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In this paper, the negative ion behavior in a C4F8 inductively coupled plasma (ICP) is investigated using a hybrid model. The model predicts a non-monotonic variation of the total negative ion density with power at low pressure (10-30 mTorr), and this trend agrees well with experiments that were carried out in many fluorocarbon (fc) ICP sources, like C2F6, CHF3, and C4F8. This behavior is explained by the availability of feedstock C4F8 gas as a source of the negative ions, as well as by the presence of low energy electrons due to vibrational excitation at low power. The maximum of the negative ion density shifts to low power values upon decreasing pressure, because of the more pronounced depletion of C4F8 molecules, and at high pressure (~50 mTorr), the anion density continuously increases with power, which is similar to fc CCP sources. Furthermore, the negative ion composition is identified in this paper. Our work demonstrates that for a clear understanding of the negative ion behavior in radio frequency C4F8 plasma sources, one needs to take into account many factors, like the attachment characteristics, the anion composition, the spatial profiles, and the reactor configuration. Finally, a detailed comparison of our simulation results with experiments is conducted. [ABSTRACT FROM AUTHOR]

Despite the innumerous papers regarding the study of the ionic liquids as a potential candidate for CO2 capture, many details concerning the structure and dynamics of CO2 in the system are still to be revealed, i.e., the correlation between the local environment structure and the dynamic properties of the substance. This present work relied on the performance of molecular dynamics both for the neat [C2mim][Tf2N] and [C2mim][Tf2N]/CO2 mixtures in an attempt to elucidate the local environment of CO2 and their effects on the dynamic properties of [C2mim][Tf2N]. A slight change in the orientation of the cation and anion could be observed, which was correlated to the cation and anion moving away from each other in order to receive the carbon dioxide. The gas molecules pushed both the cation and the anion away to create sufficient void to its accommodation. The diffusion coefficient of [C2mim]+ is higher than [Tf2N]- regardless the increase of the CO2 concentration. The addition of CO2 in the ionic liquid has shown an increase of 4-5 times for the diffusivity of ions, which was related to the decrease of cation-anion interaction strength. The transport properties' results showed that the addition of CO2 in the ionic liquid generates the fluidization of the system, decreasing the viscosity as a consequence of the local environment structure changing. Likewise, the effect of the type of anion and cation on the system properties was studied considering [Ac]- and [BMpyr]+ ions, showing large effects by the change of anion to [Ac]- which rise from the strong [C2mim]+-[Ac]- interaction, which conditions the solvation of ions by CO2 molecules. [ABSTRACT FROM AUTHOR]

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The present study deals with the primary biodegradability of ionic liquids in order to obtain a greater insight into their fate under different environmental conditions. The focus was thereby on the biodegradation potential of ionic liquid anions when undergoing aerobic and anaerobic biological waste water treatment. Five technologically relevant fluoroorganic and cyano-based ionic liquid anions were investigated as alkaline salts (Li (CF3SO2)2N, K (C2F5)3PF3 and Na N(CN)2, K C(CN)3, K B(CN)4 respectively). Their biodegradability was determined in activated sludge over a period of around 60 days by specific analysis of the anion using ion chromatography. Additionally, the antimicrobial activity of the test compounds towards the activated sludge organisms was tested in inhibition studies. Because of the technologically desirable chemical, thermal and electrochemical stability of these anions, their biodegradability is questioned. The results seem to support the hypothesis: although the concentrations used did not inhibit the inoculum, none of these anions could be biodegraded under either aerobic or denitrifying conditions. The present paper provides information concerning the biodegradability of ionic liquids in waste water treatment plants and gives a first systematic view of the aerobic and anaerobic biodegradability of fluoroorganic and cyano-based ionic liquid anions and therefore supports further hazard assessment. [ABSTRACT FROM AUTHOR]

Six coordination complexes: {[H 2 NMe 2 ][Co(CHO 2) 3 ]} n (1), [Co(bpy)(CHO 2) 2 ] n (2), [Cu(dmf)(CHO 2) 2 ] 2 (3), {[H 2 NMe 2 ][Cu(CHO 2) 3 ]} n (4), [H 2 NMe 2 ] 4 [Fe 4 O 2 (dmf) 4 (SO 4) 6 ] (5) and [Co 3 (bpy)(SO 4) 3 ] n (6) have been efficaciously synthesized using solvothermal techniques and slow evaporation. Two compounds (5 and 6) containing the sulfate anion (SO 4 2−) with iron (III) and cobalt (II) had never been described in the Cambridge Structural Database. In all complexes, the transition metal is hexacoordinated with a distorted octahedral geometry and displays a three-dimensional supramolecular architecture through hydrogen bonding interactions [N H⋯O]. Formate (CHO 2 −) and sulfate (SO 4 2−) anions were very important to the assembly of the three-dimensional MOFs and can be regarded as the template for all structures. All metal-organic complexes were identified by single-crystal X-ray diffraction, elemental composition and Fourier-transform infrared spectroscopy. In this paper, we propose the PM7 and ONIOM calculations as two effective methods in the determination of hydrogen storage. The weight percentage (wt %) of the hydrogen stored in the small cavities of the PCPs studied were: (1) 1.03 wt %, (4) 1.01 wt %, (6) 0.28 wt %. Image 1 • Small anions produce interesting and variable crystalline structures. • Formate and sulfate are very important templates in supramolecular architecture. • Hydrogen bonds between the layers with the anions extend the 3D arrays. • Hydrogen storage capacity was determined by PM7 and ONIOM methods. • PM7 consumes less computing time than other methods. [ABSTRACT FROM AUTHOR]

A microwave-assisted method for the synthesis of Re(VII)-selective anion exchange resins is proposed within this paper. The procedure involved (1) the copolymerization of vinylbenzyl chloride (VBC) and divinylbenzene (DVB), followed by (2) the modification thereof using 1-(3-aminopropyl)imidazole. Synthesis was carried out by applying different sets of microwave heating. Then, samples based on VBC-co-DVB copolymer, obtained conventionally or under exposure to microwaves, were applied by adsorbing ReO 4 − ions from solutions acidified at 0.1 M HCl containing oxoanions of Re(VII), Mo(VI) and V(V), as well as Cu(II). The studies covered adsorption behavior at equilibrium and the selective properties of the prepared resins. The maximum Re(VII) adsorption capacity of 303 mg g−1 was achieved by the resin, that was obtained under constant exposure to microwaves at each stage of the synthesis procedure. All the resins selectively separated Re(VII) from Mo(VI). Selectivity of the adsorption towards ReO 4 − ions was up to 200-fold greater when compared to the 6-fold molar excess of Mo(VI) ions. Terms and symbols. Unlabelled Table C e Equilibrium solute concentration (mg dm−3) DVB Divinylbenzene K D Partition coefficient, mL g−1 K f Freundlich constant K L Langmuir constant (L mg−1) n Freundlich parameter, dimensionless Q 0 Monolayer capacity (mg g resin) q e Equilibrium adsorption capacity (mg g−1) R2 Correlation coefficient R L Separation factor, dimensionless S Styrene s i Selectivity index, dimensionless VBC Vinylbenzyl chloride Unlabelled Image • Two stage, microwave-assisted synthesis of anion exchange resins is proposed. • Polymers separated Re(VII) from Mo(VI) despite excess of the latter one. • Microwave heat allowed to control the adsorption efficiency. [ABSTRACT FROM AUTHOR]

