Bioinspired molecular electrets: bottom-up approach to energy materials and applications

Abstract

Abstract. The diversity of life on Earth is made possible through an immense variety of proteins that stems from less than a couple of dozen native amino acids. Is it possible to achieve similar engineering freedom and precision to design electronic materials? What if a handful of nonnative residues with a wide range of characteristics could be rationally placed in sequences to form organic macromolecules with specifically targeted properties and functionalities? Referred to as molecular electrets, dipolar oligomers and polymers composed of non-native aromatic beta-amino acids, anthranilamides (Aa) provide venues for pursuing such possibilities. The electret molecular dipoles play a crucial role in rectifying charge transfer, e.g., enhancing charge separation and suppressing undesired charge recombination, which is essential for photovoltaics, photocatalysis, and other solar-energy applications. A set of a few Aa residues can serve as building blocks for molecular electrets with widely diverse electronic properties, presenting venues for bottom-up designs. We demonstrate how three substituents and structural permutations within an Aa residue widely alter its reduction potential. Paradigms of diversity in electronic properties, originating from a few changes within a basic molecular structure, illustrate the promising potentials of biological inspiration for energy science and engineering.

Bioinspired approach toward molecular electrets: synthetic proteome for materials

“…9, Table 1), which is similar to what we observe for the other Aa residues [31,34]. We focus on aprotic solvents to preserve the integrity of the hydrogen bond between the N-terminal amide proton and the C-terminal carbonyl oxygen.…”

Biomimetic and bioinspired molecular electrets. How to make them and why does the established peptide chemistry not always work?

“…Combining the structural motifs of protein helices, responsible for the intrinsic macrodipoles, with the concepts of biological arrays that mediate long-range CT, we developed bioinspired molecular electrets based on anthranilamide (Aa) structures ( Fig. 1) [1,[50][51][52][53][54]. Similar to protein helices, ordered amide and hydrogen bonds generate macrodipoles along the backbones of the Aa oligomers.…”

“…1), the Aa oligomers have a high propensity for aggregation [51], which may decrease the enthusiasm for their use as "well-behaved" structural motifs as reflected by the limited number of publications. Because the Aa conjugates are polypeptides, we developed a set of electron-rich non-native Aa residues as building blocks for hole-transfer molecular electrets [53,[55][56][57][73][74][75]. Using alkyl-containing substituents as side chains, especially as R 2 ( Fig.…”

Dipole-induced effects on charge transfer and charge transport. Why do molecular electrets matter?

“…36 (Figure 1a). [120][121][122][123][124][125][126] Anthranilamide molecular electrets possess intrinsic dipoles, which in similarity with protein helices, originate from ordered arrangement of amide and hydrogen bonds (Figure 1a). 15-16, 38, 61 Similar to DNAs and PNAs, these bioinspired electrets contain closely positioned aromatic moieties that can provide pathways for long-range CT (Figure 1b).…”