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 Electrochemical (Bio)Sensors Based on Covalent Organic Frameworks (COFs)(Sensors, 2022) Martínez-Periñán, Emiliano; Martínez-Fernández, Marcos; Segura Castedo, José Luis; Lorenzo, EncarnaciónCovalent organic frameworks (COFs) are defined as crystalline organic polymers with programmable topological architectures using properly predesigned building blocks precursors. Since the development of the first COF in 2005, many works are emerging using this kind of material for different applications, such as the development of electrochemical sensors and biosensors. COF shows superb characteristics, such as tuneable pore size and structure, permanent porosity, high surface area, thermal stability, and low density. Apart from these special properties, COF’s electrochemical behaviour can be modulated using electroactive building blocks. Furthermore, the great variety of functional groups that can be inserted in their structures makes them interesting materials to be conjugated with biological recognition elements, such as antibodies, enzymes, DNA probe, aptamer, etc. Moreover, the possibility of linking them with other special nanomaterials opens a wide range of possibilities to develop new electrochemical sensors and biosensors.Item Synthesis and electronic properties of nitrogen-doped π-extended polycyclic aromatic dicarboximides with multiple redox processes(Journal of Materials Chemistry C, 2021) Alonso-Navarro, Matías J.; Harbuzaru, Alexandra; Martínez-Fernández, Marcos; Pérez Camero, Paula; López Navarrete, J. Teodomiro; Ramos, M. Mar; Ponce Ortiz, Rocío; Segura Castedo, José LuisIn this work, a series of nitrogen-doped polycyclic aromatic mono and dicarboximides was designed, and their synthesis is reported by an innovative synthetic procedure that avoids metal-based cross-coupling reactions. A combined theoretical, electrochemical, optical spectroscopy and material characterization study allows the investigation of the interplay of different effects such as (i) the type of solubilizing chain, (ii) the all-acceptor vs. donor–acceptor nature of the novel systems, and (iii) the molecular ordering, on the ability to stabilize multiple charges and on the OTFT device response characteristics. The amphoteric redox behavior of some of the novel systems allow to obtain ambipolar mobilities while the electron mobility values of the three all-acceptor systems can be rationalized in terms of supramolecular aggregation and enhanced film-forming ability.Item Following the light: 3D-printed COF@poly(2-hydroxyethyl methacrylate) dual emissive composite with response to polarity and acidity(Journal of Materials Chemistry A, 2022) Martínez-Fernández, Marcos; Gavara, Raquel; Royuela, Sergio; Fernández-Ecija, Laura; Ignacio Martínez, José; Zamora, Félix; Segura Castedo, José LuisA new imine-based covalent organic framework (COF) functionalized in its cavities with moieties of the chromophore Nile Red has been synthesized and characterized. Using mechanical (ultrasonics) and chemical (acid-self-exfoliation) methods, exfoliation of the COF powder has been explored in water and water/organic media. In the latter, the obtained colloids exhibit dual emission originating from the Nile Red units (red) and the COF framework (green) that can be employed to prepare ratiometric sensors of polarity and acidity. Thus, taking advantage of the in situ exfoliation of the material in methacrylic monomers, free-standing polymeric films that preserve the optical properties of the exfoliated COF have been prepared. Finally, 3D liquid crystal display (LCD) additive manufacturing has been employed to prepare the dual emissive composites as tailored 3D-printed objects.Item Evaluation of the oxygen reduction reaction electrocatalytic activity of postsynthetically modified covalent organic frameworks(ACS Sustainable Chemistry & Engineering, 2023) Martínez-Fernández, Marcos; Martínez-Periñán, Emilio; Martínez, José I.; Gordo-Lozano, Marta; Zamora, Felix; Segura Castedo, José Luis; Lorenzo, EncarnaciónThe pyrolysis of organic precursors to produce heteroatomic-doped carbonaceous materials has emerged as a powerful tool to construct metal-free heterogeneous electrocatalysts due to their low cost and their environmental friendliness. However, the lack of control in the atomic positions or the location of the chemical functionalities makes it difficult to establish structure–property relationships. Herein, we report an easy strategy to compare the electrocatalytic oxygen reduction reaction (ORR) performance of metal-free and