Organic Carboxylic Acids Research Articles

Ingress of carbon with ions of organic carboxylic acids (formate, acetate, and oxalate) in the snow cover of frozen landscapes

Ingress of carbon with ions of organic carboxylic acids (formate, acetate, and oxalate) in the snow cover of frozen landscapes

The Mechanism of Adsorption, Diffusion, and Photocatalytic Reaction of Organic Molecules on TiO2 Revealed by Means of On-Site Scanning Tunneling Microscopy Observations

The interaction of organic molecules and titanium dioxide (TiO2) plays a crucial role in many industry-oriented applications and an understanding of its mechanism can be helpful for the improvement of catalytic efficiency of TiO2. Scanning tunneling microscopy (STM) has been proved to be a powerful tool in characterizing reaction pathways due to its ability in providing on-site images during the catalytic process. Over the past two decades, many research interests have been focused on the elementary reaction steps, such as adsorption, diffusion, and photocatalytic reaction, occurring between organic molecules and model TiO2 surfaces. This review collects the recent studies where STM was utilized to study the interaction of TiO2 with three classes of representative organic molecules, i.e., alcohols, carboxylic acids, and aromatic compounds. STM can provide direct evidence for the adsorption configuration, diffusion route, and photocatalytic pathway. In addition, the combination of STM with other techniques, including photoemission spectroscopy (PES), temperature programmed desorption (TPD), and density functional theory (DFT), have been discussed for more insights related to organic molecules-TiO2 interaction.

A water stable metal–organic framework with 1D nanotube pores for 5-fluorouracil delivery and anti-brain tumor activity

The employment of porous carriers for anticancer drug delivery has gained much attention in recent years for their excellent drug-loading capacity and controlled release performance. In this work, by utilizing a rigid organic aromatic carboxylic acid ligand, a new Zn(II)–organic framework {[Zn2(bptc)(H2O)]·(DMAc)3(H2O)4}n (1, DMAc is in short of N,N-dimethylacetamide, H4bptc is in short of biphenyl-3,3′,5,5′-tetracarboxylic acid ligand), with considerable water stability has been prepared using the solvothermal technology. The structural analysis result reveals that complex 1 is constructed from fourfold helical metal chains whose net could be simplified into a (6,8)-connected topology. Moreover, complex 1 shows 1D nanotube channels with a window size of 10.7 × 10.7 A2 along the [001] direction and reveals a large accessible voids of 51.7%. The desolvated 1 (1a) was used to study the loading and releasing of the 5-fluorouracil (5-Fu), which reveals that 1a could uptake around 51.2 wt% of 5-Fu and nearly 85.6% of the absorbed 5-Fu could be released in PBS (7.4 for the pH value) in 100 h at 37 °C. In connection to these, in vitro cytotoxicity of compound 1 together with the anticancer performance of 5-Fu-loaded 1a was evaluated against human oral epidermal cells and human brain tumor cells SF17 via MTT assays.

Ions of Organic Carboxylic Acids (Formic, Acetic, and Oxalic) in the Snow Cover of Permafrost Landscapes of Boreal Eastern Siberia

The distribution of ions of organic carboxylic acids (formic, acetic, and oxalic) was investigated in the snowpack of permafrost landscapes of the boreal zone of Eastern Siberia. The contents of formate-, acetate-, and oxalate-ions were determined in permafrost landscapes of different zones of latitudinal and mountain- belt types. The maximum contents of organic carboxylic acid ions were observed in the snow cover of middle-taiga landscapes. The input rate of the ions into the snow cover of middle-taiga and mountain landscapes is controlled by altitudinal zonation and correlates with the total mass of plant organisms, which are the main source of organic carboxylic acids in the atmosphere. The obtained data suggest that organic carboxyl acid ions were supplied mainly by the atmosphere (74–90%), whereas the contribution of soil respiration was minor. The upward migration of organic carboxylic acid ions from the substrate to the snow cover depends on soil and snow temperature. Cooling of the soil surface below–5°C results in a considerable decrease in the migration of organic carboxylic acid ions from soil to snow.

