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Molecules (Basel, Switzerland) Feb 2020In order to improve the suitability of NaBH as a clean fuel, its decomposition temperature needs to be decreased to below 535 °C, while its hydrogen release must be as...
In order to improve the suitability of NaBH as a clean fuel, its decomposition temperature needs to be decreased to below 535 °C, while its hydrogen release must be as high as possible. In this work, the influence of a collection of first and second period transition metal fluorides on the destabilization of NaBH is studied on samples produced by ball milling NaBH with 2 mol% of a metal fluoride additive. The effects obtained by increasing additive amount and changing oxidation state are also evaluated for NbF, CeF, and CeF. The as-milled products are characterized by in-house power X-ray diffraction, while the hydrogen release and decomposition are monitored by temperature programmed desorption with residual gas analysis, differential scanning calorimetry, and thermogravimetry. The screening of samples containing 2 mol% of additive shows that distinctive groups of transition metal fluorides affect the ball milling process differently depending on their enthalpy of formation, melting point, or their ability to react at the temperatures achieved during ball milling. This leads to the formation of NaBF in the case of TiF, MnF, VF, CdF, NbF, AgF, and CeF and the presence of the metal in CrF, CuF, and AgF. There is no linear correlation between the position of the transition metal in the periodic table and the observed behavior. The thermal behavior of the products after milling is given by the remaining NaBH, fluoride, and the formation of intermediate metastable compounds. A noticeable decrease of the decomposition temperature is seen for the majority of the products, with the exceptions of the samples containing YF, AgF, and CeF. The largest decrease of the decomposition temperature is observed for NbF. When comparing increasing amounts of the same additive, the largest decrease of the decomposition temperature is observed for 10 mol% of NbF. Higher amounts of additive result in the loss of the NaBH thermal signal and ultimately the loss of the crystalline borohydride. When comparing additives with the same transition metal and different oxidation states, the most efficient additive is found to be the one with a higher oxidation state. Furthermore, among all the samples studied, higher oxidation state metal fluorides are found to be the most destabilizing agents for NaBH. Overall, the present study shows that there is no single parameter affecting the destabilization of NaBH by transition metal fluorides. Instead, parameters such as the transition metal electronegativity and oxidation state or the enthalpy of formation of the fluoride and its melting point are competing to influence the destabilization. In particular, it is found that the combination of a high metal oxidation state and a low fluoride melting point will enhance destabilization. This is observed for MnF, NbF, NiF, and CuF, which lead to high gas releases from the decomposition of NaBH at the lowest decomposition temperatures.
Topics: Borohydrides; Fluorides; Humans; Hydrogen; Metals; Renewable Energy
PubMed: 32059356
DOI: 10.3390/molecules25040780 -
Biomolecules Oct 2019In addition to our previous efforts toward bioenzymatic and chemical transformations of ricinoleic acid and oleic acid to their corresponding ,-dicarboxylic acids via...
In addition to our previous efforts toward bioenzymatic and chemical transformations of ricinoleic acid and oleic acid to their corresponding ,-dicarboxylic acids via their ester intermediates driven in cells, several efficient oxidation conditions were investigated and optimized for the conversion of -hydroxycarboxylic acids to ,-dicarboxylic acids. Pd/C-catalyzed oxidation using NaBH in a basic aqueous alcohol and Ni(II) salt-catalyzed oxidation using aqueous sodium hypochlorite were considered to be excellent as a hybrid reaction for three successive chemical reactions (hydrogenation, hydrolysis, and oxidation) and an eco-friendly, cost-effective, and practical approach, respectively. Omega-hydroxycarboxylic acids and -aminocarboxylic acid were also easily prepared as useful building blocks for plastics or bioactive compounds from the bioenzymatically driven ester intermediate. The scope of the developed synthetic methods can be utilized for large-scale synthesis and various derivatizations.
