Interfacial Charge Modulation: An Efficient Strategy for Boosting Spatial Charge Separation on Semiconductor Photocatalysts

Surface modulation via injection or extraction of charge carriers in microelectric devices has been used to tune the energy band alignment for desired electrical and optical properties, yet not well recognized in photocatalysis field. Here, taking semiconductor bismuth tantalum oxyhalides (Bi₄TaO₈X) as examples, chemically inactive molybdenum oxide (MoO₃) with a large work function is introduced to qualitatively tune the properties of interfacial charges, achieving an evidently enhanced upward band bending and intensive built‐in electric field. Such a simple charge modulation exhibits a remarkable improvement in photocatalytic water oxidation, reaching an apparent quantum efficiency of 25% at the input wavelength of 420 nm. The validity and generality of surface charge modulating strategy are further demonstrated using other semiconductors (e.g., C₃N₄) and decorators (e.g., V₂O₅). The findings not only provide a promising strategy for rationally manipulating the interfacial built‐in electric field in photocatalysis but also pave the way to learn from microelectronic technologies to construct artificial photosynthesis systems for solar energy conversion.     

From Pb to Bi: A Promising Family of Pb‐Free Optoelectronic Materials and Devices

Lead‐based organic–inorganic hybrid perovskite materials are widely used in optoelectronic devices due to their excellent photophysical properties. However, the main issues which hinder its commercialization are the toxicity caused by lead and the intrinsic instability of the material. Recently, many lead‐free halide materials with good intrinsic stability have been reported, among which bismuth‐based halide materials have attracted extensive research due to their structure and promising optoelectronic properties. In this review, bismuth‐based materials are divided into binary BiX₃ (X = I, Br, Cl), ternary A_aBi_bX_a+3b (A = Cs, Rb, MA, Ag, etc.), and quaternary A₂AgBiX₆ (A = Cs, Rb, MA, etc.) according to its elemental composition. The structure and optoelectronic properties of bismuth‐based halide materials, which may be helpful for the development of bismuth‐based halide materials and lead‐free perovskites in the future, are summarized and highlighted.     

Water, temperature, and vegetation regulation of methyl chloride and methyl bromide fluxes from a shortgrass steppe ecosystem

Temperate grasslands are considered to be a significant sink for CH₃Br, although large uncertainties exist about the magnitude of this sink because of a paucity of field measurements. Here, we report the results of a combined field and laboratory study that investigated the effects of water, temperature, and plant community composition on CH₃Cl and CH₃Br fluxes in a semiarid temperate grassland. A novel stable isotope tracer technique was also employed to deconvolute simultaneous production and oxidation of CH₃Cl and CH₃Br. Net and gross fluxes were measured from different landforms (ridges, floodplains) and cover types (grass‐dominated, shrub‐dominated) to capture a representative range of hydrologic regimes, temperatures, and plant communities. In field experiments, net CH₃Cl and CH₃Br uptake was observed at all grass‐dominated sites (?400±77 nmol CH₃Cl m^?2 day^?1 and ?3.4±0.9 nmol CH₃Br m^?2 day^?1), while net CH₃Cl emission (439±58 nmol CH₃Cl m^?2 day^?1) was observed at sites dominated by the shrub Atriplex canescens, indicating that this plant is a strong CH₃Cl producer. Gross CH₃Cl and CH₃Br oxidation were comparable with estimates from other dryland ecosystems (507±115 nmol CH₃Cl m^?2 day^?1 and 9.1±2.2 nmol CH₃Br m^?2 day^?1), although CH₃Br oxidation rates were at least five times lower than those observed in more mesic temperate grasslands. We suggest that estimates of the temperate grassland CH₃Br sink should be reduced by ≥19% (≥1.8 Gg yr^?1) to account for the weaker sink strength of semiarid environments. Identification of A. canescens as a ‘new’ CH₃Cl source may have important ramifications for the global atmospheric budget of CH₃Cl, given the global distribution of this plant and its congeners and their widespread presence in many dryland ecosystems. Laboratory experiments revealed that soil water was the chief regulator of CH₃Cl and CH₃Br oxidation, while temperature had no observed effect between 14 and 26 °C. Oxidation rates rose most rapidly between 0.4% and 5% volumetric water content, suggesting that methyl halide‐oxidizing bacteria respond strongly to small inputs of water under the very driest conditions. Soil drying and rewetting experiments did not appear to affect the oxidation of CH₃Cl and CH₃Br by soil microorganisms, which are presumably adapted to frequent wet/dry cycles.     

