Aliphatic Dicarboxylate Research Articles

Polyoxometalate-Dicarboxylate Hybrid Dimers with {SiW10Cr2} Nodes: Syntheses, Structures, and Mass Spectrometric Characterization.

The current study describes a new family of hybrid dimers constructed from secondary building blocks based on a dichromium-substituted silicodecatungstate, {SiW10Cr2}, and flexible dicarboxylate ligands of varied lengths. All five polyoxometalate-organic hybrid compounds exhibit an entropically favored, cyclic dimer motif that contains just two {SiW10Cr2} clusters─the minimum to form a closed loop, linked by two aliphatic dicarboxylates, as revealed by single-crystal X-ray diffraction. Due to the kinetic inertness of such Cr3+-based hybrid dimers, ESI-MS has become a particularly useful technique for the characterization of these paramagnetic, NMR-unfriendly systems.

Synthesis and Properties of Photocurable Polymers Derived from the Polyesters of Glycerol and Aliphatic Dicarboxylic Acids.

The rapid development of 3D printing technology and the emerging applications of shape memory elastomer have greatly stimulated the research of photocurable polymers. In this work, glycerol (Gly) was polycondensed with sebacic, dodecanedioic, or tetradecanedioic acids to provide precursor polyesters with hydroxyl or carboxyl terminal groups, which were further chemically functionalized by acryloyl chloride to introduce sufficient, photocurable, and unsaturated double bonds. The chemical structures of the acrylated polyesters were characterized by FT IR and NMR spectroscopies. The photoinitiated crosslinking behavior of the acrylated polyesters under ultraviolet irradiation without the addition of any photoinitiator was investigated. The results showed that the precursor polyesters that had a greater number of terminated hydroxyls and a less branched structure obtained a relatively high acetylation degree. A longer chain of aliphatic dicarboxylic acids (ADCAs) and higher ADCA proportion lead to a relatively lower photopolymerization rate of acrylated polyesters. However, the photocured elastomers with a higher ADCA proportion or longer-chain ADCAs resulted in better mechanical properties and a lower degradation rate. The glass transition temperature (Tg) of the elastomer increased with the alkyl chain length of the ADCAs, and a higher Gly proportion resulted in a lower Tg of the elastomer due to its higher crosslinking density. Thermal gravimetric analysis (TGA) showed that the chain length of the ADCAs and the molar ratio of Gly to ADCAs had less of an effect on the thermal stability of the elastomer. As the physicochemical properties can be adjusted by choosing the alkyl chain length of the ADCAs, as well as changing the ratio of Gly:ADCA, the photocurable polyesters are expected to be applied in multiple fields.

Two Cd(II) MOFs of Flexible Aliphatic Dicarboxylate Ligands and 1,4-Bis[(2-methyl-1H-imidazol-1-yl)-methyl]benzene: Synthesis, Crystal Structures and Selective Sensing of Fe3+

Two Cd(II) MOFs of Flexible Aliphatic Dicarboxylate Ligands and 1,4-Bis[(2-methyl-1H-imidazol-1-yl)-methyl]benzene: Synthesis, Crystal Structures and Selective Sensing of Fe3+

Cadmium(II) coordination polymers based on 3,3′-azobis(pyridine) and some aliphatic dicarboxylates: Hydrothermal synthesis, crystal structures, thermal stabilities and photoluminescence

