Chain Carboxylic Acids Research Articles

New mesoporous perovskite ZnTiO 3 and its excellent catalytic activity in liquid phase organic transformations

A new mesoporous perovskite ZnTiO 3 material has been synthesized by the evaporation-induced self-assembly (EISA) method using non-ionic surfactant Pluronic P123 as template. After calcination of the dried gel of equimolar concentrations of Zn(II) and Ti(IV) at 673 K, a new perovskite mesophase of ZnTiO 3 (MZT-11) formed, having highly crystalline cubic ZnTiO 3 pore wall. Interestingly, in the absence of P123 but otherwise identical synthesis conditions showed no cubic structure and a mixed phase consisting of ZnO and TiO 2 phases (ZT-11). The BET surface area of the mesoporous perovskite materials (MZT-11) was 136 m 2 g −1 and the average dimension of the pores was ca. 5.1 nm. The material was thoroughly characterized by different analytical methods including small and wide angle powder XRD, FE SEM, TEM, FT IR, UV–visible, photoluminescence (PL) and X-ray fluorescence (XRF) analysis. This new mesoporous perovskite material showed excellent catalytic activity in the Friedel-Crafts (FC) benzylation of aromatics and in the Fischer esterification of different long chain carboxylic acids in the presence of methanol under solvent-free conditions.

A low cost universal photoelectrochemical detector for organic compounds based on photoelectrocatalytic oxidation at a nanostructured TiO 2 photoanode

A photoelectrochemical detector (PECD) was developed for determination of organic compounds in flow injection analysis (FIA) and high performance liquid chromatography (HPLC) based on the extraordinary oxidation power of nanostructured TiO 2 photoanodes under UV illumination. The PECD is a simple, small, and compact photoelectrochemical cell consisting of low cost components such as a TiO 2 nanostructured photoanode and a UV-LED. Compared with conventional FIA and HPLC selective detectors, such as UV–Vis detector, electrochemical detector and fluorescent detector, the PECD has the advantage of being low cost, non-selective and sensitive. Using the FIA mode, the analytical principle of the PECD was demonstrated by detecting a large variety of organic compounds, such as sugars, amino acids, alcohol, straight chain carboxylic acids, and aromatic carboxylic acid. The PECD was subsequently coupled with a typical FIA and HPLC system for the determination of sugars. For the application in FIA, under the optimum experimental conditions, the linear ranges for glucose and sucrose were 25–600 μM and 25–500 μM, respectively, with the same detection limit of 10 μM. When the PECD was coupled with a HPLC system, the linear range for both glucose and sucrose was 7.5–200 mM with the same detection limit of 1 mM under the optimal experimental conditions.

Nanoparticles Change the Ordering Pattern of n-Carboxylic Acids into Nanorods on HOPG

This paper describes the formation of organic nanorods induced by monolayer-protected inorganic nanoparticles. Alkanes and alkane derivatives, such as n-carboxylic acids, self-assemble on highly oriented pyrolytic graphite (HOPG) into a persistent molecular packing structure that is dictated by the epitaxial interaction between the carbon chain plane and the HOPG basal plane. Carboxylic acids form 2-D crystalline layers consisting of nanostripe domains whose periodicity is one or two times the molecular chain length. However, when the molecular ordering occurs in the vicinity of a nanoparticle, this persistent HOPG-dominated nanostripe pattern is disrupted, and nanorods attached to the nanoparticles become the dominant structure. In order to understand the underlying mechanism of the nanoparticle-mediated nanorod formation, the effects of film-forming conditions, carboxylic acid chain length, nanoparticle size, and chemical composition of the nanoparticle are examined. It is determined that carboxylic acid nanorods can be induced by nanoparticles of different core materials including CdSe, CdS, and Au, as long as the protecting monolayer allows sufficient dispersion and colloidal stability of the nanoparticles in solution. A carboxylic chain length range amenable to the nanorod formation is identified, as is the relationship between the nanoparticle size and the number of nanorods per nanoparticle. This study contributes to the understanding of seed-mediated crystallization and molecular ordering. Moreover, it defines the parameters governing solution-based formation of hybrid nanostructures and nanopatterns incorporating dual functionality as defined by the inorganic nanoparticle and organic nanorod, respectively.

