Efficient synthesis of pillar[5]quinone for rapid identification of aromatic nitro explosives.

An efficient synthesis of pillar[5]quinone (Q5) is reported for the rapid identification of aromatic nitro explosives. A record-high synthetic yield of 96% on a gram scale for Q5 can be achieved via a two-step reaction process involving the demethylation of pillar[5]arene to hydroxypillar[5]arene, followed by oxidation with Oxone to form Q5. In addition, by modifying amino silicon spheres with Q5 to prepare a stationary phase material (Q5-Sil) for high-performance liquid chromatography (HPLC), efficient separation of eight typical aromatic nitro-explosives was achieved using a single column. The underlying mechanism of the separation of aromatic nitro-explosives in the Q5-Sil-packed column resulted from dipole-dipole interactions, hydrophobic effects, and steric factors between Q5 and analytes. This work achieved the quantitative synthesis of Q5, established a novel method of macrocyclic modification of chromatographic column stationary phase materials, and provided a mixed mechanism for the HPLC-based separation of aromatic nitro-explosives, expanding the interdisciplinary applications of macrocyclic supramolecular chemistry in the field of analytical separation science.