Aggregation induced emission (AIE) compounds with barbiturate groups: the relationship between intermolecular hydrogen bonding and AIE effects

Barbiturate group, as a group with aggregation induced emission (AIE) effect, has multiple hydrogen bond donor and acceptor sites, but few people pay attention to the relationship between the intermolecular hydrogen bond of barbiturates and AIE phenomenon. In this paper, a barbiturate molecule BNCA-1 with carboxyl group (–COOH) was designed and synthesized and the effect of intermolecular hydrogen bond formation on molecular AIE phenomenon was analyzed. Firstly, the intramolecular charge transfer effect of BNCA-1 molecule was studied by molecular computation. According to molecular spectral analysis, it was found that BNCA-1 has strong AIE phenomenon in aprotic mixed solvent. In order to clearly understand the specific binding sites of intermolecular hydrogen bonds, two other AIE compounds with similar structures (BNCA-0 and DM-BNCA-1) were designed and synthesized. Through the comparison of molecular fluorescence phenomena, the enhancement of AIE effect of intermolecular hydrogen bond was proved. On this basis, the AIE molecule BNCA-2 and BNCA-3 were synthesized, and it was understood that the intermolecular distance would have influence on the AIE effect of molecules. We believed that this study will increase the understanding of barbiturate AIE compounds and contribute to the study of the important role of hydrogen bonds in the fluorescence of AIE compounds.