A series of hypergolic salts based on [B12H11NH3]− anion were synthesized. The resulting six salts were characterized by 1H and 13C NMR, IR, ESI-MS and EA. Their key properties were measured or calculated, including melting points (133.9–210.7 °C), decomposition temperatures (215.6–278.2 °C), and heats of formation (−40.1 to 1073.0 J g−1). As expected, the [B12H11NH3]− salts (1–6) possess higher specific impulses (274.9–276.8 s) than the corresponding [B12H12]2− salts (269.8–272.6 s). When the fuel/oxidizer combinations range from 20% to 50%, specific impulse values of the salts are still maintained at a high level of above 269 s. [ABSTRACT FROM AUTHOR]

As fascinating examples of closely connected multiple π-electronic systems involving noncovalent interactions, the cooperatively interlocked [2+1]-type anion complexes of well-designed π-electronic molecules are reported. The anion-responsive π-electronic molecules investigated in this study are the boron complexes of dipyrrolyldiketones bearing arylethynyl moieties at the pyrrole α-positions. Diverse substituents were introduced at the terminal aryl moieties, thus controlling the cooperativity to form [2+1]-type complexes. Theoretical studies showed that this cooperativity was induced by effective interactions between the introduced arylethynyl moieties. The investigations of the anion-binding processes showed that the first and second bindings to the guest anion were energetically almost equivalent, indicating the fundamental and important features of the electronic states of the halide anions. Furthermore, the interlocked anion complexes, whose geometries were distorted from the orthogonal arrangements, had the racemic states of the chiral conformations, either of which was induced by ion pairing with an appropriate chiral π-electronic cation, resulting in the chiroptical property as shown by circular dichroism. [ABSTRACT FROM AUTHOR]

A new family of hexanuclear titanium(iv)-oxo-carboxylate cluster K7H[Ti6O9(ida)6]Cl2·13H2O {Ti6O9} has been synthesized via the H2O2-assisted reaction between TiCl4 and iminodiacetate ligands. This cluster was fully characterized by single-crystal X-ray diffraction and a wide range of analytical methods, including FT-IR, UV/vis spectroscopy as well as electrochemistry and thermogravimetric analysis. As a new type of carboxylate substituted Ti-oxo-cluster, the structural motif of the {Ti6O9} cluster consists of one symmetric {Ti6O6} hexagonal prism with two staggered triangular {Ti3O3} subunits linked by three μ2-O bridges. The {Ti6O9} polyanions are linked by K+ cations to form a novel 3D architecture. The structural information and stability of the {Ti6O9} polyanion in aqueous solution were thoroughly investigated by solid-state/solution NMR, ESI-MS spectroscopy. Moreover, this Ti-oxo cluster exhibits remarkable potential as a visible-light homogeneous photocatalyst for degradation of rhodamine B (RhB). Finally, a proposed peroxotitanium(iv)-mediated photocatalytic pathway involved is illustrated by spectroscopic data. [ABSTRACT FROM AUTHOR]

Triarylborane substituted naphthalimide 3 was designed and synthesized by the Sonogashira cross-coupling reaction. The electronic absorption and emission spectra of the triarylborane naphthalimide 3 show red shifted absorption and emission as compared to 4-bromonaphthalimide 2. The sensing behaviour of 3 was studied for different anions. The triarylborane naphthalimide 3 selectively detects F− and CN− ions in the presence of Cl−, Br−, I− and NO2− ions. The effect of F− and CN− ions on the structure of 3 was studied by performing DFT calculations. The theoretical calculations show good agreement with the experimental results. The detection limits for F− and CN− were found to be 2.01 × 10−10 M and 3.94 × 10−10 M respectively. [ABSTRACT FROM AUTHOR]

Imidazolium- and benzimidazolium-substituted diacetylenes with bromide or nitrogen-rich dicyanamide and tricyanomethanide anions were synthesized and used as precursors for the preparation of N-doped carbon materials. On pyrolysis under argon at 800 °C both halide precursors afforded graphite-like structures with nitrogen contents of about 8.5 %. When the dicyanamide and tricyanomethanide precursors were thermolyzed at the same temperature, graphite-like structures were obtained that exhibit nitrogen contents in the range 17-20 wt %; thereby, the benefit of associating a polymerizing cation with a polymerizing anion in a single precursor was demonstrated. On pyrolysis at 1100 °C the nitrogen contents of the latter pyrolysates remain high (ca. 6 wt %). Adsorption measurements with krypton at 77 K indicated that the materials are nonporous. The highest electrical conductivity was observed for a pyrolysate with one of the lowest nitrogen contents, which also has the highest degree of graphitization. Thus, the quest for N-rich carbons with high electrical conductivities should include both maximization of the nitrogen content and optimization of the degree of graphitization. Crystallographic investigation of the precursors and spectroscopic characterization of the pyrolysates prepared by heating at 220 °C indicate that construction of the final carbon framework does not involve the intermediate formation of a polydiacetylene. [ABSTRACT FROM AUTHOR]

New hybrid POM based on Lindqvist-type polyoxometalates [M6O19]8− (M = Nb, Ta) and organometallic fragment {Cp*Rh}2+ have been isolated and characterized. X-ray quality crystals of K4[(Cp*Rh)2Nb6O19]·20H2O (1) and Cs4[(Cp*Rh)2Ta6O19]·18H2O (2) were obtained from solutions with {Cp*Rh} : [M6O19]8− stoichiometry 2 : 1. The solution behavior of the hybrid polyoxoanions was studied with ESI-MS and 1H DOSY NMR. Amongst the poorly investigated chemistry of polyoxotantalates, complex 2 is the first complex bearing a grafted organometallic fragment. The formation of 1 : 1 complexes was detected by ESI-MS techniques. [ABSTRACT FROM AUTHOR]

