Improved version of oligo(2,4-diaminotoluene): synthesis, characterization, understanding, and application

Here, an attempt has been made to synthesize a high-quality fluorescent oligo(2,4-diaminotoluene) suitable for the development of a probe. The work introduces a new unique type of template (i.e., cage made of water-alcohol co-solvents) for oligomer containing 5-6 repeating units with remarkable water solubility and strong photoluminescence. Almost 16-fold enhancement of fluorescence properties compared to analogously structured polymer reported earlier has been achieved through aggregation-induced emission (AIE). Modern techniques like FTIR, NMR, PXRD, TGA, DTG, MALDI-TOF MS, SEM, TEM, SAED, and DLS are used to confirm the formation of the desired oligomer. Due to the high quantum yield (0.49), narrow emission band (full width at half maximum = 45 nm), and suitable chemical structure, the oligomer could be used as a potential fluorescent chemo-sensor for arsenic species. The reproducible LOD (2.47 mM) and wide LDR (0-100 mM) values along with robustness make the system highly relevant as an analytical tool. The structure, spectral properties, and sensing abilities of the oligomer have been understood in the light of computational chemistry.