Single-atom substitution enables supramolecular diversity from dipeptide building blocks.

Scarel, Erica; Bellotto, Ottavia; Rozhin, Petr; Kralj, Slavko; Tortora, Mariagrazia; Vargiu, Attilio V; De Zorzi, Rita; Rossi, Barbara et al. · Soft Matter · 2022

basic_science · Level V

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Abstract

Dipeptides are popular building blocks for supramolecular gels that do not persist in the environment and may find various applications. In this work, we show that a simple substitution on the aromatic side-chain of phenylalanine with either fluorine or iodine enables supramolecular diversity upon self-assembly at neutral pH, leading to hydrogels or crystals. Each building block is characterized by <sup>1</sup>H- and <sup>13</sup>C-NMR spectroscopy, LC-MS, circular dichroism, and molecular models. The supramolecular behaviour is monitored with a variety of techniques, including circular dichroism, oscillatory rheology, transmission electron microscopy, attenuated total reflectance Fourier-transformed infrared spectroscopy, visible Raman spectroscopy, synchrotron-radiation single-crystal X-ray diffraction and UV Resonance Raman spectroscopy, allowing key differences to be pinpointed amongst the halogenated analogues.

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