π-Conjugated materials are highly attractive owing to their unique optical and electronic properties. Covalent organic frameworks (COFs) offer a great opportunity for precise arrangement of building units in a π-conjugated crystalline matrix and tuning of the properties through choice of functionalities or post-synthetic modification. With this review, we aim at summarizing both the most representative as well as emerging strategies for the synthesis of π-conjugated COFs. We give examples of direct synthesis using large, π-extended building blocks. COFs featuring fully conjugated linkages such as vinylene, pyrazine, and azole are discussed. Then, post-synthetic modification methods that result in the extension of the COF π-system are reviewed. Throughout, mechanistic insights are presented when available. In the context of their utilization as film devices, we conduct a concise survey of the prominent COF layer deposition techniques reported and their aptness for the deposition of fused aromatic systems.
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http://dx.doi.org/10.1002/chem.202401344 | DOI Listing |
Nano Lett
January 2025
Synergetic Extreme Condition High-Pressure Science Center, State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.
Covalent-organic frameworks (COFs) are dynamic covalent porous organic materials constructed from emissive molecular organic building blocks. However, most two-dimensional (2D) COFs are nonemissive or weakly emissive in the solid state owing to the intramolecular rotation and vibration together with strong π-π interactions. Herein, we report a pressure strategy to achieve the bright multicolor emission from yellow to red in the 2D triazine triphenyl imine COF (TTI-COF).
View Article and Find Full Text PDFInorg Chem
January 2025
Industrial Research Institute of Nonwovens & Technical Textiles, Shandong Engineering Research Center for Specialty Nonwoven Materials, College of Textiles & Clothing, Qingdao University, Qingdao, Shandong 266071, P. R. China.
Promoting the rate of the oxygen reduction reaction (ORR) is critical for boosting the overall energy efficiency of the flexible zinc-air batteries (FZABs). Inspired by nature, we designed "branch-leaf" like hierarchical porous carbon nanofibers with ultralow loadings of Ir nanoparticles (NPs) derived from covalent-organic framework/metal-organic framework (COF/MOF) core-shell hybrids. The as-obtained Ir/FeZn-hierarchical porous carbon nanofibers (HPCNFs) showcase enhanced ORR performance, and the ultralow Ir loading reduces the cost while maintaining catalytic capacity.
View Article and Find Full Text PDFNanoscale
January 2025
Dept. of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA.
Identifying facile strategies for hierarchically structuring crystalline porous materials is critical for realizing diffusion length scales suitable for broad applications. Here, we elucidate synthesis-structure-function relations governing how room temperature catalytic conditions can be exploited to tune covalent organic framework (COF) growth and thereby access unique hierarchical morphologies without the need to introduce secondary templates or structure directing molecules. Specifically, we demonstrate how scandium triflate, an efficient catalyst involved in the synthesis of imine-based COFs, can be exploited as an effective growth modifier capable of selectively titrating terminal amines on 2D COF layers to facilitate anisotropic crystal growth.
View Article and Find Full Text PDFDalton Trans
January 2025
Department of Chemistry, Central Tribal University of Andhra Pradesh (CTUAP), Andhra Pradesh, 535003, India.
Hydrogen is a zero-emissive fuel and has immense potential to replace carbon-emitting fuels in the future. The development of efficient H sensors is essential for preventing hazardous situations and facilitating the widespread usage of hydrogen. Chemiresistors are popular gas sensors owing to their attractive properties such as fast response, miniaturization, simple integration with electronics and low cost.
View Article and Find Full Text PDFJ Sep Sci
January 2025
Electroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
Herein, an amino-functionalized covalent organic framework was synthesized and accommodated in the pores of porous hollow fiber. In this context, tetra (4-aminophenyl) porphyrin was synthesized for preparing the desired covalent organic framework as the extracting sorbent and employed for hollow fiber solid-phase microextraction of tebuconazole and propiconazole. With respect to the amino groups of the as-synthesized porphyrin-based covalent organic framework, the extracting device has the ability of establishing a hydrogen bond with the selected model analytes.
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