Coupling fullerene into porous aromatic frameworks for gas selective sorption

Porous organic polymers (POPs) for environmental remediation

Modern global industrialization along with the ever-increasing growth of the population has resulted in continuous enhancement in the discharge and accumulation of various toxic and hazardous chemicals in the environment. These harmful pollutants, including toxic gases, inorganic heavy metal ions, anthropogenic waste, persistent organic pollutants, toxic dyes, pharmaceuticals, volatile organic compounds, etc., are destroying the ecological balance of the environment. Therefore, systematic monitoring and effective remediation of these toxic pollutants either by adsorptive removal or by catalytic degradation are of great significance. From this viewpoint, porous organic polymers (POPs), being two- or three-dimensional polymeric materials, constructed from small organic molecules connected with rigid covalent bonds have come forth as a promising platform toward various leading applications, especially for efficient environmental remediation. Their unique chemical and structural features including high stability, tunable pore functionalization, and large surface area have boosted the transformation of POPs into various macro-physical forms such as thick and thin-film membranes, which led to a new direction in advanced level pollutant removal, separation and catalytic degradation. In this review, our focus is to highlight the recent progress and achievements in the strategic design, synthesis, architectural-engineering and applications of POPs and their composite materials toward environmental remediation. Several strategies to improve the adsorption efficiency and catalytic degradation performance along with the in-depth interaction mechanism of POP-based materials have been systematically summarized. In addition, evolution of POPs from regular powder form application to rapid and more efficient size and chemo-selective, "real-time" applicable membrane-based application has been further highlighted. Finally, we put forward our perspective on the challenges and opportunities of these materials toward real-world implementation and future prospects in next generation remediation technology.

Synthesis of microporous polymers with exposed C60 surfaces by polyesterification of fullerenol

Microporous polymers with exposed C₆₀ surfaces have been synthesized by a new pathway of crosslinking fullerenol and terephthaloyl chloride or 1,3,5-benzenetricarbonyl trichloride via esterification. The resulting polymers are insoluble solids containing a large ratio of C₆₀ with hydroxy groups and possess micropores with high specific surface area up to 657 m² g^-1. The microporous polymers thus obtained exhibit enhanced hydrogen spillover, which is a unique property of the C₆₀ surface.

A Facile and Highly Efficient Approach to Obtain a Fluorescent Chromogenic Porous Organic Polymer for Lymphatic Targeting Imaging

Porous organic polymers have an open architecture, excellent stability, and tunable structural components, revealing great application potential in the field of fluorescence imaging, but this part of the research is still in its infancy. In this study, we aimed to tailor the physical and chemical characteristics of indocyanine green using sulfonic acid groups and conjugated fragments, and prepared amino-grafted porous polymers. The resulting material had excellent solvent and thermal stability, and possessed a relatively large pore structure with a size of 3.4 nm. Based on the synergistic effect of electrostatic bonding and π–π interactions, the fluorescent chromogenic agent, indocyanine green, was tightly incorporated into the pore cavity of POP solids through a one-step immersion method. Accordingly, the fluorescent chromogenic POP demonstrated excellent imaging capabilities in biological experiments. This preparation of fluorescent chromogenic porous organic polymer illustrates a promising application of POP-based solids in both fluorescence imaging and biomedicine applications.

Incorporating Fullerenes in Nanoscale Metal-Organic Matrixes: An Ultrasensitive Platform for Impedimetric Aptasensing of Tobramycin

The rational design and preparation of available fullerene@metal-organic matrix hybrid materials are of profound significance in electrochemical biosensing applications due to their unique photoelectric properties. In this work, C₆₀@UiO-66-NH₂ nanocomposites serve as greatly promising materials to modify electrodes and fix aptamers, resulting in a remarkable electrochemical aptasensor for impedimetric sensing of tobramycin (TOB). Nanoscale composites have preferable electroactivity and small particle size with more exposed functional sites, such as Zr(IV) and -NH₂, to immobilize aptamers for enhanced detection performance. As we know, most of the electrochemical impedance aptasensors require a long time to complete the detection process, but this prepared biosensor shows the rapid quantitative identification of target TOB within 4 min. This work expands the synthesis of functional fullerene@metal-organic matrix hybrid materials in electrochemical biosensing applications.

