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Fabricating insoluble and infusible porous materials into gels for advanced applications is of great importance but has formidable challenges. Here, we present a general, facile, and scalable protocol to fabricate covalent organic framework (COF) gels using a group-protection synthesis strategy. To prove the generality of this strategy, we successfully prepared 10 types of COF organohydrogels with high crystallinity, porosity, good mechanical properties, and excellent solvent and freezing resistance. Notably, these COF organohydrogels can easily transform into hydrogels, organogels, and aerogels, breaking the gaps between different types of COF gels. An in-depth mechanism investigation unveils that the group-protection strategy effectively slows down the formation rate and regulates the morphology of COFs, benefiting the formation of cross-linked nanofibers/nanosheets to produce COF gels. We also find that the hydrogen bond network formed by the organic/water binary solvent and functional groups in the COF skeletons plays a vital role in creating organohydrogels and maintaining frost resistance and solvent resistance. As an application demonstration, COF gels installed with photoresponsive azobenzene groups show excellent solar energy absorption, photothermal conversion, and water transmission performances, demonstrating great potential in solar desalination. This work enriches the synthesis toolboxes for COF gels and expands the application scope of COFs.

Exploring new materials to manufacture proton-conducting membranes(PEMs) for fuel cells is highly significant. In this work, we fabricated two robust and highly crystalline porous covalent organic frameworks(COFs) viaa stepwise synthesis strategy. The synthesized COF structures are integrated into high-density azo and amino groups, which allow to anchor acids for accelerating proton conduction. Moreover, the COFs exhibit good chemical stability and high hydrophilicity. These features make them potential platforms for proton conduction applications. Upon loaded with H3PO4, the COFs(H3PO4@COFs) deliver a high proton conductivity of 3.15×10−2S/cm at 353 K under 95% relative humidity(RH). Furthermore, membrane electrode assemblies are fabricated using H3PO4@COF-26as the solid electrolyte for a single fuel cell outputting a maximum power density of 18 mW/cm2.

To date, numerous zirconium cluster-based metal–organic frameworks (Zr-MOFs) with attractive physical properties have been achieved thanks to tailorable organic linkers and versatile Zr clusters. Nevertheless, in comparison with the most-used high-symmetry organic linkers, low-symmetry linkers have rarely been exploited in the construction of Zr-MOFs. Despite challenges in predicting the structure and topology of the MOF, linker desymmetrization presents opportunities for the design of Zr-MOFs with unusual topologies and unexpected functionalities. Herein, we report for the first time the construction of two robust Zr-MOFs (IAM-7and IAM-8) from two pyrrolo-pyrrole-based low-symmetry tetracarboxylate linkers with a rare rhombic shape. The low symmetry of the linkers arises from the asymmetric pyrrolo-pyrrole core and the varying branch lengths, which play a critical role in the structural diversity between IAM-7and IAM-8seen from the structural analysis and lead to hydrophilic channels that contain uncoordinated carboxylate groups in the structure of IAM-7. Furthermore, the proton conductivity of IAM-7displays a high temperature and humidity dependence where the proton conductivity increases from 2.84 × 10–8S cm–1at 30 °C and 40% relative humidity (RH) to 1.42 × 10–2S cm–1at 90 °C and 95% RH, making it among one of the most conductive Zr-MOFs. This work not only enriches the library of Zr-MOFs but also offers a platform for the design of low-symmetry linkers toward the structural diversity or irregularity of MOFs as well as their structure-related properties.

Presented herein is a group of highly stable Zr-based metal–organic frameworks with bowl-shaped dihydroanthracene-based tetratopic linkers as building blocks. Structural analysis reveals that these frameworks are all two-dimensional but comprise three distinct connectivities of Zr6nodes. By using the steric hindrance of the nonplanar linker, the connectivity of Zr6node can be tuned from 8-c to unusual 4-c. Further, through either one-pot synthesis or postsynthetic linker installation strategies, the connectivity of Zr6node can be tuned from 8-c to 10-c by the insertion of a secondary linear dicarboxylate linker, from which not only the temperature-dependent flexibility of the structure can be effectively controlled with enhanced rigidity and thermal stability but also a scaffold for postsynthetic metalation of Pd(II) catalyst for Heck coupling reaction is offered.

We present here the synthesis of one enantiomeric pair of metal–organic framework materials comprised of a unique multioriented double-helix structure from an achiral spirocenter ligand. Our study clearly shows that the chiral MOF material encompasses concurrently multiple nonlinear-optical functions in the solid state: the noncentrosymmetric structural feature brings the chiral MOF high second-harmonic-generation efficiency; the incorporation of the spirocenter ligand can efficiently produce two-photon-excited photoluminescence with a larger-action cross-sectional value.

It is generally believed that mechanical amplification by cochlear hair cells is necessary to enhance the sensitivity and frequency selectivity of hearing. In the mammalian ear, the basis of cochlear amplification is believed to be the voltage‐dependent electromotility of outer hair cells (OHCs). The avian basilar papilla contains tall and short hair cells, with the former being comparable to inner hair cells, and the latter comparable to OHCs, based on their innervation patterns. In this study, we sought evidence for somatic electromotility by direct measurements of voltage‐dependent length changes in both tall and short hair cells at nanometre resolution. Microchamber and whole‐cell voltage‐clamp techniques were used. Motility was measured with a photodiode‐based measurement system. Non‐linear capacitance, an electrical signature of somatic motility, was also measured to complement motility measurement. Significantly, chick hair cells did not exhibit somatic motility nor express non‐linear capacitance. The lack of somatic motility suggests that in avian hair cells the active process resides elsewhere, most likely in the hair cell stereocilia.