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Photo-response molecular-scale movement has been well developed in azobenzene photochromic molecules. However, material capable of converting this molecular-scale movement to macroscopic work remains a formidable challenge. Here, we describe an exquisite photomechanical effect observed in an azobenzene-Gd(III) MOF. The single crystal of this material displays complex motion including walking, rolling, self-rotating, swing, and finally popping, dependent on the exposed time under UV and the size of the crystals. Consequently, this functional material gives the direct and impressive evidence to support the potential of MOF material in photomechanical motion.

Uranium is the most radioactive element using in the nuclear industry and nuclear technology application. However, it is harmful for environment and human health due to its high toxicity and mobility. Thus designing effective material for uranium removal is highly desirable. In this paper, a novel adsorbent of nZVI@Zn-MOF-74 prepared by anchoring nZVI on Zn-MOF-74 was investigated for the removal of uranium from aqueous solutions. Impressively, nZVI was synthesized for the first time by a spraying approach in a simple and convenient manner. The experimental results indicated that nZVI@Zn-MOF-74 can significantly enhance the removal of U(VI) than both Zn-MOF-74 material and nZVI, leading to high adsorption capacity up to 348 mg/g at pH = 3 and 298 K. The origin, as unveiled by XPS, is due to both U(VI) adsorption from Zn-MOF-74 and U(VI)-to-U(IV) reduction by nZVI.

Hydrogen-bonded frameworks (HOFs) with permanent microporosity are still hard to obtain, due to the inherent nature of easy-to-collapse of HOF skeleton on solvent removal. On the other hand, tuning the electronic structure of HOFs by incorporating redox-active units for expanding the functionality of this class of material presents a waiting-for unveiled and highly desired field. In this work, the redox-active imide unit was utilized to construct HOF. The resultant HOF (namely ECUT-HOF-30) enables robust microporous structure of ca. 4.0 Å, performing effective separation of C2H2/CO2 via the unique molecular recognition from imide oxygen atoms. Whilst exciting optoelectronic active properties such as photochromism and electrochromism were observed in this HOF. The proof-of-concept results open up a gate for fundamental design of advanced HOFs with redox-active unit and versatility.

In this work, we found that the open-metal site in a metal-organic framework (MOF) can be used to enhance such selectivity. Hydrogenation of phenylacetylene over such a catalyst enables ultrahigh styrene selectivity of 92% at full conversion with a turnover frequency of 98.1 h-1. The origin of ultrahigh selectivity, as unveiled by density functional theory calculation, is due to a coordination interaction between the open Zn(II) site and the C≡C bond of phenylacetylene.

Herein we report a novel azo metal-organic framework (MOF), namely Zn2(DMF)(ADC)2(L)0.5 (ECUT-100, H2ADC=azobenzene-4,4'-dicarboxylic acid, L=N, N'-di(pyridin-4-yl)naphthalene-1,4-dicarboxamide), showing a polycatenated 3D array of interlaced 2D bilayers. Without any pre-treatment the as-synthesized ECUT-100 samples effectively adsorb U(VI), leading to the ultrahigh adsorption capacity up to 381 mg/g. This value is greatly higher than that observed in most established porous adsorbents. The origin is primarily due to the free standing azo and amide groups from ADC2- and L ligands that may provide special interactions with U(VI) ions.

In this work, we designed a hybrid catalyst composed of a metal–organic framework (MOF), Pt nanoparticles (NPs), and ferric oxide, namely, Co-MOF-74@(Pt@Fe2O3), which enables not only high turnover frequencies of up to 245.7 h–1 but also ultrahigh 100% selectivity toward cinnamyl alcohol in the hydrogenation of cinnamaldehyde under mild conditions. This excellent performance is attributed to the fact that such a hybrid catalyst enables not only strong steric constraint to provide the favored C═O adsorption of cinnamaldehyde but also strong metal–support interaction to lower the electron density of Pt NPs.