Topics: Borohydrides; Dicarboxylic Acids; Green Chemistry Technology; Hydrogenation; Hydrolysis; Oxidation-Reduction; Ricinoleic Acids
PubMed: 31590242
DOI: 10.3390/biom9100566 -
International Journal of Molecular... Jun 2021is an opportunistic human pathogen that has become a nosocomial health problem worldwide. The pathogen has multiple drug removal and virulence secretion systems, is...
is an opportunistic human pathogen that has become a nosocomial health problem worldwide. The pathogen has multiple drug removal and virulence secretion systems, is resistant to many antibiotics, and there is no commercial vaccine against it. is a zoonotic pathogen that is on the Select Agents list. The bacterium is the deadliest pathogen known to humans and antibiotic-resistant strains are appearing naturally. There is no commercial vaccine against the pathogen, either. In the current work, novel compounds based on metallacarborane cage were studied on strains of and a substitute, . The representative compounds had IC values below 10 µM against and values of 20-50 μM against . Artificial generation of compound-resistant suggested a common mechanism for drug resistance, the first reported in the literature, and suggested -linked metallacarboranes as impervious to cellular mechanisms of resistance generation. SEM analysis of the compound-resistant strains showed that the compounds had a predominantly bacteriostatic effect and blocked bacterial cell division in . The compounds could be a starting point towards novel anti- drugs and the strategy presented here proposes a mechanism to bypass any future drug resistance in bacteria.
Topics: Anti-Bacterial Agents; Boranes; Humans; Organometallic Compounds; Pseudomonas Infections; Pseudomonas aeruginosa; Yersinia Infections; Yersinia enterocolitica
PubMed: 34201818
DOI: 10.3390/ijms22136762 -
The Journal of Organic Chemistry Mar 2022In this study, we successfully synthesized boranophosphate (PB), phosphorothioate (PS), and phosphate (PO) chimeric oligonucleotides (ODNs) as a candidate for the...
In this study, we successfully synthesized boranophosphate (PB), phosphorothioate (PS), and phosphate (PO) chimeric oligonucleotides (ODNs) as a candidate for the antisense oligonucleotides (ASOs). The PB/PS/PO-ODNs were synthesized utilizing -boranophosphonate, -phosphonothioate, and -phosphonate monomers. Each monomer was condensed with a hydroxy group to create -boranophosphonate, -phosphonothioate, and -phosphonate diester linkages, which were oxidized into PB, PS, and PO linkages in the final stage of the synthesis, respectively. As for condensation of an -phosphonothioate monomer, regulating chemoselectivity was necessary since the monomer has two nucleophilic centers: S and O atoms. To deal with this problem, we used phosphonium-type condensing reagents, which could control the chemoselectivity. In this strategy, we could synthesize PB/PS/PO oligomers, including a 2'-OMe gapmer-type dodecamer. The physiological and biological properties of the synthesized chimeric ODNs were also evaluated. Insights from the evaluation of physiological and biological properties suggested that the introduction of suitable -modification and sugar modification at proper sites of ODNs would control the duplex stability, nuclease resistance, RNase H-inducing ability, and one base mismatch discrimination ability, which are critical properties as potent ASOs.
Topics: Boranes; Oligonucleotides, Antisense; Organophosphonates; Phosphates; Phosphorothioate Oligonucleotides; Solid-Phase Synthesis Techniques
PubMed: 34908418
DOI: 10.1021/acs.joc.1c01812 -
The Journal of Organic Chemistry May 2014Diazo compounds, boranes, and acyl imines undergo a three-component Mannich condensation reaction under catalyst-free conditions to give the anti β-amino carbonyl...
Diazo compounds, boranes, and acyl imines undergo a three-component Mannich condensation reaction under catalyst-free conditions to give the anti β-amino carbonyl compounds in high diastereoselectivity. The reaction tolerates a variety of functional groups, and an asymmetric variant was achieved using the (-)-phenylmenthol as chiral auxiliary in good yield and selectivity. These β-amino carbonyl compounds are valuable intermediates, which can be transformed to many potential bioactive molecules.
