ChemInform Abstract: Synthesis,Structure, and Electronic Structure of CsAgGa2Se4.

The new title compound is prepared from a mixture of AgGaSe₂ (obtained from the elements at 900 °C, 2 d) and CsI in the molar ratio 1:2 (silica tube, Ar, 800 °C, 48 h).     

Electronic Structure and Redox Properties of Metal Nitride Endohedral Fullerenes M3N@C2n (M=Sc,Y, La,and Gd; 2n=80, 84, 88, 92, 96)

An extensive study of the redox properties of metal nitride endohedral fullerenes (MNEFs) based on DFT computational calculations has been performed. The electronic structure of the singly oxidized and reduced MNEFs has been thoroughly analyzed and the first anodic and cathodic potentials, as well as the electrochemical gaps, have been predicted for a large number of M₃N@C_2n systems (M=Sc, Y, La, and Gd; 2n=80, 84, 88, 92, and 96). In particular, calculations that include thermal and entropic effects correctly predict the different anodic behavior of the two isomers (I_h and D_5h) of Sc₃N@C₈₀, which is the basis for their electrochemical separation. Important differences were found in the electronic structure of reduced M₃N@C₈₀ when M=Sc or when M is a more electropositive metal, such as Y or Gd. Moreover, the changes in the electrochemical gaps within the Gd₃N@C_2n series (2n=80, 84, and 88) have been rationalized and the use of Y‐based computational models to study the Gd‐based systems has been justified. The redox properties of the largest MNEFs characterized so far, La₃N@C_2n (2n=92 and 96), were also correctly predicted. Finally, the quality of these predictions and their usefulness in distinguishing the carbon cages for MNEFs with unknown structures is discussed.     

Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

An ab initio theoretical investigation has been performed on planar or quasi-planar octa-and ennea-coordinate Al and Ga centered in X@B8- and X@B9 (X=Al, Ga). These high symmetry molecular wheels all turned out to be true minima of the systems and σ+π double aromatic in nature, similar to the previously characterized D8h B@B8- both electronically and geometrically. Adiabatic and vertical detachment energies of the anions and the ionization potentials of the neutrals have been calculated to aid their eventua...     

Extraction of Gallium (III) with O,O, S-Triethyldithiophosphate

Abstract

A method is presented for the rapid solvent extraction of gallium (III) with o, o, s-triethyldithiophosphate. Quantitative extraction results from 4–9 M hydrochloric acid, using 100% extractant. The extract-able species is H[GaCl₄]·2(C₂H₅ O₂)₂ P(S)SC₂H₅.     

Spectrofluorimetric Determination of Gallium with 5-Bromosalicylidene-o-Aminophenol

Abstract

A method for the determination of trace amounts of gallium has been developed, based on the formation of a fluorescent complex between Ga (III) and 5-Bromosalicylidene-o-aminophenol (5-BrSOAPh). With excitation at 425 nm the chelate has an emission maximum at 520 nm. The reaction is carried out at apparent pH (pH?) 5.40 in an aqueous-ethanol medium (60% V/V ethanol). The influence of the reaction variables is discussed.     

Series of compositions Bi2(M′xM1−x)4O9 (M′, M=Al, Ga, Fe; 0≤x≤1) with mullite-type crystal structure: Synthesis, characterization and O/O exchange experiment

Series of compositions Bi₂(M′_xM_1−x)₄O₉ with x=0.0, 0.1,…, 1.0 and M′/M=Ga/Al, Fe/Al and Fe/Ga were synthesized by dissolving appropriate amounts of corresponding metal nitrate hydrates in glycerine, followed by gelation, calcination and final heating at 800 °C for 24 h. The new compositions with M′/M=Ga/Al form solid-solution series, which are isotypes to the two other series M′/M=Fe/Al and Fe/Ga. The XRD data analysis yielded in all cases a linear dependence of the lattice parameters related on x. Rietveld structure refinements of the XRD patterns of the new compounds, Bi₂(Ga_xAl_1−x)₄O₉ reveal a preferential occupation of Ga in tetrahedral site (4 h). The IR absorption spectra measured between 50 and 4000 cm⁻¹ of all systems show systematic shifts in peak positions related to the degree of substitution. Samples treated in ¹⁸O₂ atmosphere (16 h at 800 °C, 200 mbar, 95% ¹⁸O₂) for ¹⁸O/¹⁶O isotope exchange experiments show a well-separated IR absorption peak related to the M-¹⁸O_c-M vibration, where O_c denotes the common oxygen of two tetrahedral type MO₄ units. The intensity ratio of M-¹⁸O_c/M-¹⁶O_c IR absorption peaks and the average crystal sizes were used to estimate the tracer diffusion coefficients of polycrystalline Bi₂Al₄O₉ (D=2×10⁻²² m²s⁻¹), Bi₂Fe₄O₉ (D=5×10⁻²¹ m²s⁻¹), Bi₂(Ga/Al)₄O₉ (D=2×10⁻²¹ m²s⁻¹) and Bi₂Ga₄O₉ (D=2×10⁻²⁰ m²s⁻¹).     

Synthesis and Characterization of Cationic Low‐Valent Gallium Complexes of Cryptand[2.2.2]

The synthesis and characterization of two bimetallic, cationic low‐valent gallium–cryptand[2.2.2] complexes is reported. The reaction of cryptand[2.2.2] with Ga₂Cl₄ gave two different cations, [Ga₃Cl₄(crypt‐222)]⁺ ( 1 ) or [Ga₂Cl₂(crypt‐222)]²⁺ ( 2 ), depending on whether or not trimethylsilyl triflate (Me₃SiOTf) was added as a co‐reagent. Complexes 1 and 2 are the first examples of bimetallic cryptand[2.2.2] complexes, as well as the first low‐valent gallium–cryptand[2.2.2] complexes. Computational methods were used to evaluate the bonding in the gallium cores.     

Immobilization of thiabendazole-specific monoclonal antibodies to silicon substrates via aqueous silanization

Monoclonal antibodies specific for thiabendazole were immobilized to silicon, silicon dioxide, stoichiometric silicon nitride, and silicon-rich silicon nitride surfaces. This work provides the foundation for the development of a homogeneous sensor system for rapid detection and quantification of thiabendazole residues in produce and animal tissue. Immobilization was performed via aqueous silanization of the substrate followed sequentially by treatment with glutaraldehyde and contact with antibody solution in the presence of detergent. Surfaces were challenged with thiabendazole-horseradish peroxidase conjugate in an ELISA format to estimate immobilized antibody load. A stable and reproducible surface loading of 2 x 10¹¹ antibodies/cm² was obtained only after surfaces received postimmobilization treatments to remove nonspecifically adsorbed antibody. No difference in surface loading was noted when using 30% hydrogen peroxide rather than nitric acid for silanol activation. Little difference was noted among the antibody loadings achieved on the various silicon substrates. Bound antigen-enzyme conjugate was eluted with 0.1N acetic acid and reproducible surface activity was measured for up to four consecutive antigen challenges. Immobilized antibody surfaces were stabilized with 2% sucrose, dehydrated at 37‡C and stored in vacuum or stored at 4‡C in phosphate buffered saline containing 0.01% sodium azide without significant loss of activity.