Three new Cd(II) coordination polymers (CPs), namely, [Cd2(µ-phsuc)2(µ-abpy)2(H2O)2]n (1), {[Cd(μ3-glu)(μ-abpy)]⋅3H2O}n (2) and {[Cd(μ-dmglu)(μ-abpy)(H2O)]⋅H2O}n (3), were synthesized by hydrothermally from 3,3′-azobis(pyridine) (abpy) using three different aliphatic dicarboxylic acids [phenyl succinic acid (phsucH2), glutaric acid (gluH2) and 3,3′-dimethyl glutaric acid (dmgluH2)]. The structures of 1–3 were characterized by elemental analysis, infrared spectroscopy (IR), single crystal X-ray and powder X-ray diffraction (PXRD) techniques. X-ray diffraction studies have revealed that 1–3 crystallize in the monoclinic system, P21/n space group (1) and C2/c space group (2, 3). 1 and 2 show 3D structure, whereas 3 exhibits an interesting 2-fold interpenetrating 2D structure. The thermal stabilities of the CPs were studied by thermal analysis (TG/DTA) techniques. In addition, the photoluminescence properties of the CPs have been investigated.

{Mo126W30}: Polyoxometalate Cages Shaped by π–π Interactions

AbstractHere we report the formation of giant {Mo126W30} polyoxometalate cages templated by π‐conjugated planar ligands. Their inorganic shells incorporate arrays of 18 stacked aromatic carboxylates, such as 1,3,5‐benzenetricarboxylate or 5‐nitroisophthalate, and the assembly is stabilized by multiple π–π interactions. NMR data confirmed that the cages are stable in solution and the inner aromatic templates can be postsynthetically replaced by selected aliphatic dicarboxylates, paving the way for endo‐functionalization and exploration of the reactivities within the cage cavities.

{Mo126 W30 }: Polyoxometalate Cages Shaped by π-π Interactions.

Here we report the formation of giant {Mo126 W30 } polyoxometalate cages templated by π-conjugated planar ligands. Their inorganic shells incorporate arrays of 18 stacked aromatic carboxylates, such as 1,3,5-benzenetricarboxylate or 5-nitroisophthalate, and the assembly is stabilized by multiple π-π interactions. NMR data confirmed that the cages are stable in solution and the inner aromatic templates can be postsynthetically replaced by selected aliphatic dicarboxylates, paving the way for endo-functionalization and exploration of the reactivities within the cage cavities.

Structural and spectroscopic studies of spontaneously formed crystalline Eu(iii)-aliphatic dicarboxylates at room temperature.

Complexation of actinides and lanthanides with carboxylic organic ligands is a critical issue affecting radionuclide migration from deep geological disposal systems of spent nuclear fuel. A series of Eu(iii)–aliphatic dicarboxylate compounds, as chemical analogs of radioactive Am(iii) species, Eu2(Ox)3(H2O)6, Eu2(Mal)3(H2O)6, and Eu2(Suc)3(H2O)2, were synthesized and characterized using X-ray crystallography and time-resolved laser fluorescence spectroscopy to examine the ligand-dependent binding modes and the corresponding changes in spectroscopic properties. Powder X-ray crystallography results confirmed that all of the compounds presented a crystalline polymer structure with a trigonal prism square-face tricapped polyhedron geometry centered on Eu(iii) in a nine-coordinate environment involving nine oxygen atoms. This study captures the transition of the coordination modes of aliphatic dicarboxylate ligands from side-on to end-on binding as the carbon chain length increases. This transition is illustrated in malonate bindings involving a combination of side-on and end-on modes. Strongly enhanced luminescence, especially for the hypersensitive peak, indicates a low site symmetry in the formation of solid compounds. The number of remaining bound water molecules was estimated from the resultant increased luminescence lifetimes, which were in good agreement with crystal structures. The excitation–emission matrix spectra of these crystalline polymers suggest that Ox ligands promote the sensitized luminescence of Eu(iii), especially in the UV region. In the case of Mal and Suc ligands, charge transfer occurs in the opposite direction from Eu(iii) to the ligands under UV excitation, resulting in weaker luminescence.

Plumbing the uncertainties of solvothermal synthesis involving uranyl ion carboxylate complexes

Uranyl ion complexes with long-chain, saturated or unsaturated aliphatic dicarboxylate ligands illustrate how solvo-hydrothermal synthetic conditions sometimes result in the formation of species different from those hoped for.

