Carbonyl Bond Research Articles

Biofilm mediated degradation of commercially available LDPE films by bacterial strains isolated from partially degraded plastic

AbstractBiodegradation is an attractive approach for the elimination of synthetic polymers, pervasively accumulated in natural environments and generating ecological problems. The present work investigated the degradation of low‐density polyethylene (PE) by three Bacillus sp., that is, ISJ36, ISJ38, and ISJ40. The degree of biodegradation was assessed by measuring hydrophobicity, viability, and total protein content of bacterial biofilm attached to the PE surface. Although all three bacterial strains were able to establish an active biofilm community on the PE surface, ISJ40 showed better affinity toward PE degradation than the other two. Bacterial colonization and physical changes on the PE surface were visualized by scanning electron microscopy. Fourier transform infrared spectroscopy analysis revealed alteration in the intensities of functional groups along with an increase in the carbonyl bond indexes. The study results suggest that the Bacillus strain ISJ40 can be used as a potential degrader for the eco‐friendly treatment of PE waste.

Regulating contents evolution of valence bonds on carbon surface to inhibit dissolution of polysulfides during production

Polysulfides (Li2Sx) have become key points that limit capacity improvement of lithium-sulfur batteries because of their high solubility. Oxygen-containing functional groups (such as C–O–H, C–O–C and CO) can effectively relieve a large amount of polysulfide dissolution due to their strong polarity. However, their types and contents on polysulfide-capturing abilities are still unknown. Therefore, three kinds of electrodes containing different contents of hydroxyl (C–O–H), ether (C–O–C) and carbonyl (CO) groups on carbon surface are controlled by changing pyrolysis times of dandelion. Electrochemical performance of lithium-sulfur batteries is tested to analyze influence of these groups on polysulfide-capturing abilities. It is discovered that CO and C–O–H groups can obviously inhibit shuttle effects of polysulfides during their initial production. In addition, a large number of CO bonds are converted to C–O–H bonds. More C–O–H bonds facilitate reversible capture of polysulfides and improve capacities. The introduction of C–O–C groups is not suitable for capturing more polysulfides rapidly and the appearance of ether groups limits conversion process of C–O–H groups. Both S load and discharging/charging process can effectively regulate evolution of three valence bonds, which is conducive to improving rate performance of lithium-sulfur batteries.

Validation of Local Hybrid Functionals for Excited States: Structures, Fluorescence, Phosphorescence, and Vibronic Spectra.

Local hybrid functionals are evaluated in linear-response TDDFT computations for a broad range of excited-state properties including excited-state structures, fluorescence, and phosphorescence energies and the vibronic shape of absorption and phosphorescence spectra. Computation of such properties requires the optimization of excited states, which is facilitated by the recent implementation of excited-state gradients for local hybrid functionals in the TURBOMOLE program (Grotjahn, R.; Furche, F.; Kaupp, M. J. Chem. Theory Comput. 2019, 15, 5508). Comparison with coupled-cluster reference values reveals competitive performance of local hybrids for excited-state bond lengths with particular advantages for carbon-halogen, carbon-carbon, and carbon-nitrogen bonds. As with most global and range-separated hybrid functionals, carbonyl and thionyl bonds in n → π* excited states are found to be too compact. For the emission energies, results depend on the multiplicity of the excited state. While the local hybrid functionals tested perform moderately well, comparable to global hybrids, for singlet states (fluorescence energies), they provide outstanding accuracy for triplet states (phosphorescence energies), only matched by those from the highly empirical M06-2X hybrid functional. The assessment of the shape of vibronic spectra reveals rather small differences between local hybrid functionals and conventional hybrid functionals with comparable exact-exchange admixture. The advantages for phosphorescence energies and the robust performance for the shape of vibronic spectra are combined to showcase the potential of local hybrid functionals for the prediction of phosphorescence spectra.

Mid-infrared metabolic imaging with vibrational probes.

