Bismuth Centers Research Articles

Bismuthenium Cations for the Transport of Chloride Anions via Pnictogen Bonding

AbstractOur interest in the design of heavy pnictogen‐based Lewis acids for anion trafficking across biological membrane mimics has led us to investigate trivalent bismuthenium cations as chloride anion transporters. Here, we describe two chlorodiarylbismuthines, elaborated on a peri‐substituted naphthalene backbone and stabilized by an adjacent thio‐ or seleno‐ether functionality that engages the bismuth center in a Ch→Bi interaction (Ch=chalcogen). These new derivatives are stable in aqueous environment and readiliy transport chloride anions across the membrane of phospholipid‐based vesicles loaded with KCl. In addition to establishing the use of such motifs in anion transport, this investigation shows that the Lewis acidity, lipophilicity, and thus chloride transport properties depend on the nature of the chalcogen.

What Determines the Lewis Acidity of a Bismuthane? Towards Bi-Based FLPs.

Aiming at intramolecular frustrated Lewis pairs (FLPs) based on soft Lewis acidic bismuth centers, a phosphine function was combined with a dichloridobismuthane unit on a phenylene backbone utilizing a scrambling approach. The reaction between two equivalents of BiCl3 and (o-(Ph2P)C6H4)3Bi yielded (o-(Ph2P)C6H4)BiCl2(THF), the structure of which indicated Bi…P interactions and thus a pronounced Lewis acidity at the bismuth center that was confirmed by the Gutmann-Beckett method. However, the system turned out to be insufficient to be utilized for FLP reactivity. Hence, the chloride ligands were exchanged by iodide and C2F5 substituents, respectively. Despite a lower electronegativity the iodide compound exhibits a shorter Bi…P contact, while the C2F5 substituents led to a further decrease of the Lewis acidity, despite their high group electronegativity. DFT calculations rationalized this by a quenching of the Lewis acidity inherent to the σ*(Bi-C) orbital by negative hyperconjugation from occupied p-orbitals at the F atoms. Furthermore, it turned out that the strength of the covalent Bi-X σ-bond is a more important factor than the charge at Bi in determining the energetic accessibility and thus Lewis acidity of the antibonding σ*(Bi-C) orbital.

Activation and Catalytic Degradation of SF6 and PhSF5 at a Bismuth Center.

In this work, we report the catalytic degradation of SF6 and PhSF5 using N,C,N pincer bismuthinidene complexes (1 and 5). Exposure of SF6 and PhSF5 to 1 results in the reduction of the S(VI) substrates and concomitant formation of Bi(III) and Bi(II) compounds, which were isolated and characterized. The oxidized bismuth-based products were demonstrated to undergo reduction with PMe3, recovering the starting complex 1. Having established a synthetic redox cycle, the catalytic degradation of SF6 and PhSF5 was developed through ligand optimization to 5, leading to a 528 TON for SF6 and the first reported TON for PhSF5 (3.2).

Bismuthenium Cations for the Transport of Chloride Anions via Pnictogen Bonding.

Our interest in the design of heavy pnictogen-based Lewis acids for anion trafficking across biological membrane mimics has led us to investigate trivalent bismuthenium cations as chloride anion transporters. Here, we describe two chlorodiarylbismuthines, elaborated on a peri-substituted acenaphthene backbone and stabilized by an adjacent thio- or seleno-ether functionality that engages the bismuth center in a Ch→Bi interaction (Ch = chalcogen). These new derivatives are stable in aqueous environment and readiliy transport chloride anions across the membrane of phospholipid-based vesicles loaded with KCl. In addition to establishing the use of such motifs in anion transport, this investigation shows that the Lewis acidity, lipophilicity, and thus chloride transport properties depend on the nature of the chalcogen.