Ionic Porous Aromatic Framework as a Self-Degraded Template for the Synthesis of a Magnetic γ-Fe2O3/WO3·0.5H2O Hybrid Nanostructure with Enhanced Photocatalytic Property

An ionic porous aromatic framework is developed as a self-degraded template to synthesize the magnetic heterostructure of γ-Fe₂O₃/WO₃·0.5H₂O. The Fe₃O₄ polyhedron was obtained with the two-phase method first and then reacted with sodium tungstate to form the γ-Fe₂O₃/WO₃·0.5H₂O hybrid nanostructure. Under the induction effect of the ionic porous network, the Fe₃O₄ phase transformed to the γ-Fe₂O₃ state and complexed with WO₃·0.5H₂O to form the n-n heterostructure with the n-type WO₃·0.5H₂O on the surface of n-type γ-Fe₂O₃. Based on a UV-Visible analysis, the magnetic photocatalyst was shown to have a suitable band gap for the catalytic degradation of organic pollutants. Under irradiation, the resulting γ-Fe₂O₃/WO₃·0.5H₂O sample exhibited a removal efficiency of 95% for RhB in 100 min. The charge transfer mechanism was also studied. After the degradation process, the dispersed powder can be easily separated from the suspension by applying an external magnetic field. The catalytic activity displayed no significant decrease after five recycles. The results present new insights for preparing a hybrid nanostructure photocatalyst and its potential application in harmful pollutant degradation.

Molecularly Imprinted Porous Aromatic Frameworks for Molecular Recognition

Porous aromatic frameworks (PAFs) are an important class of porous materials that are well-known for their ultralarge surface areas and superb stabilities. Basically, PAF solids are constructed from periodically arranged phenyl fragments connected via C-C bonds (generally), which provide vast accessible surfaces that can be modified with functional groups and intrinsic pathways for rapid mass transfer. Molecular imprinting technology (MIT) is an effective method for producing binding sites with a specific geometry and size that complement a template object. This review focuses on the integration of MIT into PAF structures via state-of-the-art coupling chemistry to expand the application of porous materials in the fields of metal ion extraction (including the nuclear element uranium) and selective catalysis. Additionally, a concise outlook on the rational construction of molecularly imprinted porous aromatic frameworks is discussed in terms of developing next-generation porous materials for broader applications.

A Porous Aromatic Framework Functionalized with Luminescent Iridium(III) Organometallic Complexes for Turn-On Sensing of 99TcO4. ACS APPLIED MATERIALS & INTERFACES 2020;12:15288-15297. [PMID: 32131587 DOI: 10.1021/acsami.0c01929]

Contamination of ⁹⁹TcO₄^-, a problematic radioactive anion in the nuclear fuel cycle, in groundwater has been observed in a series of legacy nuclear sites, representing a notable radiation hazard and environmental concern. The development of convenient, rapid, and sensitive detection methods is therefore critical for radioactivity control and remediation tasks. Traditional detection methods suffer from clear demerits of either the presence of large interference from coexisting radioactive species (e.g., radioactivity counting methods) or the requirement of extensive instrumentation and analysis procedure (e.g., mass spectrometry). Here, we constructed a luminescent iridium(III) organometallic complex (Ir(ppy)₂(bpy)⁺; ppy = 2-phenylpyridine, bpy = 2,2^'-bipyridine)-grafted porous aromatic framework (Ir-PAF) for the first time, which can be utilized for efficient, facile, and selective detection of trace ReO₄^-/TcO₄^- in aqueous solutions. Importantly, the luminescence intensity of Ir-PAF is greatly enhanced in the presence of ReO₄^-/TcO₄^-, giving rise to a distinct turn-on sensor with the detection limit of 556.9 μg/L. Such a superior detection capability originates from the highly selective and strong interaction between ReO₄^-/TcO₄^- and Ir(ppy)₂(bpy)⁺, leading to an efficient pre-enrichment of ReO₄^-/TcO₄^- during analysis and subsequently a much weaker nonradiative decay of the luminescence of Ir(ppy)₂(bpy)⁺, as illustrated by density functional theory (DFT) calculation as well as quantum yield and fluorescence lifetime measurements. Successful quantification of trace ReO₄^- in simulated Hanford low-activity waste (LAW) solution containing large excess of Cl^-, NO₃^-, and NO₂^- was demonstrated, highlighting the bright future of luminescent PAFs in the area of chemical sensing.

Porous Aromatic Frameworks as a Platform for Multifunctional Applications

Porous aromatic frameworks (PAFs), which are well-known for their large surface areas, associated porosity, diverse structures, and superb stability, have recently attracted broad interest. Taking advantage of widely available building blocks and various coupling strategies, customized porous architectures can be prepared exclusively through covalent bonding to satisfy necessary requirements. In addition, PAFs are composed of phenyl-ring-derived fragments that are easily modified with desired functional groups with the help of established synthetic chemistry techniques. On the basis of material design and preparative chemistry, this review mainly focuses on recent advances in the structural and chemical characteristics of PAFs for potential utilizations, including molecule storage, gas separation, catalysis, and ion extraction. Additionally, a concise outlook on the rational construction of functional PAFs is discussed in terms of developing next-generation porous materials for broader applications.