High-performance thin-film composite membranes with surface functionalization by organic phosphonic acids

Forward osmosis (FO), a novel promising technology for water treatment, has not progressed significantly beyond the conceptualization. A bottleneck is the lack of suitable membranes with high separation performance, good antifouling properties and chemical stability. In this work, a 3-step surface modification approach is employed to develop a thin-film composite polyamide (TFC PA) membrane, i.e., PEI grafting, acid functionalization (organic phosphonic acid or carboxylic acid), and the calcium mineralization. Effects of the organic acid type on membrane properties are investigated with various characterizations, in terms of chemical changes, surface properties, and morphology. The separation performance, antifouling properties and chemical stability of modified membranes are studied systematically. In comparison with the control membrane and those modified by organic carboxylic acids, membranes modified by organic phosphonic acids exhibit the higher FO water flux, lower reverse salt flux, lower fouling propensity, a better pH tolerance, as well as a superior chlorine resistance. The surface functionalized TFC membrane developed in this work therefore holds a great potential for wide membrane-based separation applications in various harsh environments.

Development of Fast-Dissolving Amorphous Solid Dispersion of Itraconazole by Melt Extrusion of its Mixture with Weak Organic Carboxylic Acid and Polymer.

The purpose of this study was to explore the feasibilityof developing amorphous solid dispersion (ASD) by inducing acid-base interaction at an elevated temperature using hot melt extrusion. Itraconazole and glutaric acid, which do not form salt with each other, were selected as, respectively, model basic drug and weak organic acid. A 1:4:1w/w mixture of itraconazole, glutaric acid and a polymer, Kollidon®VA64, was melt extruded at 95°C. The ground extrudate was characterized by DSC and PXRD and then tested for dissolution at pH1.2, followed by a change in pH to 5.5. Despite the high melting point of 168°C, itraconazole dissolved in glutaric acid at around the melting temperature of acid (~98°C), and physically stable ASD was produced when the formulation was extruded at 95°C. Capsules containing 100-mg equivalent of itraconazole dissolved rapidly at pH1.2 producing highly supersaturated solution. When the pH was changed from 1.2 to 5.5, very fine suspensions, facilitated by the presence of Kollidon®VA64, was formed. Physically stable ASD of itraconazole with high drug load was prepared by interaction with glutaric acid in a hot melt extruder. This may be used as a platform technology for the development ASD of most poorly water-soluble basic drugs.

Identifying Catalytically Active Mononuclear Peroxoniobate Anion of Ionic Liquids in the Epoxidation of Olefins

The organic carboxylic acid coordinated monomeric peroxoniobate-based ionic liquids (ILs) [TBA][NbO(OH)2(R)] (TBA = tetrabutylammonium; R = lactic acid (LA), glycolic acid (GLY), malic acid (MA)) were prepared and fully characterized by elemental analysis, NMR, IR, Raman, TGA, 93Nb NMR, and HRMS. These IL catalysts exhibited not only high catalytic activity for the epoxidation of olefins under very mild reaction conditions, as the turnover frequency of [TBA][NbO(OH)2(LA)] reached up to 110 h–1, but also satisfactory recyclability in the epoxidation by using only 1 equiv of hydrogen peroxide as an oxidant. Meanwhile, this work revealed that the ILs underwent structural transformation from [NbO(OH)2(R)]− to [Nb(O–O)2(R)]− (R = LA, GLY, MA) in the presence of H2O2 by a subsequent activity evaluation, characterization, and first-principles calculations. Moreover, the organic carboxylic acid coordinated monomeric peroxoniobate-based ILs were investigated using density functional theory (DFT) calculations, whic...

Corrosion inhibition of carbon steel by hydrotalcites modified with different organic carboxylic acids for organic coatings

Hydrotalcites intercalated with sebacate (HT-SB) were prepared by a coprecipitation method. The synthesized powder was characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta potential measurements. The inhibitor release from HT-SB in a chloride solution has been determined by total organic content (TOC) analysis. The inhibitive action of HT-SB on carbon steel was investigated and compared with hydrotalcites intercalated by benzoate (HT-BZ) and 2-benzothiazolythio-succinic acid (HT-BTSA) using electrochemical measurements and SEM/EDX analysis. The results showed that the zeta potential of modified hydrotalcites and the release of corrosion inhibitors from modified hydrotalcites depend on the chemical structure of inhibitors. The anodic polarization curves showed that the three modified hydrotalcites behave as anodic corrosion inhibitors with an efficiency, at a concentration of 3 g/L, of 94% for HT-SB, 81% for HT-BZ and 92% for HT-BTSA. These efficiencies are higher than those measured for the organic inhibitors in chloride solutions highlighting a synergistic effect due to the combination of the hydrotalcite structure and carboxylate inhibitors. The inhibition effect of modified hydrotalcite depends not only on the intercalated organic inhibitors but also on the capability of adsorption of the hydrotalcite structure on a steel surface. HT-SB was easily dispersed in an epoxy coating improving the barrier properties at concentrations lower than 5 wt.%. The best protection was obtained with 1.5 wt.% HT-SB.