nonpyrolyzed materials by postsynthetic modification of covalent organic frameworks (COFs) via click-chemistry. This method facilitates the evaluation of different active centers using materials with the same morphology and prevents active site agglomeration by covalently anchoring these moieties inside of a porous and crystalline framework. In this study we developed a series of diimide-based materials (XDI0.17-COFs) with a loading of 7.65 × 10–4 mol of active site/mg of host COF. The bulk COFs have been delaminated to perform electrode modification by drop-casting. The electrocatalytic response toward the ORR has been studied in alkaline media obtaining the best results for the NDI0.17-COF with an onset potential of 0.77 V (vs reversible hydrogen electrode, RHE) and a limiting current of 4.2 mA/cm2 by a preferred pathway toward water electroreduction. Finally, an adequate combination of density functional theory with the thermochemical Gibbs free energy formalism has been used to theoretically rationalize the ORR mechanism in these metal-free and nonpyrolyzed materials. We have obtained theoretical ORR overpotentials for each COF system agreeing with the experimental observation, which correlate with the ability of the NDI, BzDI, and PDI molecular blocks to accommodate electrons. Our work provides a guideline on how to study the electrocatalytic performance of different organic moieties in metal-free and non-pyrolyzed COFs avoiding their de novo synthesis by using the click postsynthetic methodology.Item Electrochemical (bio)sensors based on covalent organic frameworks (COFs)(Sensors, 2022) Martínez-Periñán, Emiliano; Martínez-Fernández, Marcos; Segura Castedo, José Luis; Lorenzo, EncarnaciónCovalent organic frameworks (COFs) are defined as crystalline organic polymers with programmable topological architectures using properly predesigned building blocks precursors. Since the development of the first COF in 2005, many works are emerging using this kind of material for different applications, such as the development of electrochemical sensors and biosensors. COF shows superb characteristics, such as tuneable pore size and structure, permanent porosity, high surface area, thermal stability, and low density. Apart from these special properties, COF’s electrochemical behaviour can be modulated using electroactive building blocks. Furthermore, the great variety of functional groups that can be inserted in their structures makes them interesting materials to be conjugated with biological recognition elements, such as antibodies, enzymes, DNA probe, aptamer, etc. Moreover, the possibility of linking them with other special nanomaterials opens a wide range of possibilities to develop new electrochemical sensors and biosensors.Item Covalent organic frameworks based on electroactive naphthalenediimide as active electrocatalysts toward oxygen reduction reaction(Applied Materials Today, 2022) Martínez-Fernández, Marcos; Martínez-Periñán, Emiliano; Royuela, Sergio; Martínez, José ; Zamora, Felix; Lorenzo, Encarnación; Segura Castedo, José LuisDeveloping organic electrocatalysts toward the oxygen reduction reaction (ORR) that avoid heteroatom doping processes and high-temperature carbonization is of great significance for the maturing of fuel cell applications. Herein, a series of two-dimensional imide-based covalent organic framework (COFs) electrocatalysts toward the ORR is reported. The hydrodynamic electrochemical study reveals that 3.5 electrons are exchanged during the ORR indicating that the process catalyzed by these COFs has a clear preference for the 4-electron reduction pathway. The COFs contain conjugated electroactive napthalenediimide (NDI) moieties that provides the active sites for the electrocatalysis and promotes the formation of COFs with face-to-face π-π stacked structures to provide intrinsic porosity and large surface areas. These COFs can be essentially considered as an organized pattern of active sites embedded in the pore walls of the COF. The choice of suitable comonomers with variable distortions from planarity offers the possibility of obtaining these electroactive COFs with similar redox ability but different degrees of porosity and interlaminar spacing. This work evidences a new insight into developing novel families of electrocatalysts from COFs. Structure and stacking fashion of the COF-systems are investigated on the basis of DFT calculations, as well as the photoabsorption spectra of the representative molecular entities and a proof-of-concept rationalization of the intermediate steps of the ORR mechanism.