Synthesis Of Ga Research Articles

A Rare Example of a Gallium-Based Lewis Superacid: Synthesis and Reactivity of Ga(OTeF5)3.

The Lewis superacid Ga(OTeF5)3 has been synthesized and characterized, revealing a monomeric structure in solution and a dimeric structure in the solid state. Isolated adducts of Ga(OTeF5)3 with strong and weak Lewis bases have been characterized spectroscopically as well as by single-crystal X-ray diffractometry. The Lewis acidity of this new species has been evaluated by means of different experimental and theoretical methods, which has allowed to classify it as one of only a few examples of a gallium-based Lewis superacid. The high Lewis acidity of Ga(OTeF5)3 was used to amplify the strength of the Brønsted acid HOTeF5, leading to the protonation of diethyl ether. Furthermore, Ga(OTeF5)3 was utilized to access the strong oxidizing system Ga(OTeF5)3/Xe(OTeF5)2 in SO2ClF, which was successfully employed in the synthesis of the dimethyl chloronium salt [Cl(CH3)2][Ga(OTeF5)4], a strong electrophilic methylation reagent.

Solution studies, synthesis and antibacterial activity of Ga(III) complexes with bis-kojate derivatives

Given the recognized major problem of microbial drug resistance for human health, new metal-based drugs have been currently explored for their antimicrobial properties, including gallium-based compounds as potential metallophores that could perturb Fe’s interactions with proteins. Herein we have designed and synthesized two bis-kojate ligands (named L4 and L6) and studied their Ga(III) complexes for their physico-chemical and biological properties. In particular a detailed study of their complexation properties in aqueous solution, showed equilibrium models with formation of quite stable dinuclear 2:3 metal:ligand complexes, though with different stability. Solid state complexes were also prepared and characterized and complementary DFT studies indicated that [Ga2(L4)3] complex, with higher stability, seems to adopt a three-ligand bridging conformation, while that for L6 adopt a one ligand bridging conformation. Preliminary investigation of the antibacterial activity of these gallium complexes showed antipseudomonal activity, which appeared higher for the complex with L4, a feature of potential interest for the scientific community.

Investigation of group 13 elements as potential candidates for p-type dopants in the narrow-gap thermoelectric semiconductor α-SrSi2

AbstractTo investigate the possibility of p-type doping of α-SrSi2, a promising as an eco-friendly thermoelectric material, the energy changes of substitutions of the Si site of α-SrSi2 by group 13 elements were evaluated using first-principles calculations. It is found that Ga doping was the most energetically favorable dopant while In is the most unfavorable. We examined the synthesis of Ga- and In-doped α-SrSi2 using the vertical Bridgeman method and investigated their thermoelectric properties. The Ga atoms were doped to α-SrSi2 successfully up to 1.0 at. %, while In atoms could not be doped as suggested by calculations. For experimental prepared Ga-doped samples, the carrier density was observed to increase with Ga doping, from 3.58 × 1019 cm−3 for undoped α-SrSi2 to 4.49 × 1020 cm−3 for a 1.0 at. % Ga-doped sample at 300 K. The temperature dependence of carrier concentrations was observed to change from negative to positive with increasing Ga content. In addition, the temperature dependence of the Seebeck coefficient was also observed to change from negative to positive with increasing Ga content. The results indicate that α-SrSi2 undergoes a semiconductor–metal transition with Ga doping. The power factor for the undoped sample was quite high, at 2.5 mW/mK2, while the sample with 0.3 at. % Ga had a value of 1.1 mW/mK2 at room temperature.

Direct Conjugation of Gallium-(III)-Corroles to Short Interfering RNA(siRNA) Providing Real-Time siRNA Imaging and Gene Silencing.