Effects of molecular design parameters on plasticizer performance in poly(vinyl chloride): A comprehensive molecular simulation study

Plasticizers for poly(vinyl chloride) (PVC), including ortho- and tere-phthalates, trimellitates, citrates, and various aliphatic dicarboxylates, are systematically studied with all-atom molecular simulation. Effects of plasticizer molecular structure on its performance, as measured by performance metrics including its thermodynamic compatibility with PVC, effectiveness of reducing the material’s Young’s modulus, and migration rate in the PVC matrix, are evaluated in the framework of seven molecular design parameters. Previous experimental findings on the plasticizer structure-performance relationship are also reviewed. Comparison with experiments establishes the reliability of our simulation predictions. The study aims to provide a comprehensive set of guidelines for the selection and design of high-performance plasticizers at the molecular level. Molecular mechanisms for how each design parameter influences plasticizer performance metrics are also discussed. Moreover, we report a nontrivial dependence of plasticizer migration rate on temperature, which reconciles seemingly conflicting experimental reports on the migration tendency of different plasticizers.

Synthesis, Characterization, and Solid-State Structural Chemistry of Uranium(IV) Aliphatic Dicarboxylates

Examinations of uranium(IV) complexation by aliphatic dicarboxylates, ranging from the three-carbon malonate to the six-carbon adipate, yielded six novel phases. Single crystals of the compounds we...

Novel Salt-Cocrystals of Berberine Hydrochloride with Aliphatic Dicarboxylic Acids: Odd-Even Alternation in Physicochemical Properties.

In this study, various structurally similar aliphatic dicarboxylic acids, namely, succinic acid, glutaric acid, adipic acid, and pimelic acid, were employed as coformers to obtain phase pure cocrystals with berberine chloride (BCl) by a slow solvent evaporation method. The structures of the four novel salt-cocrystals of BCl were determined by single crystal X-ray diffraction analysis and their solid-state properties were characterized. Compared with BCl·2H2O, all the cocrystals showed a higher melting point, improved powder dissolution and intrinsic dissolution rate (IDR), and lower hygroscopicity. It is noteworthy that the melting points and IDRs of these cocrystals exhibit an odd-even alternation with the carbon chain length of the acids.

Efficient naked eye sensing of tartrate/malate based on a Zn-Xylenol orange complex in water and membrane-based test strips

A new strategy for the real-time and naked-eye quantitative determination of tartrate and malate in aqueous solutions at physiological pH and with practical polypropylene membrane-based tests strips was developed by straightforward assembly Zn2+ ions and xylenol orange (3,3-bis [N,N-bis(carboxymethyl) aminomethyl]-o-cresolsulfonephthalein tetrasodium sodium salt, XO). The chromogenic dinuclear complex [Zn2 (XO) (H2O)x], 1 was studied in-deep as visual chemosensor for aliphatic dicarboxylates, oxyanions and nucleoside triphosphates. Complex 1 was highly sensitive and selective for visual detection of α-hydroxydicarboxylates such as tartrate and malate over non-hydroxylated dicarboxylates (oxalate, malonate, maleate, fumarate and succinate), citrate, oxyanions and nucleoside triphosphates in micromolar concentration range. Addition of tartrate and malate at pH = 7.4, gave rise to rapid color change from purple to golden with detection limit of 11 μmolL−1 for tartrate. On the basis of spectroscopic tools (UV–Vis, 1H NMR) and DFT calculations the efficient colorimetric change upon addition tartrate is attributed to a complexation process, through simultaneous coordination of the carboxylate and hydroxyl groups, to the Zn atoms with high affinity (log K = 5.08) and binding energy calculated in 8.7 kcal mol−1. The complex 1 is an order the magnitude more selective for tartrate than malate.Finally, the combination of complex 1 with polypropylene membranes negatively charged with carboxylate groups on surface generates flexible and cheap tests strips allows for the selective visual detection of tartrate in micromolar concentration range with good selectivity over other common dicarboxylates and oxyanions.