Five hexanitratoneodymate-based rare earth complexes (1–5) were synthesized using a straightforward method. Purple plate crystals of 1 were isolated and the crystal structure was determined by single-crystal X-ray diffraction with respect to the coordination mode of the nitrate anion to the central Nd(iii) ion. (1: monoclinic system P21/c, a = 15.9460(3) Å, b = 10.2457(6) Å, c = 33.323(3) Å, β = 91.8108(17)°, V = 3109.11(11) Å3, Z = 4). The central Nd(iii) ion is surrounded by six bidentate nitrate ligands, with a major trend towards high symmetry of the [Nd(NO3)6]3− anion as an icosahedron. Thermal properties were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Complexes 3–5 are found to be room temperature liquids, and their excitation and emission spectra were recorded. These complexes exhibit intense near-infrared (NIR) luminescence emission, which originates from interconfigurational f–f transitions 4F3/2→4IJ multiplet (J = 9/2–13/2). These liquid Nd(iii) complexes are of interest as potential NIR luminescent soft materials with high thermal stability. [ABSTRACT FROM AUTHOR]

The luminescent dimeric ternary lanthanide-cyclen complexes (2-(Ln.1)2; Ln = Tb/Eu) were designed and both their self-assembly formation and their ability to detect anions via displacement assays were investigated using spectrophotometric titrations in MeOH solution. The formation of 2-(Tb.1)2 and 2-(Eu.1)2 was investigated in solution, and determination of the binding constants and stoichiometry showed that the former was formed almost exclusively over the 1 : 1 complex 2-(Tb.1) after the addition of two equivalents of 2; while for 2-(Eu.1)2 a mixture of both stoichiometries existed even after the addition of four equivalents of 2. Of these two systems, 2-(Tb.1)2 was studied in details as a probe for anions, where significant changes where observed in the photophysical properties of the complex; with the characteristic Tb(III)-centred emission being fully switched off upon the sensing of phosphates and nitrate, giving rise to the formation of a H2PO4 -:Tb.1 complex in a 1 : 2 stoichiometry upon sensing of H2PO4 - by 2-(Tb.1)2, while NO3 - gave 1 : 1 complex formation and two equivalents of NO3 -·Tb.1 [ABSTRACT FROM AUTHOR]

A para-nitrophenyl functionalized C3v symmetric flexible tripodal amide ligand, L, shows remarkable solvent dependent dual binding behaviour towards the octahedral hexafluorosilicate anion in solid state. In DMSO solvent the ligand encapsulates the hexafluorosilicate anion within its dimeric capsular assembly, whereas in the case of DMF solvent the ligand stabilizes the hexafluorosilicate anion via side cleft binding. The binding dissimilarities of the hexafluorosilicate anion in the complexes are also confirmed by Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

A new 2,3,4,5-tetrafluorophenyl substituted tripodal amide-based receptor L1 and its pentafluorophenyl substituted analogue L2 were explored for halide binding studies in their solution and solid states. Comparative solution state binding studies of halides with L1 and L2 were carried out by ¹H-NMR titration in CDCl3. Detailed solution state ¹H-NMR studies show that halides bind with L1 and L2 with 1 : 1 stoichiometry in general. Binding constants of the halides with L1 and L2 were calculated by ¹H-NMR titration studies where the fluoride shows selectivity over other halides and the fluoride binding constants (log K) with these two receptors were found to be 3.94 and 3.35, respectively. Single crystal X-ray structure analysis of the triamide receptors, L1 and L2, revealed two different conformations where L1 possesses a pre-organized C3v symmetric tripodal cleft, whereas in the case of L2 three arms are devoid of structural pre-organization to achieve a C3v symmetric cleft. Single crystal X-ray diffraction studies of the cases of complexes formed between L2 and fluoride/chloride, [L2(F)(CHCl3)][N(Bu)4] (1) and [L2(Cl)(CHCl3)][N(Bu)4] (2), respectively, were also carried out to elucidate the structural evidence of anion encapsulation. A detailed structural analysis of complexes 1 and 2 shows that the fluoride and chloride are engulfed in the C3v symmetric cavity of L2 with three strong N--H⋯anion interactions where a CHCl3 molecule acts as a cap that closes the open end of the C3v symmetric cleft via C--H⋯anion and CHCl3--C6F5 interactions. [ABSTRACT FROM AUTHOR]

By a pH value controlled synthesis strategy, hydrothermal reactions of Cd(NO3)2·4H2O with mixed-ligands of 5-amino-tetrazole (Hatz) and 1,2,4,5-benzenetetracarboxylic acid (H4btec) yielded two 3D cadmium(II) coordination polymers (CPs) of {K[Cd2(atz)(btec)(H2O)2]}n (1) and [Cd3(OH)(atz)(btec)(H2O)2]n·nH2O (2). Their structures were determined by elemental analysis (EA), infrared spectra (IR), thermogravimetric analysis (TGA) and single-crystal/powder X-ray diffraction. The results reveal that both 1 and 2 are 3D architectures. In 1, the Cd(II) ions are connected together by μ2-atz and (μ6-btec4-, generating a rare (4,6)-connected anion framework. The anti-cation K+ ions locate the micropores and weakly interact with the carboxyl oxygen of the (μ6-btec4- ligands. In 2, six Cd(II) ions are linked together through two n3-OH- and two (μ3-atz- to form a [Cd6(μ3-OH)2(μ3-atz)2]8+ unit, which is further connected with other equivalent units by (μ-btec4- spacers, resulting in a rare (5,10)-connected porous framework. The photoluminescent investigation illustrates that 1 and 2 show strong emissions at 470 and 457 nm upon excitation at 350 and 370 nm, respectively. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation by IR spectroscopy and elemental analysis of ten new Ag(I)-L complexes are described. Of these complexes, nine are characterised by single crystal X-ray diffraction: {[Ag(L)](CF3SO3)·½H2O}∞ (1), {[Ag(L)](ClO4)·1/2H2;)∞ (2), {[Ag2(L)2(CH3CN)](ClC4)2·H2O)∞ (3), {[Ag2(L)2(CH3CN)2](ClO4)2·CH3CN)∞ (4), {[Ag2(L)2(CH3CN)2](PF6)2·2CH3CN)∞ (5), {[Ag(L)2](CF3SO3)4/2H2OL (6), {[Ag(L)2](BF4)∞(7), {[Ag(L)2](PF6))∞ (8) and {[Ag(L)2](PF6)·2CH3CN)∞ (9). The primary structures of 1-6 were meso-helical one-dimensional (1D) polymers, while 7 was a helical 1D polymer and 8 and 9 were (4,4) networks. Complexes 1-5 possessed 1:1 metal-to-ligand (M: L) ratios, while complexes 6-9 possessed 1:2 M: L ratios. The meso-helical chains of complexes 1 and 2 were di-μ-bridged at the Ag(I) nodes by the counteranions CF3SC>3- and CIO4-, respectively, while the meso-helical chains of complexes 3-5 were di-μ-bridged at the Ag(I) nodes by the CH3CN molecules. The effect of counteranions and solvent molecules on delicate anion-Ag, π-π-stacking and argentophilic interactions was studied through complexes 1-5. The 1D chains of complexes 6 and 7 possessed monodentate L ligand side arms. The uncoordinated N-donors of these side arms were inclined towards the Ag(I) centre of the adjacent chains and demonstrated narrower Ag-Npy-Cg(pyridyl) angles. In the case of complexes 8 and 9, wider Ag-Npy-Cg(pyridyl) angles and stronger N⋯Ag interactions resulted in (4,4) nets. The effects of the size and the nature of the counteranions on the topology were studied through complexes 6-9. [ABSTRACT FROM AUTHOR]