Intense green‐, red‐emitting Tb3+, Tb3+/Bi3+‐doped and Sm3+, Sm3+/La3+‐doped Ca2Al2SiO7 phosphors

This paper focuses on an optical study of a Tb³⁺/Bi³⁺‐doped and Sm³⁺/La³⁺‐ doped Ca₂Al₂SiO₇ phosphor synthesized using combustion methods. Here, Ca₂Al₂SiO₇:Sm³⁺ showed a red emission band under visible light excitation but, when it co‐doped with La³⁺ ions, the emission intensity was further enhanced. Ca₂Al₂SiO₇:Tb³⁺ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi³⁺ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices.     

Cation‐tunable blue phosphor Ca2PO4Cl:Eu2+: enhancive emission and site occupancy

A series of blue phosphors Ca_1.98–xM_xPO₄Cl:0.02Eu²⁺ (M = Mg and Sr) with different values of x were synthesized using a high‐temperature solid‐state reaction. X‐Ray diffraction and photoluminescence measurements were used to study the phase structure and luminescence properties. Ca₂PO₄Cl:0.02Eu²⁺ exhibits a tunable emission intensity and color due to the incorporation of Sr²⁺ or Mg²⁺. The incorporation of Sr²⁺ reduces the luminescence intensity and results in a slight red shift in the emission band. The incorporation of Mg²⁺ results in enhanced emission and a clear blue shift in the emission band along with a tunable chromatic coordination. Under excitation at λ = 334 nm, the emission intensity of the Mg²⁺‐doped Ca₂PO₄Cl:0.02Eu²⁺ is found to be 250% that of Ca₂PO₄Cl:0.02Eu²⁺. The luminescence behaviors of the as‐synthesized phosphors are discussed according to the host crystal structure and site occupancy of Eu²⁺. The results indicate that Mg²⁺‐doped Ca₂PO₄Cl:Eu²⁺ is more applicable as a near‐UV‐convertible blue phosphor for white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Enhancement in anti-tubercular activity of indole based thiosemicarbazones on complexation with copper(I) and silver(I) halides: Structure elucidation,evaluation and molecular modelling

A series of monomeric tetrahedral complexes of stoichiometry, [MX(HL)(Ph₃P)₂] (In case of M = Cu, H¹L, X = I, 1; Br, 2; Cl, 3; H³L, X = I, 4; Br, 5; Cl, 6; H⁴L, X = I, 7; Br, 8; Cl, 9 and in case of M = Ag, H¹L, X = Cl, 13; Br, 14; H²L, X = Cl, 15, Br 16; H³L, X = Cl, 17, Br, 18) were synthesized by the reaction of copper (I) or silver (I) halides with indole-3-thiosemicarbazone (H¹L) or 5-methoxy indole-3-thiosemicarbazone (H²L) or 5-methoxy indole-N¹-methyl-3-thiosemicarbazone (H³L), whereas dimers of stoichiometry, [Cu₂(μ-X)₂(η¹-S-H²L)₂(Ph₃P)₂] (X = I, 10; Br, 11; Cl, 12) were obtained by the reaction of copper (I) halides with indole-N¹-methyl-3-thiosemicarbazone (HIntsc-N¹-Me, H²L). The synthesized complexes were characterized using NMR (¹H and ¹³C) and single crystal X-ray diffraction (H²L, 3, 7, 8, 10, 11 and 13) as well as elemental analysis. Anti- M. tuberculosis activity of ligands (H¹L-H⁴L) and their metal complexes (1–18) were evaluated against M. tuberculosis H37RV strain ATCC 27294. It has been observed that there is unusual enhancement in anti TB activity of these ligands on complexation with copper (I) and silver (I). Molecular modelling studies in the active binding site are also giving complementary theoretical support for the experimental biological data acquired.     