Understanding metabolism is indispensable to unraveling the mechanistic basis of many physiological and pathological processes. However, in situ metabolic imaging tools are still lacking. Herein we introduce a framework for mid-infrared (MIR) metabolic imaging by coupling the emerging high-information-throughput MIR microscopy with specifically designed IR-active vibrational probes. Three categories of small vibrational tags including azide bond, 13C-edited carbonyl bond and deuterium-labeled probes are presented to interrogate various metabolic activities in cells, small organisms and mice. Two MIR imaging platforms are implemented including broadband Fourier transform infrared (FTIR) microscopy and discrete frequency infrared (DFIR) microscopy with a newly incorporated spectral region (2000–2300 cm−1). Our technique is uniquely suited for metabolic imaging with high-information-throughput. In particular, we performed single-cell metabolic profiling including heterogeneity characterization, and large-area metabolic imaging at tissue/organ level with rich spectral information.

Exploring in situ integration of pongamia oil to improve barrier properties of polyurethane coatings

AbstractPolyurethane coatings have been the focus of continuous innovation, such as bio‐based coatings and self‐healing coatings. This study investigates the route achieving superior coatings by in situ integration of pongamia oil during the curing process. Stronger urethane and carbonyl bonds for these oil‐modified coatings are observed using Fourier transform infra‐red spectroscopy. Thermogravimetric analysis reveals an increase in their thermal stability. A sustained high coating resistance and an increased Bode impedance (by ∼102 Ω cm2) for the oil‐modified coatings is observed using electrochemical impedance spectroscopy, which is corroborated by the cyclic corrosion test. Scanning electron microscopy depicts a roughened coating morphology with an increased water contact angle due to the integrated oil‐polyurethane polymer chains. Further, a preliminary computational fluid dynamics confirms this inhibited electrolyte mass flow through an oil‐modified coating with denser regions as compared to a clear coating. A consolidated schematic model incorporating the experimental and simulation results is proposed.

Polyimide/metal-organic framework hybrid for high performance Al - Organic battery

Aluminum(Al)-organic batteries are considered as a great alternative option for next generation energy storage devices. The recent Al-organic batteries propose new storage mechanisms of cationic aluminum complex ([AlClx]3−x, x ​= ​1 or 2) distinguished from traditional AlCl4−, represent an important breakthrough for aluminum batteries. However, the electrochemical storage mechanisms (value of x in [AlClx]3−x) are related to different types of organic materials, the poor cycling stability caused by inevitable dissolution of organic materials in electrolyte, and the complex synthetic process restrict the development of Al-organic batteries. Herein, polyimide (PI)/metal-organic frameworks (MOFs) hybrid material synthesizing from a facile one-pot strategy as cathode material in Al-organic battery is reported, providing with high specific capacity and excellent cycle stability. The PI/MOFs hybrid electrode achieves capacity of 83 ​mA ​h ​g−1 ​at 1000 ​mA ​g−1 with high coulombic efficiency (almost 100%). It also exhibits an excellent cycle performance of 1800 cycles with only a capacity decay of 0.0067% per cycle. Furthermore, the electrochemical storage mechanism of PI/MOFs is evaluated by ex-situ X-ray photoelectron spectroscopy and energy dispersive X-ray spectrum, which demonstrate that the cationic chloroaluminates interact with reduced carbonyl bonds in PI during discharge is AlCl2+. These findings are of great significance for the basic understanding of the working mechanism of PI compound cathode in Al-organic batteries, which may serve as a solid foundation for further development of novel organic cathode materials and their composites for Al-organic batteries.

Comparison and study on the asymmetric uranyl—salophen to the single carbonyl molecules

Theoretical study of the asymmetric uranyl−salophen (AUS) on the unsaturated aldehyde or ketone is a focus of present research. This study underlines the complexes of asymmetric uranyl−salophen (as modified by unilateral benzene) to single carbonyl molecules, including formaldehyde, acetone, cyclopentanone, and cyclohexanone, using the density functional theory of quantum chemistry. Our results suggest that the C=O double bond of the single carbonyl molecules is weakened by the asymmetric uranyl−salophen. Both the negative charge of oxygen atoms and the positive charge of carbon atoms from the C=O bond of the single carbonyl have increased, and the binding energies and stability between asymmetric uranyl−salophen and acetone, cyclopentanone, or cyclohexanone were higher than that of formaldehyde. These new findings could be used as an important reference for the study of other complexes that the asymmetric uranyl−salophen to the complex carbonyl molecules.