In order to develop efficient visible light-driven photocatalysts for environmental applications, novel g-C3N4/nanocage ZnS composites have been successfully fabricated via an anion exchange route using ZIF-8 as a self-sacrificing template. The as-prepared g-C3N4/ZnS composites were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy and photoluminescence. In addition, the photocatalytic oxidation of organic contaminants in aqueous solution was investigated with the g-C3N4/ZnS composite system under visible light irradiation by using rhodamine B as a model compound. The results indicate that the g-C3N4/ZnS composite photocatalysts show higher photocatalytic activity than the single component (pure g-C3N4 or ZnS). More specifically, the optimum photocatalytic activity of the g-C3N4/ZnS composite was achieved with a weight ratio of 6 :1, which is as high as 37.8 and 2.8 times those of individual ZnS and g-C3N4 under visible light irradiation. The enhanced photocatalytic activity of g-C3N4/ZnS is mainly attributed to an efficient electron-hole separation at the interface of the two semiconductors, as determined by photoluminescence spectroscopy. Moreover, it is observed that 'O2- is the main active species in the photocatalytic oxidation of RhB solution using a g-C3N4/nanocage ZnS composite. [ABSTRACT FROM AUTHOR]

Combinations of neutral tetrakis meta-pyridyl appended calix[4]arene derivatives in 1,3-A conformation as meta tectons 3 (tetrakis-meta-pyridyl-tetrathiacalix[4]arene) and 4 (tetrakis-meta-pyridyltetrathiatetramercapto-calix[4]arene) with MX2, behaving as a neutral metallatecton, lead to the formation of 2- and β-D neutral coordination networks. In all cases, the metal centre adopts a distorted octahedral geometry with the two anions occupying the two apical positions. For compound 3-CdX2 (X = Cl or Br), 4-CdBr2 and 4-FeCl2 similar porous diamondoid 3D networks, resulting from the tetrakis monodentate behaviour of the organic tectons, are formed. In marked contrast, for 4-CoX2 (X = Cl or Br), only two out of the four pyridyl units take part in the connectivity pattern leading thus to the formation of 2D grid type architectures. [ABSTRACT FROM AUTHOR]

Low-dimensional mixed anion compounds Ba18F18In8S21 (1) and Barf10In4S10 (2), are synthesized and characterized. These compounds crystallize in the space group P42/ncm(138) with a = b = 22.0703(8) Å, c = 12.6143(9) Å, and V = 6144.4(6) Å3 (Z = 4) for 1 and Pnma(62) with a = 12.5686(8) Å, b = 19.2822(12) Å, c = 12.5835(9) Å, and V = 3049.6(3) Å3 (Z = 4) for 2. Compound 1 contains the unusual one-dimensional fluorite type [Ba16F18] ionic region and [BaIn8S21] covalent region, whereas 2 has a two-dimensional fluorite type [Ba2F2] block and the unique tetranuclear [In4S10]8- anion. The first principles electronic structure calculation performed with density functional theory (DFT) indicates that the two compounds are both direct band semiconductors with a gap of 2.28 eV for 1 and 2.23 eV for 2. [ABSTRACT FROM AUTHOR]

Three ion-pair complexes based on spin-crossover [Mn(5-Br-sal-N-1,5,8,12)]ClO4 with TBA2[Ni(mnt)2], TBA2[Pt(mnt)2] (mnt = maleonitriledithiolate) and TBA[Ni(dmit)2] respectively (dmit = 2-thioxo-1,3- dithiole-4,5-dithiolato) have been synthesized and structurally characterized. Complexes 1 [Mn(5-Br-sal- N-1,5,8,12)]2[Ni(mnt)2] and 2 [Mn(5-Br-sal-N-1,5,8,12)]2[Pt(mnt)2] are isomorphic and show the axial compression of the octahedral coordination environment of MnIII ions. With the temperature increasing the equatorial metal-ligand bond lengths show significant elongation, but the axial bond lengths remain unchanged. Complex 3 [Mn(5-Br-sal-N-1,5,8,12)][Ni(dmit)2].CH3CN contains π-π, p-π and H-bonds weak interactions. Magnetic investigation shows the spin-crossover phenomena for 1 and 2, and T1/2 has been increased by 230 K comparing with the reactant complex. However, no spin-crossover was observed in complex 3, and theoretical calculations show that there are weak antiferromagnetic couplings mediated through π-π interactions. [ABSTRACT FROM AUTHOR]

A mixed-ligand monometallic ruthenium(II) complex of composition [(bipy)2Ru(tpy-Hbzim-dipy)](ClO4)2 (1), where tpy-Hbzim-dipy = 4'-[4-(4,5-di-pyridin-2-yl-1H-imidazol-2-yl)-phenyl]-[2,2';6',2"]terpyridine and bipy = 2,2'-bipyridine has been synthesized and characterized using standard analytical and spectroscopic techniques including X-ray crystallography. The complex displays very intense, ligand centered absorption bands in the UV and moderately intense MLCT bands in the visible region. On excitation at the MLCT bands, the complex exhibits strong luminescence at room temperature with lifetimes in the range of 116-257 ns, depending upon the nature of the solvents. The complex is found to undergo one reversible oxidation in the positive potential window (0 to +1.8 V) and two successive quasi-reversible reductions in the negative potential window (0 to -2.0 V). Both anion and cation binding properties of the receptor were thoroughly investigated in acetonitrile solution using 1H NMR, absorption, steady state and timeresolved emission spectral studies and by cyclic voltammetry. The anion sensing studies revealed that the receptor acts as a "turn on" luminescence sensor for H2PO4 - and HSO4 - ions, and as a "turn off" sensor for F- and AcO- ions. It is evident that in the presence of excess F- and AcO- ions, deprotonation of the imidazole N-H fragment of the receptor occurs, an event which is signaled by the change of color from orange yellow to red visible to the naked eye. On the other hand, the probable mode of interaction of the receptors with H2PO4 - and HSO4 - ions is through hydrogen bonding interaction. The cation-sensing properties showed that the receptor was found to exhibit a colorimetric sensing ability that was highly selective for Fe2+, as evidenced by the distinct color change from yellow orange to deep red-violet to the naked eye over the other cations studied (Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Hg2+). [ABSTRACT FROM AUTHOR]

