Metal–organic framework cathodes usually exhibit low capacity and poor electrochemical performance for Li‐ion storage owing to intrinsic low conductivity and inferior redox activity. Now a redox‐active 2D copper–benzoquinoid (Cu‐THQ) MOF has been synthesized by a simple solvothermal method. The abundant porosity and intrinsic redox character endow the 2D Cu‐THQ MOF with promising electrochemical activity. Superior performance is achieved as a Li‐ion battery cathode with a high reversible capacity (387 mA h g−1), large specific energy density (775 Wh kg−1), and good cycling stability. The reaction mechanism is unveiled by comprehensive spectroscopic techniques: a three‐electron redox reaction per coordination unit and one‐electron redox reaction per copper ion mechanism is demonstrated. This elucidatory understanding sheds new light on future rational design of high‐performance MOF‐based cathode materials for efficient energy storage and conversion.

Two‐dimensional conductive metal–organic frameworks (2D c‐MOFs) as an emerging class of multifunctional materials have attracted extensive attention due to their predictable and diverse structures, intrinsic permanent porosity, high charge mobility, and excellent electrical conductivity. Such unique characteristics render them as a promising new platform for electrical related devices. This Minireview highlights the recent key progress of 2D c‐MOFs with emphasis on the design strategies, unique electrical properties, and potential applications in electrochemical energy storage. The thorough elucidation of structure–function correlations may offer a guidance for the development of 2D c‐MOFs based next‐generation energy storage devices.

We herein develop a two-in-one molecular design strategy for facile synthesis of 2D imine based covalent organic frameworks (COFs). The integration of two different functional groups (i.e., formyl and amino groups) in one simple pyrene molecule affords a bifunctional building block: 1,6-bis­(4-formylphenyl)-3,8-bis­(4-aminophenyl)­pyrene (BFBAPy). Highly crystalline and porous Py-COFs can be easily prepared by the self-condensation of BFBAPy in various solvents, such as CH2Cl2, CHCl3, tetrahydrofuran, methanol, ethanol, acetonitrile, and dimethylacetamide, etc. The current work, to the best of our knowledge, is a rare case of COF synthesis that exhibits excellent solvent adaptability. Highly crystalline Py-COF thin films have been facilely fabricated on various substrates and exhibit potential applications in hole transporting layers for perovskite solar cells. Furthermore, the versatility of this two-in-one strategy was also verified by two additional examples. The current work dramatically reduces the difficulty of COF synthesis, and such two-in-one strategy is anticipated to be applicable for the synthesis of other COFs constructed by different building blocks and linkages.

2D conductive metal–organic frameworks (2D c‐MOFs) are promising candidates for efficient electrocatalysts for the CO2 reduction reaction (CO2RR). A nitrogen‐rich tricycloquinazoline (TQ) based multitopic catechol ligand was used to coordinate with transition‐metal ions (Cu2+ and Ni2+), which formed 2D graphene‐like porous sheets: M3(HHTQ)2 (M=Cu, Ni; HHTQ=2,3,7,8,12,13‐Hexahydroxytricycloquinazoline). M3(HHTQ)2 can be regarded as a single‐atom catalyst where Cu or Ni centers are uniformly distributed in the hexagonal lattices. Cu3(HHTQ)2 exhibited superior catalytic activity towards CO2RR in which CH3OH is the sole product. The Faradic efficiency of CH3OH reached up to 53.6 % at a small over‐potential of −0.4 V. Cu3(HHTQ)2 exhibited larger CO2 adsorption energies and higher activities over the isostructural Ni3(HHTQ)2 and the reported archetypical Cu3(HHTP)2. There is a strong dependence of both metal centers and the N‐rich ligands on the electrocatalytic performance.

A conjugated copper(II) catecholate based metal–organic framework (namely Cu‐DBC) was prepared using a D2‐symmetric redox‐active ligand in a copper bis(dihydroxy) coordination geometry. The π‐d conjugated framework exhibits typical semiconducting behavior with a high electrical conductivity of ca. 1.0 S m−1 at room temperature. Benefiting from the good electrical conductivity and the excellent redox reversibility of both ligand and copper centers, Cu‐DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g−1 at a discharge rate of 0.2 A g−1. Moreover, the symmetric solid‐state supercapacitor of Cu‐DBC exhibits high areal (879 mF cm−2) and volumetric (22 F cm−3) capacitances, as well as good rate capability. These metrics are superior to most reported MOF‐based supercapacitors, demonstrating promising applications in energy‐storage devices.

As a result of their extraordinarily large surfaces and well-defined pores, the design of a multifunctional metal-organic framework (MOF) is crucial for drug delivery but has rarely been reported. In this paper, a novel drug delivery system (DDS) based on nanoscale MOF was developed for use in cancer diagnosis and therapy. This MOF-based tumor targeting DDS was fabricated by a simple postsynthetic surface modification process. First, magnetic mesoporous nanomaterial Fe-MIL-53-NH was used for encapsulating the drug and served as a magnetic resonance contrast agent. Moreover, the Fe-MIL-53-NH nanomaterial exhibited a high loading capacity for the model anticancer drug 5-fluorouracil (5-FU). Subsequently, the fluorescence imaging agent 5-carboxyfluorescein (5-FAM) and the targeting reagent folic acid (FA) were conjugated to the 5-FU-loaded Fe-MIL-53-NH, resulting in the advanced DDS Fe-MIL-53-NH-FA-5-FAM/5-FU. Owing to the multifunctional surface modification, the obtained DDS Fe-MIL-53-NH-FA-5-FAM/5-FU shows good biocompatibility, tumor enhanced cellular uptake, strong cancer cell growth inhibitory effect, excellent fluorescence imaging, and outstanding magnetic resonance imaging capability. Taken together, this study integrates diagnostic and treatment aspects into a single platform by a simple and efficient strategy, aiming for facilitating new possibilities for MOF use for multifunctional drug delivery.

An amazing millimeter-sized lanthanide metal–organic framework, Tb-MOF, was synthesized. Due to the larger volume, Pb2+ ions can be sensitively and selectively detected by visible fluorescence quenching of Tb-MOF. Additionally, a Tb-MOF crystal film with an ultra-high recognition ability of Pb2+ ions has been fabricated successfully.

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