Electrocatalytic proton reduction by dinuclear cobalt complexes in a nonaqueous electrolyte

Two dinuclear CoII complexes 1 and 2 have been synthesized and characterized using various spectroscopic methods. Both the complexes were employed for H+ reduction in organic media. Faradaic efficiency of 82–90% was obtained for the H2 evolution.

Protonation of cyclen-based chelating agents containing fluorescent moieties

The fluorescence emission properties of 1,4,7,10-tetraazacyclododecane-based receptors with appended heteroaromatic fluorophores are tuned by photoinduced electron and proton transfer processes.

Fluorescence turn off-on probe (β-cyclodextrin-hydroxyquinoline) for monitoring of Cd2+ ions and tetracycline

In this paper, a photoluminescent turn off-on switch probe β-cyclodextrin-hydroxyquinoline (β-CD-HQ) was efficiently applied for detection and measurement of Cd²⁺ ions and detection of tetracycline. The proposed assay has shown an excellent selective fluorescence response toward Cd²⁺ ions over other ions like Al³⁺, Pb²⁺, Zn²⁺, Co²⁺, K⁺, Na⁺ and Sr²⁺. The fluorescence emission intensity of the probe is slightly affected by competing ions. In optimum pH value, 4, the limit of detection and linear concentration range were 0.05 nM and 0.1-1.5 nM, respectively. Additionally, the extraordinary output signal of β-CD-HQ was utilized to investigate the logic behavior of β-CD-HQ in the aqueous media. Accordingly, a solid support logic circuit was made by producing the fluorescence output signal under the stimulation of Cd²⁺ ions and tetracycline as inputs.

Time-resolved luminescence detection of peroxynitrite using a reactivity-based lanthanide probe

Peroxynitrite (ONOO-) is a powerful and short-lived oxidant formed in vivo, which can react with most biomolecules directly. To fully understand the roles of ONOO- in cell biology, improved methods for the selective detection and real-time analysis of ONOO- are needed. We present a water-soluble, luminescent europium(iii) probe for the rapid and sensitive detection of peroxynitrite in human serum, living cells and biological matrices. We have utilised the long luminescence lifetime of the probe to measure ONOO- in a time-resolved manner, effectively avoiding the influence of autofluorescence in biological samples. To demonstrate the utility of the Eu(iii) probe, we monitored the production of ONOO- in different cell lines, following treatment with a cold atmospheric plasma device commonly used in the clinic for skin wound treatment.

Self-reporting of payload release in polymer coatings based on the inner filter effect

New polymeric nanoparticle sensors are developed for monitoring the release of non-fluorescent payloads in coatings by the naked eye.

Quinoline-Conjugated Ruthenacarboranes: Toward Hybrid Drugs with a Dual Mode of Action

The role of autophagy in cancer is often complex, ranging from tumor-promoting to -suppressing effects. In this study, two novel hybrid molecules were designed, containing a ruthenacarborane fragment conjugated with a known modulator of autophagy, namely a quinoline derivative. The complex closo-[3-(η6 -p-cymene)-1-(quinolin-8-yl-acetate)-3,1,2-RuC2 B9 H10 ] (4) showed a dual mode of action against the LN229 (human glioblastoma) cell line, where it inhibited tumor-promoting autophagy, and strongly inhibited cell proliferation, de facto blocking cellular division. These results, together with the tendency to spontaneously form nanoparticles in aqueous solution, make complex 4 a very promising drug candidate for further studies in vivo, for the treatment of autophagy-prone glioblastomas.

Proton diffusion dynamics along a diol as a proton-conducting wire in a photo-amphiprotic model system

We investigated the dynamics of excited-state proton transfer (ESPT) of photo-amphiprotic 7-hydroxyquinoline (7HQ) in the presence of a hydrogen (H)-bond bridging diol in a polar aprotic medium. The formation of 1 : 1 H-bonded complexes of 7HQ with various diols of different alkane chain lengths was revealed using steady-state electronic spectroscopy. With femtosecond-resolved fluorescence spectroscopy, cyclic H-bonded 1 : 1 complexes were found to undergo facile ESPT from the acidic enol to the basic imine group of 7HQ via the H-bond bridge. Through quantum chemical calculations, we found that the proton-transfer rate of the well-configured H-bonded complex correlated with the intramolecular H-bond length of a H-bond wiring diol molecule. Noncyclic, singly H-bonded 7HQ with a diol molecule was observed to undergo ESPT once another diol molecule diffuses to the noncyclic complex and accomplishes the formation of a reactive cyclic H-bonded 7HQ-(diol)₂ complex, which was evidenced by the observation that the overall proton-transfer rate constant decreases when a longer-chain diol was used as the bridging wire part. The kinetic isotope effect on the proton relay was investigated to confirm that the nature of the activation barrier for the proton diffusion along the wire is isotope-sensitive proton tunnelling, while for the non-cyclic configuration, the isotope-insensitive H-bond bridge formation is a prerequisite for ESPT.

Excimer formation and dual fluorescence emission of a hydroxyquinoline based macrocyclic tripod: existence of intra and intermolecular π-stacking

The excited state reaction of 1,4,7-tris-(5-methylene-8-hydroxyquinoline)-1,4,7-triazacyclononane was studied in solution. The intramolecular-π-stacked tripod shows pH-dependent eximer emission and dual fluorescence due to intermolecular π-stacking.