Fabrication of thiophene/dicyanovinyl aggregation-induced fluorescent materials for preferable detection of picric acid

Abstract A family of aggregation-induced emission (AIE) luminescent molecules D1−D5 has been designed having the same 2-(thiophen-2-ylmethylene)malononitrile (TMM) skeleton in order to further investigate the AIE mechanism. TMM is an interesting structure with the combination of the restriction of intramolecular rotations and vibrations in a single molecule. As expected, dyes D1, D3, and D4 show clear AIE behaviors based on the different pyridine and tetraphenylethylene groups. Single crystal structure for D3 shows that the thiophene ring is coplanar with the malononitrile unit, showing a strong intramolecular conformational locking with the S1⋯N2 distance of 3.329(13) A. Furthermore, fluorescent titration results suggest that this family presents potential chemosensors for picric acid (PA). The quenching percentage for chromophores D1, D3, and D4 is 66%, 74% and 80%, respectively, when the concentration of PA is 7.2 × 10−5 mol/L. In addition, electrochemistry and theoretical energy gaps, as well as relative potential energy calculations have been carried out for full comparison, which turns out that TMM derivatives have great importance in terms of fabricating and expanding the future fluorescent materials.