查看更多>>摘要：Müller's hydrocarbon is a well-known open-shell singlet diradicaloid,yet its structural determination and redox property remain elu-sive due to its extremely high reactivity.Herein,we report the successful synthesis and full characterizations of the first neutral bo-ron-centered analogue(4)of Müller's hydrocarbon,along with the first dianionic boron-centered analogue(52-)featuring three isola-ble redox states.In the presence of two equivalents of N-heterocyclic carbene(NHC),reduction of 4,4"-bis(triisopropylphenyl-bromoboryl)terphenyl 3 with potassium graphite afforded NHC-stabilized boryl diradicaloid 4 with a near-pure diradical character(y0=0.93).Stepwise reductions of 4,4"-bis(dimesitylboryl)terphenyl 5 in THF yielded the isolable monoradical anion 5"and diradical dian-ion 52-,respectively,accompanied by a decreasing aromaticity within the conjugated spacer.Experimental studies and theoretical analyses revealed that both 4 and 52-exhibit large spin distributions at boron atoms,open-shell singlet ground states,and small sin-glet-triplet energy gaps.
查看更多>>摘要：Many-body interactions in condensed matter could lead to emergent phenomena spanning superconductivity,ferromagnetism,ex-citon 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 tun-ing of Coulombic interaction or magnetic coupling among lattice sites.Such atomic-level designability combined with high crystallin-ity 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 correla-tions,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 charac-terizations to reveal insights into the nature of physical properties of MOFs.
查看更多>>摘要：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 de-mand 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 synergis-tic 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.
查看更多>>摘要：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 conven-tional 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 rein-force the absorption of these two materials.Therefore,consolidating and summarizing such efforts are crucial and necessary.This re-view 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 as-sociated with RE doping in such materials are delineated,and the upcoming prospects for its application are highlighted.
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