Emissions of volatile fatty acids from feed at dairy facilities

Abstract Recent studies suggest that dairy operations may be a major source of non-methane volatile organic compounds in dairy-intensive regions such as Central California, with short chain carboxylic acids (volatile fatty acids or VFAs) as the major components. Emissions of four VFAs (acetic acid, propanoic acid, butanoic acid and hexanoic acid) were measured from two feed sources (silage and total mixed rations (TMR)) at six Central California Dairies over a fifteen-month period. Measurements were made using a combination of flux chambers, solid phase micro-extraction fibers coupled to gas chromatography mass spectrometry (SPME/GC–MS) and infra-red photoaccoustic detection (IR-PAD for acetic acid only). The relationship between acetic acid emissions, source surface temperature and four sample composition factors (acetic acid content, ammonia-nitrogen content, water content and pH) was also investigated. As observed previously, acetic acid dominates the VFA emissions. Fluxes measured by IR-PAD were systematically lower than SPME/GC–MS measurements by a factor of two. High signals in field blanks prevented emissions from animal waste sources (flush lane, bedding, open lot) from being quantified. Acetic acid emissions from feed sources are positively correlated with surface temperature and acetic acid content. The measurements were used to derive a relationship between surface temperature, acetic acid content and the acetic acid flux. The equation derived from SPME/GC–MS measurements predicts estimated annual average acetic acid emissions of (0.7 + 1/−0.4) g m −2 h −1 from silage and (0.2 + 0.3/−0.1) g m −2 h −1 from TMR using annually averaged acetic acid content and meteorological data. However, during the summer months, fluxes may be several times higher than these values.

Synthesis, Characterization and Photoluminescence of CdS Hyperbranched Nanocrystals by a Simple Solution Chemistry Method

We report the synthesis of CdS hyperbranched nanocrystals using a simple hot coordination solvents method. Transmission electron microscopy studies showed that the length of the arms and the angle of branching could be controlled by varying organic surfactants in terms of amount and type. It was found that long chain carboxylic acids favored the synthesis of CdS hyperbranched nanocrystals. Although their absorption spectra of CdS hyperbranched nanocrystals did not display sharp features, the photoluminescence spectra showed two emission peaks, i.e., the corresponding luminescence peak around 486 nm originates from the band edge and the broad band emission from 560 nm extended to the region of near infrared arises from trap-related recombination of as-prepared CdS hyperbranched nanocrystals.

Directing oxidation of cobalt nanoparticles with the capping ligand

The oxidation of Co nanoparticles stabilized with various ligands has been studied in an autoclave. Tridodecylamine stabilized Co nanoparticles with different sizes (8 nm, 22 nm and 36 nm) were prepared by thermal decomposition of Co 2(CO) 8 in dodecane. The oxidation of the particles was studied by introducing oxygen into the autoclave and following the oxygen consumption with a pressure meter. Tridodecylamine capped particles were initially oxidized at a high rate, however, the oxidation layer quickly inhibited further oxidation. The thickness of the oxide layer estimated from the oxygen consumption was 0.8 nm for all three particle sizes showing that the oxidation is size independent in the studied particle size range. The tridodecylamine ligand was exchanged for various long chain carboxylic acids and the oxidation was studied. While the carboxylic acids give a slower initial oxidation rate, the formed oxide layer does not inhibit further oxidation as effectively as in the case of tridodecylamine. TEM studies show that tridodecylamine capping leads to particles with a metal core surrounded by an oxide layer, while particles capped with long chain carboxylic acids form hollow cobalt oxide shells.

The biological behaviours of pine wood modified with linear chain carboxylic acid anhydrides against soft rot fungi

The work described in this paper has demonstrated that chemically modified Corsican pine sapwood with a homologous series of linear chain carboxylic acid anhydrides afforded bioprotection against soft rot decay. By varying the reaction time, various levels of modifications were obtained. The results indicated that the breakdown caused by fungi is reduced by chemical modification at these levels of modification. There was no significant reduction in feeding above 20% WPG (weight percent gain due to modification) suggesting that modification to WPGs greater this certain level did not cause additional protection. The type of anhydride employed had little influence on breakdown behaviour.

