A new ratiometric fluorescent probe for sensing lysosomal HOCl based on fluorescence resonance energy transfer strategy.

In this paper, ratiometric imaging of lysosomal HOCl was realized with a molecular probe (CR-Ly) based on fluorescence resonance energy transfer by using coumarin as the donor and rhodamine as acceptor. CR-Ly showed high sensitivity and fast response to HOCl. Moreover, CR-Ly exhibited excellent selectivity and sensitivity for HOCl over other biologically relevant species. Furthermore, it was successfully utilized to image the endogenous HOCl with low cytotoxity. And CR-Ly was capable of targeting lysosomes and monitoring lysosomal hypochlorous acid changes owing to the presence of the morpholine moiety. We believe that probe CR-Ly would be helpful to further research on the HOCl-associated diseases in lysosomes.

A pyrazolo[1,5-a]pyridine-based ratiometric fluorescent probe for sensing Cu2+ in cell.

Ratiometric fluorescent probes based on FRET mechanism have attracted great attention due to their large pseudo-Stokes shifts and built-in correction for environmental effects. However, most donors failed to meet the requirement that the emission of the donor must overlap well with the absorption of the acceptor. Therefore, searching for new fluorophore to construct FRET system is in great need. In this paper, a new fluorescent dye pyrazolo[1,5-a]pyridine was synthesized and used as a donor in the FRET system for ratiometric sensing of Cu2+. The probe is based on FRET and PET mechanism. It shows high selectivity and sensitivity toward Cu2+ (detection limit 30 nM). Furthermore, it was successfully used to detect Cu2+ in Glioma cells.

A FRET based ratiometric fluorescent probe for detection of sulfite in food.

A new fluorophore pyrido[1,2-a]benzimidazole based ratiometric fluorescent probe for the selective detection of sulfite ions in water was investigated. It shows large (pseudo) Stokes shifts (260 nm), high FRET efficiency, high selectivity and sensitivity. A distinct color change from red to colorless was observed and importantly, it proves to be a convenient and efficient tool to detect the sulfite levels in sugar samples.

Theoretical study on the substitution reactions of the germylenoid H2GeLiF with SiH3X (X = F, Cl, Br).

The substitution reactions of H2GeLiF (G) with SiH3X (X = F, Cl, Br) were investigated using calculations performed at the QCISD/6-311++G (d, p)//B3LYP/6-311+G (d, p) level of theory. The results led to the following conclusions. (i) The substitutions are nucleophilic reactions. There are two substitution paths, I and II, which both lead to the germane H2GeFSiH3. The enantiomers of this germane are obtained via these two paths if an H in SiH3X is replaced with a different group or atom. (ii) Both substitution pathways show the same order of barrier heights (SiH3F > SiH3Cl > SiH3Br). The difference between the bond energies of Li-X and Si-X may explain the precedence among the substitution reactions of G with SiH3X. Path I has a lower activation barrier than path II, indicating that path I is more favorable. (iii) Comparison between the relevant insertion and substitution reactions shows that substitutions are more favorable and that the substitution product H2GeFSiH3 predominates over the insertion product. (iv) The substitution reactions of H2GeLiF with SiH3X are exothermic.

Phenazin-5-ium bromide.

In the title compound, C(12)H(9)N(2) (+)·Br(-), the protonated tricyclic ring system is slightly twisted, with a dihedral angle of 3.9 (1)° between the two outer benzene rings. In the crystal, N-H⋯Br and C-H⋯Br hydrogen bonds link two cations and two bromide anions into centrosymmetric assemblies, which are further packed into stacks along [010] via π-π inter-actions between the aromatic rings [centroid-centroid distance = 3.725 (4) Å].