Synergistic effect of oxygen vacancies and in-situ formed bismuth metal centers on BiVO4 as an enhanced bifunctional Li–O2 batteries electrocatalyst

Bismuth Vanadate (BiVO4) is a promising oxide-based photoanode for electrochemical applications, yet its practical use is constrained by poor charge transport properties, particularly under dark conditions. This study introduces a novel BiVO4 variant (Bi-BiVO4-10) that incorporates abundant oxygen vacancies and in-situ formed Bi metal, significantly enhancing its electrical conductivity and catalytic performance. Bi-BiVO4-10 demonstrates superior electrochemical performances compared to conventional BiVO4 (C-BiVO4), demonstrated by its most positive half-wave potential with the highest diffusion-limiting current in the oxygen reduction reaction (ORR) and earliest onset potential in the oxygen evolution reaction (OER). Notably, Bi-BiVO4-10 is explored for the first time as an electrocatalyst for lithium-oxygen (Li–O2) cells, showing reduced overcharge (610 mV) in the first cycle and extended cycle life (1050 h), outperforming carbon (320 h) and C-BiVO4 (450 h) references. The enhancement is attributed to the synergy of oxygen vacancies, Bi metal formation, increased surface area, and improved electrical conductivity, which collectively facilitate Li2O2 growth, enhance charge transport kinetics, and ensure stable cycling. Theoretical calculations reveal enhanced chemical interactions between intermediate molecules and the defect-rich surfaces of Bi-BiVO4-10, promoting efficient discharge and charge processes in Li–O2 batteries. This research highlights the potential of unconventional BiVO4-based materials as durable electrocatalysts and for broader electrochemical applications.

Cluster Formation of Self-Assembled Triarylbismuthanes and Charge Transport Characterizations of Gold-Triarylbismuthane-Gold Junctions.

Organometallic molecules are promising for molecular electronic devices due to their potential to improve electrical conductance through access to complex orbital covalency that is not available to light-element organic molecules. However, studies of the formation of organometallic monolayers and their charge transport properties are scarce. Here, we report the cluster formation and charge transport properties of gold-triarylbismuthane-gold molecular junctions. We found that triarylbismuthane molecules with -CN anchoring groups form clusters during the creation of self-assembled submonolayers. This clustering is attributed to strong interactions between the bismuth (Bi) center and the nitrogen atom in the -CN group of adjacent molecules. Examination of the influence of -NH2 and -CN anchoring groups on junction conductance revealed that, despite a stronger binding energy between the -NH2 group and gold, the conductance per molecular unit (i.e., molecule for the -NH2 group and cluster for the -CN group) is higher with the -CN anchoring group. Further analysis showed that an increase in the number of -CN groups from one to three within the junctions leads to a decrease in conductance while increasing the size of the cluster. This demonstrates the significant effects of different anchoring groups and the impact of varying the number of -CN groups on both the charge transport and cluster formation. This study highlights the importance of selecting the appropriate anchoring group in the design of molecular junctions. Additionally, controlling the size and formation of clusters can be a strategic approach to engineering charge transport in molecular junctions.

Formation of E-band luminescence-active centers in bismuth-doped silica fiber via atomic layer deposition.

In this study, a Si defect structure was added into the silica network in order to activate the bismuth and silica structure active center. TD-DFT theoretical simulations show that the Bi and Si ODC(I) models can excite the active center of the E-band at 1408 nm. Additionally, the Bi-doped silica fiber (BDSF) with improved fluorescence was fabricated using atomic layer deposition (ALD) combined with the modified chemical vapor deposition (MCVD) technique. Some tests were used to investigate the structural and optical properties of BDSF. The UV-VIS spectral peak of the BDSF preform is 424 cm-1, and the binding energy of XPS is 439.3 eV, indicating the presence of Bi° atom in BDSF. The Raman peak near 811 cm-1 corresponds to the Bi-O bond. The Si POL defect lacks a Bi-O structure, and the reason for the absence of simulated active center from the E-band is explained. A fluorescence spectrometer was used to analyze the emission peak of a BDSF at 1420 nm. The gain of the BDSF based optical amplifier was measured 28.8 dB at 1420 nm and confirmed the effective stimulation of the bismuth active center in the E-band.

From an Isolable Bismolyl Anion to an Yttrium-Bismolyl Complex with μ-Bridging Bismuth(I) Centers and Polar Covalent Y-Bi Bonds.

Invited for the cover of this issue is the group of Selvan Demir at the Michigan State University. The cover art depicts the helicopter landing of the first crystallographically characterized bismolyl anion potassium salt in a desert oasis landscape with pyramids of elemental bismuth. Read the full text of the article at 10.1002/chem.202302687.

From an Isolable Bismolyl Anion to an Yttrium-Bismolyl Complex with μ-Bridging Bismuth(I) Centers and Polar Covalent Y-Bi Bonds.