Incorporation of Fluorescent-Labeled Non-α-Amino Carboxylic Acids into the N-Terminus of Proteins in Response to Amber Initiation Codon

Abstract Incorporation of non-natural amino acid derivatives containing fluorescent groups into proteins is a useful method for protein analyses. Here, we investigated the incorporation of fluorescent-labeled non-α-amino carboxylic acids into the N-terminus of proteins in response to the UAG initiation codon. A series of TAMRA-labeled amino carboxylic acids were synthesized and attached to an amber suppressor initiator tRNA derived from Escherichia coli initiator tRNA. Fluorescent-labeled amino carboxylic acids were successfully incorporated into the N-terminus of streptavidin by adding TAMRA-acylated initiator tRNAs to an E. coli cell-free translation system, although the incorporation efficiency differed depending on the amino carboxylic acid chain length. Based on this observation, 3-aminopropionic acid derivatives labeled with BODIPY, rhodamine, and cyanine fluorophores were designed and synthesized. The fluorescent-labeled 3-aminopropionic acid derivatives developed using BODIPY and rhodamine dyes could be incorporated with good efficiency. On the other hand, 6-aminohexanoic acid was effectively incorporated when labeled with cyanine dyes. The present study demonstrates that translation initiation can accept a wide variety of non-natural substrates and provides a useful method for N-terminal-specific labeling of proteins with various fluorophores.

Mechanical behaviour of pine wood chemically modified with a homologous series of linear chain carboxylic acid anhydrides

The work described in this paper demonstrated that acetylation of pine wood up to 16.4 weight percent gain has a positive effect on the compression strength. Higher modification levels resulted in a reduction of the compression strength of wood, compared to the untreated wood. A comprehensive investigation of the effect of molecular size of the substituent group of softwood modified with linear chain carboxylic acid anhydrides, namely acetic, propionic, butyric, valeric, hexanoic, upon the compression strength has also been performed. It was found that the improvement of compression strength imparted by chemical modification is independent of the degree of bulking of the cell wall, but correlates well with the degree of substitution of the cell wall hydroxyl groups.

Aleuritic (9,10,16-trihydroxypalmitic) acid self-assembly on mica

Aleuritic (9,10,16-trihydroxypalmitic) acid self-assembly on mica from solution has been studied using AFM, ATR-FTIR and MD simulations. The goal of this study is to define the role of hydroxyl groups in the interaction between molecules as reference data to understand the mechanism of formation of synthetic and natural biopolyesters from polyhydroxylated long chain carboxylic acids. In a confined structure, such as the one imposed by a vertically self-assembled layer on mica, aleuritic acid has a tendency to adopt a monolayer configuration ruled by the lateral interactions between molecules via the two secondary hydroxyl groups. This (2D) growth competes with the multilayer formation (3D), which is conditioned by the terminal primary hydroxyl group. As the self-assembly spatial constraint is relaxed, MD has shown that the structure tends to become an amorphous and crosslinked phase that can be characterized by topographic and friction force AFM data.

Designer molecular probes for phosphonium ionic liquids

Investigations into the extent of structuring present in phosphonium based ionic liquids (ILs) have been carried out using photochromic molecular probes. Three spiropyran derivatives containing hydroxyl (BSP-1), carboxylic acid (BSP-2) and aliphatic chain (C(14)H(29)) (BSP-3) functional groups have been analysed in a range of phosphonium based ionic liquids and their subsequent physico-chemical interactions were reported. It is believed that the functional groups locate the probe molecules into specific regions based upon the interaction of the functional groups with particular and defined regions of the ionic liquid. This structuring results in thermodynamic, kinetic and solvatochromic parameters that are not predictable from classical solvent models. BSP-1 and BSP-2 exhibit generally negative entropies of activation ranging from -50 J K(-1) mol(-1) to -90 J K(-1) mol(-1) implying relatively low solvent-solute interactions and possible anion interactions with IL polar functional groups. Higher than expected activation energies of 60 kJ mol(-1) to 100 kJ mol(-1) obtained for polar probes maybe be due to IL functional groups competing with the charged sites of the merocyanine (MC) isomer thus reducing MC stabilisation effects. Differences in thermal relaxation rate constants (2.5 x 10(-3) s(-1) in BSP-1 and 3 x 10(-4) s(-1) in BSP-2 in [P(6,6,6,14)][dbsa]) imply that while the polar probe systems are primarily located in polar/charged regions, each probe experiences slightly differing polar domains. BSP-3 entropies of activation are positive and between 30 J K(-1) mol(-1) to 66 J K(-1) mol(-1). The association of the non-polar functional group is believed to locate the spiropyran moiety in the interfacial polar and non-polar regions. The thermal relaxation of the MC form causes solvent reorientation to accommodate the molecule as it reverts to its closed form. Slow thermal relaxation rate constants were obserevd in contrast to high activation energies (5 x 10(-4) s(-1) and 111.91 kJ mol(-1) respectively, for BSP-3 in [P(6,6,6,14)][dbsa]). This may be due to steric effects arising from proposed nano-cavity formation by the alkyl chains in phosphonium based ILs.

