It is urgent to recycle polyethylene terephthalate (PET) effectively, since it is the most consumed synthetic polyester and its improper disposal has caused significant environmental pollution. The existing chemical recycling methods highly rely on the nucleophilic substitutions and hydrogenative depolymerizations, which typically require the use of excess of nucleophiles, excess strong acids or bases, expensive metal catalysts, and explosive gas atmosphere. Here, we demonstrate a mild and efficient protocol for oxidative depolymerization of PET to terephthalic acid using only an O 2 balloon. Terephthalic acid can be recycled from PET-containing materials including a series of plastic products in daily life. The employing of relatively low loading of iron complex, the most earth-abundant transition metal, as the catalyst and the preliminary results on the large-scale reaction using 38 g of PET waste demonstrate the practical feasibility of this degradation method. This method can be also applicable for selective degradation of PET from mixed plastics. This work represents a rare example of a selective oxidative depolymerization and demonstrates the great potentials of such a concept in polyester recycling.
The precise syntheses of transition–rare-earth metal clusters with desired structures remain a great challenge. Herein, by utilizing SO 4 2- anion released by in-situ decomposition of sodium dodecyl sulfate (SDS) as a template, a series of novel high-nuclearity 3d-4f clusters, formulated as [Ni 24Pr 22(µ 3-OH) 31(pida) 24(SO 4) 4(NO 3) 9(CH 3COO) 3]·Br 4·(NO 3) 11·16H 2O·25CH 3OH ( 1, H 2pida = N-phenyliminodiacetic acid), [Ni 24Nd 22(µ 3-OH) 31(pida) 24(SO 4) 4(NO 3) 9(CH 3COO) 3]·Br 4·(NO 3) 11·14H 2O·24CH 3OH ( 2) and [Ni 24Gd 22(µ 3-OH) 36(bida) 24(SO 4) 7(NO 3) 3(CH 3COO) 3]·(SO 4)·Br 4·(NO 3) 4·31H 2O·32CH 3OH ( 3, H 2bida = N-benzyliminodiacetic acid), have been successfully isolated. X-ray crystal structure analyses reveal that all the cationic {Ni 24RE 22} cores in 1— 3 possess a ball-like structure with C 3 v symmetry, and can be viewed as consisting of an inner {RE 22} core and an outer {Ni 24} shell. From 1 and 2 to 3, due to the lanthanide contraction effect, the coordination numbers for rare-earth metal centers in {RE 22} are different, resulting in different number of SO 4 2- and NO 3 - anions to support and stabilize the skeleton structures. Meanwhile, the magnetic properties of complexes 1— 3 were also studied. The result revealed that complexes 1— 3 show antiferromagnetic/ferrimagnetic interactions, and 3 exhibits magneto-caloric effect at ultralow temperatures with a maximum –Δ S m (magnetic entropy change) value of 33.03 J·kg −1·K −1 at 3.0 K and 7 T.
Electrocatalysis technology can effectively promote the hydrodechlorination of chloramphenicol (CAP) to reduce the bio-toxicity. However, there are still some challenges such as low degradation rate and poor stability. Here, we prepared porous N, O co-doped carbon supported Pd nanoparticles composites (Pd NPs/NO-C) for electrocatalytic degradation of CAP. The doping of N and O not only effectively enhanced the interaction between substrate and CAP, promoting the mass transfer process, but also enhanced the anchoring effect on Pd nanoparticles, avoiding the occurrence of aggregation. The prepared composites achieved removal efficiency of CAP over 99% within 1 h, and the rate constant was as high as 6.72 h -1, outperforming previous reported electrocatalysts. Additionally, Pd NPs/NO-C composites showed a wide range of pH tolerance, excellent ion interference resistance and long-term stability. Our work unravels the importance of mass transfer processes in solution to electrocatalytic hydrodechlorination and provides new research ideas for catalysts design.
Unsymmetric sulfides and selenides have great applications in the pharmaceutical field. Herein, we describe the reductive coupling reaction of xanthate esters with sulfur-containing and selenium-containing compounds (thio(seleno)sulfonates and disulfides(selenides)) under the nickel-catalyzed condition. It provides a mild and effective method for the synthesis of unsymmetric sulfides and selenides which has the advantages of mild reaction conditions, high yields and a wide range of substrates.
An efficiently catalytic method toward the synthesis of indolin-2-ones featuring an allylic derived C3-quaternary stereocenter via an intramolecular Heck cyclization/Suzuki coupling of N-substituted- N-(2-bromophenyl)acrylamides and organoboron reagents was successfully developed by using a 1, 3-bis(2, 6-diisopropylphenyl)acenaphthoimidazol-2-ylidene (AnIPr)-ligated oxazoline palladacycle. It enabled a very broad substrate scope tolerating different functional groups, electronic properties and steric bulkiness. Notably, it revealed a great potential to build diverse heterocycle-fused indoline alkaloids via the same intermediate 3-allyl-1, 3-dimethylindolin-2- one.
