General Approach for Constructing Mechanoresponsive and Redox-Active Metal-Organic and Covalent Organic Frameworks by Solid-Liquid Reaction: Ferrocene as the Versatile Function Unit.

We report for the first time the construction of mechanoresponsive and redox-active metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) by anchoring ferrocene (Fc) pendants as mechanophores in the pore wall. This work outlines a simple, general, and low-cost route to tailor MOFs and COFs by a Fc unit for mechanoresponsive nature, the release of Fe ions, redox behavior, and modulation of the skeleton charge together.

Ammoniating Covalent Organic Framework (COF) for High-Performance and Selective Extraction of Toxic and Radioactive Uranium Ions.

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).

Ultralow-Content Palladium Dispersed in Covalent Organic Framework for Highly Efficient and Selective Semihydrogenation of Alkynes.

Developing noble-metal-based catalysts with ultralow loading to achieve excellent performance for selective hydrogenation of alkynes under mild reaction conditions is highly desirable but still faces huge challenges. To this end, a SO3H-anchored covalent organic framework (COF-SO3H) as the support was deliberately designed, and then ultralow-content Pd (0.38 wt %) was loaded by a wet-chemistry immersion dispersion method. The resulting Pd0.38/COF-SO3H composite exhibits outstanding performance for the selective hydrogenation of phenylacetylene with 97.06% conversion and 93.15% selectivity to styrene under mild reaction conditions (1 bar of H2, 25 °C). Noticeably, the turnover frequency value reaches as high as 3888 h-1, which outperforms most of reported catalysts for such use. Moreover, such a catalyst also exhibits excellent activity for a series of other alkynes and high stability without obvious loss of catalytic performance after five consecutive cycles.

Applying MOF+ technique for in situ preparation of a hybrid material for hydrogenation reaction.

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.

Pd@Zn-MOF-74: Restricting a Guest Molecule by the Open-Metal Site in a Metal-Organic Framework for Selective Semihydrogenation.

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.

Hybrid Catalyst of a Metal-Organic Framework, Metal Nanoparticles, and Oxide That Enables Strong Steric Constraint and Metal-Support Interaction for the Highly Effective and Selective Hydrogenation of Cinnamaldehyde.

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.

Functionalizing a Metal-Organic Framework by a Photoassisted Multicomponent Postsynthetic Modification Approach Showing Highly Effective Hg(II) 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.

Synthesis and biological evaluation of open-chain analogs of cyclic peptides as inhibitors of cellular Shp2 activity.

A series of open-chain analogs of cyclic peptides was designed and synthesized using sansalvamide A as a model compound. All compounds exhibited low antitumor activity. Furthermore, the evaluation of their inhibitory potency toward IMPDH, SHP2, ACHE, proteasome, MAGL, and cathepsin B showed that all of the compounds were potent against protein tyrosine phosphatase Shp2. Specifically, compounds 1a, 1d, 2b, and 2f were found to inhibit SHP2 with IC50 values in the low micromolar range and good selectivity. Based on the molecular docking results, the binding modes of the chain cyclic peptides in the active center of SHP2 were discussed.

Enhanced electrochemical performance at screen-printed carbon electrodes by a new pretreating procedure.

A new method for the pretreatment of screen-printed carbon electrodes (SPCEs) by two successive steps was proposed. In step one, fresh SPCEs were soaked into NaOH with high concentration (e.g. 3 M) for tens to hundreds of minutes, and the resulted electrodes were called as SPCE-I. In step two, SPCE-I were pre-anodized in low concentration of NaOH, which were designated as SPCE-II. The pretreated electrodes showed remarkable enhancement in heterogeneous electron transfer rate constant (k0) increased from 1.6x10(-4) cms(-1) at the fresh SPCE to 1.1x10(-2) cms(-1) at SPCE-I for Fe(CN)6(3-/4-) couple. The peak to peak separation (deltaE(p)) in cyclic voltammetry was reduced from ca. 480 to 84 mV, indicating that the electrochemical reversibility was greatly promoted, possibly due to the removing of polymers/oil binder from the electrode surfaces. The electroactive area (A(ea)) of the electrode was increased by a factor of 17 after pretreatment in step one. Further analysis by the electrochemical impedance method showed that the electron transfer resistance (R(ct)) decreased from ca. 2100 to 1.4 ohms. These pretreated electrodes, especially SPCE-II, exhibited excellent electrocatalytic behavior for the redox of dopamine (DA). Interference from ascorbic acid (AA) in the detection of DA at SPCE-II could be effectively eliminated due to the anodic peak separation (190 mV) between DA and AA, which resulted from the functionalization of the electrode surface in the pretreatment of step two. Under optimum conditions, current responses to DA were linearly changed in two concentration intervals, one was from 3.0x10(-7) to 9.8x10(-6) M, and the other was from 9.8x10(-6) to 3.3x10(-4) M. The detection limit for DA was down to 1.0x10(-7) M.