Effect of the substituents on luminescent behaviors of the salts based on 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl)diphenol

•The luminescent properties can be mediated by the substituent groups such as methyl, hydroxyl and carboxylate groups.•The emission wavelengths with 429, 434 and 460 nm can be observed.•The C…C close contacts with the values of 0.1, 4.0 and 7.6% can be found.•The order of the emission maxima is consistent with that of the C…C close contacts.•The hydroxyl hydrogen atoms located at two phenyl rings of the cations show trans-, trans-cis, and cis-cis-conformation.