Proton sharing and transfer in some zwitterionic compounds based on 4-oxo-4-((1-phenethylpiperidin-4-yl)(phenyl)amino)alcanoic acids.

Three compounds, each derived from Fentanyl and differing essentially only in the length of a carboxylic acid chain, were synthesized and yielded four crystal structures three of which share several structural similarities, including the length of the chain, while the fourth, with a shorter chain, is quite different. The chain length has a significant influence on the crystal structures formed. The 'three atom' chain compounds are all solvated zwitterions which feature a hydrogen-bonded 'dimer' between adjacent zwitterions. The formation of this large dimer leaves available a second carboxylate O atom to take part in hydrogen bonding interactions with solvent molecules. The shorter 'two atom' chain compound was difficult to crystallize and required the use of synchrotron radiation to measure X-ray diffraction data. It does not form the same dimer motif observed in the 'three atom' chain compounds and has not formally formed a zwitterion; although there is evidence of proton sharing or disorder X-ray data are insufficient to create a disordered model, and the compound was modeled as formally neutral based on O-H and N-H distances. Room temperature analyses showed the proton transfer behavior to be independent of crystal temperature, and nuclear magnetic resonance studies show proton transfer behavior in solution. The formation of a zwitterionic hydrogen-bonded dimer is implicated in providing some stability during crystal growth of the easily crystallized 'three atom' chain compounds.

Stability of biodiesel and its blends: A review

Biodiesel consists of long chain fatty acid esters derived from feed stocks such as vegetable oils, animal fats and used frying oil, etc. which may contain more or less unsaturated fatty acids which are prone to oxidation accelerated by exposure to air during storage and at high temperature may yield polymerized compounds. Auto oxidation of biodiesel can cause degradation of fuel quality by affecting the stability parameters. Biodiesel stability includes oxidation, storage and thermal stability. Oxidation instability can led to the formation of oxidation products like aldehydes, alcohols, shorter chain carboxylic acids, insolubles, gum and sediment in the biodiesel. Thermal instability is concerned with the increased rate of oxidation at higher temperature which in turn, increases the weight of oil and fat due to the formation of insolubles. Storage stability is the ability of liquid fuel to resist change in its physical and chemical characteristics brought about by its interaction with its environment and may be affected by interaction with contaminants, light, factors causing sediment formation, changes in color and other changes that reduce the clarity of the fuel. These fuel instabilities give rise to formation of undesirable substances in biodiesel and its blends beyond acceptable quantities as per specifications and when such fuel is used in engine, it impairs the engine performance due to fuel filter plugging, injector fouling, deposit formation in engine combustion chamber and various components of the fuel system. The present review attempts to cover the different types of fuel stabilities, mechanism of occurrence and correlations/equations developed to investigate the impact of various stability parameters on the stability of the fuel. A review of the use of different types of natural and synthetic antioxidants has also been presented which indicates that natural antioxidants, being very sensitive to biodiesel production techniques and the distillation processes have varying impacts on fuel stability and available literature is very much scarce. The work on the use of synthetic antioxidants on the stability of biodiesel (both distilled and undistilled) from various resources has indicated that out of various 8 synthetic antioxidants studied so far only 3 antioxidants have been found to increase the fuel stability significantly. However, effectiveness of these antioxidants is in the order of TBHQ > PY > PG.

