Andrew Hirst
Supramolecular Dendritic Gels

Project Overview

Low molecular weight dendritic peptides induce physical gelation in a wide variety of organic fluids, only in the presence of a complementary guest, a diamine molecule. Since gelation occurs as a result of cooperative non-covalent interactions, i.e., hydrogen bonding, van der Waals, pi - pi stacking etc, these physical gels exhibit thermally reversible behaviour. In addition, they are easily transformed into isotropic solutions on heating. Electron microscopy reveals a three-dimensional network of intertwined fibre-like structures that possess highly directional aggregation. This two-component gelling system provides the opportunity for tuning one or both of the molecular components in order to elucidate the effect of subtle structural changes on gel formation (1). This current research highlights the possibilities in which macroscopic properties (e.g. Tgel) and microstructural features of the gel can be controlled (2). Particular attention is focused on the importance of the molar concentration, molecular structure of diamine and the ratio of the dual components.

One of the key aspects of this dendritic organogel is its inherent chirality, a feature that occurs as a consequence of using L-lysine to construct the dendritic branches. Over 30% of all drugs are chiral, and many more are synthesised as racemic mixtures, yet it is often the case that only one enantiomer is active, with the other enantiomer being a less active version or at worst a seriously toxic compound. It is the intention of this research to exploit the multiple chiral centres inherent within the structure of the L-lysine based dendritic gel to enable separation of enantiomers relevant to the pharmaceutical industry.

During my time in Dave's group I have co-written a significant number of papers and reviews - including two papers published in JACS, and three in Chem Eur J (one rated VIP by the referees). These references can be found listed on the publications section of this website.

International collaborations - Netherlands (Dr Martin Feiters, Nijmegen), Spain (Dr. Bea Escuder, Castellon). International conferences - Japan (Nanomaterials conference 2006). International Dendrimer Symposia (Berlin and Michigan).