The synthesis and first structural characterization of the [K(18-crown-6)] bismolyl Bitet (C4 Me4 Bi) contact ion pair (1) is presented. Notably, according to Natural Resonance Theory calculations, the Bitet anion of 1 features two types of leading mesomeric structures with localized anionic charge and two lone pairs of electrons at the BiI center, as well as delocalized anionic charge in the π-conjugated C4 Bi ring. The lone pairs at Bi enable a unique bridging coordination mode of the bismolyl ligand, as shown for the first rare earth metal bismolyl complex (Cptet 2 Y)2 (μ-η1 -Bitet )2 (2). The latter results from the salt metathesis reaction of KBitet with Cptet 2 Y(BPh4 ) (Cptet =C5 Me4 H). The Y-Bi bonding interaction in 2 of 16.6 % covalency at yttrium is remarkably large.

N‐Heterocyclic Thione‐Coordinated Dinuclear Bismuth(III) Trihalides with a Rare Geometry

AbstractTwo thione‐coordinated dinuclear bismuth(III) halides were isolated with a rare geometry and characterized using FT‐IR, NMR, and single‐crystal X‐ray diffraction techniques. The sterically less crowded N‐heterocyclic thione ligand gave bismuth(III) chloride‐thione complex in cis isomeric form, while the sterically more crowded N‐heterocyclic thione ligand gave dinuclear bismuth(III) bromide‐thione complex in facial isomeric form. Continuous shape measurement (CShM) revealed that the bismuth centres in cis‐bismuth(III) chloride‐thione complex adopts distorted octahedral geometry with the CShM values of 2.103, which is remarkably different compared to the facial‐dinuclear bismuth(III) bromide‐thione complex (1.071 and 0.391).

Coordination Chemistry of the Antimony(III) and Bismuth(III) Cations using Bis(α-iminopyridine) as Ligand.

Bis(alpha-iminopyridine) L has been employed as the redox non-innocent Schiff-base ligand to coordinate with cationic antimony(III) and bismuth(III) centers. Mono- and di- cationic compounds: [LSbCl2 ][CF3 SO3 ] 1, [LBiCl2 ][CF3 SO3 ] 2, [LSbCl2 ]2 [Sb2 Cl8 ] 3, [LBiCl2 ]2 [Bi2 Cl8 ] 4, [LSbCl][CF3 SO3 ]2 5, [LBiCl][CF3 SO3 ]2 6 have been isolated and characterized using single crystal X-ray crystallography in the solid-state and solution-state NMR studies. These compounds have been prepared from PnCl3 (Pn=Sb, Bi) and chloride abstracting agent such as Me3 SiCF3 SO3 or AgCF3 SO3 in the presence of L. The Bi tri-cationic species forms heteroleptic compound 7, being coordinated by two types of Schiff-base donors L and L'. The latter has been in situ generated by the cleavage of one of the two imines present in L.

Antibacterial performance of heterocyclic organobismuth (III) complexes based on bidentate C,O‐coordinating ligands: Synergism of ligand identity and coordination number

A series of heterocyclic organobismuth (III) complexes based on bidentate C,O‐coordinating ligands were designed and synthesized as antimicrobials. Antibacterial assays showed that complexes of this type are more effective for Gram‐positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis) than Gram‐negative ones (Escherichia coli and Pseudomonas aeruginosa). Their activities are especially relevant to the synergism of lipophilicity, geometry, and stability, which depends on both the identity of coordinating ligands and the coordination number at the bismuth center. By comparison, the hypervalent 14‐Bi‐6 species diarylbismuth nitrate (8) was found to exhibit the most potent inhibitory effect, together with a high degree of selectivity, which gives an IC50(LO2)/MIC(Staphylococcus aureus) ratio of up to 23.08. Time–kill analysis demonstrated that complex 8 is bacteriostatic at low concentrations while displaying significant bactericidal activity at high doses. The results of drug resistance experiments suggested that complex 8 can inhibit the formation of bacterial biofilm and consequently delay or prevent the development of drug resistance. Furthermore, complex 8 also showed high inhibition efficiency against several drug‐resistant Staphylococcus aureus, and the MIC values are within the range of 0.39–1.56 μM, thus indicating the lack of cross‐resistance between this organometallic compound and commonly used antibiotics.

Reactivity of a Cationic Bismuth Amide towards Unsymmetric Heterocumulenes.

