The quantum behaviour of electrons in materials is the foundation of modern electronics and information technology
, and quantum materials with topological electronic and optical properties are ...essential for realizing quantized electronic responses that can be used for next generation technology. Here we report the first observation of topological quantum properties of chiral crystals
in the RhSi family. We find that this material class hosts a quantum phase of matter that exhibits nearly ideal topological surface properties originating from the crystals' structural chirality. Electrons on the surface of these crystals show a highly unusual helicoid fermionic structure that spirals around two high-symmetry momenta, indicating electronic topological chirality. The existence of bulk multiply degenerate band fermions is guaranteed by the crystal symmetries; however, to determine the topological invariant or charge in these chiral crystals, it is essential to identify and study the helicoid topology of the arc states. The helicoid arcs that we observe on the surface characterize the topological charges of ±2, which arise from bulk higher-spin chiral fermions. These topological conductors exhibit giant Fermi arcs of maximum length (π), which are orders of magnitude larger than those found in known chiral Weyl fermion semimetals
. Our results demonstrate an electronic topological state of matter on structurally chiral crystals featuring helicoid-arc quantum states. Such exotic multifold chiral fermion semimetal states could be used to detect a quantized photogalvanic optical response, the chiral magnetic effect and other optoelectronic phenomena predicted for this class of materials
.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Cu(I)-catalyzed annulation–halotrifluoromethylation and cyanotrifluoromethylation of enynones have been established, enabling multibond formations of the synthesis of quaternary carbon-centered ...1-indanones in moderate to good chemical yields. The reaction of enynones with Togni’s reagent and chloro- or bromotrimethylsilane afforded halo- and CF3-containing 1-indenones. However, the addition of K3PO4 as a base into the catalytic system led to forming cyano-anchored (Z)-1-indanones as major stereoisomeric products. This strategy exhibits remarkable compatibility with a wide range of enynones.
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Two 8,8′ disubstituted binaphthyl ligands have been designed and synthesized in 3.1% and 11.4% overall yield, respectively. X-ray structure analysis demonstrated that a unique chiral microenvironment ...was created. With the assistance of a new aggregation-induced polarization (AIP) technology, chiral aggregates were determined as the fraction of polar solvent increased in the nonpolar/polar solvent system, which indicated their potential in modern asymmetric synthesis and catalysis.
A new chiral phosphine ligand and its diol derivative have been designed and synthesized asymmetrically.
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The first thiazolium salt-catalyzed C-C triple bond cleavage of benzene-linked allene-ynes has been established. The reaction pathway involves 2+2 cycloaddition and ring-opening of in situ generated ...cyclobutenes with H
O under mild and convenient conditions, and provides practical access to substituted 1-naphthols with potentially valuable applications.
Fractal structures with self‐similarity are of fundamental importance in the fields of aesthetic, chemistry and mathematics. Here, by taking advantage of constructs the rational geometry‐directed ...precursor design, we report the construction of two fascinating Platonic solids, the Sierpiński tetrahedron ST‐T and the Sierpiński octahedron ST‐O, in which each possesses a fractal Sierpiński triangle on their independent faces. These two discrete complexes are formed in near‐quantitative yield from the multi‐component self‐assembly of truncated Sierpiński triangular kernel L1 with tribenzotriquinacene‐based hexatopic and anthracene‐based tetratopic terpyridine ligands (L3 and L4) in the presence of metal ions, respectively. The enhanced stabilities of the 3D discrete structures were investigated by gradient tandem mass spectrometry (gMS2). This work provides new constructs for the imitation of complex virus assemblies and for the molecular encapsulation of giant guest molecules.
