Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe, Cr or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design strategy will allow the development of other selective heterogeneous catalysts for important yet challenging transformations.
Here, the synthesis of a wafer‐scale ultrathin 2D imine polymer (2DP) film with controllable thickness from simple benzene‐1,3,5‐tricarbaldehyde (BTA) and p‐phenylenediamine (PDA) building blocks is reported using a Schiff base polycondensation reaction at the air–water interface. The synthesized freestanding 2DP films are porous, insulating, and more importantly, covalently linked, which is ideally suited for nonvolatile memristors that use a conductive filament mechanism. These devices exhibit excellent switching performance with high reliability and reproducibility, with on/off ratios in the range of 102 to 105 depending on the thickness of the film. In addition, the endurance and data retention capability of 2DP‐based nonvolatile resistive memristors are up to 200 cycles and 8 × 104 s under constant voltage stress at 0.1 V. The intrinsic flexibility of the covalent organic polymer enables the fabrication of a flexible memory device on a polyimide film, which exhibits as reliable memory performance as that on the rigid substrate. Moreover, the 2DP‐based memory device shows outstanding thermal stability and organic solvent resistance, which are desirable properties for applications in wearable devices.
Metal-organic frameworks (MOFs) as selectivity regulators for catalytic reactions have attracted much attention, especially MOFs and metal nanoparticle (NP) shelled structures, e.g., MOFs@NPs@MOFs. Nevertheless, making hydrophilic MOF shells for gathering hydrophobic reactants is challenging. Described here is a new and viable approach employing conjugated micro- and mesoporous polymers with iron(III) porphyrin (FeP-CMPs) as a new shell to fabricate MIL-101@Pt@FeP-CMP. It is not only hydrophobic and porous for enriching reactants, but also possesses iron sites to activate C=O bonds, thereby regulating the selectivity for cinnamyl alcohol in the hydrogenation of cinnamaldehyde. Interestingly, MIL-101@Pt@FeP-CMP can achieve a high turnover frequency ( 1516.1 h ), with 97.3 % selectivity for cinnamyl alcohol at 97.6 % conversion.
etc., is essentially crucial to help combat these hazards and build a sustainable society. Among them, rechargeable battery has been regarded as a key technology. In the past decade, we have witnessed that the prevailing lithium-ion batteries (LIBs) made our society more portable, intelligent, and cleaner. [17][18][19] Nevertheless, the limited lithium resources and rising cost hinder their applications in the long run, especially in the field of large-scale stationary energy storage for renewable energy resources (e.g., solar, tide, and wind power). Thus, it is a huge stimulus for researchers to explore more sustainable rechargeable battery systems, which are expected to involve abundant and nontoxic metals to reduce the cost and impacts on environment.Diversified rechargeable batteries such as, the monovalent sodium-ion batteries (SIBs), [20][21][22][23][24] potassium-ion batteries (PIBs), [25][26][27] bivalent zinc-ion batteries (ZIBs), [28][29][30][31] magnesium-ion batteries (MIBs), [32][33][34][35] calcium-ion batteries (CIBs), [36][37][38][39] and trivalent aluminum-ion batteries (AIBs), [40][41][42] have emerged and shown great energy storage promise. As depicted in Figure 1a, those nonlithium metals are much more abundant than Li, especially Al, Ca, Na, K, and Mg, all of which rank the top-8 abundant elements in earth crust. For SIBs and PIBs, since Al would not form alloys with Na and K, Al foil can be used as anode collector, which further lowers the prices of SIBs and PIBs. On the other hand, the higher standard potential of Na/Na + (−2.71 V vs standard hydrogen electrode, SHE) and K/K + (−2.93 V) and their heavier atomic weights make energy densities of SIBs and PIBs intrinsically lower than that of LIBs. For multivalent-ion batteries, the multielectron transfer enables their volumetric capacities (e.g., 5857 and 8056 mA h cm −3 for Zn and Al, respectively) higher than that of Li (2042 mA h cm −3 ). [43,44] Additionally, the small cation radius of Zn 2+ (0.74 Å), Mg 2+ (0.72 Å), and Al 3+ (0.54 Å) indicate that many intercalation electrode materials typical in LIBs may be also potential hosts for reversible intercalation of these multivalent ions. Combining all the above merits, one can anticipate that these emerging rechargeable batteries would be considered as promising alternatives to LIBs.In quest of safe, cost-effective, and high-performance rechargeable batteries, two technical routes have been
