Synthesis of molecular species for supramolecular assembly

This thesis details the synthesis and study of molecular species designed to form supramolecular assemblies, in particular for surface deposition purposes. The first chapter gives a brief introduction to supramolecular chemistry concepts and the basis on which this project is built. The importance of non-covalent bonding interactions to form complex architectures capable of self-assembly is discussed, in particular hydrogen bonds and pi-pi interactions with a series of examples from the literature to illustrate the work that has been accomplished over the past few years in various fields of supramolecular chemistry and nanotechnology in particular. The present project aims at the design, the synthesis and the characterisation of two different groups of compounds, namely p-terphenyl tetracarboxylic acid derivatives and manganese based single molecule magnets. The former are dealt with in the second chapter of the present thesis. The scientific background and the recent results obtained following the surface deposition of p-terphenyl-3,5,3',5'-tetracarboxylic acid are explained and discussed in the introduction. The focus of the research is to design and synthesise similar derivatives, i.e capable of self-assembling to produce similar ordered arrays on surfaces as observed for the parent molecule, but bearing some specific functional groups that are anticipated to either induce a change in the observed assembly process or even impart the molecular functionality upon the assembly. The third chapter of the thesis describes the synthesis and functionalisation of manganese-based single molecule magnets, which are believed to be promising candidates for future applications such as high-density data storage. The crystal structures of some derivatives are discussed and a crystallographic comparative study between the as-synthesised derivatives and literature examples is detailed. In addition, the magnetic properties of selected complexes are discussed and compared. Finally, the results resulting from surface deposition studies that have been carried out in collaboration with the School of Physics and Astronomy at the University of Nottingham are presented in the last section of this chapter

Synthesis of molecular species for supramolecular assembly

This thesis details the synthesis and study of molecular species designed to form supramolecular assemblies, in particular for surface deposition purposes. The first chapter gives a brief introduction to supramolecular chemistry concepts and the basis on which this project is built. The importance of non-covalent bonding interactions to form complex architectures capable of self-assembly is discussed, in particular hydrogen bonds and pi-pi interactions with a series of examples from the literature to illustrate the work that has been accomplished over the past few years in various fields of supramolecular chemistry and nanotechnology in particular. The present project aims at the design, the synthesis and the characterisation of two different groups of compounds, namely p-terphenyl tetracarboxylic acid derivatives and manganese based single molecule magnets. The former are dealt with in the second chapter of the present thesis. The scientific background and the recent results obtained following the surface deposition of p-terphenyl-3,5,3',5'-tetracarboxylic acid are explained and discussed in the introduction. The focus of the research is to design and synthesise similar derivatives, i.e capable of self-assembling to produce similar ordered arrays on surfaces as observed for the parent molecule, but bearing some specific functional groups that are anticipated to either induce a change in the observed assembly process or even impart the molecular functionality upon the assembly. The third chapter of the thesis describes the synthesis and functionalisation of manganese-based single molecule magnets, which are believed to be promising candidates for future applications such as high-density data storage. The crystal structures of some derivatives are discussed and a crystallographic comparative study between the as-synthesised derivatives and literature examples is detailed. In addition, the magnetic properties of selected complexes are discussed and compared. Finally, the results resulting from surface deposition studies that have been carried out in collaboration with the School of Physics and Astronomy at the University of Nottingham are presented in the last section of this chapter

Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rhombus tilings

The degree of randomness, or partial order, present in two-dimensional supramolecular arrays of isophthalate tetracarboxylic acids is shown to vary due to subtle chemical changes such as the choice of solvent or small differences in molecular dimensions. This variation may be quantified using an order parameter and reveals a novel phase behaviour including random tiling with varying critical properties as well as ordered phases dominated by either parallel or non-parallel alignment of neighbouring molecules, consistent with long-standing theoretical studies. The balance between order and randomness is driven by small differences in the intermolecular interaction energies, which we show, using numerical simulations, can be related to the measured order parameter. Significant variations occur even when the energy difference is much less than the thermal energy highlighting the delicate balance between entropic and energetic effects in complex self-assembly processes

Synthesis of molecular species for supramolecular assembly

This thesis details the synthesis and study of molecular species designed to form supramolecular assemblies, in particular for surface deposition purposes. The first chapter gives a brief introduction to supramolecular chemistry concepts and the basis on which this project is built. The importance of non-covalent bonding interactions to form complex architectures capable of self-assembly is discussed, in particular hydrogen bonds and pi-pi interactions with a series of examples from the literature to illustrate the work that has been accomplished over the past few years in various fields of supramolecular chemistry and nanotechnology in particular. The present project aims at the design, the synthesis and the characterisation of two different groups of compounds, namely p-terphenyl tetracarboxylic acid derivatives and manganese based single molecule magnets. The former are dealt with in the second chapter of the present thesis. The scientific background and the recent results obtained following the surface deposition of p-terphenyl-3,5,3',5'-tetracarboxylic acid are explained and discussed in the introduction. The focus of the research is to design and synthesise similar derivatives, i.e capable of self-assembling to produce similar ordered arrays on surfaces as observed for the parent molecule, but bearing some specific functional groups that are anticipated to either induce a change in the observed assembly process or even impart the molecular functionality upon the assembly. The third chapter of the thesis describes the synthesis and functionalisation of manganese-based single molecule magnets, which are believed to be promising candidates for future applications such as high-density data storage. The crystal structures of some derivatives are discussed and a crystallographic comparative study between the as-synthesised derivatives and literature examples is detailed. In addition, the magnetic properties of selected complexes are discussed and compared. Finally, the results resulting from surface deposition studies that have been carried out in collaboration with the School of Physics and Astronomy at the University of Nottingham are presented in the last section of this chapter.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Guest-induced growth of a surface-based supramolecular bilayer

Self-assembly of planar molecules on a surface can result in the formation of a wide variety of close-packed or porous structures. Two-dimensional porous arrays provide host sites for trapping guest species of suitable size. Here we show that a non-planar guest species (C60) can play a more complex role by promoting the growth of a second layer of host molecules (p-terphenyl-3,5,3″,5″-tetracarboxylic acid) above and parallel to the surface so that self-assembly is extended into the third dimension. The addition of guest molecules and the formation of the second layer are co-dependent. Adding a planar guest (coronene) can displace the C60 and cause reversion to a monolayer arrangement. The system provides an example of a reversible transformation between a planar and a non-planar supramolecular network, an important step towards the controlled self-assembly of functional, three-dimensional, surface-based supramolecular architectures.We thank the UK Engineering and Physical Sciences Research Council for financial support under grant EP/D048761/1. M.S.thanks the European Research Council for an Advanced Grant.N.R.C.acknowledges the receipt of a Royal Society Leverhulme Trust Senior Fellowship.S