Topics: Amino Acids; Azo Compounds; Boranes; Catalysis; Imines; Molecular Structure; Stereoisomerism
PubMed: 24787904
DOI: 10.1021/jo5003505 -
Chemphyschem : a European Journal of... Nov 2022Alkali metal borohydrides are promising candidates for large-scale hydrogen storage. They react spontaneously with water, generating dihydrogen and metaborate salts....
Alkali metal borohydrides are promising candidates for large-scale hydrogen storage. They react spontaneously with water, generating dihydrogen and metaborate salts. While sodium borohydride is the most studied, potassium has the best chance of commercial application. Here we examine the physical and chemical properties of such self-hydrolysis solutions. We do this by following the hydrogen evolution, the pH changes, and monitoring the reaction intermediates using NMR. Most studies on such systems are done using dilute solutions, but real-life applications require high concentrations. We show that increasing the borohydride concentration radically changes the system's microstructure and rheology. The changes are seen already at concentrations as low as 5 w/w%, and are critical above 10 w/w%. While dilute solutions are Newtonian, concentrated reaction solutions display non-Newtonian behaviour, that we attribute to the formation and (dis)entanglement of metaborate oligomers. The implications of these findings towards using borohydride salts for hydrogen storage are discussed.
Topics: Borohydrides; Salts; Hydrogen; Hydrolysis; Potassium
PubMed: 36069265
DOI: 10.1002/cphc.202200428 -
Molecules (Basel, Switzerland) Sep 20222,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) is an excellent coupling reagent for the preparation of highly structured multifunctional molecules. Three component...
2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) is an excellent coupling reagent for the preparation of highly structured multifunctional molecules. Three component systems based on porphyrin, cyanuric chloride and carborane clusters were prepared by a one-pot stepwise amination of cyanuric chloride with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, followed by replacement of the remaining chlorine atoms with carborane - or -nucleophiles. Some variants of 1,3,5-triazine derivatives containing porphyrin, carborane and residues of biologically active compounds such as maleimide, glycine methyl ester as well as thioglycolic acid, mercaptoethanol and hexafluoroisopropanol were also prepared. A careful control of the reaction temperature during the substitution reactions will allow the synthesis of desired compounds in a good to high yields. The structures of synthesized compounds were determined with UV-vis, IR, H NMR, B NMR, MALDI-TOF or LC-MS spectroscopic data. The dark and photocytotoxicity as well as intracellular localization and photoinduced cell death for compounds , , , and were evaluated.
Topics: Boranes; Chlorine; Magnetic Resonance Spectroscopy; Maleimides; Mercaptoethanol; Molecular Structure; Porphyrins; Triazines
PubMed: 36234729
DOI: 10.3390/molecules27196200 -
Molecules (Basel, Switzerland) Jun 2020-CBH can perform as a novel core of globular periphery-decorated macromolecules. To do this, a new class of di and tetrabranched -carborane derivatives has been...
-CBH can perform as a novel core of globular periphery-decorated macromolecules. To do this, a new class of di and tetrabranched -carborane derivatives has been synthesized by a judicious choice of the synthetic procedure, starting with 9,10-I-1,7--CBH. The 2a-NPA (sum of the natural charges of the two bonded atoms) value for a bond, which is defined as the sum of the NPA charges of the two bonded atoms, matches the order of electrophilic reaction at the different cluster bonds of the icosahedral -and - carboranes that lead to the formation of B-I bonds. As for -carborane, most of the 2a-NPA values of B-H vertexes are positive, and their functionalization is more challenging. The synthesis and full characterization of dibranched 9,10-R-1,7--carborane (R = CHCHCH, HO(CH), Cl(CH), TsO(CH), CHCOO(CH), CHCOO(CH), N(CH), CHCHCH, and CHCN(CH)) compounds as well as the tetrabranched 9,10-R-1,7-R--CBH (R = CHCHCH, HO(CH)) are presented. The X-ray diffraction of 9,10-(HO(CH))-1,7--CBH and 9,10-(CHCHCH)-1,7--CBH, as well as their Hirshfeld surface analysis and decomposed fingerprint plots, are described. These new reported tetrabranched -carborane derivatives provide a sort of novel core for the synthesis of 3D radially grown periphery-decorated macromolecules that are different to the 2D radially grown core of the tetrabranched -carborane framework.
