A pillar[5]arene-based three-component supramolecular copolymer for the fluorescence detection of spermine

The supramolecular polymerization of a bis-pillar[5]arene dicarboxylic acid monomer (H) in the presence of a mixture of complementary bis-guests –1,12-dodecanediyl-bis-1,1′-1H-imidazole (G1) and bis-N,N'-(6-(1H-imidazole)decyl)-perylene bisimide (G2)– produces an AA/BB-type supramolecular copolymer H/G1/G2 that retains the properties of the parent bi-component systems, that is, H/G1 solubility and H/G2 photoresponsiveness. The supramolecular copolymer showed stimuli-responsiveness, reacting to the presence of the cancer marker, spermine (S), by disassemblying and releasing G2. Once released, the perylene bisimide monomer (quenched in the copolymer by host-to-guest electron transfer), showed a remarkable increase of emission intensity. ESI-MS data are fully consistent with the formation of the H/G1/G2 copolymer, and AFM investigations on films cast from H/G1/G2 and H/G1/G2 + S solutions demonstrated that the supramolecular copolymer sensing abilities are retained also in the solid state.