No abstract

Three perfluorinated Cu-based metal-organic frameworks (MOFs) were prepared starting from extensively fluorinated biphenyl-based ligands accessed via C-H functionalization. These new materials are highly hydrophobic: with water contact angles of up to 151 ± 1°, they are among the most water-repellent MOFs ever reported.

Two mesoporous fluorinated metal-organic frameworks (MOFs) were synthesized from extensively fluorinated tritopic carboxylate- and tetrazolate-based ligands. The tetrazolate-based framework MOFF-5 has an accessible surface area of 2445 m(2) g(-1), the highest among fluorinated MOFs. Crystals of MOFF-5 adsorb hydrocarbons, fluorocarbons, and chlorofluorocarbons (CFCs)-the latter two being ozone-depleting substances and potent greenhouse species-with weight capacities of up to 225%. The material exhibits an apparent preference for the adsorption of non-spherical molecules, binding unusually low amounts of both tetrafluoromethane and sulfur hexafluoride.

and the global desire to avoid the most destructive consequences of climate change led to an exponential growth of research into alternative and sustainable battery technologies. [1][2][3][4] While transitionmetal-based inorganic compounds have been primarily used as cathodes, especially in Li-ion batteries (LIBs), the pace of the development of organic electrode materials continues to accelerate. [2] Organic compounds are considered to be more environment-friendly compared to their inorganic counterparts. They are also composed of light and naturally abundant elements (C, H, N, O, and S) eliminating the need for expensive and toxic metals, and can be prepared directly from renewable resources or synthesized from readily available small molecules. As a result, organic electrode materials could reduce energy consumption and CO 2 release during mass production, unlike materials containing transition metals which come from exhaustible mineral resources and require intensive mining, processing, and disposal. Small-molecule organic compounds can be rationally designed and synthesized with high precision to contain welldefined redox-active functional groups. Due to this unparalleled chemical and structural tunability, a large number of Organic electrode materials possess many advantages such as low toxicity, sustainability, and chemical/structural tunability toward high energy density. However, to compete with inorganic-based compounds, crucial aspects such as redox potential, capacity, cycling stability, and electronic conductivity need to be improved. Herein, a comprehensive strategy on the molecular design of small organic electron-acceptor-molecule-hexaazatrianthranylene (HATA) embedded quinone (HATAQ) is reported. By introducing conjugated quinone moieties into the electron-deficient hexaazatriphenylene-derivative core, HATAQ with highly extended π-conjugation can yield extra-high capacity for lithium storage, delivering a capacity of 426 mAh g −1 at 200 mA g −1 (0.4C). At an extremely high rate of 10 A g −1 (19C), a reversible capacity of 209 mAh g −1 corresponding to nearly 85% retention is obtained after 1000 cycles. A unique network of unconventional lockand-key hydrogen bonds in the solid-state facilitates favorable supramolecular 2D layered arrangement, enhancing cycling stability. To the best of the authors' knowledge, the capacity and rate capability of HATAQ are found to be the best ever reported for organic small-molecule-based cathodes. These results together with density functional theory studies provide proof-of-concept that the design strategy is promising for the development of organic electrodes with exceptionally high energy density, rate capability, and cycling stability.

Porous molecular crystals are an emerging class of porous materials that is unique in being built from discrete molecules rather than being polymeric in nature. In this study, we examined the effects of molecular structure of the precursors on the formation of porous solid-state structures with a series of 16 rigid aromatics. The majority of these precursors possess pyrazole groups capable of hydrogen bonding, as well as electron-rich aromatics and electron-poor tetrafluorobenzene rings. These precursors were prepared using a combination of Pd- and Cu-catalyzed cross-couplings, careful manipulations of protecting groups on the nitrogen atoms, and solvothermal syntheses. Our study varied the geometry and dimensions of precursors, as well as the presence of groups capable of hydrogen bonding and [π···π] stacking. Thirteen derivatives were crystallographically characterized, and four of them were found to be porous with surface areas between 283 and 1821 m g. Common to these four porous structures were (a) rigid trigonal geometry, (b) [π···π] stacking of electron-poor tetrafluorobenzenes with electron-rich pyrazoles or tetrazoles, and