Developing New Hydrogen Bonded Alkaline Earth Metal-Organic Complexes

Abstract

This investigation addresses the understudied area of the research and development of hydrogen bonded metal-organic complexes featuring the alkaline earth metals magnesium and calcium. This work presents the crystal structures and thermal behaviour of a series of metal-organic and organic crystalline complexes synthesised from metal salts and pyridine carboxylic, dicarboxylic acid and chloranilic acid ligands, characterised primarily by X-ray diffraction.Chapter 1 introduces crystal engineering, intermolecular interactions, and functional crystalline materials, followed by a literature review addressing metal-organic frameworks (MOFs), hydrogen bonded metal-organic complexes, magnesium MOFs and alkaline earth metal complexes synthesised from pyridine carboxylic, dicarboxylic and tricarboxylic acid and chloranilic acid.Chapter 2 outlines the theory of the techniques used to analyse the synthesised materials, focusing on single crystal X-ray diffraction, followed by Chapter 3 which documents the sample preparation and the experimental details.Chapter 4 describes the crystal structures of fourteen coordination complexes synthesised from magnesium and calcium salts and the three isomers of pyridine carboxylic acid. This work was carried out in order to identify structural trends such as the most common coordination geometries of the metal centres, the ways in which the ligands coordinate and any recurring hydrogen bonding motifs.Chapter 5 discusses attempts to synthesise an alkaline earth metal analogue of a metal-containing ‘metalloligand’ of the formula M(C7H4NO4)2(H2O)2, in which the metal (M) is N,O-chelated by pyridine-2-carboxylate-4-carboxylic acid, and the subsequent combination of these materials with the diamines o-tolidine and m-xylylenediamine. This chapter also reports the structure of a magnesium coordination complex resulting from a hydrothermal reaction, and the subsequent transformation of this complex to a new crystal structure which contains the doubly deprotonated magnesium analogue of the originally targeted ‘metalloligand’.Chapter 6 describes the crystal structures of three complexes synthesised from pyridine carboxylic acids and chloranilic acid, and the complex resulting from the combination of one of these organic ‘supramolecular ligands’ with a copper salt. Finally, two new calcium-chloranilate coordination polymers are reported, one of which has an interesting anionic 3D structure.

Date of Award	9 Dec 2015
Original language	English
Awarding Institution	University of Bath
Supervisor	Chick Wilson (Supervisor)