Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

Lorenzo Catti; Shinji Aoyama; Michito Yoshizawa

doi:10.3762/bjoc.20.5

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

Beilstein J Org Chem. 2024 Jan 8:20:32-40. doi: 10.3762/bjoc.20.5. eCollection 2024.

Authors

Lorenzo Catti¹, Shinji Aoyama¹, Michito Yoshizawa¹

Affiliation

¹ Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.

Abstract

Efficient water-solubilization of nanocarbons is desirable for both their biological and material applications, but so far has mainly relied on covalent modifications or amphiphiles featuring ionic side-chains. Here, we report a facile 2-4-step synthesis of pyridinium-based, bent aromatic amphiphiles with modular nonionic side-chains (i.e., CH₃ and CH₂CH₂(OCH₂CH₂)₂-Y (Y = OCH₃, OH, and imidazole)). The new amphiphiles quantitatively self-assemble into ≈2 nm-sized aromatic micelles in water independent of the side-chain. Importantly, efficient water-solubilization and nonionic surface modification of various nanocarbons (e.g., fullerene C₆₀, carbon nanotubes, and graphene nanoplatelets) are achieved through noncovalent encircling with the bent amphiphiles. The resultant imidazole-modified nanocarbons display a pH-responsive surface charge, as evidenced by NMR and zeta-potential measurements. In addition, solubilization of a nitrogen-doped nanocarbon (i.e., graphitic carbon nitride) in the form of 10-30 nm-sized stacks is also demonstrated using the present amphiphiles.

Keywords: aromatic micelle; nanocarbon; nonionic surface modification; pyridinium; water-solubilization.

Grants and funding

This work was supported by JSPS KAKENHI (Grant No. JP22H00348/JP23K17913/JP22H05560/JP23K13760). S.A. thanks the Tokyo Tech Advanced Human Resource Development fellowship.