A novel self-dispersed β nucleating agent for isotactic polypropylene and its unique nucleation behavior and mechanism

Adding β nucleating agent (β-NA) is the most effective way to induce β-form in isotactic polypropylene (iPP). However, the problem of agglomeration and poor dispersion result in the low nucleation efficiency of β-NA. We reported herein a novel self-dispersed β nucleating agent of iPP, zinc salt of bicycle [2.2.1] hept-5-ene-2-dodecanamide-3-carboxylate (NBDA30), which exhibited a unique nucleation behavior during the crystallization of iPP. The results showed that the content of β crystal of iPP nucleated with 0.2 wt% NBDA30 can reach 0.82 (kβ value), implying that NBDA30 is an effective β nucleating agent of iPP. Polarized optical microscopy (POM) analyses showed that the NBDA30 gradually melted upon increasing temperature and then the melt induced the crystallization of iPP. The unique nucleation behavior was first reported in this study and the nucleation mechanism of iPP induced by NBDA30 was revealed by POM, fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM) and scanning electron Microscope (SEM). The results indicated that the NBDA30 was converted into ZnO nanoparticles and the group of ROO¯ chemically adsorbed on the surface of ZnO nanoparticles (NPs). The problem of agglomeration of ZnO nanoparticles was well solved by in situ thermal decomposition of NBDA30 and the compatibility of ZnO and iPP matrix was greatly improved by chemical adsorption of organic carboxylic acid on the surface of ZnO NPs. Therefore, the nucleation efficiency of ZnO NPs was greatly increased. The preparation method of self-dispersed nucleating agent can potentially be extended to other nucleating agent or additives to prevent them from aggregating.

Feasibility of Detecting Bioorganic Compounds in Enceladus Plumes with the Enceladus Organic Analyzer.

Enceladus presents an excellent opportunity to detect organic molecules that are relevant for habitability as well as bioorganic molecules that provide evidence for extraterrestrial life because Enceladus' plume is composed of material from the subsurface ocean that has a high habitability potential and significant organic content. A primary challenge is to send instruments to Enceladus that can efficiently sample organic molecules in the plume and analyze for the most relevant molecules with the necessary detection limits. To this end, we present the scientific feasibility and engineering design of the Enceladus Organic Analyzer (EOA) that uses a microfluidic capillary electrophoresis system to provide sensitive detection of a wide range of relevant organic molecules, including amines, amino acids, and carboxylic acids, with ppm plume-detection limits (100 pM limits of detection). Importantly, the design of a capture plate that effectively gathers plume ice particles at encounter velocities from 200 m/s to 5 km/s is described, and the ice particle impact is modeled to demonstrate that material will be efficiently captured without organic decomposition. While the EOA can also operate on a landed mission, the relative technical ease of a fly-by mission to Enceladus, the possibility to nondestructively capture pristine samples from deep within the Enceladus ocean, plus the high sensitivity of the EOA instrument for molecules of bioorganic relevance for life detection argue for the inclusion of EOA on Enceladus missions. Key Words: Lab-on-a-chip—Organic biomarkers—Life detection—Planetary exploration. Astrobiology 17, 902–912.

A PRELIMINARY STUDY OF THE UTILIZATION OF LIQUID SMOKE FROM PALM KERNEL SHELLS FOR ORGANIC MOUTHWASH

Palm kernel shells are a waste product of the palm oil industry. They have a high content of cellulose, hemicellulose, and lignin, all of which can be converted through a pyrolysis process into liquid smoke that contains the oxidized organic compounds, ketones, aldehydes, phenols, and carboxylic acid groups with antimicrobial properties. The objective of this research is to study the potential use of grade 1 liquid smoke as organic mouthwash. This research considers liquid smoke’s antimicrobial properties and focuses on analyzing its ability to inhibit the growth of streptococcus mutans living in the oral cavity. The liquid smoke used was produced by pyrolysis performed in temperatures of 340-420oC. In order to obtain grade 1 liquid smoke, distillation was subsequently carried out at 190oC. The ability of the produced liquid smoke to inhibit streptococcus mutans was then tested for its minimum inhibitory concentration and diameter of inhibitory region. Both minimum inhibitory concentration and diameter of inhibitory region tests were performed with a liquid smoke concentration of 0.005-0.1 mg/ml. Test results of the minimum inhibitory concentration showed that the liquid smoke possesses good antimicrobial properties against streptococcus mutans, while test results of the diameter of inhibitory region was medium at 6-9 mm. The highest diameter of inhibitory region was obtained from liquid smoke created from pyrolysis performed at 400oC and a concentrate of 0.1 mg/ml.