A novel 3D metal−organic framework (MOF)-{[Tb 3 (CBA) 2 (HCOO)(μ 3 -OH) 4 (H 2 O)]•2H 2 O•0.5DMF} n (S-1) was synthesized by the solvothermal method. The crystal structure indicates that [Tb 4 O 4 ] cubane clusters selfassemble into an infinite chain by sharing vertex, which is further linked to adjacent chains through 1,1-cyclobutanedicarboxylic acid ligand (H 2 CBA), resulting in a honeycomb arrayed framework. S-1 possesses excellent water stability and still retains intact structure after exposure to water for 10 weeks or boiling water for 10 weeks. Interestingly, S-1 acts as a luminescence sensor to selectively and sensitively detect quercetin with the limit of detection (LOD) as low as 0.23 ppm (7.6 × 10 −7 M). The relationship between relative luminescence intensity and concentration obeys linear in the range of 0−300 ppm (0−993 μM), which allows quantitative detection of quercetin. Importantly, S-1 can be reused at least six times with almost no change in luminescent intensity. Compared with the high performance liquid chromatography−mass spectrometry (HPLC−MS) method, S-1 was used to determine the content of quercetin in onionskin and apple peel samples with satisfactory results. Furthermore, a portable S-1 test paper is also developed and expected to be applied in practice. To our knowledge, S-1 is the first example of MOFs as luminescent sensor for quercetin.
On account of unique characteristics, the integration of metal–organic frameworks as active materials in electronic devices attracts more and more attention. The film thickness, uniformity, area, and roughness are all fatal factors limiting the development of electrical and optoelectronic applications. However, research focused on ultrathin free‐standing films is in its infancy. Herein, a new method, vapor‐induced method, is designed to construct centimeter‐sized Ni3(HITP)2 films with well‐controlled thickness (7, 40, and 92 nm) and conductivity (0.85, 2.23, and 22.83 S m−1). Further, traditional transfer methods are tactfully applied to metal–organic graphene analogue (MOGA) films. In order to maintain the integrity of films, substrates are raised up from bottom of water to hold up films. The stripping method greatly improves the surface roughness Rq (root mean square roughness) without loss of conductivity and endows the film with excellent elasticity and flexibility. After 1000 buckling cycles, the conductance shows no obvious decrease. Therefore, the work may open up a new avenue for flexible electronic and magnetic devices based on MOGA.
In this work, we synthesized a series of microcrystalline MnxN100−x-MOF-74 (N = Fe, Co and Ni) materials by a one-pot reaction.
Metal-organic frameworks (MOFs) as selectivity regulators for catalytic reactions have attracted muchattention, especially MOFs and metal nanoparticle (NP) shelled structures,e .g., MOFs@NPs@MOFs.N evertheless,m aking hydrophilic MOF shells for gathering hydrophobic reactants is challenging.D escribed here is an ew and viable approach employing conjugated micro-and mesoporous polymers with iron(III) porphyrin (FeP-CMPs) as an ew shell to fabricate MIL-101@Pt@FeP-CMP.I ti sn ot only hydrophobic and porous for enriching reactants,b ut also possesses iron sites to activate C = Ob onds,t herebyr egulating the selectivity for cinnamyl alcohol in the hydrogenation of cinnamaldehyde. Interestingly,MIL-101@Pt@FeP-CMP sponge can achieve ahigh turnover frequency (1 516.1 h À1 ), with 97.3 %s electivity for cinnamyl alcohol at 97.6 %conversion.
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