Structural and optical properties of pillared Eu3+-containing layered double hydroxides intercalated by 2- to 12-carbon aliphatic dicarboxylates

While the versatile composition of layered double hydroxides (LDHs) allows the introduction of almost any polyvalent cation in their structure, the exchangeable negatively charged ions intercalated between the plates increase their vast range of functionalities. Here we report on the preparation and optical properties of pillared Eu3+-substituted ZnAl LDHs intercalated by aliphatic dicarboxylates: ‒OOC‒(CH2)n–2‒COO‒. The basal distance in these materials is dependent on the size and packing of the intercalated anions. By varying the number (n) of carbon atoms in the aliphatic chain from 2 to 12, the interlayer gallery of these ZnAlEu LDHs is considerably expanded from 0.9 to 2.1 nm. In the interlayer gallery, the aliphatic dicarboxylates form a monolayer, with the aliphatic chain inclined by an angle α ≈ 63° with the hydroxide layers. The carbon atom in the COO– group is 0.43 nm far from the metal plane, showing that these carboxylates are not grafted in the brucite-like layers. These LDHs are thermally stable up to around 150 °C, after which dehydroxylation of the hydroxide layers is observed. The Judd-Ofelt intensity parameters were obtained and compared to the Eu3+-containing complexes with the same ligand series indicating a more symmetrical and less polarizable chemical environment around the rare earth ion.

Sustained Release of Linezolid from Prepared Hydrogels with Polyvinyl Alcohol and Aliphatic Dicarboxylic Acids of Variable Chain Lengths.

A series of hydrogels with a specific release profile of linezolid was successfully synthesized. The hydrogels were synthesized by cross-linking polyvinyl alcohol (PVA) and aliphatic dicarboxylic acids, which include succinic acid (SA), glutaric acid (GA), and adipic acid (AA). The three crosslinked hydrogels were prepared by esterification and characterized by equilibrium swelling ratio, infrared spectroscopy, thermogravimetric analysis, mechanical properties, and scanning electron microscopy. The release kinetics studies of the linezolid from prepared hydrogels were investigated by cumulative drug release and quantified by chromatographic techniques. Mathematical models were carried out to understand the behavior of the linezolid release. These data revealed that the sustained release of linezolid depends on the aliphatic dicarboxylic acid chain length, their polarity, as well as the hydrogel crosslinking degree and mechanical properties. The in vitro antibacterial assay of hydrogel formulations was assessed in an Enterococcus faecium bacterial strain, showing a significant activity over time. The antibacterial results were consistent with cumulative release assays. Thus, these results demonstrated that the aliphatic dicarboxylic acids used as crosslinkers in the PVA hydrogels were a determining factor in the antibiotic release profile.

Study of Aqueous Am(III)-Aliphatic Dicarboxylate Complexes: Coordination Mode-Dependent Optical Property and Stability Changes.

The thermodynamics of Am(III) complex formation in natural groundwater systems is one of the major topics of research in the field of high-level radioactive waste management. In this study, we investigate the absorption and luminescence properties of aqueous Am(III) complexes with a series of aliphatic dicarboxylates in order to learn the thermodynamic complexation behaviors in relation to binding geometries. The formation of Am(III) complexes with these carboxylate ligands induced distinct red shifts in the absorption spectra, which enabled chemical speciation. The formation constants determined by deconvolution of the absorption spectra showed a linear decrease for the three ligands (oxalate (Ox), malonate (Mal), and succinate (Suc)) and a mild decrease for the remaining ligands (glutarate (Glu) and adipate (Adi)). Time-resolved laser fluorescence spectroscopy (TRLFS) was used to obtain information about the aqua ligand, which indirectly indicated the bidentate bindings of these dicarboxylate ligands. A complementary attenuated total reflectance Fourier transform infrared (ATR-FTIR) study on Eu(III), which is a nonradioactive analogue of Am(III) ion, showed that the coordination modes differ depending on the alkyl chain length. Ox and Mal bind to Am(III) via side-on bidentate bindings with two carboxylate groups, resulting in the formation of stable 5- and 6-membered ring structures, respectively. On the other hand, Suc, Glu, and Adi form end-on bidentate bindings with a single carboxylate group, resulting in a 4-membered ring structure. Density functional theory calculations provided details about the bonding properties and supported the experimentally proposed coordination geometries. This study demonstrates that coordination mode-dependent changes in optical properties occur along with thermodynamic stability changes in Am(III)-dicarboxylate complexes.

