Assembly of peptide–thiophene conjugates: the influence of peptide content and location

Abstract

Biomolecule-directed self-assembly of p-conjugated oligomers has attracted great attention in the past decade. In this contribution, two conjugates composed of quaterthiophene and tetrapeptide (Gly-Val-Gly-Val) were synthesised, namely peptide-thiophene -peptide (PTP) and thiophene -peptide -thiophene (TPT), to investigate the influence of peptide content ratio and its location in the molecular structures on the nanostructures and properties of the assemblies. Both conjugates formed organogels consisting of left-handed twisted nanostructures; however, anti-parallel b-sheets were observed in PTP while parallel b-sheets were obtained for TPT, although in both cases oligothiophenes adopted an H-like stacking mode. Obvious solvent-induced supramolecular chirality inversion from the oligothiophene segment was observed for PTP while such phenomenon was not clear for TPT. PTP and TPT gels also showed different stabilities towards temperature increase, as evidenced by variable-temperature circular dichroism study. From the data, it is suggested that the rational design of the location and ratio of peptide plays a key role in constructing materials with determined properties based on peptidethiophene conjugates.

Sequence-dependent mechanical, photophysical and electrical properties of pi-conjugated peptide hydrogelators

“…The two bulkiest dipeptides, -II and -FF, showed bimodal emission profiles similar to the reported emission profiles of longer oligothiophenes and quaterthiophenes in less polar solvents. 60,62,63 The CD spectra of the assembled (acidic) peptide solutions (Fig. 9c) reveal a diversity of locally chiral chromophore environments.…”

Solvent-Induced Supramolecular Assembly of a Peptide-Tetrathiophene-Peptide Conjugate

“…The synthesis of PTP has been reported in our previous report (Guo et al, 2013). And it could form gels in some aprotic solvents (THF, dioxane, and acetone) and also protic solvents (methanol and ethanol) as reported in our previous work.…”

“…Here, a peptide-tetrathiophene-peptide (PTP) conjugate (Figure 1) was used as a model object to explore the manipulation of morphology and supramolecular chirality of the assemblies via simply changing the solvent polarity. There are some significant features for PTP: Gly-(L-Val)-Gly-(L-Val) segments at both ends of the thiophene backbone are relatively hydrophilic than the thiophene core and can provide hydrogen bond sites through which β-sheet structures could be formed (Wall et al, 2011; Guo et al, 2013); the thiophene core decorated with two octyls in the middle is a hydrophobic part and can form π-π stacking as well (Lehrman et al, 2012; Guo et al, 2014); the linkers between the thiophene and peptide are flexible and then the spatial location of both hydrophilic and hydrophobic parts in the supramolecular assemblies can be freely tuned under certain conditions. Thus PTP gives chances to tune the self-assembly by verifying the solvent polarity, since H-bonding and π-π stacking are the driving forces for the self-assembly of peptide-thiophene conjugates (Guo et al, 2017b).…”

Redox‐Active Peptide‐Functionalized Quinquethiophene‐Based Electrochromic π‐Gel

“…Av ariety of biomolecules such as peptides, [1,2] carbohydrates, [3][4][5] nucleobases [6,7] and nucleotides [8] haveb eenf unctionalized with semiconducting organic p-conjugated systemf or the synthesis of self-assembledn anostructuresw hichh ave beenu sedi nt he developmento fs upramolecular electronics. [9][10][11][12][13] Oligothiophene, [14][15][16][17][18] oligo(p-phenylenevinylene)( OPV), [19,20] diacetylene (DA), [21] benzo[ghi]perylenem onoimide (BPI), [22] naphthalened iimide (NDI) [23] andp erylened iimide (PDI) [24][25][26] have been conjugatedw ithv arious peptidem otifs. Ubiquitously, the main objectivei st oa ssemble p-conjugated units into ah ighly-ordered superstructure fore ffective charge-carrier mobility.…”