Substituent-Induced Supramolecular Aggregates of Edge Functionalized Nanographenes

Precisely controlled molecular assemblies often display intriguing morphologies and/or functions arising from their structures. The application of the concept of the self-assembly for controlling the aggregation of nanographenes (NGs) is challenging. The title NGs are those carrying both long alkyl chains and tris(phenylisoxazolyl)benzene (TPIB) on the edge. The former group secures the affinity of NGs for organic solvents, and the latter group drives the 1D arrangement of NGs through the interactions between the TPIB units. The concentration-dependent and temperature variable ¹ H NMR, UV-vis, and PL spectra demonstrate the aggregation of NGs in 1,2-dichloroethane, and the aggregation is controllable by the regulation of the solvent polarity. AFM images give the stacked structures of the NGs, and these aggregates turn out to be network polymeric structures at a high concentration. These observations demonstrate that the synergy of the face-to-face interactions between the surfaces and the interactions between the TPIB units are effective for controlling the self-assembly of the NGs.