Uranium is not only a radioactive element but also an important nuclear-energy source. Thus the design of material for effective uranium adsorption is highly desirable from both environmental and energy considerations. In this work, a new azo-MOF was explored such use. It shows excellent U(VI) removal performance with the adsorption capacity up to 200 mg/g. The adsorption, as disclosed by the adsorption kinetics, is dominated by chemical adsorption, mainly due to coordination interaction between azo/amide and U(VI) ions. The results suggest that design of material with free-standing azo or amide groups benefits to U(VI) removal.

We present here the first use of a photoassisted multicomponent postsynthetic modification method to anchor a ZIF-90 scaffold with a pyrimidinethione fragment. The resultant materials, namely, ZIF-90-THP and ZIF-90-THF, show ultrahigh Hg(II) adsorption capacity values of up to 596 and 403 mg/g, respectively, relative to the pristine ZIF-90, which just affords a corresponding value of 47 mg/g, suggesting a 12.7- and 8.6-fold enhancement in the Hg(II) adsorption capacity.

In this study, we present the first case of applying the MOF+ technique for in situ preparation of a hybrid material, namely, Zn-MOF-74@ (Pd@Fe2O3). This as-synthesized material can well maintain both the integrity of the framework and porosity. Notably, Zn-MOF-74@(Pd@Fe2O3) exhibits outstanding catalytic performance in the hydrogenation reaction of alkene and semihydrogenation reaction of phenylacetylene, thus providing a new guideline for the design of MOF-based hybrid materials for catalytic purpose.

The separation of C2H2/C2H4 mixtures is of industrial importance in the production of high-purity C2H2 and C2H4. The primary objective of this work is to enhance the selectivity of C2H2/C2H4 separation by developing a method for appropriate modification of porous adsorbents. Toward this end, directly doping low-content Na+ ions into covalent organic frameworks (COFs) via cation exchange is proposed in this work. Relative to the pristine COF, COF-ECUT-1, with C2H2 and C2H4 adsorption capacities of 55.39 cm3 g−1 and 28.63 cm3 g−1, the Na+-anchored phase with just 4.0 wt% sodium content, Na@COF-ECUT-1, enables largely enhanced adsorption ability with the corresponding values of 89.70 cm3 g−1 and 49.26 cm3 g−1, respectively. As a result, the adsorption selectivity of C2H2 over that of C2H4 is enhanced from 6.33 to 9.41, and the separation potential estimated by the simulated transient breakthrough is largely improved about three-fold. The density functional theory (DFT) calculation reveals that the trap of Na+ within the COF channel affords strong affinity towards C2H2 or C2H4 through Na–π interactions and relatively stronger contact for C2H2 than for C2H4 is observed. This result is in line with the experimental results of both enhanced C2H2 and C2H4 adsorption capacity and C2H2/C2H4 separation performance. This work outlines a general and simple method to enhance the gas separation performance upon COF materials.

An ideal porous adsorbent toward uranium with not only large adsorption capacity and high selectivity but also broad applicability even under rigorous conditions is highly desirable but still extremely scarce. In this work, a porous adsorbent, namely [NH4]+[COF‐SO3 −], prepared by ammoniating a SO3H‐decorated covalent organic framework (COF) enables remarkable performance for uranium extraction. Relative to the pristine SO3H‐decorated COF (COF‐SO3H) with uranium adsorption capacity of 360 mg g−1, the ammoniated counterpart of [NH4]+[COF‐SO3 −] affords ultrahigh uranium uptake up to 851 mg g−1, creating a 2.4‐fold enhancement. Such a value is the highest among all reported porous adsorbents for uranium. Most importantly, a large distribution coefficient, K d U, up to 9.8 × 106 mL g−1 is observed, implying extremely strong affinity toward uranium. Consequently, [NH4]+[COF‐SO3 −] affords highly selective adsorption of uranium over a broad range of metal ions such as SU/Cs = 821, SU/Na = 277, and SU/Sr = 124, making it as effective uranium adsorbent from seawater, resulting in amazing uranium adsorption capacity of 17.8 mg g−1. Moreover, its excellent chemostability also make it an effective uranium adsorbent even under rigorous conditions (pH = 1, 8, and 3 m acidity).

