“…Akin to Schiff base, azine can also act as an AIE unit and proton acceptor to form intramolecular hydrogen bonding with the o ‐hydroxyl group on benzene (Scheme 2D,E), [ 40, 41, 48, 54, 61, 67, 75, 79, 82, 84, 85, 87, 91, 92, 94, 95, 97, 98, 104– 106, 111, 115, 117, 173–178 ] naphthalene (Scheme 2F), [ 49, 80, 174 ] and coumarin rings (Scheme 2H). [ 93, 179 ] Among these compounds, symmetric salicylaldehyde azine derivatives (SAA, Scheme 2E) [ 41, 61, 75, 79, 87, 91, 92, 94, 95, 97, 98, 104–106, 111, 115 , 117, 175–178 ] have gained the most popularity in construction of ESIPT‐based AIEgens because they are easily synthesized from salicylaldehyde derivatives and hydrazine hydrate even in one step.…”