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[EN] In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR-FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide (S3). NB emission at 672 nm is highly quenched inside S3, yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of beta-galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK-Mel-103 and breast cancer 4T1 cells and in vivo in palbociclib-treated BALB/cByJ mice bearing breast cancer tumor., R.M. thanks financial support from the Spanish Government (RTI2018-100910-B-C41 and RTI2018-101599-B-C22 (MCUI/AEI/FEDER, UE)) and the Generalitat Valenciana (PROMETEO 2018/024). M.O. thanks the financial support from SAF2017-84689-R project and MINECO/AEI/FEDER, UE and the Generalitat Valenciana (PROMETEO/2019/065). B.L.-T. is grateful to the Spanish Ministry of Economy for her PhD grant. I.G. thanks her contract from IDM. J.F.-B. and M.A. thank the UPV for their postdoctoral fellowship.

Fluorescent solid 5-pyridylimidazobenzothiadiazole displays a remarkable solvatofluorochromism and with Zn(AcO)2 and Cd(AcO)2, either in solution or under solvent-free conditions, forms ion-pair complexes that in the solid state can be discriminated and separated by fluorescence measurements and selective extraction with diethyl ether or chloroform.

The preparation of 2,7-disubstituted benzobisimidazoles decorated with substituents displaying different electrooptical properties is described. The presence of redox, chromogenic, and fluorescent groups at the heteroaromatic core, which acts as ditopic binding site, made these receptors potential candidates as multichannel probes for ions. The triad 4 behaves as a selective redox and fluorescent chemosensor for HSO4(-) and Hg(2+) ions, whereas receptor 5 acts as a redox and chromogenic chemosensor molecule for AcO(-) and SO4(2-) anions. The change in the absorption spectra is accompanied by a color change from yellow to orange, while sensing of Zn(2+), Hg(2+), and Pb(2+) cations is carried out only by electrochemical techniques. Receptor 6 exhibits a remarkable cathodic shift of the oxidation wave only in the presence of AcO(-), H2PO4(-), and HP2O7(3-) anions, whereas addition of Pb(2+) induces an anodic shift. A new low energy band in the absorption spectra, which is responsible for the color change from colorless to pale yellow, and an important increase of the monomer emission band is observed only in the presence of H2PO4(-), and HP2O7(3-) anions. The most salient feature of the receptor 6 is its ability to act as a multichannel (redox, chromogenic, and fluorescent) chemodosimeter for Cu(2+), and Hg(2+) metal cations.

The bisferrocene-benzobisimidazole triad behaves as a selective redox and fluorescent chemosensor for HSO(4)(-) and Hg(2+) ions, exhibiting an easily detectable signal change in both the redox potential of the ferrocene/ferrocinium redox couple and in the emission band which is red-shifted (Δλ = 10-13 nm) and enhanced in intensity (Chelation Enhanced Fluorescence, CHEF = 486-225) upon complexation with these ions, in EtOH solutions.

Aryl or heteroaryl 5-substituted imidazo-benzothiadiazole derivatives were synthesized and shown to display remarkable solvatofluorochromism and selectively sense mercury(II) cations, acetate anions, and nitroaromatic derivatives, with discrimination between p-nitrophenol and picric acid. These novel sensors are of importance these days, as the detection of explosives is a high priority in issues of national security and environmental protection. To determine the ion binding properties of the sensors, their absorption and fluorescence emission spectra upon binding different cations and anions were compared. Significant shifts in the spectra were only observed for mercury(II) and acetate. The binding of these two ions was further studied using (1)H NMR. The binding properties of different nitroaromatic compounds were also determined, and the results showed the importance of the presence of a phenol group in the guest molecule. Specifically, the two sensors were shown to discriminate between p-nitrophenol and picric acid. Finally, the mechanism of fluorescence quenching upon addition of nitrophenols was determined by computational methods.

The ferrocene-imidazopyrene dyad, bearing the imidazole ring as the only receptor site, acts as a redox and optical molecular sensor for ion pairs, exhibiting an easily detectable signal change in the redox potential of the ferrocene/ferrocinium redox couple and in the emission spectrum. Perturbation of the emission spectrum follows the order Pb(2+)Hg(2+)Zn(2+) for cations and H(2)PO(4)(-)AcO(-) for anions.

