Evolution of covalent organic frameworks: from design to real-world applications

Covalent Organic Frameworks are highly versatile porous materials that have attracted much attention over the last few years. This review summarizes the timeline of its development, highlighting the shifts in the targets deemed necessary to use them in real-world applications. We have collected aspects concerning COF formation and the strategies developed to gain chemical stability by using different linkages between the initial building blocks and modulating the structural characteristics of COFs. Importantly, we have also included elements concerning material processability that has been incorporated in the research field of COFs but are essential to solving many different applications of COFs. Finally, we included a summary section providing headlines of this research field to get closer to real applicationsThis work has been supported by the Spanish MICINN (PID2019- 106268GB-C32, and TED2021-129886B-C42) and through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018- 000805-M). We also thank financial support to the Comunidad de Madrid (MAD2D-CM) and MICINN (Planes complementarios, Materiales Avanzados

Electrochemical Double-Layer capacitor based on Carbon@ covalent organic framework aerogels

High energy demand results in comprehensive research of novel materials for energy sources and storage applications. Covalent organic frameworks (COFs) possess appropriate features such as long-range order, permanent porosity, tunable pore size, and ion diffusion pathways to be competitive electrode materials. Herein, we present a deep electrochemical study of two COF-aerogels shaped into flexible COF-electrodes (ECOFs) by a simple compression method to fabricate an electrochemical double-layer capacitor (EDLC). This energy storage system has considerable interest owing to its high-power density and long cycle life compared with batteries. Our result confirmed the outstanding behavior of ECOFs as EDLC devices with a capacity retention of almost 100 % after 10 000 charge/discharge cycles and, to our knowledge, the highest areal capacitance (9.55 mF cm−2) in aqueous electrolytes at higher scan rates (1000 mV s−1) for COFs. More importantly, the hierarchical porosity observed in the ECOFs increases ion transport, which permits a fast interface polarization (low τ0 values). The complete sheds light on using ECOFs as novel electrode material to fabricate EDLC devicesThis work has been supported by the Spanish MINECO (PID2019-106268GB-C32) and through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805

Iron Oxyhydroxide-Covalent Organic Framework Nanocomposite for Efficient As(III) Removal in Water

The presence of heavy metal ions in water is an environmental issue derived mainly from industrial and mineral contamination. Metal ions such as Cd(II), Pb(II), Hg(II), or As(III) are a significant health concern worldwide because of their high toxicity, mobility, and persistence. Covalent organic frameworks (COFs) are an emerging class of crystalline organic porous materials that exhibit very interesting properties such as chemical stability, tailored design, and low density. COFs also allow the formation of composites with remarkable features because of the synergistic combination effect of their components. These characteristics make them suitable for various applications, among which water remediation is highly relevant. Herein, we present a novel nanocomposite of iron oxyhydroxide@COF (FeOOH@Tz-COF) in which lepidocrocite (γ-FeOOH) nanorods are embedded in between the COF nanoparticles favoring As(III) remediation in water. The results show a remarkable 98.4% As(III) uptake capacity in a few minutes and impressive removal efficiency in a wide pH range (pH 5−11). The chemical stability of the material in the working pH range and the capability of capturing other toxic heavy metals such as Pb(II) and Hg(II) without interference confirm the potential of FeOOH@Tz-COF as an effective adsorbent for water remediation even under harsh conditionsThis work has been supported by the Spanish MINECO (PID2019-106268GB-C32 and PCI2019-103594) and through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M

Ingeniería de moldeado de redes orgánicas covalentes

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Inorgánica. Fecha de Lectura: 26-01-2023Esta tesis tiene embargado el acceso al texto completo hasta el 26-07-2024Designing materials to achieve ordered structures is a chemistry and materials science target. In this context, covalent organic frameworks (COFs) offer a platform for tailoring organic materials with ordered structures, enabling topology-guided integration of organic units to form crystalline porous material. COFs are novel-type porous materials made of light elements joined by covalent bonds with a wide range of applications, from water purification to energy storage. However, the as-synthesized COF crystallites integrate through wild covalent self-assembly, leading to their precipitation as polycrystalline powders. As a result, their potential is hindered from being exploited. In this thesis, novel synthesis strategies have been designed to produce imine-based COFs' macroscopic objects in a more suitable way to reach their top potential application. The first introductory chapter of this work desires to provide a state-of-the-art overview of COFs, explaining their general aspects, possible processing methodologies and potential applications. The first work provides a high-yield "one-pot" green synthesis of imine-based COFs in water. Additionally, this aqueous synthesis can be achieved under microwave conditions, significantly reducing the reaction time. In the second work, we first report a simple three-step method to produce COFaerogels based on sol-gel transition. The resultant COF-aerogel have extremely low densities, high hierarchical porosity, and outstanding mechanical properties. Moreover, they show excellent water-contaminant capacity, with high removal efficiency. The third work describes a simple compression method to prepare large-scale, free-standing homogeneous and porous imine-based COF-membranes with dimensions in the centimetre range and excellent mechanical properties. COFmembranes fabricated upon compression show good performances for separating gas mixtures of industrial interest, N2/CO2 and CH4/CO2Finally, two-additional works have been carried out to show COFs' potential possibilities. The first study presented a new procedure for the post-synthetic functionalization of imine-based COFs using a heterogeneous solid-gas reaction without a copper catalyst. The second study describes a general process for the preparation of centimetre-scale, hierarchically porous, monolithic COFs. These two works elevate the possibility of these versatile organic porous materials to be applied in a wide variety of applications. To sum up, evolution of COFs chemistry from chemical design of non-scalable, non-processable structures to a bulk-scale processable form tries to promote COFs for practical/industrial applications. In this thesis, it will be discussed about novel synthetic strategies to reach imine-based COF in an eco-friendlier way and their processability into macroscopic objects on large-scal

β-Ketoenamine-linked covalent organic frameworks synthesized via gel-to-gel monomer exchange reaction: From aerogel monoliths to electrodes for supercapacitors

Covalent organic frameworks (COFs) possess intrinsic nanoscale pores,limiting mass transport and impacting their utility in many applications, suchas catalysis, supercapacitors, and gas storage, demanding efficient diffusionthroughout the material. Hierarchical porous structures, integrating largermacropores with inherent micro-/meso-pores, facilitate rapid mass transport.Recently, the fabrication of aerogel monoliths is reported exclusively fromimine-linked COFs, offering flexibility in aerogel composition. However,challenges in synthesizing robust -ketoenamine-based COFs withcomparable surface areas prompted innovative synthetic approaches.Leveraging the dynamic nature of COF bonds, in this work efficient monomerexchange from imine to partially -ketoenamine-linked COFs within the gelphase is demonstrated. These aerogels can be transformed into electrodesusing the compression technique. The new flexible electrodes-based-ketoenamine-linked COF composites with C super P exhibit superiordurability and redox activity. Through supercapacitor assembly, the-ketoenamine-linked COF electrodes outperform their imine-basedcounterparts, showcasing enhanced capacitance (88 mF cm−2 ) and stability athigh current densities (2.0 mA cm−2 ). These findings underscore the promiseof -ketoenamine-linked COFs for pseudocapacitor energy storageapplicationsPDC2022-133498-I00, TED2021-129886B-C42, PID2019-106268GB-C32, PID2022-38908NB-C31, MAT2016-77608-C3-1-P, PCI2018-093081, RTI2018-095622-B-I0