Discovering new modifications for oligonucleotide therapeutics is essential for expanding its application to new targets and diseases. In this project, we focus on conjugating metaled ligands to short interfering RNAs (siRNAs) to investigate robust and simple conjugation methods for adding new properties such as real-time imaging to the siRNA. Here we report the chemical synthesis of novel Ga-(III)-corroles for their direct conjugation to siRNAs. Ga-(III)-corrole-siRNAs showed promising results when evaluated for gene silencing and live cell imaging. The knockdown activity of the firefly luciferase reporter gene was measured to evaluate gene silencing activity. Gene silencing studies from two 5'-Ga-(III)-labeled-siRNAs exhibited dose-dependent knockdown with IC50s of 812.7 and 451.4 pM, which is comparable to wild-type (IC50=439.7 pM) in the absence of red light, and IC50s of 562.9 and 354.5 pM, which is also comparable to wild-type (IC50=337.4 pM), in the presence of red light. In addition, imaging studies with Ga-(III)-corrole-modified siRNAs showed intense fluorescence in HeLa cells, highlighting that the Ga-(III)-corrole modification is an effective fluorophore for siRNA tracing and imaging. Moreover, the photodynamic activity of free base corrole vs the Ga-(III)-corrole was evaluated. Results show an increase of light cytotoxicity of the corrole ligand upon the addition of Ga-(III); however, no phototoxicity was observed when Ga-(III) ligands were linked to siRNA. In conclusion, Ga-(III)-corrole-siRNAs show promising results for applications in simultaneous real-time imaging and gene silencing.

Synthesis and Characterization of a Porous Ga2O3 Material with a Low Dielectric Constant

Synthesis and Characterization of a Porous Ga₂O₃ Material with a Low Dielectric Constant

OsGA3ox genes regulate rice fertility and plant height by synthesizing diverse active GA.

Gibberellin (GA) is an important hormone, which is involved in regulating various growth and development. GA biosynthesis pathway and synthetase have been basically clarified. Gibberellin 3β hydroxylase (GA3ox) is the key enzyme for the synthesis of various active GA. There are two GA3ox genes (OsGA3ox1 and OsGA3ox2) in rice, and their physiological functions have been preliminarily studied. However, it is not clear how they work together to synthesize active GA to regulate rice development. In this study, the knockout mutants ga3ox1 and ga3ox2 were obtained by CRISPR/Cas9 technology. The pollen fertility of ga3ox1 decreased significantly, while the plant height of ga3ox2 decreased significantly. It shows that OsGA3ox1 is necessary for normal pollen development, while OsGA3ox2 is necessary for stem and leaf elongation. Tissue expression analysis showed that OsGA3ox1 was mainly expressed in unopened flowers, while OsGA3ox2 was mainly expressed in unexpanded leaves. The GA in different tissues of wild type (WT), and two ga3ox mutants were detected. It was found that pollen fertility is most closely related to the content of GA7, and plant height is most closely related to the content of GA1. It was found that OsGA3ox1 catalyzes GA9 to GA7 in flowers, which is closely related to pollen fertility; OsGA3ox2 catalyzes the GA20 to GA1 in unexpanded leaves, thereby regulating plant height; OsGA3ox1 catalyzes the GA19 to GA20 in roots, regulating the generation of GA3. OsGA3ox1 and OsGA3ox2 respond to developmental and environmental signals, and cooperate to synthesize endogenous GA in different tissues to regulate rice development. This study provides a reference for clarifying its role in GA biosynthesis pathway and further understanding the function of OsGA3ox.

Top-down vs. bottom-up synthesis of Ga–based supported catalytically active liquid metal solutions (SCALMS) for the dehydrogenation of isobutane

Supported catalytically active liquid metal solutions (SCALMS) catalysts consist of a liquid metal solution of an active metal (e.g., Pd, Rh, Pt, Ni) in a low melting metal (e.g., Ga, In, Sn) deposited on a porous support material. In the current study, we extend and optimize the recently developed top-down synthesis protocol (ultrasonication of gallium metal) to prepare GaPd, GaRh and GaPt SCALMS systems. We compare the morphological differences in the obtained catalyst materials achieved between this approach and the more traditional bottom-up synthesis protocol (in situ thermal decomposition of triethylamino-gallane complex) using electron microscopy. Moreover, the spatial distribution of the catalytically active material in the porous alumina support is evaluated using high resolution argon physisorption measurements. Both techniques strongly indicate that the bottom-up approach leads to a high degree of pore penetration while the gallium droplets are largely on the outer surface in case of the top-down method. Changes to the surface chemistry of the support were also investigated by means of NH3/CO2 temperature programmed desorption. All catalytic systems synthesized by the two synthesis methods, i.e., GaPd, GaRh and GaPt, were tested in a quartz, fixed-bed tubular reactor for isobutane dehydrogenation. All SCALMS materials, irrespective of their individual synthesis protocol, were significantly more active than their pure metal counterparts. The SCALMS catalyst prepared using the bottom-up approach showed initial productivity of 407gbutenes molM–1 min−1, 832gbutenes molM–1 min−1, and 963gbutenes molM–1 min−1 for the GaPd, GaRh and GaPt respectively. These values represent more than twice the initial activity obtained with the top-down synthesized counterparts. This activity difference can be explained by the analytically determined difference in liquid metal droplet size distribution.

