Nanomaterials (Jun 2021)

Porphyrin-Based Supramolecular Flags in the Thermal Gradients’ Wind: What Breaks the Symmetry, How and Why

  • Angelo Nicosia,
  • Fabiana Vento,
  • Giovanni Marletta,
  • Grazia M. L. Messina,
  • Cristina Satriano,
  • Valentina Villari,
  • Norberto Micali,
  • Maria Teresa De Martino,
  • Maaike J. G. Schotman,
  • Placido Giuseppe Mineo

DOI
https://doi.org/10.3390/nano11071673
Journal volume & issue
Vol. 11, no. 7
p. 1673

Abstract

Read online

The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes its symmetric state, apparently reasonless, in an asymmetrical one. Nevertheless, this occurrence could be hiding unknown inductive forces. An intriguing investigation pathway uses supramolecular aggregates of suitable achiral porphyrins, useful to mimic the natural light-harvesting systems (as chlorophyll). Using as SSB probe supramolecular aggregates of 5,10,15,20-tetrakis[p(ω-methoxypolyethyleneoxy)phenyl]porphyrin (StarP), a non-ionic achiral PEGylated porphyrin, we explore here its interaction with weak asymmetric thermal gradients fields. The cross-correlation of the experimental data (circular dichroism, confocal microscopy, atomic force microscopy, and cryo-transmission electron microscopy) revealed that the used building blocks aggregate spontaneously, organizing in flag-like structures whose thermally-induced circular dichroism depends on their features. Finally, thermal gradient-induced enantioselectivity of the supramolecular flag-like aggregates has been shown and linked to their size-dependence mesoscopic deformation, which could be visualized as waving flags in the wind.

Keywords