Electrochemistry of Molecular Systems for New Nanostructured Materials and Bioelectronic Devices

Nanomaterials have a tremendously increasing importance in our daily lives but their world is extremely wide. The main aim of this work is to implement the knowledge about these materials, focusing in particular on some of the nano allotropic forms of Carbon. This precise choice is consequence of their extreme versatility and promising properties for electronic, energetic and biological applications, which can be further improved with doping or functionalization. In the first part of my work I introduced nanotechnology and nanomaterials, highlighting their importance, recent developments and applications, trying to focus on the importance of electrochemistry in the study of such a field. Electrochemistry, in fact, through the investigation of fundamental electronic processes can exploit electrical and catalytic processes of nanomaterials and become an interface between nano and macroscopic world. The second chapter of this thesis is dedicated to the investigation of a new synthetic pathway for bottom up nano-Graphene production, using polyaromatic hydrocarbons precursors. The chemical and morphological analysis of the obtained deposits gives encouraging results about the proficient production of Carbon-base nano-assemblies. The third chapter is dedicated to the study and application of nanocarbons for energy production with particular attention to the incoming environmental problem. The objects of my study were Nitrogen-doped Graphene, as an alternative to metal catalysts for Oxygen reduction reaction (ORR), and a Bodipy chromophore coupled with a Fullerene, as an efficient system for photoelectrochemical conversion. The results obtained until now in the study of Carbon-based nanomaterials represent a good reason to further investigate their behaviour, properties and possible applications and I hope this thesis is a contribution to such a complex topic

Efficient photoinduced charge separation in a BODIPY-C60 dyad

A donor-acceptor dyad composed of a BF2-chelated dipyrromethene (BODIPY) and a C60 fullerene has been newly synthesized and characterized. The two moieties are linked by direct addition of an azido substituted BODIPY on the C60, producing an imino-fullerene-BODIPY adduct. The photoinduced charge transfer process in this system was studied by ultrafast transient absorption spectroscopy. Electron transfer toward the fullerene was found to occur selectively exciting both the BODIPY chromophore at 475 nm and the C60 unit at 266 nm on a time scale of a few picoseconds, but the dynamics of charge separation was different in the two cases. Eletrochemical studies provided information on the redox potentials of the involved species and spectroelectrochemical measurements allowed to unambiguously assign the absorption band of the oxidized BODIPY moiety, which helped in the interpretation of the transient absorption spectra. The experimental studies were complemented by a theoretical analysis based on DFT computations of the excited state energies of the two components and their electronic couplings, which allowed identification of the charge transfer mechanism and rationalization of the different kinetic behavior observed by changing the excitation conditions

correction liponitroxides epr study and their efficacy as antioxidants in lipid membranes

Correction for 'Liponitroxides: EPR study and their efficacy as antioxidants in lipid membranes' by Giovanna Mobbili et al., RSC Adv., 2015, 5, 98955–98966

Liponitroxides: EPR study and their efficacy as antioxidants in lipid membranes

A series of lipid-functionalized nitroxides having a pyrroline nitroxide moiety linked either to a glycerol or to a steroid unit has been synthesized, and their inclusion inside phospholipid bilayers has been investigated by Electron Paramagnetic Resonance (EPR) spectroscopy. The antioxidant behavior of these nitroxides has been studied in azo-initiator induced lipid peroxidation by means of the Thiobarbituric Acid Reactive Species (TBARS) assay; a correlation with their penetration depth within the bilayer has been found. The possible mechanisms involved in the antioxidant action have been considered, discussed and alternative pathways have been suggested for the synthesized liponitroxides due to their different localization. The steroid derivative is limited to scavenging radicals that are generated in the aqueous phase, while the glycerolipids can also act as chain breaking antioxidants

Efficient Photoinduced Charge Separation in a BODIPY–C₆₀ Dyad

A donor–acceptor dyad composed of a BF₂-chelated dipyrromethene (BODIPY) and a C₆₀ fullerene has been newly synthesized and characterized. The two moieties are linked by direct addition of an azido substituted BODIPY on the C₆₀, producing an imino–fullerene–BODIPY adduct. The photoinduced charge transfer process in this system was studied by ultrafast transient absorption spectroscopy. Electron transfer toward the fullerene was found to occur selectively exciting both the BODIPY chromophore at 475 nm and the C₆₀ unit at 266 nm on a time scale of a few picoseconds, but the dynamics of charge separation was different in the two cases. Eletrochemical studies provided information on the redox potentials of the involved species and spectroelectrochemical measurements allowed to unambiguously assign the absorption band of the oxidized BODIPY moiety, which helped in the interpretation of the transient absorption spectra. The experimental studies were complemented by a theoretical analysis based on DFT computations of the excited state energies of the two components and their electronic couplings, which allowed identification of the charge transfer mechanism and rationalization of the different kinetic behavior observed by changing the excitation conditions