Reactive molecular dynamics research on influences of water on aging characteristics of PMIA insulation paper

The diffusion of moisture in the meta-aramid fiber (PMIA) oil-paper insulation system and the thermal decomposition of PMIA insulation paper in different moisture contents were studied via molecular dynamics simulations. The results showed that the PMIA insulation paper had a stronger ability to absorb water molecules than the insulating oil; therefore, water molecules in the insulating oil diffuse to the insulation paper, which further affects the thermal decomposition of the PMIA insulation paper. The activation energy of the water-bearing composite model was 129.96 kJ/mol, which was 5.5% lower than that of the pure PMIA (137.61 kJ/mol). It indicated that moisture could promote PMIA decomposition. The micromechanism of the enhanced thermal decomposition of PMIA with moisture contents could be described as follows: The O–H bond of the water can easily break to generate H atoms and hydroxyl radicals (•OH). The strong activity of H atoms allows it to easily combine with the ammonia base at the end of PMIA to generate NH3. Additionally, the free •OH radical can easily combine with the amido and carbonyl bonds at two ends of PMIA, undergo an oxidation reaction, and generate an oxhydryl. Therefore, it can reduce the chemical stability of the PMIA chain and further drive thermal decomposition. Statistical data on fragments generated by the thermal decomposition of the water-bearing PMIA composite system show that the main products include H2, C/H/O-containing molecules, hydrocarbon molecules, N-bearing molecules, and free radicals.

Hydroxide-catalyzed cleavage of selective ester bonds in phosphatidylcholine: An FTIR study

Thermochemical ester bond cleavage in the phospholipid phosphatidylcholine (PC) was evaluated at reaction temperatures between ca. 20–60 °C using a series of lithium and zinc halides: lithium chloride, lithium bromide, lithium iodide, zinc chloride, zinc bromide, and zinc iodide. Hydroxides, produced via reaction between lithium or zinc halides and potassium hydroxide (KOH), cleaved selective carbonyl and phosphonyl ester bonds in PC. This reaction was studied at 21, 30, 50 and 60 °C for periods of 2 and 4 hours. Attenuated total reflectance FTIR (ATR-FTIR) spectral analysis of neat (unreacted) and reacted PC showed qualitative and quantitative evidence of carbonyl and phosphonyl ester cleavage as indicated by the appearance and increase in the asymmetric carboxylate anion stretch (∼1577 cm-1) and symmetric phosphonyl dianion stretch (∼1010 cm-1) peaks, respectively. Ester cleavage in PC was demonstrated under extremely mild conditions for lithium hydroxides. In addition, the hydrolysis was found to be selective, leaving the zwitterionic phosphorylcholine group intact. Reaction time and temperature had little to no effect in promoting hydroxide attack on the ester bonds found in PC. Finally, the results of this study show that a non-enzymatic cleavage reaction methodology based on lithium hydroxide can be used for selective ester hydrolysis under extremely mild conditions. This ester hydrolysis method allows for a fast, low temperature, and selective cleavage using a chemical catalyst.

Spectroscopic Performance and Emission Analysis of Glycine max Biodiesel

Biodiesel is an alternative, clean and green fuel because of its non-toxic, biodegradable properties. The rationale behind this research is to examine the efficiency of biodiesel extracted from Glycine max oil by means of the heterogeneous catalyst method. The biodiesel was blended with mineral diesel at different percentages (%), before being applied to test the engine performance as a source of fuel. Variations of carbon monoxide, brake thermal efficiency, hydrocarbon, exhaust gas temperature, brake specific fuel consumption, NOX and brake thermal efficiency versus load for fuels were performed. At lower load BSFC and BTE of biodiesel are almost similar to diesel. The emission of CO and HC reduce appreciably as a result of biodiesel. It was obtained that at full load condition, there was a 2.38%, 4.76%, 7.61% and 10% reduction in CO emission, with B5, B10, B15 and B20, respectively. The characterization was also done by using spectroscopy like UV–Vis and Fourier transform infrared. The characteristic of diesel and fatty acid profile was observed at 1745/cm, showing the existence of strong ester carbonyl bond (C=O) indicating the presence of fatty acid methyl ester or biodiesel in FTIR. The variable concentration of blending was established by UV–Vis absorption spectra. The linearity of absorbance declined and linear line fitted for absorbance versus the percentage of biodiesel at 320 nm showed a high coefficient of determination (R2 = 0.9651).

