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 ZnII cation with a record green terpyridine‐based luminophore with nanomolar sensitivity (125 nm). A HOMO‐raising strategy: This is the first example to reveal clearly that a new family of terpyridine molecules bearing a phenol group at the 3‐position (simplified as TPyOHs) can be prepared by tBuLi‐promoted air oxidation of simple terpyridines. The method provides a useful fluorescent probe to zinc cation and aggregation‐induced emission active molecules and Zn complex as a green luminophore.