I) Improving low photocurrent of pseudorotaxane based solar cell II) Synthesis and characterization of new Fe(0) cyclopentadienone complexes

Next to conventional solar panels that harvest direct sunlight, p-type dye-sensitized solar cells (DSSCs) have been developed, which are able to harvest diffuse sunlight. Due to unwanted charge recombination events p-type DSSCs exhibit low power conversion efficiencies (PCEs). Previous research has shown that dye-redox mediator (RM) interactions can prevent these recombination events, resulting in higher PCEs. It is unknown how the nature of dye-RM interactions affects the PCEs of pseudorotaxane-based solar cells. In this research this correlation is investigated by comparing one macrocycle, the 3-NDI, in combination with the three dyes that contains a recognition sites. 2D-DOSY-NMR experiments have been conducted to evaluate the diffusion constants (LogD) of the three couple. The research project has been stopped due to the coronavirus pandemic. The continuation of this thesis would have been to synthesize a dye on the basis of the data obtained from the diffusion tests and attempt the construction of a solar cell to then evaluate its effectiveness. During my training period I synthetized new Fe(0) cyclopentadienone compounds bearing a N-Heterocyclic Carbene ligand. The aim of the thesis was to achieve water solubility by modifications of the cyclopentadienone ligand. These new complexes have been modified using a sulfonation reaction, replacing an hydroxyl with a sulfate group, on the alkyl backbone of the cyclopentadienone ligand. All the complexes were characterized with IR, ESI-MS and NMR spectroscopy, and a new Fe(0) cyclopentadienone complex, involved as an intermediate, was obtained as a single crystal and was characterized also with X-Ray spectroscopy.

Synthesis of manganese organometallic complexes

Il presente lavoro di tesi si inserisce in un progetto di ricerca volto alla sintesi di nuovi complessi di metalli di transizione per lo sviluppo di catalizzatori da impiegare in reazioni di catalisi omogenea. In particolare il mio progetto si è concentrato sulla sintesi di complessi organometallici di manganese con leganti carbenici N-eterociclici (NHC). La scelta dei leganti è stata effettuata in modo tale da poter avere leganti chelanti NHC di tipo MIC (mesoionic carbene) sintetizzati tramite cicloaddizione tra un alchino ed un azide catalizzata da rame (CuAAC) e N-alchilazione. Lo studio di questi complessi a base di manganese è ancora tutt’oggi agli albori, leganti NHC vengono molto utilizzati grazie alla possibilità di variarne le proprietà steriche ed elettroniche e alla possibilità di formare legami forti con quasi tutti i metalli. Il manganese è stato scelto poiché un elemento abbondante, poco tossico e poco costoso. The present thesis work is part of a research project aimed at the synthesis of new transition metal complexes to be used in homogeneous catalysis reactions. In particular my project focused on the synthesis of manganese organometallic complexes with N-heterocyclic carbene ligands (NHC). The choice of ligands was carried out to have NHC chelating ligands of the class of MIC (mesoionic carbene). These ligands are synthesized by cycloaddition between alkyl and azide with a copper-catalyzed reaction (CuAAC) and N-alkylation in order to obtain MIC after deprotonation. The study of these manganese-based complexes is still in its infancy today, NHC ligands are widely used thanks to the possibility of varying their steric and electronic properties and the possibility of forming strong bonds with almost all metals. The choice of manganese was made because is an abundant, low-toxic and inexpensive element.