The rise of graphene, a natural two-dimensional polymer (2DP) with topologically planar repeat units, has challenged synthetic chemistry, and has highlighted that accessing equivalent covalently bonded sheet-like macromolecules has, until recently, not been achieved. Here we show that non-centrosymmetric, enantiomorphic single crystals of a simple-to-make monomer can be photochemically converted into chiral 2DP crystals and cleanly reversed back to the monomer. X-ray diffraction established unequivocal structural proof for this synthetic 2DP, which has an all-carbon scaffold and can be synthesized on the gram scale. The monomer crystals are highly robust, can be easily grown to sizes greater than 1 mm and the resulting 2DP crystals exfoliated into nanometre-thin sheets. This unique combination of features suggests that these 2DPs could find use in membranes and nonlinear optics.

The spatial localization of charge carriers to promote the formation of bound excitons and concomitantly enhance radiative recombination has long been a goal for luminescent semiconductors. Zero‐dimensional materials structurally impose carrier localization and result in the formation of localized Frenkel excitons. Now the fully inorganic, perovskite‐derived zero‐dimensional SnII material Cs4SnBr6 is presented that exhibits room‐temperature broad‐band photoluminescence centered at 540 nm with a quantum yield (QY) of 15±5 %. A series of analogous compositions following the general formula Cs4−xAxSn(Br1−yIy)6 (A=Rb, K; x≤1, y≤1) can be prepared. The emission of these materials ranges from 500 nm to 620 nm with the possibility to compositionally tune the Stokes shift and the self‐trapped exciton emission bands.

The vast structural and compositional space of metal halides has recently become a major research focus for designing inexpensive and versatile light sources; in particular, for applications in displays, solid-state lighting, lasing, etc. Compounds with isolated ns2-metal halide centers often exhibit bright broadband emission that stems from self-trapped excitons (STEs). The Sb­(III) halides are attractive STE emitters due to their low toxicity and oxidative stability; however, coupling these features with an appropriately robust, fully inorganic material containing Sb3+ in an octahedral halide environment has proven to be a challenge. Here, we investigate Sb3+ as a dopant in a solution-grown metal halide double perovskite (DP) matrix, namely Cs2MInCl6:xSb (M = Na, K, x = 0–100%). Cs2KInCl6 is found to crystallize in the tetragonal DP phase, unlike Cs2NaInCl6 that adopts the traditional cubic DP structure. This structural difference results in distinct emission colors, as Cs2NaInCl6:xSb and Cs2KInCl6:xSb compounds exhibit broadband blue and green emissions, respectively, with photoluminescence quantum yields (PLQYs) of up to 93%. Spectroscopic and computational investigations confirm that this efficient emission originates from Sb­(III)-hosted STEs. These fully inorganic DP compounds demonstrate that Sb­(III) can be incorporated as a bright emissive center for stable lighting applications.

Interest in hybrid organic-inorganic lead halide compounds with perovskite-like two-dimensional crystal structures is growing due to the unique electronic and optoelectronic properties of these compounds. Herein, we demonstrate the synthesis, thermal and optical properties, and calculations of the electronic band structures for one- and two-layer compounds comprising both cesium and guanidinium cations: Cs[C(NH)]PbI (I), Cs[C(NH)]PbBr (II), and Cs[C(NH)]PbBr (III). Compounds I and II exhibit intense photoluminescence at low temperatures, whereas compound III is emissive at room temperature. All of the obtained substances are stable in air and do not thermally decompose until 300 °C. Since Cs and C(NH) are increasingly utilized in precursor solutions for depositing polycrystalline lead halide perovskite thin films for photovoltaics, exploring possible compounds within this compositional space is of high practical relevance to understanding the photophysics and atomistic chemical nature of such films.

We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12–46 nm and with excellent size distribution as small as 7–8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and passivating Ga-oxide layer (2–3 nm). The mechanism of Ga nanoparticles formation is elucidated using nuclear magnetic resonance spectroscopy and with molecular dynamics simulations. Size-dependent crystallization and melting of Ga nanoparticles in the temperature range of 98–298 K are studied with X-ray powder diffraction, specific heat measurements, transmission electron microscopy, and X-ray absorption spectroscopy. The results point to delta (δ)-Ga polymorph as a single low-temperature phase, while phase transition is characterized by the large hysteresis and by the large undercooling of crystallization and melting points down to 140–145 and 240–250 K, respectively. We have observed size-tunable plasmon resonance in the ultraviolet and visible spectral regions. We also report stable operation of Ga nanoparticles as anode material for Li-ion batteries with storage capacities of 600 mAh g–1, 50% higher than those achieved for bulk Ga under identical testing conditions.

Two-dimensional hybrid organic–inorganic lead halides perovskite-type compounds have attracted immense scientific interest due to their remarkable optoelectronic properties and tailorable crystal structures. In this work, we present a new layered hybrid lead halide, namely [CH(NH2)2][C(NH2)3]PbI4, wherein puckered lead-iodide layers are separated by two small and stable organic cations: formamidinium, CH(NH2)2+, and guanidinium, C(NH2)3+. This perovskite is thermally stable up to 255 °C, exhibits room-temperature photoluminescence in the red region with a quantum yield of 3.5%, and is photoconductive. This study highlights a vast structural diversity that exists in the compositional space typically used in perovskite photovoltaics.

New Pd(0) olefin complexes, 2−5, of a binaphthalene-based chiral P,N(oxazoline) auxiliary, (S,R)-2-[4-(isopropyl)oxazol-2-yl]-2‘-diphenylphosphino-1,1‘-binaphthyl, 1, have been prepared (olefin = fumaronitrile, maleic anhydride, 4-cyclopentene-1,3-dione, and dibenzylideneacetone). These compounds reveal different dynamic behavior in solution as shown by 2-D exchange spectroscopy. Ligand 1 affords excellent enantioselectivity (up to 99% ee) in the allylic amination of a 1,3-diphenyl allyl precursor. The solid-state structure of [Pd(η3-PhCHCHCHMe)(1)]OTf, 15, has been determined and shows two different diastereomeric cations within one unit cell; that is both the si and re faces of the allyl crystallize together, the first example of this for a moderately large allyl ligand. The structure of PdCl2(1) is also reported and reveals (as does that for 15) that the oxazoline ring of 1 is twisted relative to the P−Pd−N coordination plane, thus placing this ring substituent above and not below the coordination plane. A more exact solid-state structure for Pd2(dba)3 has been determined.

LiBC ist eine neue, nur aus den leichten Elementen der Hauptgruppen bestehende Verbindung. Sie entsteht aus den Elementen in verschweißten Niobampullen bei 770 K und anschließendem kurzzeitigen Tempern bei 1 770 K in Form goldglänzender, hexagonaler Plättchen. Entsprechend Li+(BN)− bilden Bor und Kohlenstoff ebene Heterographitschichten vom Typ des isoelektronischen hexagonalen Bornitrids. Die Bereiche zwischen den Schichten sind durch Lithium vollständig aufgefüllt (P63/mmc; a = 275.2 pm; c = 705.8 pm; hP6; ZrBeSi‐Typ). Die Deformationsdichte der Valenzelektronen beweist für die BC‐Bindungen π‐Charakter und Polarisierung entsprechend (BC−). Nach chemischen und physikalischen Eigenschaften zeigt LiBC eine gewisse Phasenbreite x(Li) ≤ 1. Beim thermischen Abbau und bei chemischen Reaktionen entstehen bisher noch nicht charakterisierte BC‐Produkte. Die Oxidation von LiBC verläuft offenbar nach einem ähnlichen Mechanismus wie bei Graphit.