Examinando por Autor "Ramos, Mar"

Mostrando 1 - 5 de 5

Environmental impact analysis of surface printing and 3D inkjet printing applications using an imine based covalent organic framework: A life cycle assessment study
(Elsevier, 2023) Espada, Juan J.; Rodríguez, Rosalía; Peña, Alejandro de la; Ramos, Mar; Segura, José L.; Sánchez-Carnerero, Esther M.
Covalent organic frameworks (COFs) are emerging materials with structural modularity that allows their application in many fields. The aim of this work is to determine the environmental impact of using an imine based covalent organic framework (RT-COF-1) for both surface printing (Case A) and 3D inkjet printing (Case B) by applying Life Cycle Assessment (LCA) methodology. Experimental data on RT-COF-1 synthesis as well as results obtained by simulation of their precursors production, 1,3,5-tris-(4-aminophenyl) benzene (TAPB) and 1,3,5-benzenetricarbaldehyde (BTCA), are used. LCA results show that monomer synthesis is the most important contributor to environmental impacts in both case studies. On the other hand, the contribution of solvents used in Case A is also remarkable. The comparison between both case studies indicates that the environmental impacts of Case B is lower than that of Case A (reduction within 5%–65%). Finally, LCA results of Case B are compared to other materials used for 3D-printing, such as polymerizable ionic liquids (PILs). The results show that RT–COF–1 compares favourably with PILs in five of nine impact categories, being especially relevant the reductions achieved in the abiotic depletion and acidification potential (>90%), in the primary energy consumption (⁓35%) and carbon footprint (⁓50%), suggesting the potential of RT–COF–1 as 3D-printing material from an environmental perspective. This work is a first step for further research to highlight the main environmental burdens of using COF-based materials in this application.
Highly efficient solution-processed white organic light-emitting diodes based on novel copolymer single layer
(Elsevier, 2012) Coya, Carmen; Álvarez, Ángel Luis; Ramos, Mar; Gómez, Rafael; Seoane, Carlos; Segura, José Luis
We fabricate by solution processed methods organic light emitting diodes with single-layer structure (ITO/(PEDOT:PSS)/co-polymer/Ba/Al) and study the transport properties of the final devices. The copolymer is novel poly(fluorene-alt-phenylene) (PFP) derivatives containing co-monomers, involving red-emitting 1,8-naphthalimide units as pendant groups (0.0005, 0.005, 0.02 and 0.08 wt%) covalently attached. All the devices exhibited emission at very low driving currents in the A range (47¿73 A). White emission with luminous efficiency of 9.42 Cd/A at 50 A is obtained for the co-polymer with the smallest amount of chromophore. Commission Internationale de L¿Eclairage (CIE) coordinates evolve from almost pure white color (0.26, 0.30) for low currents to stable cool white (0.21, 0.23). Increasing naphthalimide contents leads to stable green and orange emission with 3.07, 19.5 and 6.7 Cd/A efficiencies. The current-voltage response of the devices is analyzed by means of a numerical model that includes an injection mechanism based in the microscopic hopping theory and a field-dependent carrier mobility for the bulk transport regime. The fitting results allow to estimate the dependence of carrier mobility on polymer composition in the diodes.
Post-synthetic modification of covalent organic frameworks
(Royal Society of Chemistry, 2019-07-21) Ramos, Mar; Royuela, Sergio; Segura, Jose Luis
Covalent organic frameworks (COFs) are organic porous materials with many potential applications, which very often depend on the presence of chemical functionality at the organic building blocks. Functionality that cannot be introduced into COFs directly via de novo syntheses can be accessed through post-synthetic modification (PSM) strategies. Current strategies for the post-synthetic modification of COFs involve (i) incorporation of a variety of active metal species by using metal complexation through coordination chemistry, (ii) covalent bond formation between existing pendant groups and incoming constituents and (iii) chemical conversion of linkages. (iv) The post-synthetic modification is sometimes assisted by a monomer truncation strategy for the internal functionalization of COFs. (v) Even more intriguing methods that go beyond PSM are herein termed building block exchange (BBE) which encompasses framework-to-framework transformations taking advantage of the fact that reversible bond formation is a characteristic feature of COFs. This strategy allows the use of protoCOF structures (i.e., the utilization of a parent COF as a template) for the evolution of new COF structures with completely new components. © 2019 The Royal Society of Chemistry
Scalable Synthesis and Electrocatalytic Performance of Highly Fluorinated Covalent Organic Frameworks for Oxygen Reduction
(Wiley VCH, 2023-10-16) Ramos, Mar; Martínez-Fernández, Marcos; de la Peña, Alejandro; Segura, José Luis; Rodríguez-San-Miguel, D; Zamora, Felix; Martínez-Periñán, E; Lorenzo, E; Aguilar-Galindo, F; Cabrera-Trujillo, J.J.; Vismara, R.; Navarro, J.A.R.
Abstract: In this study, we present a novel approach for the synthesis of covalent organic frameworks (COFs) that overcomes the common limitations of non-scalable solvothermal procedures. Our method allows for the roomtemperature and scalable synthesis of a highly fluorinated DFTAPB-TFTA-COF, which exhibits intrinsic hydrophobicity. We used DFT-based calculations to elucidate the role of the fluorine atoms in enhancing the crystallinity of the material through corrugation effects, resulting in maximized interlayer interactions, as disclosed both from PXRD structural resolution and theoretical simulations. We further investigated the electrocatalytic properties of this material towards the oxygen reduction reaction (ORR). Our results show that the fluorinated COF produces hydrogen peroxide selectively with low overpotential (0.062 V) and high turnover frequency (0.0757 s􀀀 1) without the addition of any conductive additives. These values are among the best reported for non-pyrolyzed and metal-free electrocatalysts. Finally, we employed DFT-based calculations to analyse the reaction mechanism, highlighting the crucial role of the fluorine atom in the active site assembly. Our findings shed light on the potential of fluorinated COFs as promising electrocatalysts for the ORR, as well as their potential applications in other fields.
V-Shaped Tröger Oligothiophenes Boost Triplet Formation by CT mediation and Symmetry Breaking
(ACS Publications, 2023-12-07) Medina Rivero, Samara; Alonso-Navarro, Matías J.; Tonnelé, Claire; Marín-Beloqui, Jose M.; Suárez-Blas, Fatima; M. Clarke, Tracey; Kang, Seongsoo; Oh, Juwon; Ramos, Mar; Kim, Dongho; Casanova, David; Segura, José L.; Casado, Juan
A new family of molecules obtained by coupling the Tröger’s base unit with dicyanovinylene-terminated oligothiophenes of different lengths has been synthesized and characterized by steady-state stationary and transient time-resolved spectroscopies. Quantum chemical calculations allow us to interpret and recognize the properties of the stationary excited states, as well as the time-dependent mechanisms of singlet-to-triplet coupling. The presence of the diazocine unit in the Tröger’s base derivatives is key to efficiently produce singlet-to-triplet intersystem crossing mediated by the role of the nitrogen atoms and of the almost orthogonal disposition of the two thiophene arms. Spin-orbit coupling mediated interstate ISC is activated by a symmetry breaking process in the first singlet excited state with a partial charge transfer character. This mechanism is characteristic of these molecular triads since the independent dicyano-vinylene oligothiophene branches do not display appreciable ISC. These results show how the Tröger’s base coupling of organic chromophores can be used to improve the ISC efficiency and tune their photophysics.