Synthesis and gas-sensitive properties of Ga doped in MOF-derived Co3O4

Synthesis and gas-sensitive properties of Ga doped in MOF-derived Co3O4

Ga–C and Ga–Ga bond formation using a NON-ligated gallyl nucleophile

We report an improved synthesis of the NON-donor stabilized potassium gallyl dimer [K{Ga(NON)}]2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethyl-xanthene) from (NON)GaI and potassium naphthalenide that avoids issues associated with over-reduction of the metal centre. The use of [K{Ga(NON)}]2 in the synthesis of Ga–E bonds has been explored through its reactions with a range of electrophiles. The reaction with (NON)GaI to give {Ga(NON)}2 via Ga–Ga bond formation mirrors the behaviour of the corresponding aluminyl compound, while Ga–C bond formation via nucleophilic attack on 1-bromopentane to give (NON)Ga(n-pentyl) avoids the retention of KBr often encountered in the formation of (more Lewis acidic) AlIII compounds. Attempted formation of a Mg–Ga bond, e.g. via the reaction of [K{Ga(NON)}]2 with (NacnacMes)MgI(OEt2), generates instead the unsymmetrical digallane(4), (NacnacMes)Ga(μ2-N,N'-NON)GaI, consistent with enhanced lability of Ga (over Al) within the NON-ligand scaffold.

Microemulsion synthesis of Ga and Sr doped BiFeO3 nanoparticles and evaluation of their ferroelectric, optical, dielectric and photocatalytic properties

A series of Ga and Sr doped bismuth ferrite (BiFeO₃) was synthesized using a facile microemulsion technique and characterized using XRD, SEM, Raman, PL and UV–vis techniques. The XRD and Raman study revealed the rhombohedral phase of Bi1-xSrxFe1-xGayO3 with R3‾c space group. The average crystalline size was in range of 28–42 nm. From P-E loop, the saturation polarization (Ps), coercivity (Hc) and remanence (Pr) were determined and value of Pr and Ps increased with increasing dopant contents. Furthermore, there was a decline in dielectric loss with increased frequency and dopant content. The PL revealed that the highly substituted material had lower re-combination rate and higher charge (e−-h+) separation, which was finally responsible for its enhanced photo-catalytic activity. For Ga and Sr doped BiFeO₃, UV–Vis absorption edge exhibited substantial red shift thus reducing bandgap from 1.91 to 1.19 eV for highest doped composition. Finally, the photocatalytic activity of the material was investigated using methyl orange (MO) as model contaminant. Bi1-xSrxFe1-xGayO3 exhibited much better photocatalytic efficiency and degraded 87% dye in comparison to pristine BiFeO3 (66%) within 70 min under solar light. Also, stability of samples was demonstrated through re-cycling experiment. Bi1-xSrxFe1-xGayO3 had higher stability and reusability compared to BiFeO₃. Based on these findings, Bi1−xSrxFe1−yGayO3 material may find use in high frequency devices and photo-catalytic applications for treatment of industrial wastes due to its promising dielectric and photo-catalytic outcomes.

Synthesis and characterisation of Ga- and In-doped CdS by solventless thermolysis of single source precursors.

