Fig. 1.

Cyclo-dipeptide dimers serve as QDs to self-assemble into QC nanostructures. a Molecular structures of cyclo-FW and cyclo-WW. b Excitation spectra of cyclo-dipeptide monomers (thin light curves, 0.05 mM) and self-assemblies (thick dark curves, 5.0 mM) in MeOH. The excitation wavelengths red shifted from 285 nm to ~305 nm after self-assembly. c UV-Vis absorption spectra of the cyclo-dipeptides after self-assembly, showing spike-like absorptions at 273 nm, 280 nm, and 289 nm, characteristic of the formation of QD structures. d MS spectra of cyclo-FW and cyclo-WW at 5.0 mM in MeOH. The dimeric MW is marked in red, and the monomeric MW is marked in black. e Schematic representing the process of cyclo-dipeptides self-assembly: the monomers form dimeric QDs, which serve as the building blocks to self-assemble into larger QC architectures. f Calculated molecular orbital amplitude plots and energy levels of the highest occupied and lowest unoccupied molecular orbitals of cyclo-FW and cyclo-WW, showing band gaps of 3.63 eV and 3.56 eV, respectively