The great efforts have been devoted to fabricate excellent hydrogenation catalysts owing to the broad applications in industrial fields. However, the preparation processes of traditional hydrogenation catalysts are often complicated. Herein, mono-valence PtI@COF was synthesized as a catalyst for semi-hydrogenation of phenylacetylene for the first time. The easily prepared SO3H-linked COF possesses a two-dimensional eclipsed layered-sheet structure, making its incorporation with metal ions feasible. The as-prepared PtI@COF composite exhibits excellent performance for semi-hydrogenation phenylacetylene with 93.5% conversion and 90.2% selectivity to styrene under mild reaction conditions (1 ​bar H2, 25 ​°C) within 20 ​min. It’s worth noting that the turnover frequency (TOF) value reaches at 3965 h-1, which outperforms most of recently reported excellent Pt-based catalysts for this reaction.

Thorium, as a nuclear-power replacement for the uranium-based nuclear reactors and an effective avenue to produce uranium source, has become a key element for the increasing energy demand. However, we now are seriously restricted to gain thorium from mineral, due to co-existence of thorium, uranium, and rare earth elements. Accordingly, there is an urgent need to develop solid extraction technique with both large thorium adsorption capacity and high adsorption selectivity. In this work, a COF (covalent organic framework) adsorbent, namely [NH4]+[COF-SO3−] was prepared for selective extraction of thorium from uranium, and rare earth elements. The selective adsorption towards Th(IV) is reflected on the large distribution coefficient (Kd) of 1.34 × 105 mL/g, the big difference up to two orders of magnitude in the adsorption capacity, and the high selectivity (more than nine). This ultrahigh Th(IV) capture up to 395 mg/g presents the largest value for Th(IV) adsorption by porous absorbents. Furthermore, the practical separation of Th(IV) from U(VI) and rare earth elements (Eu3+ and Ce3+) was for the first time executed by both the breakthrough experiment and membrane-based separation experiment. Most importantly, upon this breakthrough separation a Th(VI) solution with high purity up to 93.5% was obtained.

In this work, we report a SO3−-anchored covalent organic framework for the elimination of mercury pollution. The adsorbent of [NH4]+[COF–SO3−] enables ultrahigh Hg2+ adsorption capacity up to 1299 ​mg/g and a recorded uptake of 932.6 ​mg/g for Hg0 among all reported porous solid adsorbents for such use. The high selective adsorption towards Hg2+ is demonstrated by the large distribution coefficient (Kd) of 2.3 ​× ​105 ​mL/g. Moreover, the high selectivity tested by breakthrough experiment was achieved even among different disturbed metal ions (Pb2+, Cd2+, Zn2+, Ni2+, Co2+, Mg2+, K+). Moreover, the adsorbent also shows great recycle without detectable change of Hg2+ capture and structural damage even after four recycle. This remarkable adsorption capacity in conjunction with the fast adsorption kinetics, the strong binding affinity, high selectivity, and good recycle use makes it as a good solid adsorbent for mercury.

We present herein a new concept of hydrogen-bonded organic framework (HOF) material for highly effective electrocatalysis of overall water splitting. This HOF material, namely HOF-Co, was synthesized based on very cheap raw materials. Crystallizing bimetallic HOFs of HOF-CoxFe1-x on nickel foam (NF) can be also easily obtained via a step-by-step approach. In 1 M KOH, HOF-Co0.5Fe0.5 on the NF enables both excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance, thus leading to highly effective electrocatalysis of water splitting with a cell voltage of just 1.63 V at 10 mA cm−2. The vaule is comparable to the commercial Pt/C//IrO2 (1.59 V) and other established outstanding electrocatalysts. The mechanism, as evidenced by Density Functional Theory (DFT) calculations, is due to a significant synergistic effect from the abundant hydrogen-bond structure between coordinated water molecules and SO42- ions that affords rich and accessible active sites, in conjunction with the bimetallic effect.