The synthesis and electrochemical, optical, and ion-sensing properties of ferrocene-imidazophenazine dyads are presented. Dyad 4 behaves as a highly selective chemosensor molecule for Pb(2+) cations in CH(3)-CN/H(2)O (9:1). The emission spectrum (λ(exc) = 317 nm) undergoes an important chelation-enhanced fluorescence effect (CHEF = 47) in the presence of Pb(2+) cations, a new low-energy band appeared at 502 nm, in its UV/vis spectrun, and the oxidation redox peak is anodically shifted (ΔE(1/2) = 230 mV). The presence of Hg(2+) cations also induced a perturbation of the redox potencial although in less extension than those found with Pb(2+) cations. Dyad 7, bearing two fused pyridine rings, has shown its ability for sensing Hg(2+) cations selectively through three channels: electrochemical, optical, and fluorescent; the oxidation redox peak is anodically shifted (ΔE(1/2) = 200 mV), a new low-energy band of the absorption spectrum appeared at 485 nm, and the emission spectrum (λ(exc) = 340 nm) is red-shifted by 32 nm accompanied by a remarkable chelation-enhanced fluorescent effect (CHEF = 165). Linear sweep voltammetry revealed that Cu(2+) cations induced oxidation of the ferrocene unit in both dyads. (1)H NMR studies have been carried out to obtain information about the molecular sites which are involved in the binding process.

A ferrocene-based ion pair receptor is shown only to recognise HSO(4)(-) anions in the presence of a cobound Pb(2+) or Zn(2+) cation guest species through a perturbation of the redox potential of the ferrocene unit and a remarkable enhancement of the fluorescence.

A new chemosensor molecule 3 based on a ferrocene-imidazophenanthrophenazine dyad effectively recognizes Hg(2+) in an aqueous environment through three different channels. Upon recognition, an anodic shift of the ferrocene-ferrocenium oxidation potential (ΔE(1/2) = 240 mV) and a progressive red shift (Δλ = 17 nm) of the low energy band in its absorption spectrum is produced. The emission spectrum of 3 in an aqueous environment, CH(3)CN-EtOH-H(2)O (65:25:10), and conducted at pH = 7.4 (20 × 10(-3) M HEPES) (Φ = 0.003), is perturbed after addition of Hg(2+) cations and an intense and structureless red shift emission band at 494 nm (Δλ = 92 nm) appeared along with an increase of the intensity of the emission band (CHEF = 77), the quantum yield (Φ = 0.054) resulted in a 18-fold increase. The combined (1)H NMR data of the complex and the theoretical calculations suggest the proposed bridging coordination mode.

The synthesis, electrochemical, optical and cation-sensing properties of ferrocene-imidazoquinoxaline dyads 6, are presented. Dyad 6a behaves as a highly selective redox, chromogenic and fluorescent chemosensor molecule for Pb(2+) cations in CH(3)CN solutions; the oxidation redox peak is anodically shifted (DeltaE(1/2) = 110 mV); in the absorption spectrum a new low-energy band appeared at lambda = 463 nm, and the emission band is red-shifted (Deltalambda = 31 nm) along with an important chelation-enhanced fluorescence factor (CHEF = 276), upon complexation with this metal cation. The dyad 6b, bearing two additional pyridine rings as substituents, has shown its ability for sensing Hg(2+) cations through three different channels: the oxidation peak is anodically higher shifted (DeltaE(1/2) = 300 mV), a new low-energy band appears in the absorption spectrum at lambda = 483 nm, and the emission band was also red-shifted (Deltalambda = 28 nm) and underwent an important chelation-enhanced fluorescent factor (CHEF = 227). The changes in their absorption spectra are accompanied by color changes from yellow to orange which allow their potential use for the "naked eye" detection of these metal cations. Linear sweep voltammetry revealed that Cu(2+) cations induced oxidation of the ferrocene unit in both dyads, which is accompanied by an important increase of the emission band.