The work presented in this thesis tackles some important points concerning the collective properties of two typical categories of molecular crystals, i.e., anthracene derivatives and charge transfer crystals. Anthracene derivatives have constituted the class of materials from which systematical investigations of crystal-to-crystal photodimerization reactions started, developed and have been the subject of a new awakening in the recent years. In this work some of these compounds, namely, 9-cyanoanthacene, 9-anthacenecarboxylic acid and 9-methylanthracene, have been selected as model systems for a phenomenological approach to some key properties of the solid state, investigated by spectroscopic methods. The present results show that, on the basis of the solid state organization and the chemical nature of each compound, photo-reaction dynamics and kinetics display distinctive behaviors, which allows for a classification of the various processes in topochemical, non topochemical, reversible or topophysical. The second part of the thesis was focused on charge transfer crystals, binary systems formed by stoichiometric combinations of the charge donating perylene (D) and the charge accepting tetracyano-quinodimethane (A), this latter also in its fluorinated derivatives. The work was focused on the growth of single crystals, some of which not yet reported in the literature, by PVT technique. Structural and spectroscopic characterizations have been performed, with the aim of determining the degree of charge transfer between donor and acceptor in the co-crystals. An interesting outcome of the systematic search performed in this work is the definition of the experimental conditions which drive the crystal growth of the binary systems either towards the low (1:1) or the high ratio (3:1 or 3:2) stoichiometries.

This thesis concerns the study of complex conformational surfaces and tautomeric equilibria of molecules and molecular complexes by quantum chemical methods and rotational spectroscopy techniques. In particular, the focus of this research is on the effects of substitution and noncovalent interactions in determining the energies and geometries of different conformers, tautomers or molecular complexes. The Free-Jet Absorption Millimeter Wave spectroscopy and the Pulsed-Jet Fourier Transform Microwave spectroscopy have been applied to perform these studies and the obtained results showcase the suitability of these techniques for the study of conformational surfaces and intermolecular interactions. The series of investigations of selected medium-size molecules and complexes have shown how different instrumental setups can be used to obtain a variety of results on molecular properties. The systems studied, include molecules of biological interest such as anethole and molecules of astrophysical interest such as N-methylaminoethanol. Moreover halogenation effects have been investigated on halogen substituted tautomeric systems (5-chlorohydroxypyridine and 6-chlorohydroxypyridine), where it has shown that the position of the inserted halogen atom affects the prototropic equilibrium. As for fluorination effects, interesting results have been achieved investigating some small complexes where a molecule of water is used as a probe to reveal the changes on the electrostatic potential of different fluorinated compounds: 2-fluoropyridine, 3-fluoropyridine and penta-fluoropyridine. While in the case of the molecular complex between water and 2-fluoropyridine and 3-fluoropyridine the geometry of the complex with one water molecule is analogous to that of pyridine with the water molecule linked to the pyridine nitrogen, the case of pentafluoropyridine reveals the effect of perfluorination and the water oxygen points towards the positive center of the pyridine ring. Additional molecular adducts with a molecule of water have been analyzed (benzylamine-water and acrylic acid-water) in order to reveal the stabilizing driving forces that characterize these complexes.

In this thesis, we have dealt with several problems concerning liquid crystals (LC) phases, either in the bulk or at their interfaces, by the use of atomistic molecular dynamics (MD) simulations. We first focused our attention on simulating and characterizing the bulk smectic phase of 4-n-octyl-4'-cyanobiphenyl (8CB), allowing us to investigate the antiparallel molecular arrangement typical of SmAd smectic phases. A second topic of study was the characterization of the 8CB interface with vacuum by simulating freely suspended thin films, which allowed us to determine the influence of the interface on the orientational and positional order. Then we investigated the LC-water and LC-electrolyte water solution interface. This interface has recently found application in the development of sensors for several compounds, including biological molecules, and here we tried to understand the re-orientation mechanism of LC molecules at the interface which is behind the functioning of these sensors. The characterization of this peculiar interface has incidentally led us to develop a polarizable force field for the pentyl-cyanobiphenyl mesogen, whose process of parametrization and validation is reported here in detail. We have shown that this force field is a significant improvement over its previous, static charge non polarizable version in terms of density, orientational order parameter and translational diffusion.

Cancer is one of the principal causes of death in the world; almost 8.2 million of deaths were counted in 2012. Emerging evidences indicate that most of the tumors have an increased glycolytic rate and a detriment of oxidative phosphorylation to support abnormal cell proliferation; this phenomenon is known as aerobic glycolysis or Warburg effect. This switching toward glycolysis implies that cancer tissues metabolize approximately tenfold more glucose to lactate in a given time and the amount of lactate released from cancer tissues is much greater than from normal ones. In view of these fundamental discoveries alterations of the cellular metabolism should be considered a crucial hallmark of cancer. Therefore, the investigation of the metabolic differences between normal and transformed cells is important in cancer research and it might find clinical applications. The aim of the project was to investigate the cellular metabolic alterations at single cell level, by monitoring glucose and lactate, in order to provide a better insight in cancer research. For this purpose, electrochemical techniques have been applied. Enzyme-based electrode biosensors for lactate and glucose were –ad hoc- optimized within the project and used as probes for Scanning Electrochemical Microscopy (SECM). The UME biosensor manufacturing and optimization represented a consistent part of the work and a full description of the sensor preparation protocols and of the characterization methods employed is reported. This set-up (SECM used with microbiosensor probes) enabled the non-invasive study of cellular metabolism at single cell level. The knowledge of cancer cell metabolism is required to design more efficient treatment strategies.