Synthesis and reactions of [M(CO)4(Ph2PSiMe3)X] complexes (M = Mn,Re; X = Halogen)

The silylphosphine ligand Ph₂PSiMe₃ reacts readily with a slurry of [Re(CO)₅X] (X  Cl, Br) in polar and in non-polar solvents to yield soluble cis-[Re(CO)₄- (Ph₂PSiMe₃)X] (Ia, X  Cl;Ib, X  Br) via CO substitution. Compound I is readily hydrolyzed by water or silica gel to cis-[Re(CO)₄(Ph₂PH)X]. Compound Ib reacts with [Re(CO)₅Br] to yield [Re₂(CO)₈(μ-PPh₂)- (μ-Br)] (II), and with [Mn(CO)₅Br] to yield [MnRe- (CO)₈(μ-PPh₂)(μ-Br)] (III).The reaction of Ph₂PSiMe₃ with [Mn(CO)₅X] (X=Cl,Br,I) is highly dependent upon reaction conditions.In polar and in non-polar solvents, an excess of ligand gives mainly cis-[Mn(CO)₄(Ph₂PSiMe₃)X] (IVa, X  Cl;IVb, X  Br;IVc, X I). With ligand: [Mn(CO)₅X] reacting ratios in the range 0.5–1.0:1, the products from the three respective halomanganese complexes in THF were: (a) mainly [Mn₂(CO)₈(μ- PPh₂)(μ-Cl) (Va); (b) both [Mn(CO)₄(Ph₂PSiMe₃)Br] and [Mn₂(CO)₈(μ-PPh₂)(μ-Br)] (Vb); and (c) exclusively [Mn(CO)₄(Ph₂PSiMe₃)I]. The compounds IVa-c are stable in solution at ambient temperatures and are readily hydrolyzed by water or methanol to [Mn(CO)₄(Ph₂PH)X]. Compound IVb reacts at room temperature with [Mn(CO)₅Cl] to yield only [Mn₂- (CO)₈(μ-PPh₂)(μ-Br)] (Vb); compound IVc reacts in hot toluene with [Mn(CO)₅Cl] to yield mainly [Mn₂(CO)₈(μ-PPh₂)(μ-I)] (Vc), together with a small amount of the chloro-bridged analog.The dinuclear species II, III and Va-c appear to be formed mainly via an intermolecular elimination of Me₃SiX from the appropriate [M(CO)₄(Ph₂PSiMe₃)X] and metalpentacarbonylhalide (chloride or bromide) complexes.     

Luminescent properties of MAl(SO4)2Br:Eu3+ (M = Sr or Mg) red phosphors for near‐UV light‐emitting diodes

Eu³⁺‐activated MAl(SO₄)₂Br phosphors (where M = Mg or Sr) are successfully prepared using a wet chemical reaction technique. The samples are characterized by X‐ray diffraction (XRD) and photoluminescence (PL) spectroscopies. The XRD pattern revealed that both the samples are microcrystalline in nature. PL of Eu³⁺‐doped SrAl(SO₄)₂Br and MgAl(SO₄)₂Br phosphors exhibited characteristic red emission coming from the ⁵D₀ → ⁷F₂ (616 nm) electron transition, when excited by 396 nm wavelength of light. The maximum intensity of luminescence was observed at a concentration of 1 mol% Eu³⁺. The intensity of the electric dipole transition at 616 nm is greater than that of the magnetic dipole transition at 594 nm. The results showed that MAl(SO₄)₂Br:Eu³⁺, (M = Mg, Sr) phosphors have potential application in near‐UV light‐emitting diodes as efficient red‐emitting phosphor. Copyright © 2014 John Wiley & Sons, Ltd.     

MOF Template‐Directed Fabrication of Hierarchically Structured Electrocatalysts for Efficient Oxygen Evolution Reaction

The ever‐increasing demand for clean and renewable power sources has sparked intensive research on water splitting to produce hydrogen, in which the exploration of electrocatalysts is the central issue. Herein, a new strategy, metal–organic framework template‐directed fabrication of hierarchically structured Co₃O₄@X (X = Co₃O₄, CoS, C, and CoP) electrocatalysts for efficient oxygen evolution reaction (OER) is developed, where Co₃O₄@X are derived from cobalt carbonatehydroxide@zeolitic‐imidazolate‐framework‐67 (CCH@ZIF‐67). Unique hierarchical structure and synergistic effect of resulting catalysts endow abundant exposed active sites, facile ion diffusion path, and improved conductivity, being favorable for improving catalytic activity of them. Consequently, these derivatives Co₃O₄@X reveal highly efficient electrocatalytic performance with long‐term durability for the OER, much superior to previously reported cobalt‐based catalysts as well as the Ir/C catalyst. Particularly, Co₃O₄@CoP exhibits the highest electrocatalytic capability with the lower overpotential of 238 mV at the current density of 10 mA cm^?2. Furthermore, Co₃O₄@X can also efficiently catalyze other small molecules through electro‐oxidation reaction (e.g., glycerol, methanol, or ethanol). It is expected that the strategy presented here can be extended to the fabrication of other composite electrode materials with hierarchical structures for more efficient water splitting.     

