The pH- and salt-controlled self-assembly of [1]benzothieno[3,2-b][1]-benzothiophene-peptide conjugates in supramolecular hydrogels

Here, we report a [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) derivative functionalized with a beta-sheet-forming peptide which alternates in its sequence Phe and Glu residues. The BTBT core is a popular structural motif in the design of high-mobility organic semiconductors. The insertion of the self-assembling subunit allows control of the supramolecular organization. This molecule self-assembles in water to give hydrogels over a broad range of pH values. Hydrogelation is triggered by both pH changes and variations in salt concentrations. Transmission electron microscopy shows the formation of long-range self-assembled 1D structures. The key role of hydrogen bonding and pi-pi interactions in hierarchical self-assembly is investigated using absorption, emission, infrared and circular dichroism spectroscopy. This is the first example of demonstrating the formation of supramolecular hydrogels containing the BTBT structure.

Automated summary

This study introduces a BTBT derivative functionalized with a beta-sheet-forming peptide, which self-assembles in water to form hydrogels triggered by pH changes and variations in salt concentrations. The role of hydrogen bonding and pi-pi interactions in hierarchical self-assembly is investigated in this work.