A series of novel porous polymer frameworks (PPFs) with [3 + 4] structure motif have been synthesized from readily accessible building blocks via imine condensation, and the dependence of gas adsorption properties on the building block dimensions and functionalities was studied. The resulting imine-linked frameworks exhibit high surface area: the Brunauer–Emmett–Teller (BET) specific surface area up to 1740 m2 g–1, and a Langmuir surface area up to 2157 m2 g–1. More importantly, the porous frameworks exhibit outstanding H2 (up to 2.75 wt %, 77 K, 1 bar), CO2 (up to 26.7 wt %, 273 K, 1 bar), CH4 (up to 2.43 wt %, 273 K, 1 bar), and C2H2 (up to 17.9 wt %, 273 K, 1 bar) uptake, which are among the highest reported for organic porous materials. PPFs exhibit good ideal selectivities for CO2/N2 (14.5/1–20.4/1), and CO2/CH4 adsorption (8.6/1–11.0/1), and high thermal stabilities (up to 500 °C), thus showing a great potential in gas storage and separation applications.

Two novel porous 2D covalent organic frameworks (COFs) with periodically heterogeneous pore structures were successfully synthesized through desymmetrized vertex design strategy. Condensation of C(2v) symmetric 5-(4-formylphenyl)isophthalaldehyde or 5-((4-formylphenyl)ethylene)isophthalaldehyde with linear hydrazine linker under the solvothermal or microwave heating conditions yields crystalline 2D COFs, HP-COF-1 and HP-COF-2, with high specific surface areas and dual pore structures. PXRD patterns and computer modeling study, together with pore size distribution analysis confirm that each of the resulting COFs exhibits two distinctively different hexagonal pores. The structures were characterized by FT-IR, solid state (13)C NMR, gas adsorption, SEM, TEM, and theoretical simulations. Such rational design and synthetic strategy provide new possibilities for preparing highly ordered porous polymers with heterogeneous pore structures.

No abstract

No abstract

This review summarizes and discusses the recent progress in porous organic polymers for diverse biomedical applications such as drug delivery, biomacromolecule immobilization, phototherapy, biosensing, bioimaging, and antibacterial applications.

The development of efficient catalysts for the oxygen reduction reaction (ORR) is crucial for a number of emerging technologies, to counter energy and environment crises. Herein, we report an alkyne metathesis polymerization protocol to synthesize a conjugated microporous metalloporphyrin-based framework containing interconnected ORR catalytic centers. A simple composite of the framework and carbon black shows excellent ORR electrocatalytic activity and specificity through a four-electron reduction mechanism under both acidic and alkaline conditions. The pyrolysis of the catalyst, which is commonly involved in the preparation of ORR catalytic systems, is not necessary. Compared to monomeric metalloporphyrins, the framework shows enhanced ORR catalytic activity, presumably due to the porous and conjugated nature of the framework structure, which allows better exposure of the catalytically active sites, and efficient electron/mass transport. More importantly, the composite electrocatalyst exhibits superior durability and methanol tolerance over commercial Pt/C and metalloporphyrin monomers. Given the highly structural tunability of conjugated microporous polymers, it is conceivable that such a non-pyrolytic approach could enable the systematic exploration of the structure-activity relationship of organic framework-based ORR catalysts and eventually lead to the development of cost-effective replacements for Pt/C.

A nonconventional, water-mediated catalytic mechanism was proposed to explain the effects of residual water on the reactivity and regioselectivity of tris­(pentafluorophenyl)­borane catalyst in the ring-opening reaction of 1,2-epoxyoctane by 2-propanol. This nonconventional mechanism was proposed to operate in parallel with conventional Lewis acid-catalyzed ring-opening. Microkinetic modeling was conducted to validate the proposed reaction mechanism, with all kinetic and thermodynamic parameters derived from density functional theory (DFT) calculations. Experimental data at a variety of temperatures and water contents were captured by the model after adjustments within reasonable limits set by experimental benchmarking and accuracy of theory of a small subset of parameters. In addition, the microkinetic model was able to generate accurate predictions at reaction conditions that were not used for parameter estimation. Detailed analysis of the net reaction rates showed that >95% of the reaction flux passed through conventional Lewis-acid pathways at water levels <500 ppm, even though the borane-epoxide adduct never accounted for more than 30% of the catalyst speciation under reaction conditions. With increasing water, as much as 80% of the reaction flux utilized water-mediated reaction intermediates. Within the water-mediated mechanisms, different hydrogen bond acceptors (HBAs) influenced the reaction regioselectivity. Overall, this validated mechanism and microkinetic model provided better understanding of industrially important ring-opening catalysis with this catalyst in the presence of water and could facilitate future improvement of catalyst regioselectivity and reactivity.

We report the high hydrocarbon storage capacity and adsorption selectivity of two low-density pillar[n]arene-based SOFs. Our study would open new perspectives in the development of pillar[n]arene-based SOFs and study of their great potential in gas-storage and gas-separation applications.