Water gelation by small organic molecules.

Low molecular weight supramolecular gels consist of small molecules (gelators) that in an appropriate solvent self-assemble into nano- or micro-scale network structures resulting in the formation of a gel. Most supramolecular gels consist of two parts, namely the solvent and the gelator. However, the concept of multi-component supramolecular gels, in which more than one compound is added to the solvent, offers a facile way (e.g. by changing the ratio of the different components) to tailor the properties of the gel. The simplest multi-component gels consist of two components added to the solvent and are the most widely studied to date. There are three general classes of such multi-component gels that have been investigated. The first class requires all the added components to access the gel; that is, no component forms a gel on its own. A second class uses two (or more) gelators which can either co-assemble or self-sort into distinct assemblies and the final class consists of one (or more) gelator and one (or more) non-gelling additive which can impact the assembly process of the gelator and therefore the gel's properties.

Supramolecular gels formed from multi-component low molecular weight species

Surfactant layers at the air/water interface: structure and composition.

Surfactant systems: their use in drug delivery

Chirality seems to be intimately associated with the growth and stability of self-assembled fibrillar networks and with the most common macroscopic property of these networks, which is the thermoreversible gelation of the solvent. The presence and the relative configurations of stereogenic centers in the structure of a small molecule gelator are generally (but not always) observed to be critical to its ability to form gels. Symmetry considerations of chiral molecular packing provide thermodynamic and kinetic arguments that may explain why chirality favors fiber growth. Additionally, molecular chirality is sometimes expressed at a scale of nanometers or micrometers and gives rise to twisted or coiled fiber structures that are readily observable by microscopic techniques. These chiral fiber morphologies have already found some applications as templates for helical protein crystallization or for the growth of chiral inorganic replicas. The chiroptical properties of assembled chiral molecules, e.g., circular dichroism, allow monitoring of aggregation and may sometimes give insights into molecular packing. But determining chiral molecular arrangements in the fibers remains a challenge and requires the use of multiple techniques.

Chirality Effects in Self-assembled Fibrillar Networks.

Long-lived micellar N-alkylaldonamide fiber gels. Solid-state NMR and electron microscopic studies

The molecular conformation of N-(1-octyl)-D-gluconamide in its helical micellar fibers is determined. The all-anti conformation in three-dimensional crystals and the 4 G + conformation in DMSO solution served as references. Comparisons of 13 C CP/MAS solid-state NMR spectra of head-to-tail and tail-to-tail oriented crystals led to a 2 G - conformation for the gluconamide head groups and an all-anti conformation for the alkyl chains in the fibers. The latter result is confirmed by powder X-ray diffraction data and infrared spectra

Soenke Svenson

Papers

Long-lived micellar N-alkylaldonamide fiber gels. Solid-state NMR and electron microscopic studies

Crystalline order in probably hollow micellar fibers of N-octyl-D-gluconamide

A CPMAS 13C NMR Study of Molecular Conformations and Disorder of N-Octylhexonamides in Microcrystals and Supramolecular Assemblies

Long-Lived Micellar N-Alkylaldonamide Fiber Gels. Solid-State NMR and Electron Microscopic Studies.