Influence of Carbon Chain Length and Unsaturation on the Esterification Activity of Fatty Acids on Nb2O5 Catalyst

The influence of chain length and the extent of the saturation on the esterification activity of long chain carboxylic acids were studied on Nb2O5 catalyst. A series of individual fatty acids (capr...

Two Lysine Residues in the Bacterial Luciferase Mobile Loop Stabilize Reaction Intermediates

Bacterial luciferase catalyzes the reaction of FMNH(2), O(2), and a long chain aliphatic aldehyde, yielding FMN, carboxylic acid, and blue-green light. The most conserved contiguous region of the primary sequence corresponds to a crystallographically disordered loop adjacent to the active center (Fisher, A. J., Raushel, F. M., Baldwin, T. O., and Rayment, I. (1995) Biochemistry 34, 6581-6586; Fisher, A. J., Thompson, T. B., Thoden, J. B., Baldwin, T. O., and Rayment, I. (1996) J. Biol. Chem. 271, 21956-21968). Deletion of the mobile loop does not alter the chemistry of the reaction but decreases the total quantum yield of bioluminescence by 2 orders of magnitude (Sparks, J. M., and Baldwin, T. O. (2001) Biochemistry 40, 15436-15443). In this study, we attempt to localize the loss of activity observed in the loop deletion mutant to individual residues in the mobile loop. Using alanine mutagenesis, the effects of substitution at 15 of the 29 mobile loop residues were examined. Nine of the point mutants had reduced activity in vivo. Two mutations, K283A and K286A, resulted in a loss in quantum yield comparable with that of the loop deletion mutant. The bioluminescence emission spectrum of both mutants was normal, and both yielded the carboxylic acid chemical product at the same efficiency as the wild-type enzyme. Substitution of Lys(283) with alanine resulted in destabilization of intermediate II, whereas mutation of Lys(286) had an increase in exposure of reaction intermediates to a dynamic quencher. Based on a model of the enzyme-reduced flavin complex, the two critical lysine residues are adjacent to the quininoidal edge of the isoalloxazine.

Aging mechanism of Sulfonated poly(aryl ether ketone) (sPAEK) in an hydroperoxide solution and in fuel cell

Ex situ and in situ fuel cell degradation of a sPAEK membrane were investigated. Post-mortem analyses of the aged membrane and of the degradation products eluted in water were carried out by NMR, IR, SEC and EDX. Ex situ agings were performed in a low concentration H 2O 2 solution (0.07%) without any metallic catalyst. We exemplify that ex situ accelerated aging tests in such hydrogen peroxide solution are relevant to the chemical degradation in fuel cell. We have shown that a 500 h fuel cell test at moderate temperature (60 °C) induces significant modifications on the macromolecules such as a 40% molecular weight reduction. Degradation appears heterogeneous and limited to the cathode side. The model compound approach developed in the previous article (Perrot et al. [42]) has allowed the identification of the aging path in fuel cell. Phenolic and carboxylic acid chain ends have been identified as the main products resulting from polymer chain scissions. The ex situ lifetime (100 h) of the membrane appears very limited with respect to the in situ operating time suggesting that the low H 2O 2 concentration (0.07%) is still much higher than in fuel cell.

Substitution reactions of thorium(IV) acetate to synthesize nano-sized carboxylate complexes

Some mixed-ligand thorium(IV) complexes with the general formula [Th(OOCCH 3) 4− n L n ] (L = anions of myristic, palmitic or stearic acid and n = 1–4) have been synthesized by the stepwise substitution of acetate ions of thorium(IV) acetate with straight chain carboxylic acids in toluene under reflux. The complexes were characterized by elemental analyses, spectral (electronic, infrared, NMR and powder XRD) studies, electrical conductance and magnetic susceptibility measurements. Doubly and triply bridged coordination modes of the ligands were established by their infrared spectra and nano-size of the complexes by powder XRD. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes showed π → π*, n → π* and charge transfer transitions. Molar conductance values indicated the complex to be non-electrolytes. These are a new type of mixed-ligand thorium(IV) complexes for which a nano-sized, oxygen bridged polymeric structure has been established on the basis of physico-chemical studies.