The stabilization of polyhalides in the solid state with the support of electron-deficient pentafluorophenyl groups is described. Furthermore, a synthetic approach towards the sensitive tetraiodide dianion is described and ESI mass spectrometric evidence for its presence in solution is reported. [ABSTRACT FROM AUTHOR]

The second-generation poly(ethylene imine) dendrimer (L), based on ammonia as the initiating core molecule, forms anion and ion-pair complexes in aqueous solution. Speciation of the complex species formed and determination of the relevant stability constants were performed by means of potentiometric titration in a 0.10 M NMe4Cl solution at 298.1 K. Protonated forms of L interact with NO3−, SO42−, SeO42−, HPO42− and H2PO4− forming stable 1 : 1 anion complexes. The dendritic structure endows the molecule with a greater anion binding ability relative to analogous linear polyamines. It was previously reported that L forms stable metal complexes. We show here that protonated forms of the mononuclear complexes with Cu2+, Zn2+ and Cd2+ bind these anions, and Pb2+ complexes bind NO3−. The resulting ion-pair complexes show considerable stability thanks to the cooperative effect of the oppositely charged partners. Molecular modelling calculations show that both anion–ligand and anion–metal ion interactions can participate in stabilizing such ion-pair complexes. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) sporting anions comprising the β-diketonate functionality were prepared, fully characterized via ESI-MS, FTIR, and 1H/13C NMR, and tested in multiple scenarios. We present eight new salts based on four different β-diketonate anions, each coupled with the choline or tetrabutylphosphonium cation. The thermal stabilities and transitions of these β-diketonate salts were explored using DSC and TGA. Seven of the compounds displayed melting points at or below 100 °C and hence formally qualify as ILs. The inherent binding capability of the β-diketonate moiety made possible a task-specific IL amenable to lanthanide recognition. For example, coordination with Eu3+ was accompanied by a striking three order-of-magnitude intensification of luminescence (‘turn-on’). Additionally, these ILs display prominent acidochromism. That is, the intense visible color of β-diketonate ILs is modulated in the presence of an acid source, permitting the visual transduction of local pH changes. Utility for carbon capture was also considered, however, these ILs were essentially incapable of binding CO2. Computational studies were better able to elucidate this behavior, revealing that the association of CO2 with the β-diketonate anion is thermodynamically unfavored and sterically hindered. Despite this negative result for CO2 capture, these newly introduced β-diketonate ILs show interesting and useful physicochemical properties applicable to a number of future applications. [ABSTRACT FROM AUTHOR]

Two new asymmetric ureidic receptors L1 (1-(1H-indol-7-yl)-3-(quinolin-2-yl)urea) and L2 (1-(quinolin-2-yl)-3-(quinolin-8-yl)urea) have been synthesised and their affinity towards different anions tested in DMSO-d6. L1 adopts both in solution and in the solid state an (E,Z) conformation. A moderate affinity for acetate has been observed for L1 while no interaction has been observed for L2. The different behaviour has been ascribed to the presence/absence of the indole group. In the case of L1 the indole group causes the formation of a peculiar supramolecular architecture with two molecules of the receptor binding the anions in the (E,Z) conformation via H-bonds. L2 also adopts an (E,Z) conformation in the solid state. However, the absence of the indole group in L2 hampers the formation of the supramolecular assembly with the participation of anionic species. [ABSTRACT FROM AUTHOR]

In early reports, the boron atom of the anionic borido complexes [{(η5-C5H4R)(OC)2Mn}2B]− (R = H, Me) showed nucleophilic behavior in the presence of electrophiles such as methyl iodide and group 11 metal chlorides, akin to the ground-breaking boryl lithium of Yamashita and Nozaki. Later, a reaction with the well-known transition metal Lewis base [Pt(PCy3)2] suggested the possibility of boron-centered electrophilicity. In this paper we elucidate a third reactivity profile of the anion, nucleophilic substitution on heavier halides of group 14 metals by a manganese center. Meanwhile, other group 11 halides were found to interact with the boron center, but form structures different from those seen with gold. The basis of the discrimination of the anion between main group and transition metal halides is explored computationally, and the ditopic, ambiphilic reactivity of the anions is discussed. [ABSTRACT FROM AUTHOR]

In this paper we describe the synthesis and characterizationofthree new complexes of the 1,8-bis(3,5-dimethyl-1H-pyrazol-1-yl)-3,6-dioxaoctane ligand (L) with ZnII(1A), CdII(2A), andHgII(3A) ions. The aim of the present studyis to investigate the structural effect of the counteranion (Cl–vs ClO4–) on the typeand geometry of the structures of the complexes as well as the ligationalbehavior of the ligand. Depending on the type of the counteranion,the structural studies revealed a variety of modes of bonding (N,N-bidentate/N,O,O,N-tetradentate), coordinationgeometries (tetrahedral/octahedral), and different nuclearities (monomer/polymer).Moreover, the density functional theory computational study in combinationwith several experimental techniques as well as the investigationof the extended structures allowed us to understand the role of thedifferent anions in the structure of the complexes. [ABSTRACT FROM AUTHOR]

Synthesis of new mixed anion compounds under visible light has been considered as an elegant strategy of photocatalyst development for efficient solar light harvesting applications. Through combined experimental and theoretical studies, we show that a new single layer Sillen-Aurivillius perovskite Bi4Ti0.5W0.5O8Cl is a good photocatalyst under visible light. This compound prepared by a solid-state reaction method has an energy gap of 2.36 eV and the visible-light-driven photocatalytic activities for degrading Rhodamine B are much better than Bi4NbO8Cl. We conclude from density functional theory calculations that its promising water-splitting application is due to its direct band gap and more stronger hybridization between Bi-6s and O-2p orbitals than Bi4NbO8Cl.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Abstract: Pentazolate anion (cyclo‐N5−), and/or N3−, NO3− were used as the ligands to obtain a series of nitrogen‐rich energetic three‐dimensional (3D) frameworks [Cu(N5)(N3)]n, [Ag(N5)]n, [Ba(N5)(NO3)(H2O)3]n, and [NaBa3(N5)6(NO3)(H2O)3]n by self‐assembly. These frameworks were characterized by single‐crystal X‐ray diffraction, SEM, IR and Raman spectroscopy, elemental analysis, and thermal analysis. All the frameworks exhibited regular supramolecular structures and excellent stabilities at room temperature which can be attributed to the strong coordination bonds between cyclo‐N5− anions and metal ions. The successful stabilization of the cyclo‐N5− in more 3D multi‐ligand metal‐N5− frameworks after Na‐N5− frameworks has been demonstrated. This breakthrough offers new opportunities for the future of metal‐pentazolate frameworks and polynitrogen chemistry. [ABSTRACT FROM AUTHOR]

