An exceptionally flexible hydrogen-bonded organic framework with large-scale void regulation and adaptive guest accommodation abilities

Abstract

Flexible hydrogen-bonded organic frameworks (FHOFs) are quite rare but promising for applications in separation, sensing and host-guest chemistry. They are difficult to stabilize, making their constructions a major challenge. Here, a flexible HOF (named 8PN) with permanent porosity has been successfully constructed. Nine single crystals of 8PN with different pore structures are obtained, achieving a large-scale void regulation from 4.4% to 33.2% of total cell volume. In response to external stimuli, multimode reversible structural transformations of 8PN accompanied by changes in luminescence properties have been realized. Furthermore, a series of high-quality co-crystals containing guests of varying shapes, sizes, aggregation states and even amounts are obtained, showing that 8PN can adapt to different guests by regulating the molecular conformations and assembling forms of its building blocks. The unexpected flexibility of 8PN makes it a promising material for enriching the applications of existing porous materials.

A Hydrogen‐Bonded yet Hydrophobic Porous Molecular Crystal for Molecular‐Sieving‐like Separation of Butane and Isobutane

“…The porosity of 1′ was studied by single‐component N 2 and CO 2 isotherms at different temperatures (Figure 4 a). 1′ adsorbs little N 2 at 77 K but can adsorb considerable amount of CO 2 at 195 K, being similar with other molecular adsorbents with extremely small pore apertures [9a, 19] . Based on the saturated CO 2 uptake, the pore volume was calculated as 0.082 cm 3 g −1 , which is consistent with the crystallographic value (0.086 cm 3 g −1 for 1′ , 0.107 cm 3 g −1 for 1 ).…”

Channel Confinement of Aromatic Petrochemicals via Aryl–Perfluoroaryl Interactions With a B←N Host

“…Channel formation in transmembrane ionic transport is a vital process for living cells (Haynes and Gale, 2011). However, in contrast to the large number of natural and synthetic inorganic zeolites (Ramamurthy and Eaton, 1994; Tabacchi, 2018), there is a significant lower number of purely-organic molecules identified as reliable channel-formers in closed-packed systems (e.g., calixarene, phenylacetylene, tetraphenylethylene, triazine building blocks) (Moore, 1997; Langley and Hulliger, 1999; Dalgarno et al, 2007; Couderc and Hulliger, 2010; He et al, 2011; Huang et al, 2019; Lin et al, 2019). Understanding the formation of open cavities or channels in organic systems is essential for the development of extended systems such as Hydrogen-Bonded Organic Frameworks (HOFs) (Helzy et al, 2016; Karmakar et al, 2016) and Covalent Organic Frameworks (COFs) (Feng et al, 2012; Xu et al, 2016).…”

Semiconductive microporous hydrogen-bonded organophosphonic acid frameworks

“…Owing to their well-ordered pores, which are surrounded by inorganic and organic components, MOFs have been used in a wide range of applications, such as gas storage/separation [4][5][6][7] , catalysis [8][9][10][11][12][13] , magnetism [14][15][16] , electric conductivity [17][18][19] , proton conductivity [20][21][22] , and drug delivery [23][24][25] . In parallel to MOF research, another closely related family of supramolecular architectures known as hydrogen-bonded organic frameworks (HOFs) has attracted immense interest in recent years [26][27][28] . In HOFs, the linker connectivity is achieved via hydrogen-bonded networks rather than inorganic building units (IBUs) [29][30][31][32][33] .…”