A powerful multicomponent self‐assembly strategy has been developed that allows access to gorgeous 3D architectures with large cavities and high complexity. This approach has led to the synthesis of a Sierpiński tetrahedron and a Sierpiński octahedron with Sierpiński triangles as the panels. These two discrete complexes, with molecular weights up to 55 kDa and diameters up to 7.4 nm, were formed in near‐quantitative yields.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this study, the design and asymmetric synthesis of a series of chiral targets of orientational chirality were conducted by taking advantage of
-sulfinylimine-assisted nucleophilic addition and ...modified Sonogashira catalytic coupling systems. Orientational isomers were controlled completely using alkynyl/alkynyl levers C(sp)-C(sp) axis with absolute configuration assignment determined by X-ray structural analysis. The key structural element of the resulting orientational chirality is uniquely characterized by remote through-space blocking. Forty examples of multi-step synthesis were performed, with modest to good yields and excellent orientational selectivity. Several chiral orientational amino targets are attached with scaffolds of natural and medicinal products, showing potential pharmaceutical and medical applications in the future.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The binding strength of reactive intermediates with catalytically active sites plays a crucial role in governing catalytic performance of electrocatalysts. NiFe hydroxide offers efficient oxygen ...evolution reaction (OER) catalysis in alkaline electrolyte, however weak binding of oxygenated intermediates on NiFe hydroxide still badly limits its catalytic activity. Now, a facile ball‐milling method was developed to enhance binding strength of NiFe hydroxide to oxygenated intermediates via generating tensile strain, which reduced the anti‐bonding filling states in the d orbital and thus facilitated oxygenated intermediates adsorption. The NiFe hydroxide with tensile strain increasing after ball‐milling exhibits an OER onset potential as low as 1.44 V (vs. reversible hydrogen electrode) and requires only a 270 mV overpotential to reach a water oxidation current density of 10 mA cm−2.
NiFe hydroxide was treated by ball‐milling to enhance its binding strength to an oxygenated intermediate. The prepared NiFe hydroxide that has induced tension shows excellent oxygen evolution performance.
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A new Pd(II)-catalyzed annulation/iododifluoromethylation of enynones has been developed for the synthesis of versatile 1-indanones with moderate to good yields (26 examples). The present strategy ...enabled the concomitant incorporation of two important difluoroalkyl and iodo functionalities into 1-indenone skeletons with (E)-stereoselectivity. The mechanistic pathway was proposed, consisting of the difluoroalkyl radical-triggered α,β-conjugated addition/5-exo-dig cyclization/metal radical cross-coupling/reductive elimination cascade.
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Invited for the cover of this issue are Guigen Li's groups at Texas Tech University and Nanjing University. The cover artwork shows that chirality patterns exist from universal to molecular levels ...showing light emission properties. Read the full story of multilayer 3D chirality and its asymmetric catalytic synthesis at 10.1002/chem.202104102.
“The resulting multiple π‐assemblies exhibited remarkable optical properties in aggregated states… as well as reversible redox properties.” This and more about the story behind the front cover can be found in the article at 10.1002/chem.202104102).
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Oilseed rape (Brassica napus L.) is the second highest yielding oil crop worldwide. In addition to being used as an edible oil and a feed for livestock, rapeseed has high ornamental value. In this ...study, we identified and characterized the main floral major constituents, including phenolic acids and flavonoids components, in rapeseed accessions with different-colored petals. A total of 144 constituents were identified using ultrahigh-performance liquid chromatography–HESI-mass spectrometry (UPLC–HESI-MS/MS), 57 of which were confirmed and quantified using known standards and mainly contained phenolic acids, flavonoids, and glucosinolates compounds. Most of the epicatechin, quercetin, and isorhamnetin derivates were found in red and pink petals of B. napus, while kaempferol derivates were in yellow and pale white petals. Moreover, petal-specific compounds, including a putative hydroxycinnamic acid derivative, sinapoyl malate, 1-O-sinapoyl-β-d-glucose, feruloyl glucose, naringenin-7-O-glucoside, cyanidin-3-glucoside, cyanidin-3,5-di-O-glucoside, petunidin-3-O-β-glucopyranoside, isorhamnetin-3-O-glucoside, kaempferol-3-O-glucoside-7-O-glucoside, quercetin-3,4′-O-di-β-glucopyranoside, quercetin-3-O-glucoside, and delphinidin-3-O-glucoside, might contribute to a variety of petal colors in B. napus. In addition, bound phenolics were tentatively identified and contained three abundant compounds (p-coumaric acid, ferulic acid, and 8-O-4′-diferulic acid). These results provide insight into the molecular mechanisms underlying petal color and suggest strategies for breeding rapeseed with a specific petal color in the future.
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