Sophorolipids (SLs), an important class of glycolipid biosurfactants, consist of a sophorose (glucose disaccharide) polar head group that can be acetylated at the 6′- and/or 6′′- positions. The sophorose moiety is β-glycosidically linked to a sub terminal hydroxylated fatty acid that is either free or internally esterified at the 4′′ hydroxyl site. They self-assemble into nanostructures such as micelles and chiral supramolecular ribbons. This paper focuses on synthetic methods employed to prepare a series of SL-porphyrin conjugates. These natural synthetic hybrids were used to probe how SL-structural parameters influence the ordering and corresponding electro-optical properties of porphyrin chromophores. Sophorolipids differing in fatty acid chain length and sophorose acetylation were conjugated to zinc-porphyrin dyes by copper(I)-catalyzed azide-alkyne cycloaddition ‘click’ chemistry. Self-assembly and aggregation properties of various conjugated molecules were studied in solution by recording UV-vis and CD spectra at variable temperatures. Spectroscopic studies reveal the formation of helical J-aggregates. Structure- property relationship of various SL-porphyrin conjugates indicate that fine-tuning interactions between SL-carbohydrate hydrogen bonding groups provide a sensitive approach to control porphyrin self-assembly and corresponding optoelectronic properties.

Conjugation of chemo-enzymatically modified sophorolipids to porphyrin chromophore: Bio-based materials for organic optoelectronic applications

254th National Meeting (2017)

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