Macrocyclic tetra-imidazolium salt sensor for p-nitroaniline sensing

Macrocyclic tetra-imidazolium salt 2 was synthesized and characterized, and its crystal structure was determined by X-ray diffraction. One 30-membered macrocycle of 2 was constructed by four imidazoliums, two carbazoles and two proplenes. The recognition of 2 to aromatic compounds was studied via fluorescence spectra, UV/vis spectra, HRMS, 1H NMR and IR spectra. The results showed that 2 had high selectivity and sensitivity to p-nitroaniline (p-NA).