Screening the key genes of hepatocellular adenoma via microarray analysis of DNA expression and methylation profiles.

The aim of the present study was to identify the biomarkers involved in the development of hepatocellular adenoma (HCA) through integrated analysis of gene expression and methylation microarray. The microarray dataset GSE7473, containing HNF1α-mutated HCA and their corresponding non-tumor livers, 5 HNF1α-mutated HCA and 4 non-related non-tumor livers, was downloaded from the Gene Expression Omnibus (GEO) database. The DNA methylation profile GSE43091, consisting of 50 HCA and 4 normal liver tissues, was also downloaded from the GEO database. Differentially expressed genes (DEGs) were identified by the limma package of R. A t-test was conducted on the differentially methylated sites. Functional enrichment analysis of DEGs was performed through the Database for Annotation, Visualization and Integrated Analysis. The genes corresponding to the differentially methylated sites were obtained by the annotation files of methylation chip platform. A total of 182 DEGs and 3,902 differentially methylated sites were identified in HCA. In addition, 238 enriched GO terms, including organic acid metabolic process and carboxylic acid metabolic process, and 14 KEGG pathways, including chemical carcinogenesis, were identified. Furthermore, 12 DEGs were identified to contain differentially methylated sites, among which, 8 overlapped genes, including pregnancy zone protein and solute carrier family 22 member 1 (SLC22A1), exhibited inverse associations between gene expression levels and DNA methylation levels. The DNA methylation levels may be potential targets of HCA. The present study revealed that the 8 overlapped genes, including annexin A2, chitinase 3-like 1, fibroblast growth factor receptor 4, mal, T-cell differentiation protein like, palladin, cytoskeletal associated protein, plasmalemma vesicle associated protein and SLC22A1, may be potential therapeutic targets of HCA.

Fourfold-Interpenetrated MOF [Ni(pybz)2] as Coating Material in Gas Chromatographic Capillary Column for Separation.

A fourfold interpenetrated diamond-like topological metal-organic framework (MOF), Ni(pybz)2 [pybz = 4-(4-pyridyl)benzoate] was successfully synthesized and fully characterized. This MOF can serve as coating material in gas chromatographic capillary column for the separation of some low boiling point essential oils. The prepared columns have good recognition ability and excellent selectivity toward a series of organic compounds, including alcohols, aldehydes, ketones, carboxylic acid, ethers, ester, and amines. It is found that the strained metal sites, van der Waals interactions, C-H···π attraction, and weak nonclassical hydrogen bond contribute to the recognition and selectivity of prepared columns. The grand canonical Monte Carlo technique is used to simulate the interactions of the adsorbates with MOF. The calculated van der Waals energies agree with the results of gas chromatographic separation.

Carbon film encapsulated Pt NPs for selective oxidation of alcohols in acidic aqueous solution

Platinum is one of the best catalysts for various applications, but the deactivation of Pt nanoparticles (NPs) during alcohol oxidation is a major barrier to commercialization. In this work, multiwall carbon nanotubes supported carbon film encapsulated Pt NPs (Pt@C-MWCNTs) was synthesized and used in the selective oxidation of ethanol and glycerol in acidic aqueous solution. It was found that Pt@C-MWCNTs exhibited both higher activity and stability than bare Pt NPs. Characterization indicated that carbon film encapsulation can overcome the sintering, leaching and over-oxidation of Pt NPs during the reaction. Moreover, carbon film may also prevent the strong adsorption of organic carboxylic acid on Pt.

Preparation, Crystal structure and Luminescence Properties of Lanthanide Complexes with 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine and Organic Carboxylic Acid