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.

The aim of this thesis is to characterize the genuine nature of the non-bonding interactions, such as hydrogen, weak hydrogen and halogen bonding as well as the lone pair•••π interaction, in an environment free from solvent or matrix effects, by using rotational spectroscopy in supersonic expansion. Fluorination and methylation effects, competition between different non-covalent interactions, isomeric preferences are described in the molecular system studied as well as the proton transfer process, the Ubbelohde and the reverse Ubbelohde effects, the internal rotations, and quadrupole couplings which take place. The dissociation energies of the molecular adducts are also estimated and the structural determination of molecules and/or molecular complexes is performed by using isotopologue spectra. Conformational and tautomeric equilibria are investigated for molecules of biological interests, occasionally using the laser ablation technique. Studies have been performed in order to differentiate the enantiomers of chiral molecules, based on opposite phase detection in double quantum coherence experiments.

The aim of this thesis is the elucidation of structure-properties relationship of molecular semiconductors for electronic devices. This involves the use of a comprehensive set of simulation techniques, ranging from quantum-mechanical to numerical stochastic methods, and also the development of ad-hoc computational tools. In more detail, the research activity regarded two main topics: the study of electronic properties and structural behaviour of liquid crystalline (LC) materials based on functionalised oligo(p-phenyleneethynylene) (OPE), and the investigation on the electric field effect associated to OFET operation on pentacene thin film stability. In this dissertation, a novel family of substituted OPE liquid crystals with applications in stimuli-responsive materials is presented. In more detail, simulations can not only provide evidence for the characterization of the liquid crystalline phases of different OPEs, but elucidate the role of charge transfer states in donor-acceptor LCs containing an endohedral metallofullerene moiety. Such systems can be regarded as promising candidates for organic photovoltaics. Furthermore, exciton dynamics simulations are performed as a way to obtain additional information about the degree of order in OPE columnar phases. Finally, ab initio and molecular mechanics simulations are used to investigate the influence of an applied electric field on pentacene reactivity and stability. The reaction path of pentacene thermal dimerization in the presence of an external electric field is investigated; the results can be related to the fatigue effect observed in OFETs, that show significant performance degradation even in the absence of external agents. In addition to this, the effect of the gate voltage on a pentacene monolayer are simulated, and the results are then compared to X-ray diffraction measurements performed for the first time on operating OFETs.

The aim of the work was to explore the practical applicability of molecular dynamics at different length and time scales. From nanoparticles system over colloids and polymers to biological systems like membranes and finally living cells, a broad range of materials was considered from a theoretical standpoint. In this dissertation five chemistry-related problem are addressed by means of theoretical and computational methods. The main results can be outlined as follows. (1) A systematic study of the effect of the concentration, chain length, and charge of surfactants on fullerene aggregation is presented. The long-discussed problem of the location of C60 in micelles was addressed and fullerenes were found in the hydrophobic region of the micelles. (2) The interactions between graphene sheet of increasing size and phospholipid membrane are quantitatively investigated. (3) A model was proposed to study structure, stability, and dynamics of MoS2, a material well-known for its tribological properties. The telescopic movement of nested nanotubes and the sliding of MoS2 layers is simulated. (4) A mathematical model to gain understaning of the coupled diffusion-swelling process in poly(lactic-co-glycolic acid), PLGA, was proposed. (5) A soft matter cell model is developed to explore the interaction of living cell with artificial surfaces. The effect of the surface properties on the adhesion dynamics of cells are discussed.

The development of lithium-ion batteries (LIBs) with specific energy >200 Wh/kg plays a key role to boost the progress of sustainable transport and to promote the large-scale diffusion of electric vehicles with long electric-driving-range. The battery energy density can be increased by using high-voltage and/or high-capacity cathode materials. LiNi0.4Mn1.6O4 and LiNi0.5Mn1.5O4 are among the most promising cathode materials for the high theoretical specific capacity and high nominal operating voltage. However, the major concern is about their reactivity towards conventional electrolytes that decompose at high potentials leading to thick surface layers on the cathode resulting in capacity loss. This PhD work deals with the development of high energy and power LIBs featuring LiNi0.4Mn1.6O4 and LiNi0.5Mn1.5O4 cathodes, mainly for hybrid electric vehicle (HEV) applications. Starting from the challenging study of cell components such as electrolyte, separator, electrode conductive additive and binder, full cells with graphite anodes were assembled and tested according to the US Dept. of Energy (DOE) protocols for the use in power-assist and plug-in HEV applications. The use of a carbonate-based electrolyte with a fluorinated non-conventional lithium salt and of the reinforced polyvinylidene fluoride (PVdF) macroporous membrane as separator significantly improve the electrochemical performance of graphite//LiNi0.4Mn1.6O4 cells with respect to those with the conventional electrolyte and commercial separator. The study of different conductive additives on the cycling performance of LiNi0.5Mn1.5O4 electrodes demonstrated that reduced graphene oxides improve the electrode/electrolyte interface by acting as a protective barrier that hinders the formation of a thick passivation layer on the cathode surface. The study of water-soluble binder proved that carboxymethyl cellulose remarkably improve the cycling performance of LiNi0.5Mn1.5O4 electrodes compared to those with conventional PVdF binder. Characterization tests according DOE protocols on graphite//LiNi0.4Mn1.6O4 and graphite//LiNi0.5Mn1.5O4 confirmed that these cells meet the DOE targets of energy and power for power-assist and plug-in HEVs.

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