Wavelength tunable barbituric acid derivatives: Synthesis, aggregation-induced emission and nitroaromatic detection

Three D-π-A barbituric acid derivatives were synthesized through the knoevenagel reaction between 1,3-dicyclohexylbarbituric acid and different aldehydes (N-Ethyl-3-carbazolecarboxaldehyde, 4-Dimethylaminobenzaldehyde and 4-(N,N-diphenylamino) benzaldehyde), which were named as CB, NB and TNB, respectively. The optical analyses showed the three compounds exhibited evident aggregation-induced emission (AIE) properties in THF/water. TNB emitted the strongest intensity in the aggregate state. The results of molecular dynamics simulation (MDS) showed that TNB has the highest binding energy in the solid state, which may rationalize the stronger emission intensity of TNB. NB exhibited noticeable mechanochromic fluorescence (MCF) performance, with the powder color changing for orange to yellow-brown after being ground. Both NB and TNB exhibited photostability under excitation within 1800 s. Additionally, TNB aggregates exhibited obvious fluorescence quenching to 2, 4-dinitro-toluen (DNT) and trinitrophenols (PA). The Ksv of TNB for DNT, PA were 2.8 × 105 M−1 and 3.4 × 105 M−1 respectively, and the corresponding limits of detection (LOD) were 0.367 μM and 0.296 μM, respectively.