Research Fellow

+44 (0)131 451 4167
Room 2.40
William Perkin Building
Heriot-Watt University
Gareth Lloyd
Roles and responsibilities

Hierarchical Assembly of Supramolecular Materials

The group is primarily focused on the development of supramolecular materials based on low molecular weight gelators (LMWGs). LMWGs are a class of small compounds that are capable of gelling every known liquid, have a large number of properties, have a significant number of potential applications and are industrially important. The group aims to develop rational design of these materials and their applications. This entails understanding molecular assembly, nano-assembly and macro-assembly of the different constitutents of the materials. An important aspect of the research focuses on the concept of post-assembly modification (PAM). This entails performing chemical modifications to the dynamic supramolecular asseblies to add function to the materials.

1. Benzene Triamide (BTA) gelators

The supramolecular hydrogen bonding motif known as the benzene triamide (BTA) motif has been utilised in many research fields. We have recently begun toexplore its use in LMWGs for formation of both metallogels and hydrogels. As well as understanding the structural characteristics of these materials, we areincreasingly interested in their possible applications. These materials have potential as energy research materials, as biological applicable materials for drugdelivery and cell growth, and as sensor materials.

diagram of research process from molecular design to assembly and modification
Figure 1. General research plans entailing development of both the science behind and the applicability of the assembly of the gels. Research focuses from design to characterisation of each step of the research plan.

2. Gel Design

Although LWMGs have been know for over a century, and utilised within industrial processes for just as long, there is still a lack of knowledge about how exactly they form such interesting materials. The group is actively developing characterisation techniques utilising new technologies as well as applying known techniques to determine the molecular structures at the different dimensions of the gel materials. This includes structural molecular models of the structures of the gel fibres, imaging of the gel network of nano-fibres and rheological characterisation of the physical properties.

BTA gelators forming LMWGs
Figure 2. BTA gelators are capable of forming both metallogels and hydrogels. Molecular variation of the LMWGs, as shown in these five examples, not only results in variation of the physical properties of the gels but also the agggregation induced fluorescence of the different gels.

3. Crystal Engineering and Crystallography

There is a very close link between gel formation by LMWGs and crystallisation. Both often occur through nucleation phenomena. This has naturally led the group to research crystal engineering and develop expertise in crystallography. Primary research has focused on porosity in crystalline materials, including host: guest chemistry, and organic crystalline materials, including cocrystals.

structure showing how carbon dioxide (a) and acetylene (b,c) pack differently within the interstitial spaces of the metal coordination based macrocyclic system
Figure 3. Porous materials have important applications in future technologies. In this figure we show how crystallographic determination of guest gaseous species can illuminate the supramolecular interations between guest species and host framework. In this case, carbon dioxide (a) and acetylene (b,c) pack differently within the interstitial spaces of the metal coordination based macrocyclic system resulting in only structural changes in the host framework in the case of acetylene sorption.
Selected publications

1. A Family of Simple Benzene 1,3,5-Tricarboxamide (BTA) Aromatic Carboxylic Acid Hydrogels. R. C. T. Howe, A. P. Smalley, A. P. M. Guttenplan, M. W. R. Doggett, M. D. Eddleston, J. C. Tan & G. O. Lloyd, Chem. Commun., 2013, 49, 4268

2. Metal- and Anion-Binding Supramolecular Gels. M.-O. M. Piepenbrock. G. O. Lloyd, N. Clarke & J. W. Steed, Chem. Rev., 2010, 110, 1960.

3. Supramolecular Gels: Anion-switchable Media for Controlling Crystal Growth.J. A. Foster, M.-O. M. Piepenbrock, G. O. Lloyd, N. Clarke, J. A. K. Howard & J. W. Steed, Nature Chem., 2010, 2, 1037.

4. Anion Tuning of Chiral Bis(urea) Low Molecular Weight Gels. G. O. Lloyd, M. O. M. Piepenbrock, J. A. Foster, N. Clarke & J. W. Steed, Soft Matter, 2012, 8, 204.

5. The Use of a Cocrystal Strategy to Tune and Control the Luminescent Properties of Organic Solid-state Materials. D. P. Yan, A. Delori, G. O. Lloyd, T. Friščić, G. Day, W. Jones, M. Wei, D. Evans, X. Duan, Angew. Chem. Int. Ed., 2011, 50, 12483.