The
oxidation of alkyl thiols to disulfides has been achieved under
mild conditions using a chemiluminescent 1,2-dioxetane as a stoichiometric
oxidant. Besides the mild and biocompatible reaction conditions, this
approach offers the possibility to monitor the presence of thiols
through oxidation and chemiluminescence of the remaining dioxetane.
The synthesis of
pyridazinium salts was achieved from readily available
phenylazosulfonates in a single reaction step. The reaction proceeds via the formation of short-lived phenyldiazenes, whichowing
to the strongly acidic conditionsare partially protonated.
The phenyldiazenes then undergo a rapid cycloaddition to furans to
give pyridazinium salts via elimination of water.
The fact that the pyridazinium synthesis shows a low sensitivity toward
oxygen, although phenyldiazenes occur as intermediates, can be explained
by the very fast cycloaddition step and the partial protonation of
the phenyldiazene.
Through the linkage of two muscarinergic M 3 receptor ligands to fluorescent tetramethylrhodamine-and cyanine-5-type dyes, two novel tool compounds, OFH5503 and OFH611, have been developed. Based on the suitable binding properties and kinetics related to the M 3 subtype, both ligand-dye conjugates were found to be useful tools to determine binding affinities via flow cytometric measurements. In addition, confocal microscopy underlined the comparably low unspecific binding and the applicability for studying M 3 receptor expression in cells. Along with the proven usefulness regarding studies on the M 3 subtype, the conjugates OFH5503 and OFH611 could, due to their high affinity to the M 1 receptor, evolve as even more versatile tools in the field of research on muscarinergic receptors.
Despite their long history and their synthetic potential underlined by various recent advances, radical thiol‐yne coupling reactions have so far only rarely been exploited for the functionalization of biomolecules, and no examples yet exist for their application in live cells ‐ although natural thiols show widespread occurrence therein. By taking advantage of the particular cellular conditions of mitochondria in cancer cells, we have demonstrated that radical thiol‐yne coupling represents a powerful reaction principle for the selective targeting of these organelles. Within our studies, fluorescently labeled reactive alkyne probes were investigated, for which the fluorescent moiety was chosen to enable both mitochondria accumulation as well as highly sensitive detection. After preliminary studies under cell‐free conditions, the most promising alkyne‐dye conjugates were evaluated in various cellular experiments comprising analysis by flow cytometry and microscopy. All in all, these results pave the way for improved future therapeutic strategies relying on live‐cell compatibility and selectivity among cellular compartments.
Optical storage and photon quantification systems based on sensitive photoreactions have numerous applications. Herein, we report a highly efficient photocatalytic reaction, in which ruthenium photoredox catalysis is combined with a 1,2-dioxetane from which chemiluminescence can be triggered. In this system, blue light irradiation as optical input enables a defined inverse correlation with base-triggered, blue light emission as optical output. Comparison of readout by 1 H NMR and chemiluminescence, relative to previous optical input, underlines the reliability and usefulness of the ruthenium-dioxetane system for optical storage, sensing and ruthenium detection.
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