Peptide-Based Supramolecular Semiconductor Nanomaterials via Pd-Catalyzed Solid-Phase “Dimerizations”

Abstract

We report a streamlined method for the synthesis of peptides embedded with complex and easily variable π-conjugated oligomeric subunits from commercially available precursors. These modified peptides self-assemble under aqueous conditions to form one-dimensional nanomaterials containing networks of π-stacked conduits, despite the inclusion of π-conjugated oligomers with quadrupoles extended over larger areas. The procedure has circumvented solubility and other synthetic issues to allow for the facile formation of a diverse library of bioelectronic nanomaterials, including a complex sexithiophene-containing peptide whose nanostructures display gate-induced conductivity within field effect transistors.

Peptide Nanostructures with π‐Ways: Photophysical Consequences of Peptide/π‐Electron Molecular Self‐Assembly

“…More recently, we used organometallic cross-coupling chemistry to prepare p-conjugated oligomeric units directly on the synthesis supports. [18] For the OPV cases, we used preformed amino acid and diacid molecules as the vehicles for incorporation into the peptide backbones, leading to what we have called nonsymmetric and symmetric peptides, respectively. Representative examples of these peptides are shown in Figure 1.…”

Peptide π-Electron Conjugates: Organic Electronics for Biology?

“…39,45,46 Although solutionphase synthesis gives better yields, solid-phase synthesis enables the construction of longer peptides and coupling with longer, insoluble pi-electron systems. 45,47 Tovar and co-workers developed solid-phase synthetic approaches that are generally applicable to a wide variety of pi-electron units ("plug-andplay"). 47,48 This is important because the isolated early examples of peptide pi-electron conjugates were limited to specific chromophore compositions.…”

“…45,47 Tovar and co-workers developed solid-phase synthetic approaches that are generally applicable to a wide variety of pi-electron units ("plug-andplay"). 47,48 This is important because the isolated early examples of peptide pi-electron conjugates were limited to specific chromophore compositions. For example, solid-phase amidations and Pd-catalyzed reactions were used to initiate "dimerization" reactions between pi-electron units and resin-bound peptides that after cleavage from the resin resulted in peptide-pi-peptide triblock molecules.…”

“…For example, solid-phase amidations and Pd-catalyzed reactions were used to initiate "dimerization" reactions between pi-electron units and resin-bound peptides that after cleavage from the resin resulted in peptide-pi-peptide triblock molecules. 47 The Pd-catalyzed route has been especially applicable to longer oligothiophene units because the inherent insolubility of the requisite building blocks (e.g., quaterthiophene to sexithiophene diacids, which contain enough thiophene repeat units required to initiate charge transport) limited reasonable synthetic preparation. 46 Figure 3 shows some of these solid-phase synthetic routes.…”

“…54 More recently, Tovar and co-workers have also shown self-assembling peptide-pi-peptide 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 12 hydrogelators with biphenyl, terphenyl, (Figure 6c-d) and alternating thiophene and phenyl units as the central pi-electron core using either solid-phase amidation of a pre-formed chromophore or on-resin Pdcatalyzed cross coupling to build complex pi-electron cores. 47 Stupp and co-workers involves multiple L-lysine segments attached to a dendritic OPV unit that selfassembles in water. 55 Thin films from these peptide-OPV conjugates were used as a surface for 3T3 fibroblasts adhesion and the fluorescent amphiphiles were gradually taken up by the cells via an endocytic pathway, and thus accumulated in the lysosomes.…”