Flexible pH sensors based on printed nanocomposites of single-wall carbon nanotubes and Nafion

High-performance flexible pH sensors based on nanocomposites of single-wall carbon nanotubes (SWCNTs) and Nafion, fabricated by screen printing on flexible substrates in ambient air are demonstrated. The electrical characteristics and thus the sensing performance of the pH sensors monitoring the change in resistance of printed nanocomposite films in a wide range of pH from 1 to 12 were controlled by the number of printed layers in multi-patterns. The operational stability of the flexible pH sensors was nearly unchanged after 200 cycles of bending tests having a curvature radius of 5 mm, which is essential for intergration of flexible pH sensors into wearable nanoelectronics. The sensing mechanism of the chemiresistive pH sensors based on nanocomposites is investigated in terms of chemical reaction. The hydrogen or hydroxide ions in the pH solution interact with the carbonyl and CH bonds bonds of the nanocomposite film, which induces or withdraws positively charged carriers, respectively. In addition, a real-time pH sensor system integrated into a drone application with wireless communication and data transmitting modules is demonstrated for the simultaneous visualization of processed data and remote detection of targets on the user's smartphone based on a designed Android algorithm.

Establishment of a molecular structure model for classified products of coal-based fulvic acid

Fulvic acid (FA) is used widely in materials, medicine, and agriculture because of its unique chemical properties. FA has good chemical activity due to its molecular structure which contains many functional moieties such as hydroxyl and carboxyl groups. Moreover, FA is biologically compatible enabling its use in medicine is agriculture. The chemical activity and physical properties of FA polymers differ based on its molecular weight. In order to reveal the specific structural characteristics of FA, column chromatography was used to fractionate FA into three different molecular weight products. Elementary analysis, infrared spectroscopy, and 13C nuclear magnetic resonance were used to study the composition and content of the classified FA products. The three different molecular weights of FA all contained carboxyl groups and phenolic hydroxyl groups. Our findings show that the carboxyl group was mostly distributed at the end of the aliphatic chain, while a small portion was connected to the benzene ring. The higher molecular weight FA contained more carboxyl groups, and some oxygen elements were present in the form of carbonyl and ether bonds. The chemical formulas of the three molecular weights were C17H19NO10, C33H27NO23, and C48H37NO36, which were calculated by molecular mechanics and dynamics. The molecular structure of FA was optimised by quantum chemical calculation methods. Finally, the average molecular structure model of FA with different molecular weights was established.

INFLUENCE OF SUBSTITUTES ON THE RATE OF REACTION OF SUBSTITUTED ANILINES WITH A BENZOIC ACID, CATALYZED BY POLYBUTOXYTITANATES

The catalytic production of benzanilide by the interaction of benzoic acid with aniline is an important model process recently intensively developed in the field of the concept of «green chemistry», direct catalytic amidation, and its study is an urgent scientific and practical task. To solve this problem, the effect of substituents in the aniline core on the catalysis by polybut-oxytitanates on acylation of substituted anilines by benzoic acid was studied. The rate constants of this the second-order reaction (the first with respect to substituted aniline and benzoic acid; boiling ortho-xylene, 145 °С, nitrogen flow) are well correlated according to the Hammett equation with three straight lines for individual groups of substituents with ρ = –0.86 (electron donors), 1.12 (weak electron acceptors), –2.83 (strong electron acceptors). To explain this dependence, a variant of the catalytic amidation mechanism is proposed, which takes into account the formation of titanium butoxybenzoates in the first minutes of the reaction — a true amidation catalyst; coordination (polarization of the carbonyl bond in the interaction with the catalyst titanium atom) and acid (polarization of the carbonyl bond in the interaction with the complex of the formed substitu- ted benzanilide with the titanium butoxyben-zoates) catalysis routes. Inhibition of the catalytic reaction is associated with the presence in the mass of water, relative excess of benzoic acid and a possible amide–imide tautomerism of substituted benzanilides, accompanied by the interaction of the imide form of the latter with titanium butoxybenzoates, which does not lead to the route of acid catalysis. The rate constants for catalytic acylation of substituted anilines, containing electron-donating substituents, with benzoic acid in the air are correlated according to the Hammett equation by a straight line segment with ρ = 0.99, which is associated with the predominant influence of the oxidation processes of the corresponding amines. Catalytic acylation under comparable conditions of substituted anilines, containing electron-withdrawing substituents, oxidation processes due to atmospheric oxygen have little effect on.

