Mixed Carboxylates Research Articles

Bis(p-aminobenzoato)bis(hexadecanoato)dicopper(II): A low-temperature and thermally-stable functional metallomesogen

A novel copper (II) mixed carboxylates namely bis ( p -aminobenzoato) bis (hexadecanoato)dicopper(II), [Cu 2 ( p -H 2 NC 6 H 4 COO) 2 (CH 3 (CH 2 ) 14 COO) 2 ], from one-pot self-assembly of the corresponding ions was designed to function as a low-temperature and thermally-stable metallomesogen applications. The as-prepared copper (II) complex was characterized by means of CHNS analysis, Fourier Transform Infrared (FTIR) spectroscopy, Ultraviolet-Visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical polarized microscopy (OPM), magnetic Gouy balance, and cyclic voltammetry (CV) for the determination of its elemental compositions, chemical boding, optical properties, thermal stability, phase transition, magnetic properties and electrochemical behavior of the complex, respectively. Its melting and decomposition temperatures are 115 o C and 256 o C, respectively, and formed a smectic C mesophase on cooling from the isotropic liquid phase. Its room-temperature effective magnetic moment is 2.89 B.M., indicating a paramagnetic complex with negligible electronic communication between the two Cu(II) centers. Cyclic voltammetry shows two sets of overlapping peaks at -0.33 V and -0.38 V corresponding to Cu(II)Cu(II)-Cu(II)Cu(I) and Cu(II)Cu(I)-Cu(I)Cu(I) indicating diffusion-controlled, quasireversible reaction accompanied by extensive structural reorganizations.

Unravelling a microbial synergy to boost caproate production via carboxylates chain elongation with ethanol

Chain elongation of volatile fatty acids for medium chain fatty acids production (e.g. caproate) is an attractive approach to treat wastewater anaerobically and recover resource simultaneously. Undefined microbial consortia can be tailored to achieve chain elongation process with selective enrichment from anaerobic digestion sludge, which has advantages over pure culture approach for cost-efficient application. Whilst the metabolic pathway of the dominant caproate producer, Clostridium kluyveri, has been annotated, the role of other coexisting abundant microbiomes remained unclear. To this end, an ethanol-acetate fermentation inoculated with fresh digestion sludge at optimal conditions was conducted. Also, physiological study, thermodynamics and 16 S rRNA gene sequencing to elucidate the biological process by linking the system performance and dominant microbiomes were integrated. Results revealed a possible synergistic network in which C. kluyveri and three co-dominant species, Desulfovibrio vulgaris, Fusobacterium varium and Acetoanaerobium sticklandii coexisted. D. vulgaris and A. sticklandii (F. varium) were likely to boost the carboxylates chain elongation by stimulating ethanol oxidation and butyrate production through a syntrophic partnership with hydrogen (H2) serving as an electron messenger. This study unveils a synergistic microbial network to boost caproate production in mixed culture carboxylates chain elongation.

Linking microbial community structure and product spectrum of rice straw fermentation with undefined mixed culture

Undefined mixed culture-based fermentation is an alternative strategy for biofuels and bioproducts production from lignocellulosic biomass without supplementary cellulolytic enzymes. Mixed culture produces mixed carboxylates. To estimate the relationship between microbial community structure and product spectrum, carboxylate production was initiated by mixed cultures with different microbial community structure. All the inoculum cultures were derived from the same enrichment culture from the combination of cattle manure, pig manure compost, corn field soil and rotten wood. Due to the differences in the preparation method and culture time, the inoculum cultures for batch fermentation had high similarity in microbial community structure, while the community structure of each inoculum culture for repeated batch fermentation differed from that of another. The inoculum cultures with similar community structure led to a similar product spectrum. In batch fermentation, the selectivity of main product butyric acid stabilized around 76%. The inoculum cultures with different community structures resulted in different product spectra. In repeated batch fermentation, the butyric acid content gradually decreased to 27%, and the by-product acetic acid content steadily increased to 56%. The other by-products including propionic, valeric and caproic acids were also increased. It is deduced that keeping the microbial community structure stable makes the basic and key precondition for steady production of specific carboxylic acid with undefined mixed culture.

