Isobenzotriazolophanes: a new class of fluorescent cyclophanes as sensors for aromatic nitro explosives – picric acid

A new class of novel conjugated and highly fluorescent isobenzotriazolophanes containing electron-rich N-heterocyclic moieties, such as pyrrole, indole and carbazole, were synthesized for the first time through McMurry coupling. The carbazole-based isobenzotriazolophane with a quantum yield of 0.38 showed a positive response to the quenching of electron-deficient aromatic nitro compounds, such as picric acid (PA), selectively at micromolar concentration. The Stern–Volmer quenching constant is 8.82 × 102 M−1 and the limit of detection (LOD) of PA was found to be 19 ppm.