Bioorthogonal Phosphorogenic Rhenium(I) Polypyridine Sydnone Complexes for Specific Lysosome Labeling.

Invited for this month's cover is the group of Prof. Kenneth Kam-Wing Lo at City University of Hong Kong, Hong Kong, P. R. China. The cover picture shows the selective landing of a bioorthogonal spacecraft on a lysosomal planet modified with a strained cyclooctyne moiety in an intracellular environment with other organelles and a plethora of biomolecules. A sydnone moiety is appended to a luminescent rhenium(I) diimine unit as both an emission quencher and a bioorthogonal handle. Selective strain-promoted sydnone-alkyne cycloaddition (SPSAC) of the complex with a strained alkyne leads to impressive emission turn-on, which can be exploited in bioimaging and phototherapeutic applications. Read the full text of the article at 10.1002/cplu.202000029.