Optical and Electrical Properties of A[VS] (A = Na, K) Synthesized via a Straightforward and Scalable Solid-State Method.

Two literature-known sulfido vanadates, Na[VS] and K[VS], were obtained through a straightforward and scalable synthetic method. Highly crystalline powders of both compounds were obtained from the homogeneous molten phases of starting materials via a─comparably rapid─solid-state technique. Low-temperature structure determination, ambient temperature powder diffraction, and solid-state NMR spectroscopy verify previous structural reports and indicate purity of the obtained samples.

Formation of iminium ions during the processing of metal halide perovskites.

Ammonium ions are a key component of many organic-inorganic metal halide materials. We show that the hexagonal perovskite (MeNH)PbI is rapidly transformed to iminium-based perovskites (MeCNMeR)PbI (R = Me, Et), simply by stirring the material in the respective ketone at room temperature, triggering clear changes in the materials' photophysical properties.

Enhanced Circular Dichroism and Polarized Emission in an Achiral, Low Band Gap Bismuth Iodide Perovskite Derivative.

Lead halide perovskites and related main-group halogenido metalates offer unique semiconductor properties and diverse applications in photovoltaics, solid-state lighting, and photocatalysis. Recent advances in incorporating chiral organic cations have led to the emergence of chiral metal-halide semiconductors with intriguing properties, such as chiroptical activity and chirality-induced spin selectivity, enabling the generation and detection of circularly polarized light and spin-polarized electrons for applications in spintronics and quantum information. However, understanding the structural origin of chiroptical activity remains challenging due to macroscopic factors and experimental limitations.

Optical Properties and Metal-Dependent Charge Transfer in Iodido Pentelates.

Lead-free heavy halogenido metalates are currently under intense investigation, as they show similarly promising semiconducting properties as their famous but toxic lead relatives. A major interest in this regard is the understanding and control of optical properties with the goal of designing highly efficient photoconducting materials. Here, we present two isostructural iodido pentelates (Hpyz) E I  ⋅ 2H O (pyz=pyrazine; E=Sb, Bi).

Charge Makes a Difference: Molecular Ionic Bismuth Compounds.

Key challenges in modern synthetic chemistry include the design of reliable, selective, and more sustainable synthetic methods, as well as the development of promising candidates for new materials. Molecular bismuth compounds offer valuable opportunities as they show an intriguing spectrum of properties that is yet to be fully exploited: a soft character, a rich coordination chemistry, the availability of a broad variety of oxidation states (at least +V to -I) and formal charges (at least +3 to -3) at the Bi atoms, and reversible switching between multiple oxidation states. All this is paired with the status of a non-precious (semi-)metal of good availability and a tendency towards low toxicity.

Establishing Family Relations in Group 15 Halogenido Metalates with the Largest Molecular Antimony Iodide Anion.

Studying structurally related families of compounds is a valuable tool in understanding and predicting material properties and has been extensively used for metal halide perovskites. Due to the variable anion structures in group 15 halogenido metalates, similar family relations are still largely missing. Herein, we present compounds featuring the [Sb I ] family of anions, including the first n=5 member in [Hpyz] [Sb I ] (Hpyz=pyrazinium), which contains the largest halogenido pentelate anion reported to date.

[SMe][BiAgI], a silver iodido bismuthate with an unusually small band gap.

Iodido metalates of heavy main group elements have seen much research interest in the last years due to their possible application as absorbers in photovoltaics. However, for materials based on the non-toxic element bismuth one challenge lies in narrowing the optical band gap for sufficient solar absorption. Here, we present a new iodido silver bismuthate, [SMe][BiAgI] (1), which is prepared from solution and characterized regarding its structure, thermal stability and optical absorption.

The influence of copper on the optical band gap of heterometallic iodido antimonates and bismuthates.

Halogenido metalates of heavy main group elements are versatile semiconductor materials with broad applications. Especially the iodido metalates generally show small optical band gaps, making them suitable for photovoltaics. However, the most promising results have been generated using toxic lead-based materials, raising environmental concerns, while the related and far less toxic bismuth compounds show band gaps too large for direct use in photovoltaics.

Atomically Thin Sheets of Lead-Free 1D Hybrid Perovskites Feature Tunable White-Light Emission from Self-Trapped Excitons.

Low-dimensional organic-inorganic perovskites synergize the virtues of two unique classes of materials featuring intriguing possibilities for next-generation optoelectronics: they offer tailorable building blocks for atomically thin, layered materials while providing the enhanced light-harvesting and emitting capabilities of hybrid perovskites. This work goes beyond the paradigm that atomically thin materials require in-plane covalent bonding and reports single layers of the 1D organic-inorganic perovskite [C H N] [BiCl ]Cl. Its unique 1D-2D structure enables single layers and the formation of self-trapped excitons, which show white-light emission.