Five crystal complexes {[Eu2(TPTZ)2(mNBA)6(H2O)2]·2CH3OH}n (1), [Eu(TPTZ)(CF3COO)(H2O)5]·Cl2·CH3CH2OH (2), {[Yb2(TPTZ)2(BDC)3]·2H2O}n (3), [Yb(TPTZ)Cl(H2O)4]·Cl2 (4) and [Er(TPTZ)(TTA)Cl2] (5) (mNBA = m-nitro benzoate, BDC = terephthalate, TTA = thenoyltrifluoroacetone, TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine) have been synthesized. The single X-ray diffraction reveals that TPTZ is mainly in the trident coordination mode and organic aromatic carboxylic acids are in the multiple coordination modes in the crystals. The composition of solvents, reaction temperature and reactant ratios all affect the composition and structure of the formed crystals. Crystals 1 and 3 belong to triclinic system, while the other three belong to monoclinic system. Among them, Crystal complexes 1 and 3 are coordination polymers. The other three crystals are mononuclear complexes with LnШ ions in the asymmetric environment. Both of the Crystal complexes 1 and 2 show strong luminescence emissions of Eu3+. The luminescence lifetimes of the two complexes are 0.761 ms and 0.447 ms, respectively. In addition, their luminescence quantum efficiencies are 25.0% and 16.7%, respectively.

The role played by carbonate cementation in controlling reservoir quality of the Triassic Skagerrak Formation, Norway

Anomalously high porosities up to 30% at burial depth of >3000 m along with varying amounts and types of carbonate cements occur in the fluvial channel sandstone facies of the Triassic Skagerrak Formation, Central Graben, Norway. However, porosities of the Skagerrak Formation are lower in the Norwegian sector than in the UK sector. In this study, petrographic analysis, core examination, scanning electron microscopy, elemental mapping, carbon and oxygen isotope, fluid inclusion and microgeometry analysis are performed to determine the diagenesis and direct influence on reservoir quality, with particular focus on the role played by carbonate cementation. The sandstones are mainly fine-grained lithic-arkosic to sub-arkosic arenites and display a wide range of intergranular volumes (2.3%–43.7% with an average of 23.6%). Porosity loss is mainly due to compaction (av. 26.6%) with minor contribution from cementation (av. 12.1%). The carbonate cements are patchy in distribution (from trace to 20.7%) and appear as various types e.g. calcretes (i.e. calcareous concreted gravels), poikilitic sparite and sparry ferroan dolomite, and euhedral or/and aggregated ankerite/ferroan dolomite crystals. This study highlights the association of carbonate precipitation with the remobilisation of carbonate from intra-Skagerrak calcretes during early burial stage i.e. <500 m. During deeper burial, compaction is inhibited by carbonate cements, resulting high intergranular volume of up to 32% and 29% for fine- and medium-grained sandstones, respectively. Carbonate cement dissolution probably results from both meteoric water flow with CO2 during shallow burial, and organic CO2 and carboxylic acid during deep burial. The maximum intergranular volume enhanced by dissolution of early carbonate cements is calculated to 8% and 5% for fine- and medium-grained sandstones, respectively. Compaction continues to exert influence after dissolution of carbonate cements, which results in a loss of ∼6% intergranular volume for fine- and medium-grained sandstones. Reservoir quality of the Norwegian sector is poorer than that of the UK sector due to a lower coverage of clay mineral coats e.g. chlorite, later and deeper onset of pore fluid overpressure, lower solubility of carbonate compared to halite, and a higher matrix content.

Synthesis of Cyclic Carbonates from Alkenyl and Alkynyl Substrates

AbstractAs an extensively used chemical product, cyclic carbonate was generally synthesized by transesterification, or the cycloaddition of epoxides, diols with CO2. To reduce the production costs and expand the raw materials, alkenyl and alkynyl substrates have caused much attention in the synthesis of cyclic carbonates, such as olefins, allyl alcohols and propargylic alcohols. Based on the alkenyl substrate, the synthetic process involves a continuous reaction of oxidative carboxylation, with epoxide or halohydrin as an intermediate usually. Therefore, peroxides and nucleophiles (halogens or organic bases) are often necessary in the conversion. Using propargylic alcohols to produce α‐alkylidene cyclic carbonates, noble metal catalysts play crucial roles in alkynyl activation, and organic bases are considered to assist the intramolecular and intermolecular proton transfer and combine CO2 molecular. As the carboxyl sources in products, inorganic carbonates and organic carboxylic acids also have some applications instead of CO2. In this review, we summarized the synthetic routes of cyclic carbonates from alkenyl and alkynyl substrates in the aspect of catalyst, mechanism and the development tendency.

