Squaramide and bis-urea supramolecular gels

Abstract

In the field of supramolecular chemistry, supramolecular low molecular weight gelators (LMWG) have attracted the public attention. Supramolecular gel is a very attractive soft materials formed by non-covalent interactions. The frameworks based on non-covalent interactions give the supramolecular gels the most important properties in dynamics and reversibility. Dynamic characters provide a variety of characterisation methods and reversibility enables them to heal structures in respond of external stimuli such as light, heat and so on. This project can be divided into two main parts. At first, gel screening and characterization have done for squaramides 2.1-2.8 which came from the Dr Rob Elmes cooperative laboratory in Maynooth University. Half of the squaramaides were gelators, and one of them was metallogelator which gelled selected solvents together with copper chlorides and nitrates. In order to characterize the physical properties of gels, rheology has been carried out. Secondly, analogues 2.9-2.12 have been synthesised. After that, gel screening and characterisation proceeded for isoniazid and nicotinic hydrazide terminated gelators with both meta-disbstituted aryl linker and tetraethyl diphenylmethane linker 2.9- 2.12. All compands have been analysed by Nuclear Magnetic Resonance (NMR), Mass spectroscopy (MS) and elemental analysis. Analogues 2.9 and 2.11 were found to be good metallogelators in the presence of copper and cadmium chlorides. Gelator 2.10 was able to give a list of partial gels while 2.12 was found to be a non-gelator. The crystals obtained from the gel screen process were send for the single crystal diffraction in order to find out the structure. What is more, typical gels formed from each gelator were charicterised by rheology.