A highly enantioselective palladium-catalyzed intramolecular Heck reaction of unactivated alkenes is developed, which provides a powerful route to access a broad range of chiral 3, 3-disubstituted-2, 3-dihydrobenzofurans bearing all-carbon quaternary stereocenter of interest in pharmaceutical research. Its salient features include high yield, excellent chemo- and enantioselectivity, mild conditions, a broad substrate scope as well as versatile transformations of the product.
The cyanide anion (CN -) is known to be one of the most toxic anions. Therefore, there is an urgent need to develop a reliable, sensitive, selective, rapid and effective method for the detection of CN -. Here, a self-assembly strategy based on pillar[5]arene P5 and azine derivative AZ was used to construct supramolecular sensors, and it was found that the detection effect of CN - was significantly improved by the assembly strategy. The sensitivity of the assembled sensor P5-AZ to CN - is more than 10 times higher than that of AZ. The detect mechanism was further investigated by theoretical calculations and 1H NMR. The results showed that AZ detects CN - by a deprotonation process with fluorescence enhancement, while P5-AZ improves the sensitivity of CN - recognition through hydrogen bonding, anion-π and anion-dipole interactions, as well as the strong bonding ability of the assembly. Supramolecular assembly P5-AZ has the advantages of low toxicity, high sensitivity, and more importantly, it provides a method to detect CN - sensitivity in the aqueous phase and organisms by host-guest assembly.
Traditional reduction coupling reactions of two bromides typically rely on transition metal catalysis. Here, we introduce the development of a visible-light catalytic direct reduction coupling reaction between α-CF 3-alkyl bromides and alkynyl bromides to access valuable organic frameworks. Our research confirms the excellent compatibility of this reaction with various functional groups, which could be used to modify the substrate with biologically active molecular fragments. Mechanistic investigations, including control experiments, fluorescence quenching studies, and light-switching experiments, have provided insights into the reaction mechanism. This study paves the way for the application of visible-light catalysis in diverse synthetic transformations, offering a sustainable and efficient approach to organic synthesis.
The construction of acyclic quaternary carbon stereocenters, which are ubiquitous in many bioactive compounds, pharmaceuticals and natural products, has been a long persuit in synthetic organic chemistry. Among numerous methods, enantioselective nickel-catalysis has attracted incremental attention in recent years. This review summarizes the recent development in the asymmetric strategies, research progress, mechanistic investigations for the generation of acyclic quaternary carbon stereocenters via enantioselective nickel catalysis.
Key Scientists: In 2006, the Zhou group and RajanBabu group realized the nickel-catalyzed enantioselective hydrovinylation of α-substituted styrenes and ethylene to construct acyclic quaternary carbon stereocenters (QCSs) by using spiro- and binaphthyl phosphoramidite ligands, respectively. In 2016, Watson developed a nickel-catalyzed Suzuki-Miyaura arylation to generate acyclic QCSs via chirality transfer reaction. In 2017, the Feng and the Fu group developed nickel-catalyzed enantioselective conjugated/Michael additions to build acyclic QCSs, respectively. In 2020, the Fang group made the first success in the construction of QCSs by nickel-catalyzed hydrocyanation of alkenes and allenes. In 2021, Gregory C. Fu and co-workers disclosed a nickel-catalyzed enantioselective α-functionalization of carbonyl compounds that could form acyclic QCSs. At the same time, the Shi group constructed chiral acyclic QCSs via nickel-catalyzed functionalization of alkenes. In 2023, Kleij and co-workers applied a new strategy for Ni-catalyzed regio- and enantioselective homoallylic coupling to construct acyclic QCSs. In the same year, Tao and co-workers demonstrated a novel strategy that is dinickel-catalyzed enantioselective α-alkylation of carbonyl compounds with alkyl iodides.
Room-temperature phosphorescence (RTP) materials have experienced rapid development due to their potential in organic light- emitting diode, information security, bioimaging, etc. However, the design of chiral organic phosphors with circularly polarized RTP (CPP) property remains a formidable challenge. Here, we introduce a chiral perturbation approach using a combination of chiral binaphthol and phenoselenazine derivative to achieve CPP. The photoactivated CPP in polystyrene (PS) film demonstrates a luminescence dissymmetry factor ( g lum), emission efficiency, and RTP lifetime up to 9.32 × 10 -3, 27.0%, and 40.0 ms, respectively. The remarkable sensitivity of PS film to oxygen and temperature enables the adjustable emission colors, ranging from green to offwhite and blue under varying conditions. The doping systems, utilizing hosts of triphenylphosphine and 9-phenylcarbazole, demonstrate an extended CPP lifetime of 85.9 ms and exhibit a persistent mechanoluminescence property with low pressure response threshold as low as 0.15 N. The information security provided by this CPP material was attained via the using of diverse emission colors and afterglow generated by distinct UV irradiation times and host materials. Alternately, it can also be achieved by observing different emission patterns using R- and L-polarizer. The research has presented a reliable approach for producing CPP materials with high emission efficiency and g lum.