We report a facile and low temperature synthesis of Ga- and In-doped CdS nanoparticles from molecular precursors. Diethyldithiocarbamate complexes of Cd(II), Ga(III), and In(III), were synthesised and decomposed in tandem through solventless thermolysis, producing Ga- or In-doped CdS. The resultant MxCd1-xS1+0.5x (where M = Ga/In at x values of 0, 0.02, 0.04, 0.06, 0.08 and 0.1) particulate powder was analysed by powder X-ray diffraction, which showed that both Ga (through all doping levels) and In (at doping levels <8 mol%) were successfully incorporated into the hexagonal CdS lattice without any impurities. Raman spectroscopy also showed no significant change from CdS. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to investigate the morphology and elemental dispersion through the doped CdS materials, showing homogenous incorporation of dopant. The optical and luminescent properties of the doped MxCd1-xS1+0.5x materials were examined by UV-Vis absorption and photoluminescence spectroscopies respectively. All materials were found to exhibit excitonic emission, corresponding to band gap energies between 2.7 and 2.9 eV and surface defect induced emission which is more prominent for Ga than for In doping. Additionally, moderate doping slows down charge carrier recombination by increasing the lifetimes of excitonic and surface state emissions, but particularly for the latter process.

Synthesis, characterisation and antibacterial activity of novel Ga(III) polypyridyl catecholate complexes.

Ga(III) polypyridyl catecholate complexes of type [Ga(bipy)2(O,O)](NO3) or [Ga(phen)2(O,O)](NO3) respectively were readily synthesised on reaction of Ga(NO3)3 in methanol with 1 equivalent of catecholate ligand (2,3-DHBA, 3,4-DHBA, 2,3,4-THBA or CafA) and then 2 equivalents of either bipy or phen. The complexes were characterised in full including by X-ray crystallography, which established that the catecholate ligands coordinate the Ga(III) centres in a bidentate manner via the two deprotonated hydroxy groups. All Ga(III) complexes exhibited good in vitro antibacterial activity against the Gram-negative pathogenic bacteria Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The complexes were inactive against the Gram-positive pathogenic bacteria Staphylococcus aureus including against a methicillin-resistant Staphylococcus aureus strain (MRSA). [Ga(bipy)2(2,3-DHBA-2H)](NO3)·1.5H2O (1) was shown to be non toxic in vivo in larvae of Galleria mellonella at doses up to 2000 μg mL-1 and to offer protection at doses of 100 and 250 μg mL-1 at 48 and 96 h to larvae infected with P. aeruginosa.

OsCSN1 regulates the growth of rice seedlings through the GA signaling pathway in blue light

Blue light can regulate the photomorphogenesis of plants through blue light receptors to influence seedling growth and development. The COP9 signaling complex (CSN), a vital regulator of photomorphogenesis, is a highly conserved protein complex. CSN1 is the largest and most critical subunit in the CSN with a complex N-terminal function that supports most of the functions of CSN1 and is mainly involved in plant growth and development processes. The CSN is also required in the blue light-mediated photomorphogenesis response of seedlings. In this study, the OsCSN1 subunit of Oryza sativa subsp. japonica (rice) was edited and screened, and OsCSN1 deletion mutant, OsCSN1 weak expression mutant and OsCSN1 overexpression mutant were constructed. The mechanism of OsCSN1 and its N-terminal effects on rice seedling growth and development under blue light conditions were investigated. The addition of exogenous hormone gibberellin (GA3) and gibberellin synthesis inhibitor paclobutrazol (PAC) caused aboveground phenotypic and protein (such as CUL4 and SLR1) changes. Blue light regulates the degradation of SLR1 through OsCSN1, which regulates the growth and development of rice seedling height, the first incomplete leaf, and the coleoptile. It is hypothesized that rice affects CRY-COP1 interactions after sensing blue light signals through the cryptochrome, and the nuclear localization of COP1 is regulated by the CSN complex. OsCSN1 is a negative regulator in response to blue light. The core structural domain of action that inhibits the growth of the aboveground part of rice seedlings is located at the N-terminal of OsCSN1. OsCSN1 regulates the nuclear localization of COP1 through the COP9 signaling complex and degrades SLR1 through CUL4-based E3 ligase. Ultimately, it affects the synthesis of the endogenous hormone GA, thereby inhibiting the aboveground growth and development of rice seedlings.

