Photochemistry of self-assembled donor-acceptor architectures for photoactive supramolecular devices

Supramolecular donor-acceptor assemblies were prepared and studied with spectro-scopic methods. The two main objectives of this work were: (i) fundamental study of photoinduced energy and electron transfer processes in self-assembled supramolecular donor-acceptor complexes in solutions and (ii) self-assembly and photophysical characterization of donor-acceptor films on titanium dioxide (TiO2) surface. The study of these systems aims to develop more complex architectures for artificial photosynthesis and understand factors that affect efficiency of the photoinduced energy and electron transfer processes in natural and artificial photosynthesis. This knowledge can be used for building photoactive molecular devices such as organic solar cells. The singlet excited state energy transfer in dyads formed via axial metal–ligand coordination of free-base porphyrin to metal (Mg, Ru) complexes of pthalocyanine was observed. The position of imidazole linker group on one of the meso-aryl groups of the free-base porphyrin was used to tune the rates of energy transfer. The two-point binding provides better control over complex geometry and it was implemented utilizing metal-ligand and crown-ether coordination in zinc chlorin–fullerene supramolecular dyads. This approach allowed to increase the binding efficiency and achieve a well-defined mutual orientation between the moieties. The electron transfer rate was found to depend on the donor-acceptor distance as well as the mutual orientation of the entities and could be manipulated by changing positions of binding groups. The donor-acceptor layers were assembled on TiO2 using two methods. First, a layer of covalently linked porphyrin-pthalocyanine dyads was formed on TiO2 via supramolecular approach. Then, a new method was developed to construct donor-acceptor two-layer films using separate porphyrin and fullerene molecules. In both cases, photo-excitation of donor molecules resulted in charge-separation (CS) inside the organic layer and sequential electron transfer towards the TiO2. Furthermore, the charge recombination (CR) process was found to be slower than for systems sensitized with single chromophores

Subphthalocyanines, Phthalocyanines and Azulenocyanines: Red and NIR-Absorbing Dyes for Molecular Photovoltaics

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 23-07-201

Phthalocyanine-fullerene dyads and DNA interstrand cross-linking on surface

Tesis Doctoral inédita cotutelada por la Technische Universität Berlin y la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 15-03-2017Esta tesis tiene embargado el acceso al texto completo hasta el 15-09-201

DESIGN AND REGIOSELECTIVE SYNTHESIS OF TWO AND THREE-PRONGED C\u3csub\u3e60\u3c/sub\u3e FULLERENE DERIVATIVES AND THEIR APPLICATIONS IN MOLECULAR ELECTRONICS

Since the introduction of semiconductors in the second half of the 20th century, advancements in electronics and technology have been tremendous. In particular, the rapid development of silicon-based computer chip technology and miniaturization of electronic components has been tremendous. Since silicon-based materials have a limit in terms of size, scientists proposed that individual molecules could behave as single electronic components for high degree of miniaturization. Given that the molecules of interest must have dimensions on the nanometer scale, be able to bind to the electrode surface and have electron donor-acceptor properties, C60 fullerene has been a prime candidate for these studies. It has also been found that a covalent bond between a C60 derivative and the surface of a metal substrate enhances the electron tunneling conductance upon accepting electrons, demonstrating the importance of the design and regioselective synthesis of C60 fullerene derivatives. However, regiochemical control is very challenging given its high symmetry. The work presented here explores the synthesis, characterization and electrochemical properties of pentakis-, hexakis- and heptakis-adducts of C60 and some of its Fe-complexes under a regio-controlled protection-deprotection protocol. Derivatives were synthesized using two known reactions: cyclopropanation and 1,3-dipolar cycloaddition reactions, better known as: as the Bingel-Hirsch and Prato reactions, respectively. This approach allowed us to introduce the addends in specific positions over the sphere. For example, two pyrrolidine groups were bonded in a trans-1 relationship with respect to each other. These adducts were characterized by means of 1H, 13C, and 2D-NMR, UV-vis, MALDI-TOF MS and ESI-MS. Their electrochemical properties were analyzed by Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) experiments

Advances and Challenges in Organic Electronics

Organic Electronics is a rapidly evolving multidisciplinary research field at the interface between Organic Chemistry and Physics. Organic Electronics is based on the use of the unique optical and electrical properties of π-conjugated materials that range from small molecules to polymers. The wide activity of researchers in Organic Electronics is testament to the fact that its potential is huge and its list of potential applications almost endless. Application of these electronic and optoelectronic devices range from Organic Field Effect Transistors (OFETs) to Organic Light Emitting Diodes (OLEDs) and Organic Solar Cells (OSCs), sensors, etc. We invited a series of colleagues to contribute to this Special Issue with respect to the aforementioned concepts and keywords. The goal for this Special Issue was to describe the recent developments of this rapidly advancing interdisciplinary research field. We thank all authors for their contributions