II), Gallium Research Articles

Serving Two Masters: Effect of Escherichia coli Dual Resistance on Antibiotic Susceptibility

The prevalence of multidrug-resistant bacteria and their increased pathogenicity has led to a growing interest in metallic antimicrobial materials and bacteriophages as potential alternatives to conventional antibiotics. This study examines how resistance to excess iron (III) influences the evolution of bacteriophage resistance in the bacterium Escherichia coli. We utilized experimental evolution in E. coli to test the effect of the evolution of phage T7 resistance on populations resistant to excess iron (III) and populations without excess iron resistance. Phage resistance evolved rapidly in both groups. Dual-resistant (iron (III)/phage) populations were compared to their controls (excess iron (III)-resistant, phage-resistant, no resistance to either) for their performance against each stressor, excess iron (III) and phage; and correlated resistances to excess iron (II), gallium (III), silver (I) and conventional antibiotics. Excess iron (III)/phage-resistant populations demonstrated superior 24 h growth compared to all other populations when exposed to increasing concentrations of iron (II, III), gallium (III), ampicillin, and tetracycline. No differences in 24 h growth were shown between excess iron (III)/phage-resistant and excess iron (III)-resistant populations in chloramphenicol, sulfonamide, and silver (I). The genomic analysis identified selective sweeps in the iron (III) resistant (rpoB, rpoC, yegB, yeaG), phage-resistant (clpX →/→ lon, uvaB, yeaG, fliR, gatT, ypjF, waaC, rpoC, pgi, and yjbH) and iron (III)/phage resistant populations (rcsA, hldE, rpoB, and waaC). E. coli selected for resistance to both excess iron (III) and T7 phage showed some evidence of a synergistic effect on various components of fitness. Dual selection resulted in correlated resistances to ionic metals {iron (II), gallium (III), and silver (I)} and several conventional antibiotics. There is a likelihood that this sort of combination antimicrobial treatment may result in bacterial variants with multiple resistances.

Synthesis and photophysicochemical properties of novel thiadiazole-substituted zinc (II), gallium (III) and silicon (IV) phthalocyanines for photodynamic therapy

Peripherally electron withdrawing thiadiazole substituted phthalocyanine Zn(II), Ga(III) and axially disubstituted Si(IV) complexes have been synthesized for the first time. These new phthalocyanine compounds have been characterized by spectral methods such as FT-IR, 1H NMR, UV–vis spectra, Mass spectra and elemental analyses. In this study, the ground state electronic absorption spectra and the nature of the metal ion on the photophysical and photochemical parameters of the phthalocyanines are also presented. The closed shell and diamagnetic ions (Zn(II), Ga(III) and Si(IV)) gave high quantum yields of singlet oxygen (ΦΔ, 0.49, 0.81 and 0.86 in DMSO), which makes them potential photosensitizer for use in photodynamic therapy (PDT) of cancer.

Engineering Chemically Exfoliated Large-Area Two-Dimensional MoS2 Nanolayers with Porphyrins for Improved Light Harvesting.

Molybdenum disulfide (MoS2 ) is a promising candidate for electronic and optoelectronic applications. However, its application in light harvesting has been limited in part due to crystal defects, often related to small crystallite sizes, which diminish charge separation and transfer. Here we demonstrate a surface-engineering strategy for 2D MoS2 to improve its photoelectrochemical properties. Chemically exfoliated large-area MoS2 thin films were interfaced with eight molecules from three porphyrin families: zinc(II)-, gallium(III)-, iron(III)-centered, and metal-free protoporphyrin IX (ZnPP, GaPP, FePP, H2 PP); metal-free and zinc(II) tetra-(N-methyl-4-pyridyl)porphyrin (H2 T4, ZnT4); and metal-free and zinc(II) tetraphenylporphyrin (H2 TPP, ZnTPP). We found that the photocurrents from MoS2 films under visible-light illumination are strongly dependent on the interfacial molecules and that the photocurrent enhancement is closely correlated with the highest occupied molecular orbital (HOMO) levels of the porphyrins, which suppress the recombination of electron-hole pairs in the photoexcited MoS2 films. A maximum tenfold increase was observed for MoS2 functionalized with ZnPP compared with pristine MoS2 films, whereas ZnT4-functionalized MoS2 demonstrated small increases in photocurrent. The application of bias voltage on MoS2 films can further promote photocurrent enhancements and control current directions. Our results suggest a facile route to render 2D MoS2 films useful for potential high-performance light-harvesting applications.