Soil-to-fruit nitrogen flux mediates the onset of fruit-nitrogen remobilization and color change in citrus

In non-climacteric fruit tree species, color change is primarily controlled by the interplay between environmental conditions, nutritional factors (nitrogen and sugars) and hormones, mainly abscisic acid and gibberellins (GA), through a complex mechanism which is not completely understood. Nitrogen has a strong impact on color change, influenced by environmental changes, either locally or at the whole tree level. We use Citrus trees, as a non-climacteric model species, to understand the long-distance nitrogen signaling mechanism delaying the chloroplast-to-chromoplast transition at the molecular level. It is unknown whether nitrogen regulates the branch point of geranylgeranyl diphosphate (GGPP), the shared precursor for gibberellin, chlorophyll and carotenoid synthesis. We used 15 N to trace the root-to-fruit nitrogen flux in trees grown under soils differing in nitrogen content and temperature, and treated with NH 4 NO 3 and GA. Key genes involved in nitrogen signaling, transport and metabolism, and those from the GGPP branch point were analyzed in the fruit. Results explain how soil temperature modifies 15 N transport to play a key role in signaling citrus color change, and show that fruit-nitrogen remobilization is required for triggering degreening. Nitrogen content in the fruit modulates the onset of glutamate deamination, asparagine synthesis, nitrite assimilation and GA 1 depletion. Expression of the nitrate transporter NRT1.2, glutamate dehydrogenase and asparagine synthetase genes was high right before the start of degreening, together with NH 4 + concentration. Nitrogen delayed carotenoid synthesis (phytoene synthase gene expression) without modifying gibberellin synthesis ( ent -kaurene synthase and oxidase) at the chloroplast level. • N and GA 1 depletion from the fruit is a prerequisite for citrus color change • Cold-soil temperatures reduce 15 N translocation and trigger fruit color change • Low N flux correlates fruit protein hydrolysis, upregulating GDH, AS and NRT1.2 • GA treatment delays protein hydrolysis, NRT1.2 expression and N depletion • The first steps of synthesis of GA in the chloroplast are not modified by N

Sonochemical synthesis of supersaturated Ga–Al liquid-alloy fine particles and Al3+-doped γ-Ga2O3 nanoparticles by direct oxidation at near room temperature

In this study, we investigated the fabrication of supersaturated gallium (Ga)–aluminum (Al) liquid alloy and Al3+-doped γ-Ga2O3 nanoparticles (NPs) at near room temperature (60 °C) using sonochemical and sonophysical effects. Supersaturated Ga–Al liquid alloy microparticles (Dav = 1.72 µm) were formed and stabilized at 60 °C by the thermal nonequilibrium field provided by sonochemical hot spots. Compared with liquid Ga, supersaturated Ga–Al liquid alloy was rapidly oxidized to a uniform oxide without Al2O3 or Al deposition. Thus, ultrafine Al3+-doped γ-Ga2O3 NPs were obtained after only 1 h of ultrasonic irradiation at 60 °C. The oxidation of liquid Ga was remarkably accelerated by alloying with metallic Al and ultrasonic irradiation, and the time was shortened. The average diameter and surface area of the γ-Ga2O3-based NPs were 59 nm and 181 m2/g, respectively. Compared with γ-Ga2O3, the optical bandgap of the Al3+-doped γ-Ga2O3 NPs was broadened, and the thermal stability improved, indicating Al3+-doping into the γ-Ga2O3 lattice. However, the lattice constant of γ-Ga2O3 was almost unchanged with or without Al3+-doping. Al3+ was introduced into the defect sites of Ga3+, which were massively induced in the defective spinel structure during ultrasonic processing. Therefore, sonochemical processing, which provides nonequilibrium reaction fields, is suitable for the synthesis of supersaturated and metastable materials in metals and ceramics fields.

