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

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^II cation with a record green terpyridine-based luminophore with nanomolar sensitivity (125 nm).