Abstract.
       
After the absorption of a photon with the adequate energy, a chromophore can generate a Singlet excited state. These states can relax over a different excited state with less energy. This is calling the first singlet excited state (S1). S1 can relax to a different state called triplet (T0). Both states (S1 and T0) can experiment a relaxation towards the initial state, by means of a radiative process or a non radiative process (fluorescence and phosphorescence). The excited states can undergo easily oxidation or reduction in presence of donors or acceptors compared to the fundamental state. The photoinduced electron transfer can be generated from both S1 or T0 states. This only can be achieved if the energy of S1 and T0 is higher that the corresponding energy of the resultant states. This photoinduced electron transfer process provides charge separation (S•-/D•+ or S•+/A•-). Since the early eighties, photoinduced electron transfer processes had been deeply studied. These studies had afforded some applications with industrial potential as photovoltaic cells, electroluminiscence and photochromism.
Based on those principles, this PhD is devoted to the characterization and behavior study of the charge separation phenomena by means of photophysical techniques. In particular we will focus on laser flash photolysis. As it can been foreseen, chapters 3, 4 and 5 are devoted to the study of this phenomena in polymers derivated from fluorene, electron acceptors and electron donors. We will study this behavior in order to determine if these transitory spectras correspond or not to charge separation states. In a similar way the electrochromism of the copolymer PF4Ox will also be studied
Chapter 6 is devoted to the photoinduced electron transfer in solid materials with spheric morphology. These systems contain viologen and diphenyl anthracene as acceptor and donor. Being located in the pores of the material, diffusion of these compounds can be avoided providing a largest live time of the resultant radical ion (from the electron transfer). Thus, its potential can be determined and can be useful in the development of electroluminescent cells. 
In chapter 7 photocatalytic hydrogen generation will be studied. This will be obtained by irradiation with visible light of the system [Ru(bpy)32+]-MV++ in presence of cucurbit[n]urils. This study establishes which one of the possible capsules (depending on the size of cucurbit[n]uril) increases the global efficiency of the hydrogen generation by means of laser flash photolysis. 
Finally, chapter 8, the semiconductor behavior of new metal organic frameworks is presented. In this case, the absorption of a photon can promote an electron transfer. This electron transfer (with charge separation) makes this material able to accept or donate electrons depending on the species in direct contact and their respective redox potentials.