Supramolecular gels are formed due to the self-assembly of small gelator molecules in a suitable solvent as a result of specific weak non-covalent interactions between the gelators. Sodium deoxycholate (NaDC) is a bile salt surfactant known for its ability to form a supramolecular gel within a certain pH range. These gels are made up of aggregates out of which 40 % of the aggregates are in water and 60 % are in the gel immobilized phase. NaDC gels are reversible and considered promising candidates from a functional point of view. The objective of this work is to understand the role of cucurbit[6]uril (CB[6]) as an additive on the overall release properties of guests from NaDC gels. The information obtained from these studies will be essential in the design of ways to control the properties in gels using additives.<br/>The guests chosen for this study were pyrene and rhodamine 6G. Rhodamine 6G is a positively charged molecule that interacts with the portals of CB[6] and is mainly located in the aqueous region of the gel. Pyrene is a hydrophobic molecule that is too large to fit inside CB[6] cavity but can still have a weak interaction with CB[6]. Overall release of guests from NaDC gels was studied at CB[6]:NaDC concentration ratios of 0, 0.05, 0.1, 0.15 using a top layer method. The structural characterization was done using laser scanning fluorescence microscopy.<br/>From microscopy studies, we observed that CB[6] facilitates the incorporation of NaDC aggregates in water into the gel immobile phase resulting in larger gel features of up to 100 μm. Release studies with rhodamine 6G showed that CB[6] has no effect on the release of the guest from NaDC gels. However, pyrene release experiments showed that CB[6] slowed down the release of the guest from NaDC gels. Results from release experiments and microscopy suggest that depending on the guest hydrophobicity, localization of guests in the gel could be varied which leads to differences in the observed release patterns.

Mechanistic insights on the effect of additive on supramolecular gel system

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.