Synthesis, structure, and photocatalytic properties of Zn1–x Cu x O: CuO composites with various morphologies of aggregates

Using mixed copper zinc carboxylates as precursors, Zn1–x Cu x O: CuO composite materials with various morphologies and microstructures of aggregates were synthesized. Their structural, optical, and photocatalytic characteristics were determined.

Dark fermentation effectiveness as a key step for waste biomass refineries: influence of organic matter macromolecular composition and bioavailability

In next generation bio-based refineries, hydrolysis and primary (or extractive) fermentations by undefined microbial cultures (UMC) are precursors of secondary bio-transformations, in which H2, CO2 and mixed carboxylates are used as substrate for achieving added-value target products (e.g. bio-based chemicals, bio-plastics and pigments). Dark fermentation (DF) is the most simple UMC-driven hydrolysis and primary fermentations to extract gaseous and soluble mixtures of compounds from raw biomass. Which solid fractions (types of macro-molecules) of mixed raw organic matter (OM) are efficiently hydrolyzed + fermented during DF is an aspect that was rarely considered in depth. Here, a first attempt was made to propose a new approach for understanding the effects of DF on different fractions of biomass. A set of seven different biomasses underwent optimized DF tests and, for simplicity, only the gaseous main product, i.e. bio-hydrogen potential (BHP) production, was used as parameter to assess DF efficacy. BHP was studied in relation with OM characteristics: on one side, chemical composition (macro-molecular fractions) and, on the other side, bioavailability to UMC attack (using two different biological assays). BHP was found significantly correlated (Pearson's test for p < 0.05, n = 7) only to acid detergent lignin (negatively), soluble sugars and sugars + starch (positively). Bioavailability was negatively correlated with fibrous fractions and to fat-like fractions, but correlations with BHP were poorer (p > 0.05, n = 7). A statistical model (partial least square regression) was proposed for predicting BHP from OM characteristics, with interesting predictability. In the next future, the proposed approach should be widened to better understand the DF effectiveness not only referred to its gaseous products, but especially focusing on the wide range of soluble products (carboxylates), thought as substrates for secondary biorefinery. Copyright © 2015 John Wiley & Sons, Ltd.

1-D to 3-D lanthanide coordination polymers constructed from 5-aminoisophthalic acid and oxalic acid

Three lanthanide metal organic frameworks (MOFs) with mixed carboxylates of 5-aminoisophthalic acid (H2AIP) and oxalic acid (H2OX), namely [Yb(AIP)(OX)0.5(H2O)3]n·H2O (1), [Tb(HAIP)(OX)(H2O)]n (2), and {[Er(AIP)(OX)0.5(H2O)]·H2O}n (3) were obtained by hydrothermal reactions and characterized by elemental analysis, IR spectra and thermogravimetric analysis, as well as single crystal X-ray diffraction. These frameworks exhibit three typical structural features: complex 1 possesses one-dimensional ladder-like chain, 2 has two-dimensional layer, and 3 is three-dimensional framework. Moreover, the fluorescent property of 2 is also investigated.

Pillaring of CdCl2‐Like Layers in Lanthanide Metal–Organic Frameworks: Synthesis, Structure, and Photophysical Properties

A hydrothermal reaction of lanthanide salts, pyridine-2,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid, and water gave rise to a new series of three-dimensional mixed carboxylates (homocyclic and heterocyclic) of lanthanides with the general formula [M2(H2O)4][{C5H3N(COO)2}2{C6H4(COO)2}], M=La (I), Pr (II), and Nd (III). The structure consists of M2O14N2 dimeric units connected by pyridine-2,3-dicarboxylate moieties to form two-dimensional layers that are pillared by terephthalate units. The structures also possess two co-ordinated water molecules, which are arranged to form one-dimensional helical chains and can be reversibly adsorbed. The connectivity within the layers closely resembles that of the CdCl2 layered structure with 3(6) topology. To the best of our knowledge, this is the first observation of CdCl2 topology in lanthanide metal-organic framework compounds. Partial substitution of La3+ in I by Eu3+ and Tb3+ (2 and 4 %) gives rise to characteristic red/pink or green emission, which suggests a ligand-sensitized metal-centered emission. The Nd compound III shows interesting UV and blue emission through an up-conversion process.

