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.
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.
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.
A highly efficient, air‐ and moisture‐stable and easily recoverable magnetic nanoparticle‐supported palladium catalyst has been developed for the Suzuki, Sonogashira and Heck reactions. A wide range ...of substrates was coupled successfully under aerobic conditions. In particular, the performance of the magnetic separation of the catalyst was very efficient, and it is possible to recover and reuse it at least eight times without significant loss of its catalytic activity.
Two cycles in one pot! The synthesis of biologically important phenanthridinones has been achieved by the one‐pot formation of CC and CN bonds through a palladium‐catalyzed dual CH activation, ...which involves four bond ruptures and two bond formations (see scheme). The conversion of phenanthridinones into natural product like derivatives further demonstrates the utility of this synthetic achievement.
Abstract
The serendipitous discovery of dumb‐bell‐shaped C
120
under high‐speed vibration milling conditions is described. The mechanochemical protocol has been employed to synthesize the He‐, H
2
‐ ...or H
2
O‐encapsualted C
120
, the cross‐dimer C
130
, trimer C
180
, bridged C
60
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 C
120
.
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 first example for the ruthenium‐catalyzed ligand‐directed meta‐selective C−H mono‐ and difluoromethylation is developed, affording a variety of new meta‐mono‐ and difluoromethylated ...2‐phenylpyridines, 2‐phenylpyrimidines, and 1‐phenylpyrazoles in moderate‐to‐good yields. This new transformation exhibits broad substrate scope, good functional group tolerance, and high efficiency, and offers a practical approach to synthesize mono‐ and difluoromethylated arenes. Mechanistic studies indicate that a reaction pathway involving palladium‐initiated radical species is involved in the catalytic cycle. The new dual catalytic system consisting of compatible ruthenium(II) and palladium(0) complexes enables the key processes of C−H activation and mono‐/difluoromethyl‐radical formation to occur and achieves the meta‐selective functionalization efficiently. In addition, the present protocol can also be extended to non‐fluoromethylation.
A meta approach to fluoromethylation: The first example for the ruthenium‐catalyzed ligand‐directed meta‐selective C−H mono‐ and difluoromethylation is developed, affording a variety of new meta‐mono‐ and difluoromethylated 2‐phenylpyridines, 2‐phenylpyrimidines, and 1‐phenylpyrazoles in moderate‐to‐good yields. This new transformation exhibits broad substrate scope, good functional group tolerance, and high efficiency, and offers a practical approach to synthesize mono‐ and difluoromethylated arenes.
A novel and unusual palladium‐catalyzed 4+2 annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si−C(sp2) bond activation in synergy with ...ring expansion/insertion of cyclopropenes to form new C(sp2)−C(sp3) and Si−C(sp3) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo4.1.0heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles.
When Si−C meets C=C bond activation: Cyclopropenes were functionalized stereoselectively with benzosilacyclobutanes by palladium‐catalyzed Si−C(sp2) bond activation and a ring‐expansion/4+2 annulation sequence to form new C(sp2)−C(sp3) and Si−C(sp3) bonds of silabicyclo4.1.0heptanes. The transformation provided an array of these previously elusive highly strained bicyclic skeletons in good yields with high selectivity (see scheme).
Comprehensive Summary
A triflic anhydride‐induced annulation of benzoic acids bearing electron‐withdrawing groups with arylalkynes leading to diverse 3‐arylindenones via an unprecedented aryl ...swapping pathway under an air atmosphere and ball‐milling conditions has been disclosed. Most of the obtained 3‐arylindenones are fluorine‐containing compounds. The present mechanochemical protocol employs easily available and inexpensive benzoic acids, which unexpectedly undergo aryl swapping with arylalkynes and serve as the source of the 3‐aryl group. The current mechanochemical methodology shows advantages including no requirement of transition‐metal catalysts, ambient conditions and excellent regioselectivity for the rearrangement products, providing expedient access to 3‐arylindenones containing functional groups such as F, Cl, Br, CF3, OCF3, SCF3, OAc, Ac, CO2Et or NO2. Moreover, the applications of this method to construct analogues of PPARγ agonist and antiosteoporotic agent have been demonstrated. A plausible reaction mechanism involving aryl swapping through vinyl cation formation from arylalkyne and in situ generated benzoyl triflate, intramolecular 4‐endo‐dig cyclization, subsequent ring opening and final annulation is proposed to explain the formation of 3‐arylindenones.
The mechanochemical metal‐free annulation of benzoic acids bearing electron‐withdrawing groups with arylalkynes via an unprecedented aryl swapping pathway, regioselectively provided diverse 3‐arylindenones including bioactive and fluorine‐containing molecules.
Simultaneous electrochemical ring contraction and expansion reactions remain unexplored to date. Herein, the reductive electrosynthesis of heterocycle‐fused fulleroids from ...fullerotetrahydropyridazines and electrophiles in the presence of a trace amount of oxygen has been achieved with concurrent ring contraction and ring expansion. When trifluoroacetic acid and alkyl bromides are employed as electrophiles, heterocycle‐fused fulleroids with a 1,1,2,6‐configuration are regioselectively formed. In contrast, heterocycle‐fused fulleroids with a 1,1,4,6‐configuration are regioselectively produced as two separable stereoisomers if phthaloyl chloride is used as the electrophile. The reaction proceeds through multiple steps of electroreduction, heterocycle ring‐opening, oxygen oxidation, heterocycle contraction, fullerene cage expansion, and nucleophilic addition. The structures of these fulleroids have been determined by spectroscopic data and single‐crystal X‐ray diffraction analyses. The observed high regioselectivities have been rationalized by theoretical calculations. Representative fulleroids have been applied in organic solar cells as the third component and exhibit good performance.
The electrochemically triggered simultaneous ring contraction and expansion reaction of fullerotetrahydropyridazines with electrophiles in the presence of a trace amount of oxygen affords pyrazoline‐fused fulleroids with unprecedented 1,1,2,6‐ or 1,1,4,6‐addition patterns.