Abstract: Visible‐light‐driven conversion of CO2 to CO and high‐value‐added carbon products is a promising strategy for mitigating CO2 emissions and reserving solar energy in chemical form. We report an efficient system for CO2 transformation to CO catalyzed by bare CoP, hybrid CoP/carbon nanotubes (CNTs), and CoP/reduced graphene oxide (rGO) in mixed aqueous solutions containing a Ru‐based photosensitizer, under visible‐light irradiation. The in situ prepared hybrid catalysts CoP/CNT and CoP/rGO show excellent catalytic activities in CO2 reduction to CO, with a catalytic rates of up to 39 510 and 47 330 μmol h−1 g−1 in the first 2 h of reaction, respectively; a high CO selectivity of 73.1 % for the former was achieved in parallel competing reactions in the photoreduction of CO2 and H2O. A combination of experimental and computational studies clearly shows that strong interactions between CoP and carbon‐supported materials and partially adsorbed H2O molecules on the catalyst surface significantly improve CO‐generating rates. [ABSTRACT FROM AUTHOR]

Abstract: Eleven‐vertex closo and nido boron clusters with one or two exo‐cyano groups were obtained by a series of consecutive cage‐opening and cage‐closure reactions starting from K2[closo‐B11H11] (K21). In the first step, K21 reacts with KCN in water at elevated temperatures to yield [7‐NC‐nido‐B11H12]2− (5 a). Oxidation of 5 a with PbO2 gives [NC‐closo‐B11H10]2− (2). In analogous subsequent reactions, dianion 2 was converted with KCN regioselectively to [7,9‐(NC)2‐nido‐B11H11]2− (6 a), which was further oxidized to [(NC)2‐closo‐B11H9]2− (3). The {nido‐B11} dianions 5 a and 6 a were protonated to yield [7‐NC‐nido‐B11H13]− (5 b) and [7,9‐(NC)2‐nido‐B11H12]− (6 b). All anions were studied by NMR spectroscopy and, except for 6 b, salts of all anions were characterized by IR and Raman spectroscopy and by elemental analysis. The position of the cyano group(s) in 5 a and 6 a were confirmed by NMR data and single‐crystal X‐ray diffraction studies on [Ph4P]25 a⋅CH2Cl2 and [Et4N]26 a. The {closo‐B11} clusters are fluxional in solution. In the crystal of [EMIm]22 the BCN vertex is in the 2‐position. Two isomers of dianion 3, [2,3‐(NC)2‐closo‐B11H9]2− and [2,6‐(NC)2‐closo‐B11H9]2−, were identified in the crystal of its [Et4N]+ salt. The peak oxidation potentials Epa of anions 1–3, 5 a, 6 a, 5 b, and [nido‐B11H14]− (4 b), determined by cyclic voltammetry, increase with increasing number of cyano groups. Increasing Epa in the order 1<2<3 parallels the increasing reactivity toward cyanide anions. [ABSTRACT FROM AUTHOR]

Abstract: Sulfonates were incorporated into six novel high‐nuclearity silver(I) thiolate clusters under the guidance of anion templates varied from S2−, SO42−, α‐[Mo5O18]6−, β‐[Mo5O18]6−, [Mo2O8]4−, to [Mo4O14(SO4)]6−. Single crystal X‐ray analysis revealed that SD/Ag1, SD/Ag3, SD/Ag5, and SD/Ag6 are discrete [S@Ag60], [α‐Mo5O18@Ag36], [Mo2O8@Ag30]2, and [Mo4O14(SO4)@Ag73] clusters, respectively, whereas SD/Ag2 and SD/Ag4 are one‐dimensional (1D) chains based on the [SO4@Ag20] and [β‐Mo5O18@Ag36] cluster subunits, respectively. Their silver skeletons are protected exteriorly by thiolates and sulfonates and interiorly supported by diverse anions as templates. Structurally, cluster SD/Ag1 is a typical core–shell structure comprised of an inner Ag12 cuboctahedron and an outer Ag48 shell. The sulfate‐templated drum‐like Ag20 cluster subunits are bridged by PhSO3− to give a 1D chain of SD/Ag2. Complex SD/Ag3 and SD/Ag4 are spindle‐like Ag36 clusters with isomeric [Mo5O18]6− inside, and the latter is further extended to a 1D chain through PhSO3− bridges. A pair of [Mo2O8]4− templated gourd‐like Ag30 clusters are dimerized in a head‐to‐head fashion to form SD/Ag5. Complex SD/Ag6 is the largest cluster in this family and doubly templated by unprecedented [Mo4O14(SO4)]6− anions. Geometrically, the silver shells of SD/Ag1–SD/Ag5 show the polyhedral features of Johnson solids, instead of the usual Platonic or Archimedean solids. Solution behaviors and luminescent properties were also investigated in detail. [ABSTRACT FROM AUTHOR]

ABSTRACT The kinetics of the reactions of benzylidenecyanoacetates 1a-d (X = H, Me, OMe, and NMe2) with nitroalkyl anions 2a-c have been studied in aqueous solution at 20°C. The second-order rate constants are used to evaluate the electrophilicity parameter E of these series of Michael acceptors 1a-d according to the linear free enthalpy relationship log k (20°C) = sN ( E + N). The measured E values were found to cover a domain of reactivity, ranging from −10.07 for the most reactive electrophile 1a (X = H) to −14.04 for the less electrophile 1d (X = NMe2). Mayr's approach was found to correctly predict the rate constants for the reactions of these series of olefins 1a-d with the hydroxide ion in water and 50% water-50% acetonitrile at 20°C. Analysis of the kinetic measurements using the Brönsted relationship shows that βnuc values remain remarkably constant for changes in the nature of the substituent X. A notable finding of this work is perhaps provided by the observed large changes in the electrophilicity parameter E on going from benzylidenecyanoacetates 1 to their analogues benzylidenemalonates 3 (Δ E ∼ 9.06-10.48), whereas the replacement of second CO2Et group by the CN group in 1 to give benzylidenemalononitriles 4 has little effect on electrophilic reactivity, i.e., Δ E ∼ 0.65-0.95. This abnormal pattern in the E values has been attributed to the resonance interaction and salvation effects. On the other hand, the effect of benzylidenecyanoacetate substituents on the electrophilic reactivity was examined quantitatively on the basis of the electrophilicity parameter E, leading to linear correlation of E with Hammett-Brown substituent constants ( [ABSTRACT FROM AUTHOR]