Syntheses and structures of vinyl and aryl derivatives of carbonyl halide iron complexes

cis,trans-Fe(CO)₂(PMe₃)₂(p-Y-C₆H₄)X [X=Br, Y=H (4a), MeO (4b), Cl (4c), F (4d), Me (4e); X=I, Y=H (5); X=Cl, Y=H (6)] and cis,trans-Fe(CO)₂(PMe₃)₂(σ-CHCH₂)X [X=Br (7); X=I (8); X=Cl (9)] are prepared by reacting dihalide complexes cis,trans,cis- Fe(CO)₂(PMe₃)₂X₂ [X=Br (1), X=I (2), X=Cl (3)] with Grignard reagents p-Y-C₆H₄-MgBr (Y=H, OMe, Cl, F, Me) or CH₂CH-MgBr and with lithium reagents PhLi, CH₂CH-Li. With both reagents, the reaction proceeds following two parallel pathways: one is the metallation reaction which yields alkyl derivatives, the other affords 17 electron complexes [Fe(CO)₂(PMe₃)₂X] via monoelectron reductive elimination. The influence of the halides and organometallic reagents on the yield of the metallation reaction is discussed. The solution structure of the complexes is assigned on the basis of IR and ¹H, ¹³C, ¹⁹F, ³¹P NMR spectra. The solid state structure of complexes 4a, 5 and 6 is determined by single crystal X-ray diffractometric methods.     

Atomically Dispersed Mo Supported on Metallic Co9S8 Nanoflakes as an Advanced Noble‐Metal‐Free Bifunctional Water Splitting Catalyst Working in Universal pH Conditions

Water splitting requires development of cost‐effective multifunctional materials that can catalyze both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) efficiently. Currently, the OER relies on the noble‐metal catalysts; since with other catalysts, its operation environment is greatly limited in alkaline conditions. Herein, an advanced water oxidation catalyst based on metallic Co₉S₈ decorated with single‐atomic Mo (0.99 wt%) is synthesized (Mo‐Co₉S₈@C). It exhibits pronounced water oxidization activity in acid, alkali, and neutral media by showing positive onset potentials of 200, 90, and 290 mV, respectively, which manifests the best Co₉S₈‐based single‐atom Mo catalyst till now. Moreover, it also demonstrates excellent HER performance over a wide pH range. Consequently, the catalyst even outperforms noble metal Pt/IrO₂‐based catalysts for overall water splitting (only requiring 1.68 V in acid, and 1.56 V in alkaline). Impressively, it works under a current density of 10 mA cm^?2 with no obvious decay during a 24 h (0.5 m H₂SO₄) and 72 h (1.0 m KOH) durability experiment. Density functional theory (DFT) simulations reveal that the synergistic effects of atomically dispersed Mo with Co‐containing substrates can efficiently alter the binding energies of adsorbed intermediate species and decrease the overpotentials of the water splitting.     

Theoretical studies on identity SN2 reactions of lithium halide and methyl halide: A microhydration model

Reactions of lithium halide (LiX, X = F, Cl, Br and I) and methyl halide (CH₃X, X = F, Cl, Br and I) have been investigated at the B3LYP/6-31G(d) level of theory using the microhydration model. Beginning with hydrated lithium ion, four or two water molecules have been conveniently introduced to these aqueous-phase halogen-exchange S_N2 reactions. These water molecules coordinated with the center metal lithium ion, and also interacted with entering and leaving halogen anion via hydrogen bond in complexes and transition state, which to some extent compensated hydration of halogen anion. At 298 K the reaction profiles all involve central barriers ΔE _cent which are found to decrease in the order F > Cl > Br > I. The same trend is also found for the overall barriers (ΔE _ovr ) of the title reaction. In the S_N2 reaction of sodium iodide and methyl iodide, the activation energy agrees well with the aqueous conductometric investigation.     

