Person: Segura Castedo, José Luis
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First Name
José Luis
Last Name
Segura Castedo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
Area
Química Orgánica
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item Rigid dendritic donor-acceptor ensembles: Control over energy and electron transduction(Journal of the American Chemical Society, 2002) Guldi, Dirk; Swartz, Angela; Luo, Chuping; Gómez Aspe, Rafael; Segura Castedo, José Luis; Martín León, NazarioSeveral generations of phenylenevinylene dendrons, covalently attached to a C60 core, have been developed as synthetic model systems with hierarchical, fine-tuned architectures. End-capping of these dendritic spacers with dibutylaniline or dodecyloxynaphthalene, as antennas/electron donors, yielded new donor-bridge-acceptor ensembles in which one, two, or four donors are allocated at the peripheral positions of the well-defined dendrons, while the electron accepting fullerene is placed at the focal point of the dendron. On the basis of our cyclic voltammetry experiments, which disclose a single anodic oxidation and several cathodic reduction processes, we rule out significant, long-range couplings between the fullerene core and the end-standing donors in their ground-state configuration. Photophysical investigations, on the other hand, show that upon photoexcitation an efficient and rapid transfer of singlet excited-state energy (6 × 1010 to 2.5 × 1012 s-1) controls the reactivity of the initially excited antenna portion. Spectroscopic and kinetic evidence suggests that yet a second contribution, that is, an intramolecular electron-transfer, exists, affording C60.--dendron.+ with quantum yields (Φ) as high as 0.76 and lifetimes (τ) that are on the order of hundreds of nanoseconds (220-725 ns). Variation of the energy gap modulates the interplay of these two pathways (i.e., competition or sequence between energy and electron transfer).Item Synthesis and electropolymerization of a perylenebisimide-functionalized 3,4-ethylenedioxythiophene (EDOT) derivative(Organic Letters, 2005) Segura Castedo, José Luis; Gómez Aspe, Rafael; Reinold, Egon; Bauërle, PeterWe have developed a convenient and straightforward procedure for the preparation of functionalized 3,4-ethylenedioxythiophene (EDOT) systems by using a new chloromethyl-EDOT derivative as a versatile synthon. Based on this procedure, novel suitably functionalized perylenetetracarboxylic diimide (PDI) dye derivatives covalently linked to 3,4-ethylenedioxythiophene moieties have been synthesized and electrochemically polymerized to yield a donor-acceptor PEDOT derivative with an enhanced absorption cross-sectionItem Synthesis of conjugated fluorene- alt -thiophene polymers with pendant perylenediimide units(Journal of Organic Chemistry, 2010) Gómez Aspe, Rafael; Seoane Prado, Carlos; Segura Castedo, José LuisIn this article we present the synthesis, characterization, electrochemical, optical, and preliminary photophysical investigation of two novel poly(fluorene-alt-thiophene) conjugated polymers endowed with pendant perylenediimide electron acceptor units. We show a route to the synthesis of easily functionalizable monomers paving the way to the preparation of a variety of functionalized polymers with different properties and applications and reflecting the versatility of this synthetic methodologyItem Energy and electron transfer in a poly(fluorene-alt-phenylene) bearing perylenediimides as pendant electron acceptor groups(Macromolecules, 2007) Gómez Aspe, Rafael; Veldman, Dirk; Blanco, Raúl; Seoane Prado, Carlos; Segura Castedo, José Luis; Janssen, RenéWe describe the synthesis and characterization of a novel poly(fluorene-alt-phenylene) substituted with perylenediimide (PDI) moieties as pendant groups. Cyclic voltammetry experiments show the amphoteric nature of the material, which combines the good electron donor ability of the polymeric chain with the acceptor properties of the pendant PDI moieties. Absorption spectroscopy suggests the presence of PDI aggregates, whereas the emission spectra show a strong emission quenching of both the polymeric backbone and the PDI units. Further investigation on the energy and/or electron-transfer processes involved is carried out by temperature-dependent excitation spectra and photoluminescence lifetimes. These studies show the presence of electron transfer not only from the electron donor polymeric chain to the pendant PDI units but also, and more remarkably, to PDI aggregates both in solution and in solid state, as is further confirmed by photoinduced absorption spectroscopyItem Highly efficient light-harvesting organofullerenes(Organic Letters, 2005) Gómez Aspe, Rafael; Segura Castedo, José Luis; Martín León, NazarioDiphenylmethanofullerene-perylenebisimide dyads and triads have been prepared as light harvesters and electron acceptors for the preparation of efficient organic solar cells. The presence of swallowtail chains on the perylene unit provides enhanced solubility and allows its complete characterizationItem Supramolecular assembly of graphene with functionalized poly(fluorene-alt-phenylene): The role of the anthraquinone pendant groups(Chemical Communications, 2011) Castelaín, Marta; Salavagione, Horacio José; Gómez Aspe, Rafael; Segura Castedo, José LuisHybrid materials composed of graphene and conjugated poly(fluorene-alt- phenylene) endowed with redox-active anthraquinone moieties are prepared. Remarkable changes in the electronic properties of the polymer are observed. Effective interactions among the pendant anthraquinone and graphene, likely due to π-π stacking, are confirmed.