A cationic porous framework with mobile anions (MIL-101(Cr)-Cl) was easily and successfully synthesized by utilizing the stronger affinity of F- to Al3+ than Cr3+ in the chargebalanced framework of MIL-101(Cr). The structure, morphology and porosity of MIL-101(Cr)-Cl were characterized. The obtained new materials retain the high surface area, good thermostability, and structure topology of MIL-101(Cr). With the mobile Cl- anion, MIL-101(Cr)-Cl can be used as an ion-exchange material for anionic organic pollutions. In this work, 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model to test the absorption performance of this new material. This new material exhibited improved adsorbability compared to that of the original metal-organic frameworks (MOFs). At the same time, this material also shows high anti-interference performance with changing solution pH. [ABSTRACT FROM AUTHOR]

The reaction of Ph2P(S)ONa with B(C6F5)3 in the presence of the crown ether 15-crown-5 provided the borate complex [Na(15-crown-5)][Ph2P(S)OB(C6F5)3] (1). In one occasion a few crystals of the hydrogen-bonded complex [Na(15-crown-5)2][Ph2P(S)O...HO(S)PPh2] (2) were obtained, which formed upon the accidental hydrolysis of 1. More rationally, 2 was prepared by the reaction of Ph2P(S) OH, Ph2P(S)ONa and 15-crown-5. The molecular structures of 1 and 2 were investigated by X-ray crystallography. [ABSTRACT FROM AUTHOR]

The electrochemical synthesis is an underestimated synthesis protocol, which can lead to unexpected results. We obtained an unusual CuI complex salt with a pentanuclear anion and a heptanuclear cation. The anion [Cu5(S tBu)6]- features a trigonal prism coordination motif with a twisted arrangement. The cation [Cu7(S tBu)6(bipy)3]+ is structurally almost identical to the anion and shares therefore basic building principles. These Cu-S skeletons with additional N donor functions in the cation have relevance to biological copper proteins. Besides structural discussion and analysis, a theoretical study was performed to determine stabilizing effects. This is accomplished by means of DFT with a triple-zeta basis set and the TPSSh functional in order to highlight bonding interactions and to understand d10-d10 interactions, which are assigned a major stabilizing part. This is realized through Wiberg bond analysis and frontier orbital analysis of both ions. [ABSTRACT FROM AUTHOR]

Protonation of trans-1,2-bis(4-pyridyl)ethylene (4,4′-bpe) with dilute sulfuric acid (33 %) afforded a protonated adduct [{4,4′-bpe⋅2 H+}2{HSO4}−2{SO4}−2{H2O}2] ( 1). The neighboring olefinic bond in 1 is in a suitable range (3.931-4.064 Å) to undergo a photochemical [2+2] cycloaddition reaction. Upon irradiation with UV light (365 nm), 1 undergoes a molecular sliding involving the 4,4′-bpe⋅2 H+ units, affording 2, stabilized through OSO4⋅⋅⋅π interactions. Heating 1 to 50° C leads to a 3D hydrogen-bonded organic framework (HOF) ( 3). This process occurs through thermal dissociation of the bisulfate anion. Diffusion of iodine through the crystal lattice of 1 and 3 enables the reduction of sulfate to bisulfate, affording a 1D hydrogen-bonded chain ( 4). Solid-state 13C CPMAS NMR, IR, DSC, and powder XRD studies further support stimuli-responsive structural tuning through crystal-to-crystal transformation. All these conversions occur with significant translational and rotational movements along with a series of bond-breaking and bond-forming processes. [ABSTRACT FROM AUTHOR]

CH stretches in hydrocarbon cations often shift to lower frequencies relative to neutral molecules, because they do not have sufficient electrons to give every bond an electron pair. A parallel effect in negatively charged species has not been previously observed. Here we show that CH bond weakening occurs in alkoxide anions as a consequence of hyperconjugation. The reasoning differs somewhat from the case of positively charged ions, but the net effect is the same: to lower CH stretching frequencies by hundreds of wavenumbers. [ABSTRACT FROM AUTHOR]

Anion-π catalysis, that is the stabilization of anionic transition states on π-acidic aromatic surfaces, has so far been developed with naphthalenediimides (NDIs). This report introduces perylenediimides (PDIs) to anion-π catalysis. The quadrupole moment of PDIs (+23.2 B) is found to exceed that of NDIs and reach new records with acceptors in the core (+70.9 B), and their larger surface provides space to better accommodate chemical transformations. Unlike NDIs, the activity of PDI catalysts for enolate and enamine addition is determined by the twist of their π surface rather than their reducibility. These results, further strengthened by nitrate inhibition and circular dichroism spectroscopy, support an understanding of anion-π interactions centered around quadrupole moments, i.e., electrostatic contributions, rather than redox potentials and charge transfer. The large PDI surfaces provide access to the highest enantioselectivities observed so far in anion-π catalysis (96 % ee). [ABSTRACT FROM AUTHOR]

Anion binding properties of neutral helical foldamers consisting of urea type units in their backbone have been investigated. 1H NMR titration studies in various organic solvents including DMSO suggest that the interaction between aliphatic oligoureas and anions (CH3COO−, H2PO4−, Cl−) is site-specific, as it largely involves the urea NHs located at the terminal end of the helix (positive pole of the helix), which do not participate to the helical intramolecular hydrogen-bonding network. This mode of binding parallels that found in proteins in which anion-binding sites are frequently found at the N-terminus of an α-helix. 1H NMR studies suggest that the helix of oligoureas remains largely folded upon anion binding, even in the presence of a large excess of the anion. This study points to potentially useful applications of oligourea helices for the selective recognition of small guest molecules. [ABSTRACT FROM AUTHOR]

The title anion was synthesized by heating dimethylformamide (DMF) solution of the known Ni-centered and Ni(CO)-capped tin clusters [Ni@Sn9Ni(CO)]3−. The new anion represents the first example of face-fused nine-atom molecular clusters. The two clusters are identical elongated tricapped trigonal prisms of nido-[Sn8Ni(CO)]6− with nickel at one of the capping positions. They are fused along a triangular face adjacent to a trigonal prismatic base and made of two Sn and one Ni atoms. The new anion is structurally characterized by single-crystal X-ray diffraction in the compound (K[222-crypt])4[Sn14Ni(CO)]⋅DMF. Its presence in solution is corroborated by electrospray mass spectrometry. [ABSTRACT FROM AUTHOR]