Müller’s hydrocarbon is a well-known open-shell singlet diradicaloid, yet its structural determination and redox property remain elusive due to its extremely high reactivity. Herein, we report the successful synthesis and full characterizations of the first neutral boron-centered analogue ( 4) of Müller’s hydrocarbon, along with the first dianionic boron-centered analogue ( 5 2-) featuring three isolable redox states. In the presence of two equivalents of N-heterocyclic carbene (NHC), reduction of 4, 4″-bis(triisopropylphenylbromoboryl)terphenyl 3 with potassium graphite afforded NHC-stabilized boryl diradicaloid 4 with a near-pure diradical character ( y 0 = 0.93). Stepwise reductions of 4, 4″-bis(dimesitylboryl)terphenyl 5 in THF yielded the isolable monoradical anion 5 ·2- and diradical dianion 5 2-, respectively, accompanied by a decreasing aromaticity within the conjugated spacer. Experimental studies and theoretical analyses revealed that both 4 and 5 2- exhibit large spin distributions at boron atoms, open-shell singlet ground states, and small singlet-triplet energy gaps.
Many-body interactions in condensed matter could lead to emergent phenomena spanning superconductivity, ferromagnetism, exciton condensation,etc. The emergence of these phenomena often requires highly ordered spatial arrangements of the interacting species to enforce specific space symmetries and interacting strengths. Metal−organic frameworks (MOFs), crystalline materials formed by self-assembly of metal ions and organic ligands, allow for precise design of their crystal structures and sophisticated tuning of Coulombic interaction or magnetic coupling among lattice sites. Such atomic-level designability combined with high crystallinity and versatile types of lattices (e.g., kagome and honeycomb lattices) render MOFs as a great platform to investigate emergent physics. In this Emerging Topic, we summarize recent studies evidencing emergent phenomena in MOFs including strong correlations, superconductivity, charge density wave, long-range magnetic order, and quantum spin liquid. We highlight the great potential of MOFs as quantum materials and discuss challenges including growth of high-quality single crystals and in-depth physical characterizations to reveal insights into the nature of physical properties of MOFs.
Comprehensive Summary: The electrochemical processes of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play a crucial role in various energy storage and conversion systems. However, the inherently slow kinetics of reversible oxygen reactions present an urgent demand for the development of efficient oxygen electrocatalysts. Recently, metal-organic framework (MOF) derivatives have attracted extensive attention in electrocatalysis research due to their unique porous structure, abundant active sites, and tunable structural properties. Especially, the optimization of the electronic structure of active sites in MOF derivatives has been proven as an effective strategy to enhance the catalytic activity. In this review, we provide an overview of the electronic structure optimization strategies for active sites in MOF derivatives as advanced catalysts in various O—O bond activation reactions, including the construction of synergistic effects between multiple sites, the development of heterogeneous interfaces, the utilization of metal support interactions, and the precise modulation of organic ligands surrounding catalytic active sites at the atomic level. Furthermore, this review offers theoretical insights into the oxygen activation and catalytic mechanisms of MOF derivatives, as well as the identification of active sites. Finally, the potential challenges and prospects of MOF derivatives in electrocatalysis are discussed. This review contributes to the understanding and advancement of efficient oxygen electrocatalysis in energy systems.
Comprehensive Summary: Comprehensive Summary The utilization of rare earth (RE) elements is pivotal in wave absorption. In particular cases, RE group elements manifesting unique 4f electron layer structures are doped as impurities into certain materials, which is a practical and reliable method for regulating these materials’ magnetic and electrical properties. Moreover, ferrites and metal-organic frameworks (MOFs), standing out among conventional and emerging wave-absorbing materials, can achieve significantly enhanced wave absorption through RE doping or substitution. Numerous scholars have dedicated massive research over a substantially long time to explore the utilization of RE elements to reinforce the absorption of these two materials. Therefore, consolidating and summarizing such efforts are crucial and necessary. This review aims to clarify the underlined mechanism of electromagnetic wave (EMW) absorption and elaborate on the impact of RE doping by providing a comprehensive overview of recent progress in ferrites and MOFs dopped with RE elements. Finally, the limitations associated with RE doping in such materials are delineated, and the upcoming prospects for its application are highlighted.
Key Scientists: In 1947, J. A. Marinky et al. obtained promethium from uranium fission products. From the isolates of yttrium soil in 1794 to the discovery of promethium in 1947, it took more than 150 years. In 1975, Guangxian Xu found that the rare earth solvent extraction system has the basic “constant mixed extraction ratio” rule. In 1984, the theory of “one-cavity multi-mode” was proposed by Weigan Lin to improve the electromagnetic wave theory further and develop the theory of absorbing materials. In 1995, Omar M. Yaghi synthesized the first MOFs in history, and since then, they have been widely used in gas adsorption and separation and other fields because of their large specific surface area and adjustable pore structure. In recent years, various functional materials based on MOFS-derived carbon have been studied endlessly. Masato Sagawa, known for inventing NdFeB magnets, won the “28th Japan Prize” in 2012. In recent years, Renchao Che has promoted the development of interface theory and magnetic theory in the field of wave absorption. In addition, Jiurong Liu is committed to developing various wave-absorbing materials and the respective theoretical research and continues to promote the development of wave-absorbing materials to “thin, light, wide and strong”.