Uranyl-organic complexes: structure symbols, classification of carboxylates, and uranyl polyhedral geometries

A system of structure symbols to classify and group uranyl-organic complexes is devised. The method is applied to describe 604 published structures of uranyl-organic complexes, then to consider the complex chemistry of uranyl carboxylates. A review of the uranyl-organic structural units in monocarboxylates, polycarboxylates and mixed carboxylates is provided. The uranyl (U–O) and equatorial bond lengths are considered for well-refined structures and their trends are briefly discussed.

Design and Application of an Alkaline‐Surfactant‐Polymer Flooding System in Field Pilot Test

We have developed an inexpensive sort of flooding reagent whose major components are natural mixed carboxylates from proportionally mixed saponification residuals of cottonseed oil, tea oil, vegetable oil, and soybean oil. An orthogonal test design method was used to select one form of this flooding reagent (which is named SD) by measuring the phase behavior and another form of the flooding system: alkaline/surfactant/polymer (named SD‐ASP). The optimal composition was obtained by measuring the transient interfacial tension (IFT) at the crude oil/aqueous interface. Results of the tests show that the SD‐ASP flooding systems are tolerant to salt up to 1.5×105 mg/L and to Ca2+ and Mg2+ to 5.0×103 mg/L at 90°C, the IFTmin (the minimum of IFT) is 10−3 mN/m, and the oil recovery ratio reaches 22.77% by using the core flood experiment. The pilot tests, including a putting in and sending out in a single oil well, a group oil well and a larger well region, were all very successful, with an average input‐output ratio of 1∶4.15. All these results demonstrate that the SD‐ASP formulation is a new, very inexpensive, and highly effective flooding system.

Synthesis and cytotoxicity of new platinum(IV) complexes of mixed carboxylates

In order to develop new antitumor platinum(IV) complexes with highly tuned lipophilicity, a series of (diamine)Pt(IV) complexes of the formula [Pt IV(dach)L 3L′] or [Pt IV(dach)L 2L″ 2] (dach= trans-(±)-1,2-diaminocyclohexane; L=acetato, propionato; L′=acetato, propionato, valerato or pivalato; L″=trifluoroacetato) have been synthesized by electrophilic substitution of the tris(carboxylato)hydroxoplatinum(IV) complexes, [Pt IV(dach)L 3OH] (L=acetato, propionato), with various carboxylic anhydrides such as acetic, trifluoroacetic, pivalic and valeric anhydrides. The present platinum(IV) complexes were fully characterized by means of elemental analyses, 1H NMR, mass and IR spectroscopies. The complexes 8 and 10, satisfying the appropriate range of lipophilicity (log P=0.18–1.54), exhibited high activity (ED 50, 5.1 and 1.3 μM, respectively) compared with other complexes, which implies that the lipophilicity is an important factor for the antitumor activity of this series of complexes.

Effects of Modified Natural Mixed Carboxylates in ASP‐Flooding Systems

A series of surfactants, whose major components are natural mixed carboxylates from the heels of vegetable oil and fats such as soybean oil, vegetable oil, animal oil, and tea oil etc., was developed. An orthogonal‐test‐design method was used to screen the alkaline/ surfactant/polymer (ASP) flooding systems by measuring the transient interfacial tensions at the oil/aqueous interface, and the optimal formations were obtained. The results show that the oil recovery can be increased by 26.8% of the original oil in place (OOIP) using the core‐flood experiment. The wastewater resulting from the production of SDC (natural mixed carboxylates) also has high surface activity, especially the wastewater of SDC‐V, which was treated as SDC solution, and can increase the oil recovery ratio by 19.0% (OOIP).

Electrophilic substitution of (diamine)tetrahydroxoplatinum(IV) with carboxylic anhydrides. Synthesis and characterization of (diamine)platinum(IV) complexes of mixed carboxylates.