The iron selenidoantimonate(III) [Fe(phen)3]Sb6Se10 ( 1) (phen = 1, 10-phenanthroline) was prepared by reaction of Fe, Sb, Se, phen, and 1, 4-diazabicyclo[2.2.2]octane in MeOH and H2O mixed solvent under solvothermal conditions. 1 consists of a [Fe(phen)3]2+ cation and a two dimensional [Sb6Se10]2- anion. The [Sb6Se10]2- anion is constructed by SbSe3, SbSe4, and SbSe6 primary building blocks by corner- and edge-sharing, resulting Sb4Se4, Sb5Se5, and Sb6Se6 heterorings and a semi-cubic Sb4Se6 motif, which act as secondary building units. The octahedral SbSe6 primary unit and semi-cubic Sb4Se6 motif make compound 1 quite different from the thioantimonates(III). Compound 1 exhibits steep bandgap ( Eg) of 1.56 eV, indicating potential semiconducting property. The thermal stability of 1 was also investigated. [ABSTRACT FROM AUTHOR]

The title anion was synthesized by heating dimethylformamide (DMF) solution of the known Ni-centered and Ni(CO)-capped tin clusters [Ni@Sn9Ni(CO)]3−. The new anion represents the first example of face-fused nine-atom molecular clusters. The two clusters are identical elongated tricapped trigonal prisms of nido-[Sn8Ni(CO)]6− with nickel at one of the capping positions. They are fused along a triangular face adjacent to a trigonal prismatic base and made of two Sn and one Ni atoms. The new anion is structurally characterized by single-crystal X-ray diffraction in the compound (K[222-crypt])4[Sn14Ni(CO)]⋅DMF. Its presence in solution is corroborated by electrospray mass spectrometry. [ABSTRACT FROM AUTHOR]

Ordinary portland cement (OPC) has been extensively used in cold recycling asphalt and cold-mix asphalt as an additive in order to improve the early age performances of these mixtures. The main purpose of its application is that cement hydration benefits the strength development by consuming water and by accelerating the bitumen emulsion breaking. The aim of this study is to investigate the influence of cement on the rheology and stability of rosin-emulsified anionic bitumen emulsions. With this purpose, an anionic bitumen emulsion blended with various amounts of cement and limestone filler was studied by means of a Brookfield viscometer. Optical microscopy was used to investigate the breaking process of the bitumen emulsion and the morphology of bitumen droplets in the presence of cement and filler. In addition, the stability of anionic bitumen emulsions was studied in dependence of the pH and the calcium ion concentration. The results indicate that, unlike limestone filler, which has no significant influence on anionic bitumen emulsion, cement reacts with rosin emulsifiers and causes flocculation and partial coalescence of bitumen emulsions. This gelation of cement-bitumen emulsion blends appears to be caused by the interaction between cement grains and emulsifiers. While a decrease of the pH would lower the solubility of the emulsifiers, this is not a concern since cement dissolution increases the pH. [ABSTRACT FROM AUTHOR]

Complexes [(C4Me4)Co(CO)2{Co(P2C2 tBu2)2}] ( 1, C4Me4 = tetramethylcyclobutadiene) and [CpNi{Co(P2C2 tBu2)2}(PPh3)] ( 2, Cp = cyclopentadienyl) were synthesized by transmetalating [Tl(thf)2{Co(P2C2 tBu2)2}] with [(C4Me4)Co(CO)2I] and [CpNiBr(PPh3)]. Compounds 1 and 2 were fully characterized by X-ray crystallography, multinuclear NMR, UV/Vis, and IR spectroscopy, and elemental analysis. Their molecular structures show σ-coordination of one phosphorus atom of the [Co(P2C2 tBu2)2]- anion to the second metal atom (cobalt or nickel). Time-dependent density functional theory (TD-DFT) calculations were applied to gain insight into the electronic structures and the nature of the electronic transitions observed in the UV/Vis spectra. Cyclic voltammetry studies revealed the similar redox behavior of 1 and 2, which are reversibly oxidized to the corresponding monocations 1+ and 2+ with retention of the dinuclear structures. The cyclic voltammograms furthermore show that 1 and 2 decompose upon reduction with cleavage of the dinuclear structures into the free [Co(P2C2 tBu2)2]- anion and further uncharacterized products. [ABSTRACT FROM AUTHOR]

A novel phosphine-based tetragonal Ag4L2 cage has been assembled from a tetraphenylethylene (TPE)-based tetraphosphine and Ag+ ions. The cage structure is maintained both in solutions and in the solid state. Ag4L2 emits strong fluorescence not only in dilute solutions but also in aggregated states. The turn-on fluorescence of TPE-P4 in dilute solutions is attributed to the formation of Ag4L2. Ag4L2 shows potential as a fluorescent sensor towards anions and olefin compounds, which arises from binding of the guest anions/olefin compounds by its labile silver centres. [ABSTRACT FROM AUTHOR]

The radical anion of cyclopentasilane-fused hexasilabenzvalene was synthesized by the reduction of the corresponding neutral compound. X-ray crystallographic analysis showed a more trans-bent structure of the disilene moiety than the neutral compound. Theoretical calculations showed that the highly trans-bent structure is attributed to the hexasilabenzvalene structure. The EPR spectrum showed that an unpaired electron exists mainly at the disilene moiety. In the UV/Vis spectrum, a large bathochromic shift was observed compared with the neutral compound. [ABSTRACT FROM AUTHOR]

In the current study, two new flavones, 4'-O-geranyltricin (1) and 3'-O-geranylpolloin (2), and a new 2-(2-phenylethyl)-4H-chromen-4-one derivative, 7-hydroxyl-6- methoxy-2-(2-phenylethyl)chromone (3), have been isolated from the stem barks of A. sinensis, together with 21 known compounds 4-24. The structures of new compounds 1-3 were determined through spectroscopic and MS analyses. Compounds 2, 3, 5, 6, and 8-10 exhibited inhibition (IC50 ≤ 12.51 μM) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB). Compounds 3, 6, 8, 10, and 19 inhibited fMLP/CB-induced elastase release with IC50 values ≤ 15.25 μM. This investigation reveals bioactive isolates (especially 2, 3, 5, 6, 8, 9, 10, and 19) could be further developed as potential candidates for the treatment or prevention of various inflammatory diseases. [ABSTRACT FROM AUTHOR]