Transition‐Metal‐Free Oxidative C(sp²)−H Hydroxylation of Terpyridines: A HOMO‐Raising Strategy for the Construction of a New Super‐Stable Terpyridine Chromophores

Abstract

Direct functionalization of terpyridines is an increasingly important topic in the field of dyes and catalysis as well as supramolecular chemistry, but its synthesis and transformation is usually challenging. Herein, a HOMO-raising strategy is reported for the construction of a super-stable novel terpyridine chromophores, in which the selective oxidation of terpyridines at its 3-position was determined successfully to the synthesis of phenol-functionalization of terpyridines (TPyOHs) bearing a hydrogen bonding group. The corresponding TPyOHs displayed strong aggregation-induced emission and exhibited highly selective and visual detection of Zn cation with a record green terpyridine-based luminophore with nanomolar sensitivity (125 nm).

Spin-Forbidden Excitation Enables Infrared Photoredox Catalysis

“…1b). S0→T1 excitation has been reported for Ru(II) 8 , Ir(III) 9 , and Fe(II) 10 , but with inconsequential absorbance. While this concept has been applied to excitation of reagents 11,12 , the discovery of new photocatalysts with stronger SOC will provide a distinctive S0→T1 excitation enabling direct access to long-lived redox-active T1 states.…”

Substituents make a difference: 6,6″-modified terpyridine complexes with helix configuration and enhanced emission

“…20–24 The 4′ and 5,5″ substituted ligands mostly serve as supramolecular building blocks and are reported in metal ion detection. 25–32 It is worth mentioning that compared with the abovementioned modification, which emphasized extended conjugation and push–pull electron effect, 6,6″-modification of Tpy ligands played an more important role in coordination configuration and consequential special properties. Because of steric hindrance or synergistic coordination effect of 6,6″ substituents, these ligands were prone to form mono-ligand complexes.…”