Porous Polymers as Multifunctional Material Platforms toward Task-Specific Applications

Exploring advanced porous materials is of critical importance in the development of science and technology. Porous polymers, being famous for their all-organic components, tailored pore structures, and adjustable chemical components, have attracted an increasing level of research interest in a large number of applications, including gas adsorption/storage, separation, catalysis, environmental remediation, energy, optoelectronics, and health. Recent years have witnessed tremendous research breakthroughs in these fields thanks to the unique pore structures and versatile skeletons of porous polymers. Here, recent milestones in the diverse applications of porous polymers are presented, with an emphasis on the structural requirements or parameters that dominate their properties and functionalities. The Review covers the following applications: i) gas adsorption, ii) water treatment, iii) separation, iv) heterogeneous catalysis, v) electrochemical energy storage, vi) precursors for porous carbons, and vii) other applications (e.g., intelligent temperature control textiles, sensing, proton conduction, biomedicine, optoelectronics, and actuators). The key requirements for each application are discussed and an in-depth understanding of the structure-property relationships of these advanced materials is provided. Finally, a perspective on the future research directions and challenges in this field is presented for further studies.

Porous Organic Frameworks: Advanced Materials in Analytical Chemistry

Porous organic frameworks (POFs), a general term for covalent-organic frameworks (COFs), covalent triazine frameworks (CTFs), porous aromatic frameworks (PAFs), etc., are constructed from organic building monomers with strong covalent bonds and have generated great interest among researchers. The remarkable features, such as large surface areas, permanent porosity, high thermal and chemical stability, and convenient functionalization, promote the great potential of POFs in diverse applications. A critical overview of the important development in the design and synthesis of COFs, CTFs, and PAFs is provided and their state-of-the-art applications in analytical chemistry are discussed. POFs and their functional composites have been explored as advanced materials in "turn-off" or "turn-on" fluorescence detection and novel stationary phases for chromatographic separation, as well as a promising adsorbent for sample preparation methods. In addition, the prospects for the synthesis and utilization of POFs in analytical chemistry are also presented. These prospects can offer an outlook and reference for further study of the applications of POFs.

Open and Hierarchical Carbon Framework with Ultralarge Pore Volume for Efficient Capture of Carbon Dioxide

Amine-impregnated adsorbents are promising candidates for the selective capture of CO₂ from flue gas. The key is to develop suitable supports possessing large pore sizes and very large pore volumes, and the material has to be facilely synthesized from readily available reagents. In this work, hierarchical carbon nanosheet (CNS) featuring large pore width (30-100 nm) and extraordinarily huge pore volume (8.41 cm³/g) was prepared through controlled carbonization of glucose and dicyandiamide. The CNS was physically impregnated with pentaethylenehexamine (PEHA) to act as adsorbents for selective capture of CO₂. Owing to the unique porosity of CNS, the amount of amine loading in CNS can be ultrahigh (6 g PEHA/g CNS) in comparison with those of known amine-impregnated adsorbents, and the CO₂ capacity in a flow of 15 v/v % of CO₂ balanced in N₂ was up to 5.0 mmol/g at 75 °C. The synthesized PEHA-CNS composite materials perform well in capturing CO₂ under humid condition and display good stability in a test of 10 adsorption-desorption cycles. It is believed that the CNS synthesized in this work has great potential to act as a support material for CO₂ adsorption.

A triptycene-based porous hydrogen-bonded organic framework for guest incorporation with tailored fitting

By employing a robust and non-coplanar building block strategy, a triptycene-based hydrogen-bonded organic framework was constructed with almost no sacrifice of molecular surfaces, and it was capable of incorporating C60 molecules in high concentration in the channels with tailored fitting.

In situ synthesis of electroactive conjugated microporous fullerene films capable of supercapacitive energy storage

We describe a general strategy for synthesizing conjugated microporous fullerene thin films via a high-throughput, efficient and controllable thiophene-based electropolymerization.

Novel fullerene-based porous materials constructed by a solvent knitting strategy

Here we choose a dihydronaphthyl-functionalized C₆₀ fullerene as a building block and utilize a novel solvent knitting strategy based on Friedel–Crafts alkylation reaction to construct two kinds of novel porous materials by using dichloromethane (DCM) and 1,2-dichloroethane (DCE) as solvents and external crosslinkers.

BODIPY-containing porous organic polymers for gas adsorption

BODIPY-containing microporous organic polymers were synthesized via a Sonogashira–Hagihara coupling reaction of a BODIPY derivative and a range of aryl–alkyne monomers.