Invited for this month's cover is the Lichtenberg group of the Philipps-University Marburg (Germany). The front cover picture shows "bismuth" dressed in colors reminiscent of those found on the surface of this element. In the graphic, bismuth is craving for soft ice cream. This represents the preference of Lewis acidic bismuth centers for soft donor atoms, as demonstrated in the insertion of heterocumulenes into the Bi-N bond of a cationic bismuth amide. More information can be found in the Research Article by Crispin Lichtenberg and co-workers.

Front Cover: Reactivity of a Cationic Bismuth Amide towards Unsymmetric Heterocumulenes (ChemPlusChem 7/2023)

I scream, you scream, we all scream for ice cream! The front cover picture shows “bismuth” dressed in colors reminiscent of those found on the surface of this element. In the graphic, bismuth is craving for soft ice cream. This represents the preference of Lewis acidic bismuth centers for soft donor atoms, as demonstrated in the insertion of heterocumulenes into the Bi-N bond of a cationic bismuth amide. More information can be found in the Research Article by Crispin Lichtenberg and co-workers.

Influence of crystal structure and composition on optical and electronic properties of pyridinium-based bismuth iodide complexes.

This study investigates the impacts of structure and composition on the optical and electronic properties of a series of pyridinium-based bismuth iodide complexes. Organic substrates with various functional groups, such as 4-aminopyridine (4-Ampy), 4-methylpyridine (4-Mepy), 4-dimethylaminopyridine (4-Dmapy), and 4-pyridinecarbonitrile (4-CNpy) with different electron-donating and electron-withdrawing groups at the para position of the pyridine ring were employed. Crystallographic analysis reveals various bismuth iodide structures, including 1D chains and discrete 0D motifs. The optical band gap of these materials, identified via diffuse reflectance spectroscopy (DRS) and verified with density functional theory (DFT) calculations, is influenced by the crystal packing and stabilising interactions. Through a comprehensive analysis, including Hirshfeld surface (HS) and void assessment, the study underscores the influence of noncovalent intermolecular interactions on crystal packing. Spectroscopic evaluations provide insights into electronic interactions, elucidating the role of electron donor and acceptor substituents within the lattice. Thermogravimetric differential thermal analysis (TG-DTA) indicates structural stability up to 250 °C. Linear sweep voltammetry (LSV) reveals significant conductivity in the range of 10-20 mS per pixel at 298.15 K. X-ray absorption spectroscopy (XAS) at the Bi L3 edge indicates a similar oxidation state and electronic environment across all samples, underscoring the role of bismuth centres surrounded by iodides.

Intrinsic Charge Polarization in Bi19 S27 Cl3 Nanorods Promotes Selective CC Coupling Reaction during Photoreduction of CO2 to Ethanol.

Obtaining multi-carbon products via CO2 photoreduction is a major catalytic challenge involving multielectron-mediated CC bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO2 conversion efficiency and product selectivity. Alternatively, robust metal centers having asymmetric charge distribution can effectuate CC coupling reaction through the stabilization of intermediates, for desired product selectivity. However, generating inherent charge distribution in a single component catalyst is a difficult material design challenge. Here, a novel photocatalyst, Bi19 S27 Cl3 , is presented which selectively converts CO2 to a C2 product, ethanol, in high yield under visible light irradiation. Structural analysis through transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveals the presence of charge polarized bismuth centers in Bi19 S27 Cl3 . The intrinsic electric field induced by charge polarized bismuth centers renders better separation efficiency of photogenerated electron-hole pair. Furthermore, charge polarized centers yield better adsorption of CO* intermediate and accelerate the rate determining CC coupling step through the formation of OCCOH intermediate. Formation of these intermediates is experimentally mapped by insitu Fourier-transform infrared spectroscopy and further confirmed by theoretical calculation.

Syntheses and characterization of some homodimer complexes of bismuth(III) having a Bi…Bi linkage along with molecular modeling, antimicrobial, antioxidant and cytotoxic studies