Helically shaped cation receptor: design, synthesis, characterisation and first application to ion transport.

The methyl ester of 8-oxo-8H-indeno[2′,1′:7,8]naphtho[1,2-b]thiophene-2-carboxylic acid (1) and its corresponding PEGylated ester were synthesised and fully characterised. X-ray diffraction studies on (1) confirmed the helical structure of the receptor and that it is self-assembled into layers by π–π interactions. An in-depth study by DFT calculations and MS experiments (ESI-MS, MS/MS, IMRPD and ESI-IMS-MS) was carried out between (1) and the physiological cation K+. The formation of supramolecular complexes between (1) and K+ with different stoichiometries was demonstrated and the cation K+ preferentially interacts with the oxygen atoms of the carbonyl bond of the ketone and ester groups and the sulphur atom of the heterocycle. The ability of the two synthesized aromatic architectures to transport ions across a model lipid membrane has been studied by electrophysiology experiments. The formation of pores was observed, even at nanomolar concentrations. Since the PEGylated molecule showed more regular pore definitions than the hydrophobic molecule, the introduction of a polar hydrophilic chain made it possible to control the orientation of the aromatic architectures within the membrane.

Pseudo-Jahn-Teller effect on the lowest triplet state of para-benzoquinone involving inequivalent carbonyl bonds

Various experiments have suggested the symmetry distortion of para-benzoquinone (PBQ) at the lowest triplet (n-π*) state. The vibronic coupling of electronic states known as the pseudo-Jahn-Teller effect could be the origin of the symmetry distortion. However, previous quantum chemical calculations could not provide reliable evidence for the symmetry distortion. Here we show the pseudo-Jahn-Teller distortion is an intrinsic property of PBQ due to the vibronic coupling between two low-lying n-π* states. Consequently, PBQ takes a C2v geometry having inequivalent two carbonyl groups, but the molecule remains planar. This state involves an inequivalent n-π* electronic transition and yields a mixed-valence state.

Isoxazolone Reactivity Explained by Computed Electronic Structure Analysis

Summary of main observation and conclusionIsoxazol(2H)‐5‐one was chosen as a model molecule to study the structural features (α, β angles and carbonyl bond length) regarding lactone moiety in the isoxazolone species by computational calculation. DFT method with B3LYP 6‐311++G(2df,2p) basis set was used to carry out the optimization on a series (A and B families) of isoxazolones suitably substituted on double bond. The same computational method assisted by default solvent model was performed to evaluate the energies related to the tautomeric equilibrium of isoxazol(2H)‐5‐one and to the keto‐enol process (IRC). NPA (Natural Population Analysis) allowed us to understand how electron density is distributed on the heterocycle ring, highlighting reactive sites in chemical reactions and the possible interactions with biological targets.

Investigating reaction pathways for formic acid and lignin at HTL conditions using 13C-labeled formic acid and 13C NMR

The lignin to liquid (LtL) solvolysis is a type of hydrothermal liquefaction (HTL) that utilizes formic acid to facilitate the desired hydrodeoxygenation process to depolymerize lignin. Formic acid has been chosen due to its hydrogen donor ability, and it has proven to be a more efficient hydrogen donor than hydrogen gas and isopropanol. Based on previous experiments where the amount of carbon in the solid phase and organic phase together exceeded 100% relative to carbon in the lignin starting material, we set up experiments with 13C-labeled formic acid in order to investigate where the carbon form formic acid is incorporated. All the experiments were performed in duplicates, one with 13C-labeled formic acid and one with standard formic acid. The bio-oils from the experiments were analyzed by Nuclear Magnetic Resonance (NMR) and the spectra were compared. The 13C NMR spectra showed significant differences between oils made with standard formic acid and oils made with 13C-labeled formic acid, located in the section between δ 170 ppm and δ 180 ppm in the NMR spectra. The signal in this range arise from carbonyl bonds and shows that the carbon from formic acid ends up in the carbonyl structures of the bio-oil in compounds such as aromatic acids. This paper has also shown that the amount of formic acid plays a minor role in product composition compared to reaction temperature, which influences the product composition on a functional group level.