A novel series of (diamine)platinum(IV) complexes of mixed carboxylates have been synthesized by electrophilic substitution of the tetrahydroxoplatinum(IV) complex (dach)Pt(OH)4 (dach = trans-(+/-)-1,2-diaminocyclohexane) with three different carboxylic anhydrides, pivalic, acetic, and trifluoroacetic anhydrides. Consecutive two-step acylations with two different carboxylic anhydrides in acetone or dichloromethane gave the mixed carboxylate complexes (dach)Pt(O2CR)x(O2CR')4 - x (R = C(CH3)3 or CF3, R' = CH3, x = 1-4) including all the possible stereoisomers, which could be separated and identified by means of HPLC, column chromatography, 1H NMR, and X-ray crystallography. From analysis of the reaction products we have found that the positions of electrophilic substitution of (dach)Pt(OH)4 were influenced by the kinds of carboxylic anhydrides exhibiting different electrophilicity or steric effects. The initial substitution by the first reactant occurs more favorably on axial OH, but in the case of pivalic anhydride, equatorial substitution is favored probably because of the bulkiness of the pivalate group. Such a result seems to be related to their stereochemical factors rather than to differences in electrophilicity. The lipophilicity of the title complexes was affected not only by the carbon numbers of substituents but also by the conformation of the resulting compound.

Thermal decomposition of freeze-dried μ-oxo-carboxylates of manganese and iron

The decomposition of freeze-dried mixed carboxylates of manganese and iron was investigated by means of DTA, TG, mass spectroscopy and X-ray powder diffractometry. The three main steps of decomposition are characterized as release of (a) H 2O, (b) carboxylic acid and CO 2/CO, and (c) the corresponding carbonyl compound and CO 2. In particular, the course of process (b) strongly depends on the stability of the metal–carboxylate link in the three investigated carboxylates. Well-crystallized single-phase manganese ferrites can be obtained on decomposition of formates of appropriate composition and thermal treatment of decomposition products at 600°C while maintaining a p(O 2) within the coexistence field of manganese ferrite.

Quantitative aqueous attenuated total reflectance Fourier transform infrared spectroscopy: Part II. Integrated molar absorptivities of alkyl carboxylates

A quantitative attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopic method is developed for the analysis of total carboxylate concentration, [COO −], in aqueous solution. The short (12–13 μm) and highly reproducible pathlength of the ATR cell permits quantitative subtraction of the water peak at 1640 cm −1. Carboxylate quantitation is based on the area of the asymmetric stretching peak, which is nearly independent of compound structure. The molar absorptivity of alkyl carboxylates in water is 438 ± 58 l mol −1 cm −1, and the integrated molar absorptivity is 2.95 ± 0.08 × 10 4 l mol −1 cm −2 ( n = 15 compounds, 0.1 M ≤ [COO −] ≤ 1.5 M). The [COO −] in solutions of mixed carboxylates is measured with a root mean square error of 2.4% and a small (+1.5) positive bias. The accuracy of the method is limited by the assumption that integrated absorbance is constant for all COO − groups.

Preparation and Magnetic Properties of the Copper(II) Mixed Carboxylates with Haloacetate and Ammonioacetate

Abstract Copper(II) mixed carboxylate compounds, CuX(X′CH2COO)(R3NCH2COO)·mH2O (X=C1, Br; X′=F, Cl; R=, CH3), were prepared, and then characterized by means of magnetic susceptibility and IR-spectroscopy. The mixed carboxylates with betaine have the copper(II) acetate-type dinuclear structures. The amount of spin-exchange coupling through betaine bridges was estimated.

ESR spectra of trimeric heteronuclear clusters. II. Paramagnetic resonance of heteronuclear chromium and iron carboxylates

The shape of the ESR spectra of powder samples of trimeric heteronuclear clusters is considered. The thermal population of two Kramers ground-state doublets is shown to lead both to a temperature-dependent effective molecular g value and a structured line shape. A detailed analysis of the ESR spectra of heteronuclear Cr 2Fe- and CrFe 2-carboxylates is presented. The antisymmetric exchange parameter is shown to be relatively small for the mixed carboxylates under consideration.

Synthesis, Molecular Weights and Infrared Spectra of Mixed Carboxylate Complexes of Titanium(IV)

Abstract Mixed carboxylates of titanium (IV) with the general formula (o-C6H4O.COO)Ti(OPri)2 I, (o-C6O.COO)Ti(OPri)(OOCR) II and (o-C6H4OH.COO)Ti(OPri)(OOCR)2 III, (where R = C11H23,C15H31 and C21H43, have been synthesized and characterized. The intermolecular association in these compounds has been found to decrease in the order I > II > III. On the basis of their infrared spectra, the carboxylate groups of fatty acids have been shown to be unidentate, but that of salicylic acid appears to be bidentate in these complexes.