Anchor installation on porous polymer networks (PPNs) for high CO2 uptake

A microporous polymer based on nonconjugated hindered biphenyls that emits blue light

Microporous organic polymers that have three-dimensional connectivity stemming from monomers with tetrahedral or tetrahedron-like geometry can have high surface areas and strong fluorescence. There are however few examples of such polymers based on hindered biaryls, and their fluorescence has not been studied. Hypothesizing that the contortion in a hindered biphenyl moiety would modulate the optical properties of a polymer built from it, we synthesized a meta-enchained polyphenylene from a 2,2',6,6'-tetramethylbiphenyl-based monomer, in which the two phenyl rings are nearly mutually perpendicular. The polymer was microporous with SBET = 495 m2 g-1. The polymer absorbed near-UV light and emitted blue fluorescence despite the meta-enchainment that would have been expected to break the conjugation. A related copolymer, synthesized from 2,2',6,6'-tetramethylbiphenyl-based and unsubstituted biphenyl-based monomers, was microporous but not fluorescent.

Polypyrene Porous Organic Framework for Efficiently Capturing Electron Specialty Gases

The polypyrene polymer with an extended π-conjugated skeleton is attractive for perfluorinated electron specialty gas (F-gas) capture as the high electronegativity of fluorine atoms makes F-gases strongly electronegative gases. Herein, a polypyrene porous organic framework (termed as Ppy-POF) with an extended π-conjugated structure and excellent acid resistance was constructed. Systematic studies have shown that the abundant π-conjugated structures and gradient electric field distribution in Ppy-POF can endow it exceptional adsorption selectivity for high polarizable F-gases and xenon (Xe), which has been collaboratively confirmed by single-component gas adsorption experiments, time-dependent adsorption rate tests, dynamic breakthrough experiments, etc. Electrostatic potential distribution and charge density difference based on Grand Canonical Monte Carlo simulations and density functional theory calculations demonstrate that the selective adsorption of F-gases and Xe in Ppy-POF is attributed to the strong charge-transfer effect and polarization effect between Ppy-POF and gases. These results manifest that the POF with an extended π-conjugated structure and gradient electric field distribution has great potential in efficiently capturing electron specialty gases.

Porous Aromatic Frameworks (PAFs)

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.

Fluorinated porous organic frameworks for improved CO2 and CH4 capture

Hyperpolarized ¹²⁹Xe NMR highlights open porosity of fluorinated organic frameworks which show CO₂ and CH₄ capture with high selectivity towards N₂.

Fabrication of Composite Beads Based on Calcium Alginate and Tetraethylenepentamine-Functionalized MIL-101 for Adsorption of Pb(II) from Aqueous Solutions

In this work, a tetraethylenepentamine (TEPA)-grafted metal-organic framework material (MIL-101) was synthesized. The introduction of TEPA increased the abundance of functional groups on the MIL-101. As a powdery adsorbent, MIL-101-TEPA can be difficult to separate. In order to solve this problem, we combined MIL-101-TEPA with sodium alginate (SA) and injected the mixture into a CaCl₂ solution to solidify the powder into beads with a particle size of 3 mm. The easily recovered adsorbent was applied to the adsorption of Pb(II) from water. The structure and characterization of the adsorbent were investigated through scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). We also optimized the adsorption conditions. The results of the study showed that the adsorption process was chemisorptive and endothermic in nature. The maximum adsorption capacity of the composite beads was 558.6 mg/g. Meanwhile MIL-101-TEPA@CA showed good repeatable utilization.