Influence of π-Conjugated Backbone Length and Tail Chain Number on Self-Assembly Structures of Diaminotrizine Derivatives Revealed by STM

Diaminetriazine (DT) derivatives typically exhibit excellent liquid crystal properties, attracting numerous researchers interested in enhancing their performance. In this paper, two DT molecules (DT−10 and DT−12) are used to investigate how their backbone length and number of branches in the tail chains influence self-assembled nanostructures using scanning tunnelling microscopy (STM) at the 1-octanoic acid/graphite interface, compared to our previous report (2TDT−n, n = 10,12,16,18). DT−10 has a short backbone and a trialkoxy chain tail and DT−12 has a long backbone and a bifurcated chain tail. The STM results demonstrate that DT−10 adopts a cross-shaped nanostructure design and the DT heads take a head-to-head fashion connected by a pair of N–H···N hydrogen bindings (HBs). DT−12 assembles into a two-row linear pattern and DT heads take a side by side fashion connected by a pair of N–H···N HBs. After comparing with the results we previously reported, it is demonstrated that changes in the length of the backbone and the number of tail branches can only regulate the nanostructure of DT derivatives, however, the chain length of DT molecules is a key factor determining their assembly structure.