Using a Porphyrin Diacid Cation to Stabilize a Square-Pyramidal BiX (X = Br, Cl/Br) Unit.

Main-group halogenido metalates are a diverse class of compounds with an intricate structural chemistry and a wide range of applications. Here, we present an unprecedented anion motif in the structural chemistry of halogenido bismuthates, a square-pyramidal BiX unit. We show how the porphyrin diacid used as our compounds' counterion is templating the formation of this new motif, suggesting that other strong anion receptors may be able to stabilize unique metalate anions in future work.

(HPy)(Py)CuBiI, a low bandgap metal halide photoconductor.

Bismuth halides represent an emergent class of materials that combines semiconductor properties with non-toxic constituents. However, many simple bismuth halide compounds feature bandgaps that are significantly higher than those of the lead halide perovskites, which they are supposed to replace. One way to address this issue is the preparation of multinary metal halide materials that feature an additional metal ion.

Chemical Surface Reactivity and Morphological Changes of Bismuth Triiodide (BiI) under Different Environmental Conditions.

Layered metal halides like BiI are of current interest in connection with both 2D materials and photovoltaics. Here, we present a facile new method for the preparation of millimeter-sized BiI single crystals. We use these crystals to study the surface reactivity of their (001) cleavage planes toward various environmental conditions by measuring morphological changes using atomic force microscopy and analyzing the formed species by means of X-ray photoelectron spectroscopy and X-ray diffraction methods.

Multinary Halogenido Bismuthates beyond the Double Perovskite Motif.

Both lead halide perovskites and bismuth-based double perovskites have generated intense research interest in the past few years. There is, however, a broader class of bismuthates that transcends the double perovskite motif. These multinary halogenido bismuthates remain severely underexplored and offer rich research opportunities with regard to new structure motifs and material properties.

Synthesis of a two-dimensional organic-inorganic bismuth iodide metalate through in situ formation of iminium cations.

(Me2C[double bond, length as m-dash]NMe2)Bi2I7 represents a new layered organic-inorganic iodido bismuthate. It displays an unprecedented anion topology, a low band gap and good stability. Advanced electronic structure analysis finds the II interactions to be decisive for the compound's structural and electronic properties.

Divergent Optical Properties in an Isomorphous Family of Multinary Iodido Pentelates.

Multinary organic-inorganic metal halide materials beyond the perovskite motif can help to address both fundamental aspects such as the electronic interactions between different metalate building units and practical issues like stability and ease of preparation in this new field of research. However, such multinary compounds have remained quite rare for the halogenido pentelates, as the formation of simpler side phases can be a significant hindrance. Here, we report a family of four new multinary iodido pentelates [PPh][ECuI(nitrile)] (E = Sb, Bi; nitrile = acetonitile or propionitrile), including the first metalate with a Cu-I-Sb unit.

11/15/17 Complexes as Molecular Models for Metal Halide Double Perovskite Materials.

Thirteen neutral complexes [E M X (PPh) (L) ] (E = Bi, Sb; M = Cu, Ag; X = Cl, Br, I; L = solvent) featuring three different motifs were prepared and characterized regarding their structure, stability, and absorption spectra. While not identical in structural motif, the compounds can serve as models for the influence of the composition E/M/X on the optical properties of double perovskites AEMX (A = Cs, CHNH).

Surprising discoveries on the way to an old compound: four transient iodido antimonates.

During the synthesis of the literature-known iodido antimonate [Cu(MeCN)4]4[Sb3I11]2 (MeCN = acetonitrile), four transient compounds, [Cu(MeCN)4]4[Sb6I22]·2MeCN (1), [Cu(MeCN)4]4[Sb7I25]·MeCN (2), [Cu(MeCN)4]4[Sb10I34] (3) and [Cu(MeCN)4]4[Sb8I28] (4), were identified. The compounds appeared within hours or days and subsequently re-dissolved in the mother liquor, leading to [Cu(MeCN)4]4[Sb3I11]2 as the final product. Single crystal X-ray analysis showed that all four compounds feature unprecedented anion motifs.

Bismuth as a versatile cation for luminescence in coordination polymers from BiX/4,4'-bipy: understanding of photophysics by quantum chemical calculations and structural parallels to lanthanides.

