Recently, mechanical milling using a mixer mill or planetary mill has been fruitfully utilized in organic synthesis under solvent-free conditions. This review article provides a comprehensive ...overview of various solvent-free mechanochemical organic reactions, including metal-mediated or -catalyzed reactions, condensation reactions, nucleophilic additions, cascade reactions, Diels-Alder reactions, oxidations, reductions, halogenation/aminohalogenation,
etc.
The ball milling technique has also been applied to the synthesis of calixarenes, rotaxanes and cage compounds, asymmetric synthesis as well as the transformation of biologically active compounds.
Various solvent-free mechanochemical organic reactions can be realized by ball milling techniques.
Two‐dimensional (2D) black phosphorus (BP) has a unique band structure, but it suffers from low ambient stability owing to its high reactivity to oxygen. Covalent functionalization has been ...demonstrated to passivate the reactive BP effectively, however the reported covalent functionalization methods are quite limited to aryl diazonium and nucleophilic additions affording P−C and P−O−C single bonds, for which the retaining of one unpaired electron in the Group 15 phosphorus atom hampers the passivation effect. Now, covalent azide functionalization of BP nanosheets (BPNSs) is reported, leading to significant enhancement of the ambient stability of BP as confirmed by UV/Vis spectroscopic studies. The most stable configuration of the azide functionalized BPNSs (f‐BPNSs) is predicted by theoretical calculations, featuring the grafting of benzoic acid moiety onto BPNSs via the unprecedented P=N double bonds formed through in situ nitrene as a reactive intermediate.
Stabilizing black phosphorus (BP) via azide passivation: Azide functionalization is developed as a new covalent functionalization approach of BP nanosheets (BPNSs), leading to the formation of unprecedented P=N double bonds. These passivate the reactive BPNSs effectively and contribute to a dramatic enhancement of the ambient stability of BPNSs, with the degradation ratio inhibited by about 12 times relative to the pristine BPNSs.
A strategy for combining metal oxides and metal–organic frameworks is proposed to design new materials for sensing volatile organic compounds, for the first time. The prepared ZnO@ZIF‐CoZn ...core–sheath nanowire arrays show greatly enhanced performance not only on its selectivity but also on its response, recovery behavior, and working temperature.
High‐quality MOF thin films with high orientation and controlled thickness are extremely desired for applications. However, they have been only successfully fabricated on flat substrates. Those MOF ...2D thin films are limited by low exposed area and slow mass transport. To overcome these issues, MOF 3D thin films with good crystallinity, preferred orientation, and precisely controllable thickness in nanoscale were successfully prepared in a controllable layer‐by‐layer manner on nanowire array substrate for the first time. The as‐prepared Cu‐HHTP 3D thin film is superior to corresponding 2D thin films and showed one of the highest sensitivity, lowest LOD, and fastest response among all reported chemiresistive NH3 sensing materials at RT. This work provides a feasible approach to grow preferred‐oriented 3D MOF thin film, offering new perspectives for constructing MOF‐based heterostructures for advanced applications.
Semiconducting MOF 3D thin films with good crystallinity, preferred orientation, as well as precisely controllable thickness in nanoscale were successfully prepared in a layer‐by‐layer manner on a nanowire array substrate. Compared to 2D thin films, the Cu‐HHTP 3D thin film shows one of the highest sensitivity, lowest LOD and fastest response speed among all reported chemiresistive NH3 sensing materials at RT.
Manipulating the backbone of small molecule acceptors (SMAs) is of particular importance in developing efficient organic solar cells (OSCs). The common design is constructing 2‐arm SMAs with linear ...or curved backbones. Herein, we report an acceptor 4A‐DFIC with a 4‐arm backbone unexpectedly generated in the reaction of an electron‐rich aromatic diamine and hexaketocyclohexane. Single‐crystal X‐ray diffraction analysis indicates the rigid and twisted molecular plane and the effective molecular stacking of 4A‐DFIC in solid state. 4A‐DFIC shows a low band gap of 1.40 eV and excellent light‐harvesting capability from visible to near‐infrared region. Binary and ternary OSCs based on 4A‐DFIC gave power conversion efficiencies (PCEs) of 15.76 % and 18.60 % (certified 18.1 %), respectively, which are the highest PCEs for multi‐arm SMA‐based OSCs to date.
A 4‐arm small molecule acceptor (SMA) 4A‐DFIC was serendipitously made. Power conversion efficiencies of 15.76 % and 18.60 % were achieved in 4A‐DFIC‐based binary and ternary organic solar cells, respectively, setting new records for multi‐arm SMA‐based solar cells.
Solar interfacial water evaporation shows great potential to address the global freshwater scarcity. Water evaporation being inherently energy intensive, Joule‐heating assisted solar evaporation for ...addressing insufficient vapor under natural conditions is an ideal strategy. However, the simultaneous optimization of low evaporation enthalpy, high photothermal conversion, and excellent Joule‐heating steam generation within a single material remain a rare achievement. Herein, inspired by the biological channel structures, a large‐area film with hierarchical macro/microporous structures is elaborately designed by stacking the nanosheet of a conductive metal–organic framework (MOF), Ni3(HITP)2, on a paper substrate. By combining the above three features in one material, the water evaporation enthalpy reduces from 2455 J g−1 to 1676 J g−1, and the photothermal conversion efficiency increases from 13.75% to 96.25%. Benefiting from the synergistic photothermal and Joule‐heating effects, the evaporation rate achieves 2.60 kg m−2 h−1 under one sun plus input electrical power of 4 W, surpassing the thermodynamic limit and marking the highest reported value in MOF‐based evaporators. Moreover, Ni3(HITP)2‐paper exhibits excellent long‐term stability in simulated seawater, where no salt crystallization and evaporation rate degradation are observed. This design strategy for nanosheet films with hierarchical macro/microporous channels provides inspiration for electronics, biological devices, and energy applications.
