Porous Aromatic Frameworks (PAFs)

Abstract

Porous aromatic frameworks (PAFs) represent an important category of porous solids. PAFs possess rigid frameworks and exceptionally high surface areas, and, uniquely, they are constructed from carbon−carbon−bond−linked aromatic-based building units. Various functionalities can either originate from the intrinsic chemistry of their building units or are achieved by postmodification of the aromatic motifs using established reactions. Specially, the strong carbon−carbon bonding renders PAFs stable under harsh chemical treatments. Therefore, PAFs exhibit specificity in their chemistry and functionalities compared with conventional porous materials such as zeolites and metal organic frameworks. The unique features of PAFs render them being tolerant of severe environments and readily functionalized by harsh chemical treatments. The research field of PAFs has experienced rapid expansion over the past decade, and it is necessary to provide a comprehensive guide to the essential development of the field at this stage. Regarding research into PAFs, the synthesis, functionalization, and applications are the three most important topics. In this thematic review, the three topics are comprehensively explained and aptly exemplified to shed light on developments in the field. Current questions and a perspective outlook will be summarized. CONTENTS 3. General Strategies and Examples For PAF Functionalization 8951 3.1. Direct Synthesis 8951 3.2. Postsynthetic Modification 8952 3.3. Post Modification of PAFs with Preanchored Sites 8953 3.4. PAFs with Charged Frameworks 8953 3.5. Wettability and Polarity of PAF Frameworks 8953 4. State-of-the-Art of PAF Applications 8954 4.1. Gas Adsorption 8954 4.1.1. Hydrogen Storage 8954 4.1.2. Methane Adsorption 8958 4.1.3. CO 2 Capture 8960 4.1.4. Adsorptive Separation of Hydrocarbon Mixtures 8965 4.1.5. Capture of Ammonia 8966 4.2. Membrane Separation 8966 4.3. Adsorption of Hazardous Organic Compounds 8968 4.3.1. Capture of Hazardous Organic Chemicals 8968 4.3.2. Enrichment of Trace Organic Compounds for Analysis 8969

Triflic Acid-Promoted Adamantylation and tert-Butylation of Pyrene: Fluorescent Properties of Pyrene-Decorated Adamantanes and a Channeled Crystal Structure of 1,3,5-Tris(pyren-2-yl)adamantane

“…It has been demonstrated that di-, tri-, and tetraaryl adamantanes have a great tendency to form various types of supramolecular systems in the solid state (e.g., encapsulating crystals 8 and were used in syntheses of porous aromatic frameworks). 9 The adamantane skeleton was also used as a rigid linker between chromophoric groups. 10 Therefore, molecules bearing several pyrenyl groups in a well-defined spatial arrangement might be of interest for developing solid-state emitters, sensors, or self-assembled nanomaterials.…”

Recent Advances of Solid‐State NMR Spectroscopy for Microporous Materials

“…PAFs built by C‐C aromatic‐based building units hold great promise for gas storage and capture because of their ultrahigh surface area and high physicochemical stability. [ 98 ] Multinuclear 1 H, 13 C, and 29 Si SSNMR has been efficiently employed for structural characterization of various PAFs including PAF‐1, [ 99 ] PAF‐5, [ 100 ] JUC‐Z2, [ 101 ] JUC‐Z12, [ 102 ] mPAF‐1, [ 103 ] sulfonated PAFs [ 104 ] and PAFPORP. [ 105 ] PFA‐1 possesses high surface area of 7100 m 2 g −1 and exceptional thermal/hydrothermal stabilities.…”

Cationic Covalent‐Organic Framework as Efficient Redox Motor for High‐Performance Lithium–Sulfur Batteries

“…Thus, COFs have been regarded as the ideal candidates for the cathode substrate of Li-S batteries. [47][48][49][50] The huge π-conjugated system of COFs could provide abundant routes for electron transfer [51] and the small molar mass makes it possible for COFs-based batteries to achieve high mass specific capacity. [52,53] Unfortunately, the performances of batteries with COFs as cathode matrices are barely satisfactory, probably due to the lack of active centers contributing to the fixation of polysulfides.…”