in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec program. The interaction of 3d with fluoride was studied through H-1 NMR titrations. Semiempirical calculations to evaluate the hydrogen-donating ability of the receptors were also performed. (C) 2012 Elsevier Ltd. All rights reserved. ; We thank the Spanish Government (project MAT2009-14564-C04-01) and the Generalitat Valencia (project PROMETEO/2009/016) for support. Thanks are due to the Fundacao para a Ciencia e Tecnologia (Portugal) and FEDER-COMPETE for financial support through the Centro de Quimica - Universidade do Minho, Project PEst-C/QUI/UI0686/2011 (F-COMP-01-0124-FEDER-022716) and a Post-doctoral grant to R.M.F.B. (SFRH/BPD/79333/2011). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network ...