Topics: Boranes; Crystallography, X-Ray; Models, Molecular
PubMed: 32570849
DOI: 10.3390/molecules25122814 -
Cells Oct 2021Boron neutron capture therapy (BNCT) is a cancer-selective radiotherapy that utilizes the cancer targeting B-compound. Cancer cells that take up the compound are... (Review)
Review
Boron neutron capture therapy (BNCT) is a cancer-selective radiotherapy that utilizes the cancer targeting B-compound. Cancer cells that take up the compound are substantially damaged by the high liner energy transfer (LET) particles emitted mainly from the B(n, αLi reaction. BNCT can minimize the dose to normal tissues, but it must be performed within the tolerable range of normal tissues. Therefore, it is important to evaluate the response of normal tissues to BNCT. Since BNCT yields a mixture of high and low LET radiations that make it difficult to understand the radiobiological basis of BNCT, it is important to evaluate the relative biological effectiveness (RBE) and compound biological effectiveness (CBE) factors for assessing the responses of normal tissues to BNCT. BSH and BPA are the only B-compounds that can be used for clinical BNCT. Their biological behavior and cancer targeting mechanisms are different; therefore, they affect the CBE values differently. In this review, we present the RBE and CBE values of BPA or BSH for normal tissue damage by BNCT irradiation. The skin, brain (spinal cord), mucosa, lung, and liver are included as normal tissues. The CBE values of BPA and BSH for tumor control are also discussed.
Topics: Animals; Borohydrides; Boron Neutron Capture Therapy; Humans; Neoplasms; Phenylalanine; Relative Biological Effectiveness; Sulfhydryl Compounds; Tissue Distribution
PubMed: 34831105
DOI: 10.3390/cells10112883 -
Biomolecules Oct 2021The biocidal properties of silver nanoparticles (AgNPs) prepared with the use of biologically active compounds seem to be especially significant for biological and...
The biocidal properties of silver nanoparticles (AgNPs) prepared with the use of biologically active compounds seem to be especially significant for biological and medical application. Therefore, the aim of this research was to determine and compare the antibacterial and fungicidal properties of fifteen types of AgNPs. The main hypothesis was that the biological activity of AgNPs characterized by comparable size distributions, shapes, and ion release profiles is dependent on the properties of stabilizing agent molecules adsorbed on their surfaces. and were selected as models of two types of bacterial cells. was selected for the research as a representative type of eukaryotic microorganism. The conducted studies reveal that larger AgNPs can be more biocidal than smaller ones. It was found that positively charged arginine-stabilized AgNPs (ARGSBAgNPs) were the most biocidal among all studied nanoparticles. The strongest fungicidal properties were detected for negatively charged EGCGAgNPs obtained using (-)-epigallocatechin gallate (EGCG). It was concluded that, by applying a specific stabilizing agent, one can tune the selectivity of AgNP toxicity towards desired pathogens. It was established that was more sensitive to AgNP exposure than regardless of AgNP size and surface properties.
Topics: Anti-Bacterial Agents; Antifungal Agents; Antioxidants; Bacteria; Borohydrides; Citrates; Excipients; Fungi; Glucose; Microbial Sensitivity Tests; Silver; Surface Properties
PubMed: 34680114
DOI: 10.3390/biom11101481