CdII -Organic Frameworks Fabricated with a N-Rich Ligand and Flexible Dicarboxylates: Structural Diversity and Multi-Responsive Luminescent Sensing for Toxic Anions and Ethylenediamine.

Three metal-organic frameworks {[Cd(L)(glu)]⋅3 H2 O}∞ (1), {[Cd2 (L)2 (adi)2 ]⋅5 H2 O}∞ (2) and {[Cd(L)(sub)]⋅3 H2 O⋅DMA }∞ (3) (L=pyridine-3,5-bis(5-azabenzimidazole), H2 glu=glutaric acid, H2 adi=adipic acid and H2 sub=suberic acid) were obtained under solvothermal conditions. Complex 1 shows a 2D (4,4) network constructing of Cd2 -glu and Cd-L chains. Complex 2 presents a 2-fold interpenetrating 3D framework with pcu topology. Complex 3 is a 3D framework with cds topology. Three complexes with versatile structures were obtained by changing aliphatic dicarboxylate ligands with different lengths based on a N-rich ligand. Moreover, the fluorescence measurements indicate that complex 1 is a good multifunctional chemosensor for the detection of Cr2 O7 2- and MnO4 - anions by fluorescence quenching effect, and ethylenediamine by fluorescence enhancement effect, with detection limits of 1.196 ppm, 0.551 ppm and 64.572 ppm, respectively. Both complexes 2 and 3 can selectively sense Cr2 O7 2- anion with detection limits of 1.126 ppm for 2 and 0.831 ppm for 3 by a fluorescence quenching effect.

Odd‐Even Effect on Luminescence Properties of Europium Aliphatic Dicarboxylate Complexes

The odd-even effect in luminescent [Eu2 (L)3 (H2 O)x ]⋅y(H2 O) complexes with aliphatic dicarboxylate ligands (L: OXA, MAL, SUC, GLU, ADP, PIM, SUB, AZL, SEB, UND, and DOD, where x=2-6 and y=0-4), prepared by the precipitation method, was observed for the first time in lanthanide compounds. The final dehydration temperatures of the Eu3+ complexes show a zigzag pattern as a function of the carbon chain length of the dicarboxylate ligands, leading to the so-called odd-even effect. The FTIR data confirm the ligand-metal coordination via the mixed mode of bridge-chelate coordination, except for the Eu3+ -oxalate complex. XRD results indicate that the highly crystalline materials belong to the monoclinic system. The odd-even effect on the 4 f-4 f luminescence intensity parameters (Ω2 and Ω4 ) is explained by using an extension of the dynamic coupling mechanism, herein named the ghost-atom model. In this method, the long-range polarizabilities ( ) were simulated by a ghost atom located at the middle of each ligand chain. The values of were estimated using the localized molecular orbital approach. The emission intrinsic quantum yield ( ) of the Eu3+ complexes also presented an the odd-even effect, successfully explained in terms of the zigzag behavior shown by the Ω2 and Ω4 intensity parameters. Luminescence quenching due to water molecules in the first coordination sphere is also discussed and rationalized.

