This thesis describes a study from both a theoreticaL and an experimental point of view. I deveLop a new ru•deL for electron transport through networks of interconnected narnzparticLes In the... Show moreThis thesis describes a study from both a theoreticaL and an experimental point of view. I deveLop a new ru•deL for electron transport through networks of interconnected narnzparticLes In the Coulomb blockade regime and compare this ru•del tc experimental data. The main conclusion from this study is that cotunneLing does not give any significant contribution tc electron transport. Instead, transport is governed by perccIatLng paths thrcugh the netwcrk. Here, disorder In the array (in the form of variation of the Coulomb chargLng energy of the nanzparticLes) is the domLnating factor. Morecver, usLng Low—energy electron potentiometry, I visualise the f Low cf electrcns through the network. We find here that the contact resistance is negligibLe, and Chat the electi•zn flow 13 not impeded by small irregularities such as small and grain boundaries . Show less
Spin-crossover compounds showing thermal hysteresis exhibit magnetic and colourmetric bistablility, which is of interest for a number of applications such as information storage and optical... Show moreSpin-crossover compounds showing thermal hysteresis exhibit magnetic and colourmetric bistablility, which is of interest for a number of applications such as information storage and optical displays. Mononuclear iron(II) complexes hold considerable potential in this field, and their cooperative properties may suffer less from size reduction effects than polymeric SCO materials because the coordination environment remains well defined throughout the material. In this thesis, 13 new mononuclear spin-transition materials based on the bapbpy scaffold are described. One of these compounds, [Fe(bbpya)(NCS)2], shows one of the highest transition temperatures (418 K) recorded among known mononuclear SCO complexes. Most interestingly, it keeps a large hysteresis cycle of 21 K in spite of its high transition temperature. Meanwhile, metal dilution study on [Fe(bapbpy)(NCS)2] clearly shows that the two steps and the hysteresis cycles of the SCO are two consequences of the same phenomenon: intermolecular interactions between spin-switching molecules. Finally, a new bapphen-based ligand bearing a 12-carbon alkyl chain at the back of the tetrapyridyl ligand was prepared, which allowed self-assembling the corresponding iron(II) complex on a highly oriented pyrolytic graphite (HOPG) surface. The stable and highly ordered 2D patterns observed by STM are promising for the future study of cooperative spin crossover at surfaces. Show less
