Dendron-mediated control over self-assembly of chlorophyll rosettes into columnar vs. discrete aggregates †

Kudo, Ryo; Hanayama, Hiroki; Vedhanarayanan, Balaraman; Tamiaki, Hitoshi; Hara, Nobuyuki; Rogers, Sarah E.; Hollamby, Martin J.; Manna, Biplab; Harano, Koji; Yagai, Shiki

Abstract

Photosynthetic bacteria have evolved highly efficient light-harvesting systems by organizing chlorophyll (Chl) pigments into circular and tubular supramolecular arrays. To construct these surapmoelcular Chl arrays from the same molecular design, we synthesized two hydrogen-bonding chlorins using natural Chl-a as the starting material: free-base chlorin functionalized with hydrogen-bonding barbituric acid and second- or third-generation alkyl dendrons (G2 and G3, respectively). The barbituric acid moiety promotes the formation of a hydrogen-bonded cyclic hexamer known as rosette. In chloroform, both the synthetic Chl-a derivatives formed rosettes; however, in methylcyclohexane as a low-polarity solvent, the G2-dendron chlorin formed columnar structures by stacking rosettes, while the G3-dendron chlorin formed disc-shaped particles. AFM revealed the formation of extended helical fibers for the former and homogeneous nanoparticles, possibly single rosettes, for the latter. These results suggest that the third-generation of the dendron can inhibit the stacking of rosettes, leading to the formation of two distinct types of chlorin aggregates: circular and tubular.

Citation

Kudo, R., Hanayama, H., Vedhanarayanan, B., Tamiaki, H., Hara, N., Rogers, S. E., Hollamby, M. J., Manna, B., Harano, K., & Yagai, S. (2024). Dendron-mediated control over self-assembly of chlorophyll rosettes into columnar vs. discrete aggregates †. Organic Chemistry Frontiers, 1-7. https://doi.org/10.1039/D4QO01629G

• Journal Article Type: Article
• Acceptance Date: Oct 5, 2024
• Online Publication Date: Oct 8, 2024
• Publication Date: Oct 8, 2024
• Deposit Date: Oct 25, 2024
• Publicly Available Date: Oct 25, 2024
• Journal: Organic Chemistry Frontiers
• Print ISSN: 2052-4129
• Electronic ISSN: 2052-4129
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Pages: 1-7
• DOI: https://doi.org/10.1039/D4QO01629G
• Public URL: https://keele-repository.worktribe.com/output/952932