Stabilisation of an inorganic digallane by the phosphinobisthiolato P,S,S pincer ligand PPh(2-SC6H4)2

The pincer ligand PPh(2-HSC6H4)2 reacts with GaCl3 in the presence of triethylamine to yield the anionic gallium complex [NEt3H][Ga{PPh(2-SC6H4)2-κ3S,S′,P}{PPh(2-SC6H4)2-κ2S,S′}] (1), which undergoes cation exchange with PPh4Cl to give [PPh4][Ga{PPh(2-SC6H4)2-κ3S,S′,P}{PPh(2-SC6H4)2-κ2S,S′}] (2). Neutral complexes GaR{PPh(2-SC6H4)2-κ3S,S′,P} [R = Me (3), tBu (4)] were obtained by reaction of PPh(2-HSC6H4)2 with trialkyl gallium compounds (GaMe3, GatBu3). Compound 4 is light-sensitive and decomposes in daylight or under UV irradiation. Three decomposition products could be isolated: tetranuclear hydrido-bridged mixed-valent gallium(II)–gallium(III) complex [GaIII{PPh(2-SC6H4)-κ2S,P-μ-(2-SC6H4)-κS′}2]2(μ3-H)2GaII2 (Ga–Ga) (5), gallium(II) complex [Ga{PPh(2-SC6H4)2-κ3S,S′,P}]2 (Ga–Ga) (6), and sulfido-bridged dinuclear complex [Ga{PPh(2-SC6H4)2-κ3S,S′,P}]2(μ-S) (7). The molecular structures of 2–7 are described.

Synthesis and Crystal Structures of New Palladium(II)—Gallium(III) Complexes with Bridging Halogenide Ligands.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and Crystal Structures of New Palladium(II)—Gallium(III) Complexes with Bridging Halogenide Ligands

AbstractThe reaction of palladium(II) bromide or palladium(II) iodide with the respective gallium(III) halogenide in the presence of aromatic solvents leads to the formation of palladium(II) tetrabromo— and tetraiodogallate. The compounds are isostructural {monoclinic, C2/m, Pd[GaBr4]2: a = 1267(2), b = 808(1), c = 722(1) pm, β = 94.5(1)°; Pd[GaI4]2: a = 1363(1), b = 849.9(4), c = 756.6(7) pm, β = 95.38(3)°}. The structures contain mononuclear complexes Pd[GaX4]2, where X— = Br— (1), I— (2). The crystal structures of 1 and 2 were determined by single‐crystal X‐ray diffraction. Crystals of both compounds turned out to be similarly twinned.

Cytotoxic analogs of the iron(III) chelator pyridoxal isonicotinoyl hydrazone: effects of complexation with copper(II), gallium(III), and iron (III) on their antiproliferative activities.

This study examined if complexation with metals increased the antiproliferative activities of chelators of the pyridoxal isonicotinoyl hydrazone (PIH) class. Addition of iron(III) to some PIH analogs markedly depressed their activities, whereas it had little effect on others. The gallium(III) complex of PIH, but not its copper(II) complex, was more efficient than the apochelator at inhibiting [3H]thymidine incorporation.

Analytical separation of antimony(III) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) with cyanex 302

A method is proposed for the separation of antimony(III) (100–400 μg) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) from an aqueous solution of pH 0.5–1.5 using 8×10−3−1×10−2 mol dm−3 cyanex 302 dissolved in toluene as an extractant. The antimony is stripped from the cyanex phase with water and determined spectrophotometrically with iodide. Various experimental parameters are optimized and the probable 1∶3 stoichiometry of the extracted species is evaluated. The method is applicable to the analysis of alloys and pharmaceutical samples. The separation and determination take only 20 min.

Macrocyclic (C22H22N4) complexes of germanium(II), tin(II), gallium(III), and indium(III). Main group functionalities in unusual environments

Macrocyclic (C22H22N4) complexes of germanium(II), tin(II), gallium(III), and indium(III). Main group functionalities in unusual environments

Reactions of 15-crown-5 and bis-15-crown-5 ethers with metal acetylacetonate ions in the gas phase

1. A study was carried out on the ion-molecule reactions of ions arising in the dissociation of ferric, cobaltic, chromic, manganous, neodymium(II), gallium(III), and indium(III) acetylacetonates upon electron impact with 15-crown-5 and bis-15-crown-5. 2. The ratio of the yields of (acac)xM+L andx-1M+L ions (M is a metal, L is a macrocyclic ligand, and x=1 or 2) is determined by the case of reductionof M(x+1)+ to Mx+ and for (acac)3M complexes, this ratio decreases in the series Nd, In, Ga>Cr>Fe, Co. The rate constant for the formation of acacCoL+ ions is greater than for acacFeL+ ions. 3. The possibility of fixing transition metals in unstable oxidation states by crown ethers was demonstrated in the case of nickel.

Analytical reactions of substituted cyanoferrates: 4. Spectrophotometric determination of beryllium(II), gallium(III), and indium(III) in solution

A new spectrophotometric method for microanalysis of Be 2+, Ga 3+, and In 3+ in solution has been developed. These ions accelerate formation of colored pentacyanoazidoferrate(III) species (absorbing at 555 nm) under alkaline conditions. Ga 3+ and In + have been quantified in the ranges 0.4–4.0 and 0.4–3.0 ppm, respectively, while for Be 2+ the range extends to 10 ppm. The reaction is nonselective, but some cations and anions can be tolerated at comparable concentrations.