Quinoliporphyrin as an Aromatic Monoanionic Porphyrinoid and Its Degradation Promoted by Cu²⁺

This study presents the first synthesis and characterization of quinoliporphyrin (<b>6</b>), a unique aromatic monoanionic macrocycle featuring a quinoline unit within the porphyrinoid core. Previously, quinoline-containing porphyrins had their quinoline units positioned at peripheral locations. This structural feature exhibits exclusive reactivity with Cu²⁺, leading to rapid degradation at μM concentrations within 30 min at room temperature and the formation of a fluorogenic product (<b>7</b>). Such mild and rapid reactivity is attributed to the presence of the quinoline core.