Self-assembly of aliphatic dipeptides coupled with porphyrin and BODIPY chromophores

Abstract

In this work, the self assembly ability of chromophores covalently linked to aliphatic dipeptides is described. Altering various parameters such as the protecting group, the solvent mixture, the dipeptide and the chromophore resulted in different nanostructures.Interestingly, a peptide-porphyrin hybrid is capable of forming a hydrogel in HFIP-water solvent mixture.Living natural systems utilize self-assembly in order to fulfil their functions; thus, understanding the basic aspects of this process takes us a step closer to the comprehension of life. 1 Numerous examples in nature have inspired supramolecular scientists to synthesize molecules with self-assembling ability aiming at the construction of materials with improved properties. 2 Self-assembled architectures that mimic chlorophylls and bacteriochlorophylls in nature are of great interest for light harvesting applications. 3 A variety of bioinspired building blocks have been explored for the fabrication of self-assembling molecules including peptides, 4,5 nucleic acids, 6,7 peptide nucleic acids, 8,9 lipids etc. Of the small peptides, diphenylalanine (FF), the basic structural motif for the Alzheimer's beta amyloid polypeptide, is an aromatic dipeptide that has been extensively investigated for its self-assembling properties. 10,11 More specifically, a great number of chromophores such as porphyrins, 12-15 boron-dipyrromethenes, 16 corroles, 17 polyoxometallates 18 and ferrocene 19 have been covalently connected to FF resulting in hybrids that retained the ability to form well-defined nanostructures. In addition, small aliphatic peptides have also been investigated for their self-assembly ability. 20 In a recent example, Yan and co-workers reported that a short peptide based on

Fundamental Aspects of Xanthene Dye Aggregation on the Surfaces of Nanocluster Polyoxometalates: H‐ to J‐Aggregate Switching

“…From another point of view, the balance between H‐ and J‐aggregates is just as important for tuning supramolecular polymerization as it is for other self‐assembly processes . Moreover, H‐aggregate formation is important for materials where a high charge mobility is required.…”

Controlling Solar Hydrogen Production by Organizing Porphyrins

“…Notably, the absorption maxima of PdTCP and PtTCP upon their adsorption onto TiO 2 NPs are significantly shifted and broadened, which is a concrete evidence of porphyrin self‐assembly onto the semiconductor (Figure 2a). In particular, compared to their corresponding spectra in solution, an increase in full width at half maximum (FWHM) of 56 nm was detected [12a,c,d] . PdTCP exhibits H ‐ aggregation upon its adsorption onto TiO 2 NPs since the absorption maxima are blue‐shifted (Figure 2b).…”

Peptide-Tetrapyrrole Supramolecular Self-Assemblies: State of the Art

“…Interestingly, all the examples of hydrogel supramolecular structures involve Fmoc-pro- Fmoc/Boc protection did not particularly affect the assembly of FF (e.g., in conjugates 1a-c [52,53]) but had a remarkable impact for peptides that do not self-assemble. "Spiky spheres", "flake-shape" structures and a hydrogel were observed after the assembly of protected aliphatic dipeptides conjugates ( 45a-d and 46a-d) in hexafluoroisopropanol/water [104]. In the same solvent mixture, the noncovalent combination of a Fmoc-protected FF with a porphyrin (15) also forms a hydrogel [64].…”