A large area conductive MOFs nanosheet film with hierarchical macro/microporous structures is fabricated for interfacial seawater evaporation, which effectively reduces the water evaporation enthalpy, enhances the photothermal conversion efficiency, and refreshes the evaporation rate records for MOF‐based evaporators.
Organic–inorganic hybrid superlattices (OIHSLs) hold attractive physical and chemical properties, while the construction of single‐crystal covalent OIHSLs has not been achieved. Herein a coordination ...assembly strategy was proposed to create a single‐crystal covalent OIHSL PbBDT (BDT=1,4‐benzenedithiolate), where layered PbS2 sublattice covalently connects with benzene sublattice. The covalent bonding offers better thermo‐/chemi‐stability, inter‐sublattice electron transport, and unique organic‐group‐functionalized surface, which may enable better performances in chemical applications than non‐covalent OIHSL. These features endow PbBDT with the highest sensitivity, the lowest detection limit and excellent selectivity towards NO2 at room temperature among all chemiresistive gas‐sensing materials with reported response time less than 2 min without the need of light assistance.
A covalent organic–inorganic hybrid superlattice was designed and synthesized with a facile coordination assembly method. The surface functional groups and interlayer charge transport render the superlattice nanosheets an excellent gas sensing material with the highest sensitivity, the lowest detection limit, and exceptional selectivity towards NO2 at room temperature among all fast‐response gas‐sensing materials without the need of light assistance.
Heterostructured metal—organic framework (MOF)‐on‐MOF thin films have the potential to cascade the various properties of different MOF layers in a sequence to produce functions that cannot be ...achieved by single MOF layers. An integration method that relies on van der Waals interactions, and which overcomes the lattice‐matching limits of reported methods, has been developed. The method deposits molecular sieving Cu‐TCPP (TCPP=5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin) layers onto semiconductive Cu‐HHTP (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene) layers to obtain highly oriented MOF‐on‐MOF thin films. For the first time, the properties in different MOF layers were cascaded in sequence to synergistically produce an enhanced device function. Cu‐TCPP‐on‐Cu‐HHTP demonstrated excellent selectivity and the highest response to benzene of the reported recoverable chemiresistive sensing materials that are active at room temperature. This method allows integration of MOFs with cascading properties into advanced functional materials.
MOF‐on‐MOF thin films were prepared from Cu‐HHTP (HHTP=hexahydrotriphenylene) and Cu‐TCPP (TCPP=tetrakis(4‐carboxyphenyl)porphyrin frameworks). The properties of the MOF layers cascade to produce functionality not achieved by a single layer. The MOF‐on‐MOF films demonstrate excellent selectivity and the highest response to benzene among reported recoverable chemiresistive sensing materials active at room temperature.
Engineering the band gap chemically by organic molecules is a powerful tool with which to optimize the properties of inorganic 2D materials. The obtained materials are however still limited by ...inhomogeneous compositions and properties at nanoscale and small adjustable band gap ranges. To overcome these problems in the traditional exfoliation and then organic modification strategy, an organic modification and then exfoliation strategy was explored in this work for preparing 2D organic metal chalcogenides (OMCs). Unlike the reported organically modified 2D materials, the inorganic layers of OMCs are fully covered by long-range ordered organic functional groups. By changing the electron-donating ability of the organic functional groups and the electronegativity of the metals, the band gaps of OMCs were varied by 0.83 eV and their conductivities were modulated by 9 orders of magnitude, which are 2 and 10
times higher than the highest values observed in the reported chemical methods, respectively.
The serendipitous discovery of dumb‐bell‐shaped C120 under high‐speed vibration milling conditions is described. The mechanochemical protocol has been employed to synthesize the He‐, H2‐ or ...H2O‐encapsualted C120, the cross‐dimer C130, trimer C180, bridged C60 dimers as well as products from many other reactions of fullerenes, carbon nanotubes and graphenes. Mechanochemistry extended to various reactions of non‐fullerene molecules is briefly discussed.
What is the most favorite and original chemistry developed in your research group?
Mechanochemistry and fullerene chemistry.
How do you get into this specific field? Could you please share some experiences with our readers?
The poor solubility of fullerenes in common organic solvents prompts scientists to seek alternative protocol for fullerene chemistry. An idea of performing chemical reactions of fullerenes in the absence of any organic solvent was conceived when I was a guest research fellow in Kyoto University. That was how I first got into the mechanochemical reactions of fullerenes, and made the serendipitous discovery of fullerene dimer C120.
How do you supervise your students?
I encourage my graduate students to do scientific research of their own
ideas within the scope of my group's research interests. I usually emphasize scientific rigor and intolerance of research misconduct to the graduate students when they first join my group. I provide them my guidance on how to do each piece of scientific work including detailed discussion of encountered problems, even spectral analysis and ChemDraw drawing, manuscript writing, etc.
What is the most important personality for scientific research?
Curiosity, creativity, and persistence.
What are your hobbies?
Sports, mainly jogging and running nowadays.
How do you keep balance between research and family?
My balance has heavily leaned toward work thanks to the understanding and support from my family.
The serendipitous discovery of dumb‐bell‐shaped C120 under high‐speed vibration milling conditions is described. The mechanochemical synthesis of encapsualted C120, the cross‐dimer C130, trimer C180, bridged C60 dimers and other molecules is presented.
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