Sr2ZnWO6:Eu3+,Bi3+,Li+: a potential white‐emitting phosphor for near‐ultraviolet white light‐emitting diodes

A series of Sr₂ZnWO₆ phosphors co‐doped with Eu³⁺, Bi³⁺ and Li⁺ were prepared using the Pechini method. The samples were tested using X‐ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near‐ultraviolet (UV) and UV light. The introduction of Bi³⁺ and Li⁺ significantly enhances the fluorescence emission of Sr₂ZnWO₆:Eu³⁺ and changes the light emitted by the phosphors from bluish‐green to white. When excited at 371 nm, Sr_2–x–zZn_1–yWO₆:xEu³⁺,yBi³⁺,zLi⁺ (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high‐performance white light. Intense red–orange emission is also observed when excited by UV light. The obtained phosphor is a potential white‐emitting phosphor that could meet the needs of excitation sources with near‐UV chips. In addition, this phosphor might have promising application as a red–orange emitting phosphor for white light‐emitting diodes based on UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.     

1D Co‐Pi Modified BiVO4/ZnO Junction Cascade for Efficient Photoelectrochemical Water Cleavage

The most important factors dominating solar hydrogen synthesis efficiency include light absorption, charge separation and transport, and surface chemical reactions (charge utilization). In order to tackle these factors, an ordered 1D junction cascade photoelectrode for water splitting, grown via a simple low‐cost solution‐based process and consisting of nanoparticulate BiVO₄ on 1D ZnO rods with cobalt phosphate (Co‐Pi) on the surface is synthesized. Flat‐band measurements reveal the feasibility of charge transfer from BiVO₄ to ZnO, supported by PL measurements and photocurrent observation in the presence of an efficient hole scavenger, which demonstrate that quenching of luminescence of BiVO₄ and enhanced current are caused by electron transfer from BiVO₄ to ZnO. A dramatic cathodic shift in onset potential under both visible and full arc irradiation, coupled with a 12‐fold increase in photocurrent (ca. 3 mA cm^‐2) are observed compared to BiVO₄, resulting in ≈47% IPCE at 410 nm (4% for BiVO₄) with high solar energy conversion efficiency (0.88%). The reasons for these enhancements stem from enhanced light absorption and trapping, in situ rectifying electron transfer from BiVO₄ to ZnO, hole transfer to Co‐Pi for water oxidation, and facilitating electron transport along 1D ZnO.     

Mechanochemical Synthesis: A Tool to Tune Cation Site Disorder and Ionic Transport Properties of Li3MCl6 (M = Y,Er) Superionic Conductors

The lithium‐conducting, rare‐earth halides, Li₃MX₆ (M = Y, Er; X = Cl, Br), have garnered significantly rising interest recently, as they have been reported to have oxidative stability and high ionic conductivities. However, while a multitude of materials exhibit a superionic conductivity close to 1 mS cm^?1, the exact design strategies to further improve the ionic transport properties have not been established yet. Here, the influence of the employed synthesis method of mechanochemical milling, compared to subsequent crystallization routines as well as classic solid‐state syntheses on the structure and resulting transport behavior of Li₃ErCl₆ and Li₃YCl₆ are explored. Using a combination of X‐ray diffraction, pair distribution function analysis, density functional theory, and impedance spectroscopy, insights into the average and local structural features that influence the underlying transport are provided. The existence of a cation defect within the structure in which Er/Y are disordered to a new position strongly benefits the transport properties. A synthetically tuned, increasing degree of this disordering leads to a decreasing activation energy and increasing ionic conductivity. This work sheds light on the possible synthesis strategies and helps to systematically understand and further improve the properties of this class of materials.     

The synthesis and characterisation of some MnLnX2 complexes (n = 1, L = pyridine, 4-pyrrolidinopyridine,X = Cl,Br, I,NCS; n = 1, L = EtOH,X = Cl,Br; n = 2, L = EtOH,X = I,NCS)

Mono-ligand complexes MnLX₂ (L = pyridine, 4-pyrrolidinopyridine, X = Cl, Br, I, NCS) have been prepared. The pyridine complexes contain only bridging halide and pseudohalide groups, whereas the 4-py complexes contain both bridging and terminal bound anions. Ethanol is coordinated in Mn(EtOH)X₂ (X=C1, Br) and Mn(EtOH)₂X₂ (X=I, NCS). Although the MnLX₂ complexes have the same stoichiometry as the Mn(PR₃)X₂complexes none show any activity towaxds binding dioxygen either in the solid state or in solution.     

Adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine II. Crystal and molecular structure of SnMe2Br2AZP and further mössbauer and photoelectronic spectroscopic studies

A series of adducts of tin(IV) derivatives with 2,2′-azopyridine, AZP, has been studied by Mössbauer and X-ray photoelectronic spectroscopies and the crystal and molecular structure of SnMe₂Br₂- AZP has been determined. The linear correlation of the Mössbauer parameter isomer shift with partial atomic charge on tin suggests the occurrence of a single homologous series of isostructural adducts. The correlation of the Mössbauer parameter quadrupole splitting and C-Sn-C bond angle permits their calculation in SnMe₂X₂AZP adducts (X = Cl, Br). The N_1s binding energies, obtained by XPS data, pointed out two slightly different values for both pyridinic and azo-group nitrogens. The crystallographic study of the SnMe₂Br₂AZP adduct shows a new structure in which the Sn atom is seven-coordinated.     

The multidentate chemistry of manganese(II). III. Complexes of linear quadridentate nitrogenous ligands

Linear quadridentate nitrogenous ligands have been shown to yield three different types of Manganese(II) compound. Simple octahedral compounds of formulation Mn(quad)X₂*(where X = Cl, Br, ClO₄ or BPh₄) are obtained with most ligands. However, with sterically rigid ligands, compounds of the type [Mn(quad)₂]X₂ (X = ClO₄ or BPh₄, possibly 8-coordinate) can also be prepared, while on the other hand with less rigid ligands, bridged dimers of the type [Mn₂(quad)₃]X₄ (X = ClO₄ or BPh₄) are also obtained.     

Silver Bismuth Sulfoiodide Solar Cells: Tuning Optoelectronic Properties by Sulfide Modification for Enhanced Photovoltaic Performance

Silver bismuth iodides (Ag_aBi_bI_a+3b) are nontoxic and comparatively cheap photovoltaic materials, but their wide bandgaps and downshifted valence band edges limit their performance as light absorbers in solar cells. Herein, a strategy is introduced to tune the optoelectronic properties of Ag_aBi_bI_a+3b by partial anionic substitution with the sulfide dianion. A consistent narrowing of the bandgap by 0.1 eV and an upshift of the valence band edge by 0.1–0.3 eV upon modification with sulfide are demonstrated for AgBiI₄, Ag₂BiI₅, Ag₃BiI₆, and AgBi₂I₇ compositions. Solar cells based on silver bismuth sulfoiodides embedded into a mesoporous TiO₂ electron‐transporting scaffold, and a poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] hole‐transporting layer significantly outperform devices based on sulfide‐free materials, mainly due to enhancements in the photocurrent by up to 48%. A power conversion efficiency of 5.44 ± 0.07% (J_sc = 14.6 ± 0.1 mA cm^?2; V_oc = 569 ± 3 mV; fill factor = 65.7 ± 0.3%) under 1 sun irradiation and stability under ambient conditions for over a month are demonstrated. The results reported herein indicate that further improvements should be possible with this new class of photovoltaic materials upon advances in the synthetic procedures and an increase in the level of sulfide anionic substitution.     

Synthesis and characterisation of the halogenated azanonaboranes [(PrNH2)B8H10XNHPr] (X=Cl, Br, I) and their unexpected hydrolysis to hypho-[B5H10(μ-NHPr)]

Treatment of [(ⁱPrNH₂)B₈H₁₁NHⁱPr] with elemental halogen affords the 8-exo-halogen-substituted derivatives [(ⁱPrNH₂)B₈H₁₀XNHⁱPr] (X=Cl, Br, I). The structures of all three compounds are confirmed by NMR spectroscopy and mass spectrometry, and (for X=Br) by an X-ray diffraction study. The bromoazanonaborane undergoes hydrolytic decomposition to the new five-vertex compound [B₅H₁₀(μ-NHⁱPr)] of hypho-type structure.