Precise control over nanoscale morphologies is essential for designing advanced supramolecular systems with programmed functions. Among various molecular motifs, diketopiperazine (DKP) stands out as a promising building block due to its robust hydrogen-bonding capability. Inspired by natural products containing DKP units, we developed supramolecular assemblies based on bispyrrolidinoindoline (BPI) scaffolds fused with DKP rings. By exploiting the conformational tunability of BPI scaffolds arising from rotation around the C3a─3a' bond, we achieved precise modulation of their three-dimensional conformations and self-assembly behavior through dual substituent and stereochemical modifications. Iodination at the C5/5' positions refined conformational preferences and promoted the formation of highly ordered nano-structures. Moreover, additional stereochemical modification at the C15/15' positions successfully shifted the morphology from block-like to fibrous assemblies. These findings underscore the pivotal roles of substituent and stereochemistry in controlling nanoscale morphology, positioning BPI-based scaffolds as a versatile platform for supramolecular engineering.
Oki et al. (Fri,) studied this question.