Coordination polymers (CPs) with bismuth(iii) as a connectivity centre have been prepared from BiX3 (X = Cl-I) and 4,4'-bipyridine (bipy) in order to implement Bi-based luminescence. The products were obtained via different synthetic routes such as solution chemistry, melt syntheses or mechanochemical reactions. Five neutral and anionic 1D-CPs are presented that show a chemical parallel to trivalent lanthanides forming isostructural or closely related 1D-CPs, of which five additional compounds are described.

Ternary Iodido Bismuthates and the Special Role of Copper.

Two new, isostructural members of the title material class, [PPh][CuBiI] (1) and [PPh][AgBiI] (2), have been prepared via a facile solution route. The crystal structure of both compounds features a tetranuclear [MBiI] (M = Cu, Ag) anion that displays an unprecedented face-sharing mode of connection between BiI octahedra and MI tetrahedra, enabling close Bi···M contacts. The two compounds allow for a direct experimental and quantum chemical investigation of the influence of group 11 metal cations on the optical and electronic properties of ternary iodido bismuthate anions, indicating that Cu is a better electronic match than Ag, resulting in a significantly lower optical band gap of the copper compound.

Mechanochemical Synthesis of 3d Transition-Metal-1,2,4-Triazole Complexes as Precursors for Microwave-Assisted and Thermal Conversion to Coordination Polymers with a High Influence on the Dielectric Properties.

The complexes [MCl2 (TzH)4] (M=Mn (1), Fe (2); TzH=1,2,4-1H-triazole) and [ZnCl2 (TzH)2] (3) have been obtained by mechanochemical reactions of the corresponding divalent metal chloride and 1,2,4-1H-triazole. They were successfully used as precursors for the formation of coordination polymers either by a microwave-assisted reaction or by thermal conversion. For manganese, the conversion directly yielded 1∞ [MnCl2 TzH] (4), whereas for the iron-containing precursor, 1∞ [FeCl2 TzH] (6), was formed via the intermediate coordination polymer 1∞ [FeCl(TzH)2]Cl (5).

Synthesis of Crystalline Chalcogenides in Ionic Liquids.

Crystalline chalcogenides belong to the most promising class of materials. In addition to dense solid-state structures, they may form molecular cluster arrangements and networks with high porosity, as in the so-called "zeotype" chalcogenidometalates. The high structural diversity comes along with interesting physical properties such as semi-/photoconductivity, ion transport capability, molecular trapping potential, as well as chemical and catalytic activity.

A step closer to the binary: the (1)(∞)[Bi6I20](2-) anion.

A series of crown ether based iodidobismuthates was prepared from dibenzo-18-crown-6 (DB18C6), BiI3 and NaI or KI in acetonitrile (MeCN). The resulting compounds [(DB18C6)Na(MeCN)2]4[Bi6I22]·2MeCN (1), [(DB18C6)Na(MeCN)2]4[Bi8I28]·6MeCN (2), [(DB18C6)Na(MeCN)2]2[Bi6I20]·3MeCN (3) and [(DB18C6)K(MeCN)]4[Bi6I22]·2MeCN (4) have been used to explore the templating effect of different crown ether based cations and the influence of the I/Bi ratio and II interactions on the optical properties of iodidobismuthates. Compound 3 contains the strand-like anion (1)(∞)[Bi6I20](2-), which displays a I/Bi ratio of 3.

2∞[Bi2Cl6(pyz)4]: a 2D-pyrazine coordination polymer as soft host lattice for the luminescence of the lanthanide ions Sm3+, Eu3+, Tb3+, and Dy3+.

The 2D-coordination polymer (2)∞[Bi2Cl6(pyz)4] was synthesized from BiCl3 and a self-consuming melt of pyrazine (pyz). It proves to be a suitable soft host lattice for in situ co-doping of the lanthanide ions Sm(3+), Eu(3+), Tb(3+), and Dy(3+) during network formation. The series of luminescent networks (2)∞[Bi(2-x)LnxCl6(pyz)4] obtained exhibits an efficient antenna effect on the lanthanide ions.

Engineering metal-based luminescence in coordination polymers and metal-organic frameworks.

The rapidly growing number of luminescent coordination polymers (CPs) and metal-organic frameworks (MOFs) illustrates high interest as well as accessibility of such materials. The interplay between inorganic and organic components in these materials offers a large number of viable luminescence processes. The enormous variability of available ligand-metal combinations opens the possibility of creating luminescence "by design", based on a proper understanding of the processes involved.

Synthesis of complex polymeric telluridoindates from KInTe2.

Four new polymeric telluridoindates [K(18-crown-6)][InTe2]·2en (1) (18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane), [K([2.2.2]crypt)]2[In2Te6]·0.