Conversion of glucose to fructose over Sn and Ga-doped zeolite Y in methanol and water media

In this study, we use zeolite Y as a support for the synthesis of Sn and Ga doped zeolites aimed at the isomerization of glucose to fructose. Though these materials are inactive in water, they are active in methanol and we could ascertain a reaction pathway involving a hydride shift for the interconversion of glucose to fructose and mannose, and a Brønsted acid pathway with the formation of a methyl fructoside intermediate and its hydrolysis to fructose if water was added afterwards. By using characterizations comprising: chemisorption, XPS, XRD, HAADF-STEM and EXAFS; it was possible to demonstrate that a straightforward impregnation protocol for the preparation of our catalysts, led to Sn/Y mainly consisting of small SnO2 clusters on the external surface of the zeolite, whereas Ga/Y consisting of highly dispersed Ga species mostly inside the zeolite pores; and a catalytic activity that appears to be dominated by Brønsted acid sites.

Synthesis, mechanism and characterization of urchin-like Ga2O3 microspheres

A simple sonication–heat treatment method to prepare novel urchin-like β-Ga2O3 microspheres with uniformly distributed nanowires is reported. Its unique morphology is expected to have potential in optoelectronic devices and other fields.

Sonochemical Synthesis of Supersaturated Ga–Al Liquid-Alloy Fine Particles and Al3+-Doped γ-Ga2O3 &amp;nbsp;Nanoparticles by Direct Oxidation at Near Room Temperature

Sonochemical Synthesis of Supersaturated Ga–Al Liquid-Alloy Fine Particles and Al3+-Doped γ-Ga2O3 &amp;nbsp;Nanoparticles by Direct Oxidation at Near Room Temperature

Scalable Synthesis of Ga2O3/N‐Doped C Nanopapers as High‐Rate Performance Anode for Li‐Ion Batteries

AbstractGa2O3 is a promising anode material for lithium ion batteries (LIBs) owing to its high theoretical capacity and low lithiation potential. However, its performance improvement has been seriously hindered by the sluggish reaction kinetics. Herein, Ga2O3/N doped C nanopapers (Ga2O3/NC NPs) are firstly designed and synthesized via a scalable biomass‐aided approach. The as‐prepared Ga2O3/NC NPs deliver high reversible capacity and prominent rate capability as anode for LIBs, owing to its excellent reaction kinetics. It shows high discharge capacity of 477 mAh g−1 after 200 cycles at 0.2 A g−1, without obvious capacity attenuation upon cycling. After 3 periodic rate performance testing ranging from 0.1 to 1.6 A g−1, the reversible capacity of the Ga2O3/NC NPs still retains to 517 mAh g−1 when the current is reverting to 0.1 A g−1. The low and safe working potential, the prominent electrochemical performance and the scalable synthesis method for the Ga2O3/NC NPs endow it with great promising toward practical application.

Gibberellin Oxidase Gene Family in L. chinense: Genome-Wide Identification and Gene Expression Analysis.

GAox is a key enzyme for the transformation of gibberellins, and belongs to the 2-ketoglutarate dependent dioxygenase gene family (2ODD). However, a systematic analysis of GAox in the angiosperm L. chinense has not yet been reported. Here, we identified all LcGAox gene family members in L. chinense, which were classified into the three subgroups of GA20ox, C19GA2ox, and C20GA2ox. Comparison of the gene structure, conserve motifs, phylogenetic relationships, and syntenic relationships of gibberellin oxidase gene families in different species indicated that the gene functional differences may be due to the partial deletion of their domains during evolution. Furthermore, evidence for purifying selection was detected between orthologous GAox genes in rice, grape, Arabidopsis, and L. chinense. Analysis of the codon usage patterns showed that mutation pressure and natural selection might have induced codon usage bias in angiosperms; however, the LcGAox genes in mosses, lycophytes, and ambarella plants exhibited no obvious codon usage preference. These results suggested that the gibberellin oxidase genes were more primitive. The gene expression pattern was analyzed in different organs subjected to multiple abiotic stresses, including GA, abscisic acid (ABA), and chlormequat (CCC) treatment, by RNA-seq and qRT-PCR, and the stress- and phytohormone-responsive cis-elements were counted. The results showed that the synthesis and decomposition of GA were regulated by different LcGAox genes in the vegetative and reproductive organs of L. chinense, and only LcGA2ox1,4, and 7 responded to the NaCl, polyethylene glycol, 4 °C, GA, ABA, and CCC treatment in the roots, stems, and leaves of seedlings at different time periods, revealing the potential role of LcGAox in stress resistance.