Figure 1. Overview of molecular and supramolecular structures used in this study.

Shown are the molecular structures of an achiral (1) and chiral (2) BTA (a), both of which have been previously shown to self-assemble into high-aspect ratio fibres in aqueous solutions (b)14. Methodology to convert the terminal –OH in these structures to a terminal –NH₂, label statistically with a dye, and separate the singly labelled compounds (3a–b, 4a–b, see Supplementary Information for synthetic methodology) allows fluorescent labelling of these two supramolecular systems. Differences in the ultraviolet spectra of the two assembled fibres are seen when injected from MeOH into H₂O (c, 10 μM concentration, 0.2 vol% MeOH, equilibrated for 24 h at room temperture); however, their characterization on the mesoscale is very similar. Experimental SAXS profiles (d) of achiral (1, 0.45 wt% in H₂O) and chiral (2, 0.25 wt% in 96% H₂O/4% MeOH), fit with the Schurtenberger–Pedersen form factor, yield L_K=19.1±17.3 and 63.3±61.1 nm (1 and 2, respectively), L_c>191 nm, and r_cs=3.1±0.2 nm for the fibres. STORM (e, scale bar 2 μm) imaging shows both samples contain individual flexible fibres that are multiple microns in length.