A homodimer of bismuth(III) heteroleptic derivatives having two ligands, [{(R1)(R2)C = NO}2Bi{S2CN(CH2CH2)2O}]2 [where R1 = -C6H5, R2 = -CH3 (1); R1 = -C6H4CH3, R2 = -CH3 (2); R1 = -C6H4Cl, R2 = -CH3 (3); R1 = -C6H4Br, R2 = -CH3 (4); R1 = -C6H4OH, R2 = -H (5); R1(R2)C = C-CH2-(CH2)3-CH2 (6)], were synthesized by reaction of bismuth(III) chloride with sodium substituted oximes and morpholine dithiocarbamate in 1:2:1 stoichiometry. The complex was characterized by IR, 1H and 13C NMR spectra; the dimeric structure was assigned through LC-mass spectrometry. Distorted octahedral geometry around the central bismuth in each unit of the homodimer, linked by Bi…Bi bond, is proposed. Calculations for the two possible optimized geometries were done to determine Bi…Bi intermolecular linkage in these derivatives. Powder XRD study displayed nano range (∼30 nm) particle size and crystalline nature. The synthesized bismuth(III) derivatives were studied against four microbes viz., Bacillus subtilis, Escherichia coli, Aspergillus niger and Candida albicans. The antioxidant evaluation was carried out by FRAP assay and the cytotoxic study was accomplished through MTT analyzer. The results revealed that these derivatives were non-toxic (>50% cell viability) for 3 T3 fibroblast cell lines even at 500 µg/mL concentration.

P-Orbital Bismuth Single-Atom Catalyst for Highly Effective Oxygen Electroreduction in Quasi-Solid Zinc-Air Batteries.

P-block metals have gradually been utilized to synthesize non-noble-metal catalysts for oxygen reduction reaction (ORR) due to the easily tunable localized p-orbitals and resulted versatile electronic structures. The high-density single-atom bismuth sites (Bi-NC) anchored onto nitrogen-doped three-dimensional porous carbon are proved to possess significant electrocatalytic ORR performance. Theoretical calculations unveil positively charged bismuth centers prominently improved the adsorption capacity of N-doped carbon to O2 . The p orbitals of Bi sites within Bi-NC easily generate hybrid states with p orbitals of O2 , thus promoting charge transfer and ultimately reducing the energy barrier of ORR. Benefiting from p-orbital electrons regulation of bismuth atoms, Bi-NC exhibit ORR half-wave potential of 0.86V (vs RHE). Additionally, both liquid and quasi-solid zinc-air batteries with Bi-NC as air-cathodes achieve higher power density and specific capacity than 20wt% Pt/C, and comparable stability and round-trip efficiency with 20wt% Pt/C. The discovery sheds light on the theoretical and practical guidance for p-block metallic single-atom catalysts.

Stable broadband fiber-coupled near infrared light sources based on a bismuth heavily doped aluminosilicate optical fiber

Bismuth centers doped in glasses and crystals exhibit broadband near-infrared luminescence covering a spectral range from ∼1100 nm to ∼1800 nm, which could not be easily achieved with rare-earth ions. The luminescence between ∼1100 nm and 1250 nm of bismuth-doped aluminosilicate optical fibers depends on the concentration of Al3+ dopants and the bismuth active center. Nevertheless, conventional bismuth-doped aluminosilicate optical fiber fabricated by modified chemical vapour deposition exhibits strong quenching effect for near-infrared luminescence, which limits the optical gain per unit length for the optical fiber. As an alternative, using Bi-doped fiber preforms obtained from a nano-porous glass route, we have demonstrated the fabrication of bismuth-doped aluminosilicate optical fibers with Bi concentration of ∼5000 ppm without quenching. Here, we report a stable and reliable spontaneous emission spanning across 1070 nm–1250 nm with center wavelength of ∼1160 nm and 3-dB spectral bandwidth of ∼81 nm in this aluminosilicate bismuth-doped optical fiber. The spectral result could be promising for application in tunable and ultrafast fiber lasers.

Mesomeric Tuning at Planar Bi centres: Unexpected Dimerization and Benzyl C-H Activation in [CN2 ]Bi Complexes.

Planar bismuth(III) compounds featuring a N3 -pincer ligand environment are an unusual class of main group compounds that exhibit Lewis acidity via a 6p orbital. The ability to tune their acidity via Hammett and Coulomb effects has been demonstrated previously. Here we test the ability to tune them via mesomeric effects by replacing the central nitrogen of the [N3 ] pincer ligand with a less π-donating carbon atom to achieve a [CN2 ] ligand environment. This strategy boosts the Lewis acidity at the metal to such an extent that only strongly-bound dimers can be accessed in the condensed phase, or, if dimerization is sterically prohibited, an unusual reductive elimination occurs to give Bi(I) compounds. These results highlight the fine line separating donor/acceptor and redox chemistry at planar bismuth centres.