The thesis is focused on the investigation of the electron transfer mechanisms leading to solar fuel production and to the identification of engineering principles that can be used to design... Show moreThe thesis is focused on the investigation of the electron transfer mechanisms leading to solar fuel production and to the identification of engineering principles that can be used to design materials able to improve charge separation. Molecular systems composed of three or more subunits arranged in a Donor-Antenna-Acceptor design are required to achieve efficient photoinduced charge separation. It is shown how structural changes in the systems design can be used to systematically optimize the energy gradients and electronic coupling between the molecular subunits, necessary to achieve controlled unidirectional charge transfer. To gain insight into the mechanisms governing the charge transfer processes within a molecular system, the process of photoinduced heterogeneous electron injection is investigated through nonadiabatic dynamics simulations. Coherent electron-nuclear vibrational effects are found to drive the electron transfer process by promoting the coherent superposition of the exciton and the charge transfer quantum state. A photoanode for solar water splitting comprising the functions of light-harvesting, charge separation and catalysis is also investigated. It is observed that, following a fast heterogeneous electron injection, the system catalytic activity is driven by a proton-coupled electron transfer mechanism in which the role of the solvent is crucial. Show less
The thesis has shown that the metal porphyrin complexes are effective catalysts for both the electrochemical reduction of carbon dioxide and nitrate. pH plays an important role on both the... Show moreThe thesis has shown that the metal porphyrin complexes are effective catalysts for both the electrochemical reduction of carbon dioxide and nitrate. pH plays an important role on both the electroreduction of carbon dioxide and nitrate. The insights into the mechanism for both reactions offer the opportunity for the design of new effective catalysts in the future. Show less
Reactions on metal surfaces are of scientific interest due to the tremendous relevance of heterogeneous catalysis. Single crystal surfaces under controlled physical conditions are generally... Show moreReactions on metal surfaces are of scientific interest due to the tremendous relevance of heterogeneous catalysis. Single crystal surfaces under controlled physical conditions are generally employed as a model for the real catalysts, with the aim of improving the fundamental understanding of the adsorption of molecules on metals. In this field, computer simulations have a high potential to help with interpreting experiments as they can provide an atomic-scale movie of a chemical process. The aim of this thesis has been to apply the ab initio molecular dynamics (AIMD) technique to the study of reactions on metal surfaces. The use of AIMD bypasses the need of pre-computing and fitting a potential energy surface, since the forces acting on the nuclei are calculated `on-the-fly' at each time step of the dynamics. The advantage is that statistically accurate reaction probabilities for small molecules on metal surfaces can be calculated including surface temperature effects and lattice recoil without introducing a priori dynamical approximations on the molecular degrees of freedom. Observables derived from the reaction probability, such as the sticking coefficient, the vibrational efficacy, and the rotational alignment parameter, have been calculated and compared to available experimental data for H2+Cu(111), N2+W(110) and CH4+Pt(111). Show less
Membrane proteins are account for up to two thirds of known druggable targets. Traditionally, new drugs against this class of proteins have been discovered through HTS. However, not all GPCRs are... Show moreMembrane proteins are account for up to two thirds of known druggable targets. Traditionally, new drugs against this class of proteins have been discovered through HTS. However, not all GPCRs are amenable to traditional screening methods. Recently, fragment-based drug discovery (FBDD) has emerged as a powerful strategy to generate approved drugs against soluble targets. Now, FBDD can be applied to GPCRs with great potential advantages. In recent years, a number of FBDD techniques have been validated for use with GPCRs. The impressive growth in GPCR structure information leads to broad use of structure-based methods for hit discovery and optimization. However, the dynamic nature of GPCRs, and standard issues associated with low level expression and instability during purification, made biophysical and structural characterization of GPCRs particularly difficult. New advances in protein stabilization by using different protein engineering methods and alternative solubilization strategy have shown the potential to facilitate GPCR structural and biophysical studies. The goal of the work described in this thesis was to develop and implement efficient fragment screening methods to discover ligands of GPCRs with novel biological activities, and new advances in receptor production and stabilization to facilitate structural biology of GPCRs in the early stages of drug discovery. Show less