Magnetoluminescent Bifunctional Dysprosium-Based Phosphotungstates with Synthesis and Correlations between Structures and Properties

A series of dysprosium-based lacunary Keggin-type phosphotungstates have been prepared by the reaction of the preformed polyoxometalate (POM) precursor [P2W19O69(OH2)]14– and Dy3+ ions in the solution of organic carboxylic acid. Four POM-ligated lanthanide derivatives display four classes of configurations: three dimeric POMs with 2:1 type K2[N(CH3)4]5H4[Dy(α-PW11O39)2]·21H2O (1Dy), 2:2 type Na2[N(CH3)4]4H2[{Dy(α-PW11O39)(H2O)3}2]·28H2O (2Dy), and 2:3 type K8H3[(DyOH2)3(CO3)(α-PW9O34)2]·30H2O (3Dy), together with a tetrameric 4:8 type K14H12[Dy8(PW10O38)4(OH)4(H2O)2 (W3O14)]·57H2O (4Dy). These complexes exhibit the bifunction of luminescence and SMM properties, which indicate a bright prospect in optomagnetic devices. The solid-state fluorescence spectra of 1Dy–4Dy all show yellowish green emission resulting from the characteristic 4f–4f transitions of Dy3+ ions. However, it is interesting that 1Dy including only mononuclear Dy3+ ion has the highest luminous intensity and longest decay time in the visible or near-infrared region. Static magnetic studies reveal that 1Dy–3Dy show the thermal depopulation of Dy3+ Stark sublevels, whereas 4Dy displays the dominant ferromagnetic interactions within Dy3+ ions in the low temperatures as well as the thermal depopulation of Dy3+ Stark sublevels. The field-induced single molecule magnet (SMM) behaviors of 1Dy–4Dy are demonstrated by dynamic magnetic studies.

Deep UV Raman spectroscopy for planetary exploration: The search for in situ organics

Raman spectroscopy has emerged as a powerful, non-contact, non-destructive technique for detection and characterization of in situ organic compounds. Excitation using deep UV wavelengths (< 250nm), in particular, offers the benefits of spectra obtained in a largely fluorescence-free region while taking advantage of signal enhancing resonance Raman effects for key classes of organic compounds, such as the aromatics. In order to demonstrate the utility of this technique for planetary exploration and astrobiological applications, we interrogated three sets of samples using a custom built Raman instrument equipped with a deep UV (248.6nm) excitation source. The sample sets included: (1) the Mojave Mars Simulant, a well characterized basaltic sample used as an analog for Martian regolith, in which we detected ∼0.04 wt% of condensed carbon; (2) a suite of organic (aromatic hydrocarbons, carboxylic acids, and amino acids) and astrobiologically relevant inorganic (sulfates, carbonates, phosphates, nitrates and perchlorate) standards, many of which have not had deep UV Raman spectra in the solid phase previously reported in the literature; and (3) Mojave Mars Simulant spiked with a representative selection of these standards, at a concentration of 1 wt%, in order to investigate natural 'real world' matrix effects. We were able to resolve all of the standards tested at this concentration. Some compounds, such as the aromatic hydrocarbons, have especially strong signals due to resonance effects even when present in trace amounts. Phenanthrene, one of the aromatic hydrocarbons, was also examined at a concentration of 0.1 wt% and even at this level was found to have a strong signal-to-noise ratio. It should be noted that the instrument utilized in this study was designed to approximate the operation of a 'fieldable' spectrometer in order to test astrobiological applications both here on Earth as well as for current and future planetary missions. It is the foundation of SHERLOC, an arm mounted instrument recently selected by NASA to fly on the next rover mission to Mars in 2020.

Bioinspired Manganese Complexes and Graphene Oxide Synergistically Catalyzed Asymmetric Epoxidation of Olefins with Aqueous Hydrogen Peroxide

AbstractBioinspired manganese complexes of N4ligands and graphene oxide (GO) synergistically catalyze the highly enantioselective epoxidation of olefins (up to 99%ee), which is a rare example with GO as a co‐catalyst in asymmetric catalysis. GO as a new and key additive not only successfully functions in catalytic amounts, but also has a positive effect for improving the enantioselectivity of the asymmetric epoxidation compared with the traditional stoichiometric organic carboxylic acid method [e.g., chalcone, 95%ee(3.5 mg GO)vs. 84%ee(5 equiv., 75 mg acetic acid), ethyl cinnamate, 84%ee(3.5 mg GO)vs. 19%ee(5 equiv., 75 mg acetic acid)]. The X‐ray photoelectron spectroscopy (XPS) spectra of GO before and after the reaction indicate that the intensities of C–O become stronger after the reaction, which may have a certain relationship with hydrogen peroxide (H2O2) and gives a reasonable rationale for the large consumption of H2O2. Also, part of the hydrogen peroxide was used for the oxidation of GO.magnified image