Effects of functional groups and side chains on assembly of “X”-shaped new aggregation-induced emission molecules

Abstract

The self-assembly properties of aggregation-induced emission molecules play important roles in electroluminescence devices and fluorescence sensors because noncovalent interactions in self-assembly structures would accelerate the excitation energy consumption. However, there are only few studies to explore their self-assembly properties on the interface and there is still a great need for further understanding self-assembled mechanisms from the viewpoint of molecular design. Here, we presented three X-shaped aggregation-induced emission molecules X1, X2 and X3, which decorated with different functional groups and alkyl side chains. The self-assembly structures were revealed by scanning tunneling microscopy technique in combination with density functional theory. Results showed that X-shaped molecules self-assembled into different structures, depending on their molecular structure, especially the functional groups. Furthermore, self-assembly structures could be regulated by adjusting solution concentration. In more detail, parallel with gradually increasing solution concentration, the molecules approached closer and molecule–molecule interactions were enhanced, finally resulting in new nanostructures. The self-assembly properties of three X-shaped aggregation-induced emission molecules on the liquid/solid interface would give a guidance for further exploring the aggregation state in three-dimensional space. Meanwhile, the two-dimensional nanostructures might show special properties, which could be used in fabricating next generation functional films.