Sinthesys of heteroleptic zinc complexes for imaging in living cells

This thesis arose from an interest in luminescence heteroleptic bis(dipyrrinato) Zn (II) complexes and their application in cell imaging, due to their attractive and fascinating characteristics. Among imaging technologies, near-infrared fluorescence imaging has been dedicated immense attention owing to its low absorption and autofluorescence from surrounding organism and tissues in this specific spectral region, which minimize background interference and improve tissue depth penetration. An ideal near-infrared probe should be equipped with excellence chemical and photophysical properties. The target of this work is the synthesis of new heteroleptic bis(dipyrrinato) Zn (II) complexes having two main features: the emission in the near-infrared region and water-solubility. In order to purse these intentions, the low-energy emission was achieved by expansion of π-conjugation of simple dipyrrins using Knoevenagel condensation106 and tri(ethylene)glycol chain was introduced to increase the water solubility of the final complex. Photophysical and luminescent properties of the new complexes were investigated. Finally, with a view to a potential biological use of these new complexes in biological environments, their biocompatibility was tested using a cell viability assay: (3-(4,5-dimethylthiazol-2-yl)-2’-5’-diphenyltetrazolium bromide (MTT) assay.

Synthesis and characterization of heteroleptic Cu(I) complexes based on quinolin-yl-1,2,3-triazole and pyridin-yl-1,2,3 triazole

The present work is part of a research project that involves the study of new copper based complexes to be employed as photosensitizer in carbon dioxide photoreduction reaction. My research project is focused on the synthesis and characterization of 1,2,3 triazoles with a quinoline or pyridine in the lateral chain, which have been successively utilized to synthesize heteroleptic Cu(I) complexes. Redox potential and photophysic properties have been studied.

Synthesis, Characterization, and Applications of a Novel Cu(II)-MOF Based on a Propargylcarbamate-Functionalized Isophthalate Ligand

This work describes the synthesis of a propargylcarbamate-functionalized isophthalate ligand and its use in the solvothermal preparation of a new copper(II)-based metal organic framework named [Cu(1,3-YBDC)]ˑxH2O (also abbreviated as Cu-MOF. The characterization of this compound was performed using several complementary techniques such as infrared (ATR-FTIR) and Raman spectroscopy, X-ray powder diffraction spectroscopy (PXRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS) as well as thermal and surface area measurements. Synchrotron X-ray diffraction analysis revealed that this MOF contains a complex network of 5-substituted isophthalate anions bound to Cu(II) centers, arranged in pairs within paddlewheel (or “Chinese lantern”) structure with a short Cu…Cu distance of 2.633 Å. Quite unexpectedly, the apical atom in the paddlewheel structure belongs to the carbamate carbonyl oxygen atom. Such extra coordination by the propargylcarbamate groups drastically reduces the MOF porosity, a feature that was also confirmed by BET measurements. Indeed, its surface area was determined to be low (14.5 ± 0.8 m2/g) as its total pore volume (46 mm3/g). Successively the Cu-MOF was treated with HAuCl4 with the aim of studying the ability of the propargylcarbamate functionality to capture the Au(III) ion and reduce it to Au(0) to give gold nanoparticles (AuNPs). The overall amount of gold retained by the Cu-MOF/Au was determined by AAS while the amount of gold and its oxidation state on the surface of the MOF was studied by XPS. A glassy carbon (GC) electrode was drop-casted with a Cu-MOF suspension to electrochemically characterize the material through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The performance of the modified electrodes towards nitrite oxidation was tested by CV and chronoamperometry.

Synthesis of Metal-Binding Ligand-Containing Copolymers, Nanoparticles and Blends

In this thesis we developed three copper-containing systems. Copper shows intriguing abilities in photocatalysis, however, one of the major limitations of many copper complexes is that photochemical properties might be quenched in solution caused by π-interactions between solvent and solute, due to Jahn-Teller distortion in the excited state. As such, we herein seek to synthesise copper heteroleptic complexes that will subsequently be nanoprecipitated with a polymer. This will allow the polymer to encase the complex and prevent the solvent-induced quenching. Subsequently, the preparation of blends of polymer with the aforementioned copper complexes, at different weight ratios is sought. The preparation of the blend is particularly interesting as the catalytic properties are anticipated to be inferior on account of the low surface area. However, owing to the polymer matrix better, mechanical properties are anticipated. The blends can combine the mechanical properties of the polymer and the luminescence of the complex, with the advantage that the polymer matrix can also prevent quenching from oxygen. As final task, we developed a copper-containing monomer. The synthesis of a monomer that contains copper and can be excited under ultraviolet (UV) light is particularly interesting.

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.