Topical anti-inflammatory effect of lipophilic constituents from Alchornea floribunda and Alchornea cordifolia leaves

The leaves of Alchornea floribunda and Alchornea cordifolia are used traditionally as topical anti-inflammatory agents. Several studies have shown that the hexane extracts of the plant materials exhibited significant anti-inflammatory activity [1,2,3]. In the present study, we subjected the hexane extracts of Alchornea floribunda and Alchornea cordifolia leaves to column chromatographic separation and isolated two highly lipophilic fractions AFLF and ACLF respectively. The anti-inflammatory effects of these fractions were investigated using xylene – induced oedema as a model of inflammation. AFLF and ACLF at 5mg/ear showed significant (P<0.001) topical anti-inflammatory effect with oedema inhibitions of 64.0 and 79.0% at 2h respectively. These fractions showed significantly higher topical anti-inflammatory effect than 5mg/ear indomethacin (oedema inhibition of 48% at 2h). GC/MS analysis of these fractions revealed that AFLF is composed mainly of long chain saturated and unsaturated hydrocarbons (18.78%) and their oxygenated derivatives (1.89%), long chain carboxylic (fatty) acids (2.72%) and their esters (5.53%); while ACFL is rich in volatile oils euginol (21.26%) and cadinol (4.76%) and other constituents like long chain primary alcohols (4.78%), long chain saturated hydrocarbon, nanocosane (36.86) and steroid derivatives, ethyl iso-allocholate (4.59%) and 3-acetoxy-7,8-epoxylanostan-1-ol (15.86%). These constituents are highly lipophilic and can easily permeate lipoidal layers of skin. They may contribute significantly to the observed topical anti-inflammatory effect of Alchornea floribunda and Alchornea cordifolia leaf extracts.

Nano-sized titanium(IV) ternary and quaternary complexes with electron-rich oxygen-based bidentate ligands

Some novel ternary and quaternary complexes of titanium(IV) of general formula [Ti(acac)Cl 3− n (OOCR) n ] (R = C 15H 31 or C 17H 35 and n = 1–3) have been synthesized by stepwise substitution of chloride ions of [Ti(acac)Cl 3] by straight chain carboxylic acid anions. The complexes are characterized by their elemental analyses, spectral (infrared, FAB mass, 1H NMR and powder XRD) studies, molecular weight determination and molar conductance measurements. Infrared spectra suggested bidentate chelating nature of both acetylacetonate and carboxylate anions in the complexes. Monomeric nature of the complexes was confirmed by their molecular weight determination and FAB mass spectra. Molar conductance values indicated the complexes to be non-electrolytes in DMF. The complexes exhibited high resistance to hydrolysis. Their powder XRD data indicated the nano-size for the complexes. The coordination number of titanium(IV) in these complexes were found to be six, seven and eight which has been discussed in detail.

Stepwise Functionalization of ZnO Nanotips with DNA

A surface functionalization methodology for the development of ZnO nanotips biosensors that can be integrated with microelectronics was developed. Two types of long chain carboxylic acids linkers were employed for the functionalization of 0.5 mum thick MOCVD-grown ZnO nanotip films with single-stranded DNA (ssDNA), followed by hybridization with complementary ssDNA tagged with fluorescein. The ZnO functionalization strategy was developed for the fabrication of ZnO nanotips-linker-biomolecule films integrated with bulk acoustic wave (BAW) biosensors, and it involved three main steps. First, 16-(2-pyridyldithiol)hexadecanoic acid or N-(15-carboxypentadecanoyloxy)succinimide, both bifunctional C16 carboxylic acids, were bound to ZnO nanotip films through the COOH group, leaving at the opposite end of the alkyl chain a thiol group protected as a 2-pyridyl disulfide, or a carboxylic group protected as a N-succinimide, respectively. In the second step, ssDNA was covalently linked to each type of ZnO-linker film: the 2-pyridyl disulfide end group was substituted with 16 bases 5'-thiol-modified DNA (SH-ssDNA), and the N-succinimide ester end group was substituted with 16 bases 5'-amino-modified DNA (NH(2)-ssDNA). In the third step, the DNA-functionalized ZnO nanotip films were hybridized with complementary 5'-fluorescein ssDNA. The surface-modified ZnO nanotip films were characterized after each step by FT-IR-ATR, fluorescence emission spectroscopy, and fluorescence microscopy. This functionalization approach allows sequential reactions on the surface and, in principle, can be extended to numerous other molecules and biomolecules.