Antibacterial nanofibers based on poly(l-lactide-co-d, l-lactide) and poly(vinyl alcohol) used in wound dressings potentially: a comparison between hybrid and blend properties

Morphology, hydrophilicity, degradation, mechanical properties, drug release, bacterial resistance, and cell viability are indispensable parameters for a bioactive wound dressing. In this work, the aforementioned terms between hybrid and blend nanofibrous samples based on poly (L-lactide-co-D, L-lactide) (PLDLLA) and poly (vinyl alcohol) (PVA) containing triclosan (Tri) as an antibacterial drug were investigated. The FE-SEM images showed that the presence of Tri in the hybrid and blend samples led to bimodal, and unimodal diameter size distributions. The FTIR spectra revealed that the addition of PVA caused to shift the carbonyl bond of PLDLLA in the blend sample, and DSC thermograms exhibited the immiscibility of PVA and PLDLLA polymers in the blend. Moreover, the hybrid sample showed higher hydrophilicity with water contact angle (WCA) of 53 than the blend ones with WCA of 73 which proved by water up-take test. In the following, the antibacterial evaluation showed better results for hybrid-Tri with the maximum growth inhibitory zones of 35 mm and 48 mm for E. coli and S. aureus, respectively. On the other hand, the hybrid nanofibrous sample showed remarkable mechanical properties (tensile stress ∼19 MPa, and Young’s modulus ∼532 MPa). Finally, the SNL 76/7 fibroblast cell line culture confirmed that the hybrid-Tri nanofibrous sample had better proliferation performance than the blend-Tri sample because of the minimal cytotoxicity and maximal cell viability by MTT and acridine orange/ethidium bromide staining.

Degradability and biofouling of oxo-biodegradable polyethylene in the planktonic and benthic zones of the Arabian Gulf.

Little is known about the degradability of oxo-biodegradable polyethylene (OXO-PE) and its surface fouling bacterial communities in the marine environment. The degradation of OXO-PE, PE and polyethylene terephthalate (PET) was compared at two depths (2 m and 6 m) in the Arabian Gulf. Scanning electron microcopy (SEM) revealed more fissure formation on OXO-PE and PE than on PET, indicating physical degradation. The formation of hydroxyl groups and carbonyl bonds, by Fourier-transform infrared spectroscopy (FTIR), suggests chemical degradation of OXO-PE. Plastisphere bacterial communities on OXO-PE and PE were different than on PET. Proteobacteria, Bacteriodetes and Planctomycetes were detected on all plastics, however, sequences of Alteromonas and Zoogloea were OXO-PE-specific suggesting a possible involvement of these bacterial genera in OXO-PE degradation. We conclude that OXO-PE shows increased signs of degradation with time owing to the combination of abiotic and biotic processes, and its degradation is higher in the benthic than in the planktonic zone.

Synthesis and characterization of thin film polyelectrolytes for solid-state lithium microbatteries

A critical challenge associated with the efficient fabrication of solid-state, three-dimensional microbatteries is the synthesis of conformal, solid-state thin film electrolytes. This study presents the synthesis of lithium ion conducting thin film polyelectrolytes based on poly(methacrylic acid-co-ethylene glycol diacrylate) using initiated chemical vapor deposition. These films are transformed to lithium-bearing polyelectrolytes through an H+/Li+ ion exchange reaction in a 1M LiOCH3 solution in methanol. Infrared spectroscopy of the vibrational stretching modes associated with the carbonyl bond in methacrylic acid confirmed that the ion exchange was successful, and quantification by x-ray photoelectron spectroscopy showed that ion exchange was nearly 100% complete. Incorporation of the crosslinking comonomer ethylene glycol diacrylate (EGDA) was necessary for physical stability of the film during the ion exchange process, and four polyelectrolyte compositions with varying crosslinking densities (ethylene glycol diacrylate content) were prepared to understand its role on ionic conductivity. The highest ionic conductivity was achieved in the polymer film with the lowest crosslinking density (9 mol. % EGDA); its conductivity was determined to be 6 × 10−9 S cm−1 at 20 °C and 1 × 10−5 S cm−1 at 100 °C. The activation energy for ionic conductivity was 0.88 eV. Using atomic force microscopy, the surfaces of thin film polyelectrolytes were shown to be continuous, smooth, and pinhole-free, suggesting that these films are suitable for integration into 3D microbatteries.