Self-Assembly of Boc-Protected Diphenylalanine Functionalized with Boron-Dipyrromethane

Abstract

Peptides functionalized with fluorescent dyes can form aggregated structures that show potential for photonic and/or theranostic applications. In this study, we used the good-bad solvent method to induce the self-assembly of chromopeptides into various products, which were characterized using a multi-technique spectroscopic approach. Two hydrophobic chromopeptides were designed by attaching boron-dipyrromethane dyes to Boc-protected diphenylalanine, resulting in spherical aggregates with tunable dimensions, influenced by the compound's molar concentration and solvent composition. These aggregates exhibit distinct optical properties, including bathochromic shifts in absorption and emission bands, as well as induced chirality, suggesting different chromophore orientations within the microspheres. Moreover, the aggregates show accelerated excited-state relaxation compared to monomeric chromopeptides, primarily through non-radiative processes. This work establishes a foundation for future studies focused on optimizing the desired photophysical properties of similar chromopeptide aggregates, depending on their intended application.

Keywords: Chromopeptides, self-assembly, microparticles, diphenylalanine, supramolecular aggregates.