Rapid and One‐Step Transformation of LiAlH4 to Inorganic and Organic Anion Intercalated Li‐Al Layered Double Hydroxides

Monoclinic [LiAl2(OH)6]OH·2H2O was formed by the hydrolysis of LiAlH4 within few minutes of irradiation with microwaves as confirmed by powder X‐ray diffraction (PXRD), infrared, Raman, 27Al NMR spectroscopic, and thermal analysis experiments. The flaky morphology of crystallites was evident in microscopy images. The compound is mesoporous with surface area of 50 m2/g. When required amounts of corresponding mineral acids were added during the hydrolysis of LiAlH4, exchange of the interlayer hydroxide ion with nitrate and chloride ions was successful. This was verified by the hexagonal symmetry observed in the PXRD patterns together with the evidence gathered from infrared, 27Al NMR spectra, thermal analyses, and the substantial changes in ligand to metal charge‐transfer bands in their UV/Visible spectra. A host of Li‐Al LDH compounds intercalated with aliphatic dicarboxylate (oxalic, malonic, succinic, glutaric, adipic, and sebacic acid) anions were rapidly produced when a mixture of LiAlH4 and the respective acid was irradiated with microwaves for a few minutes. The basal spacing of the dicarboxylate anion intercalated systems increased linearly with the increase in the number of –CH2‐ groups in them. Microwave assisted reaction of ethylene glycol with [LiAl2(OH)6]OH·2H2O resulted in its intercalation.

Structural Characterization and Pharmaceutical Properties of Three Novel Cocrystals of Ethenzamide With Aliphatic Dicarboxylic Acids

Ethenzamide (ET) was screened in cocrystallization experiments with pharmaceutically acceptable coformer molecules to discover materials of improved physicochemical properties, that is, higher solubility and better stability. Three novel cocrystals of ET with glutaric, malonic, and maleic acids were obtained by neat grinding and slow evaporation from solution. The purpose of the study was to notice the changes in the geometry and interactions of ET molecule in crystalline phase introduced by different acid and relate them to physicochemical properties of pure ET. Therefore, the crystal structure of the cocrystals was determined by single crystal X-ray diffraction analysis. The powder samples were characterized by differential scanning calorimetry, Fourier-transform infrared spectroscopy, and 13C and 15N solid-state nuclear magnetic resonance spectroscopy. Spectroscopic studies were supported by gauge including projector augmented wave calculations of chemical shielding constants. The high stability of cocrystals during direct compression was proved. The solubility in simulated gastric fluids for studied cocrystals appeared to be approximately 1.6 times-fold higher than ET. The dissolution rates of all ET cocrystals were not faster than the pure drug, but after 240 min, more drugs were released.

Nitroaromatic-detecting zinc and cadmium coordination polymers with methyl-substituted aliphatic dicarboxylate and 4,4′-dipyridylamine ligands and diverse topologies

Hydrothermal reaction of a metal nitrate, a methyl-substituted aliphatic dicarboxylic acid, and the hydrogen-bonding capable 4,4′-dipyridylamine (dpa) ligand afforded four crystalline coordination polymers whose dimensionality, topology, and interpenetration scheme depends on the aliphatic tether length, methyl group position, and coordination geometry at the metal. The four new phases were structurally characterized via single-crystal X-ray diffraction. [Zn(22dmg)(dpa)]n (1, 22dmg = 2,2-dimethylglutarate) displays a system of mutually inclined interpenetrated (4,4) grid coordination polymer layers. [Zn(33dmg)(dpa)]n (2, 33dmg = 3,3-dimethylglutarate), in contrast to 1, displays a stacked arrangement of pairs of (4,4) grid coordination polymer layers, without any interpenetration. [Zn(3mad)(dpa)]n (3, 3mad = 3-methyladipate) possesses a system of four-fold interpenetrated 66dia topology coordination polymer networks. [Cd(33dmg)(dpa)]n (4) displays a 2-fold interpenetrated 41263pcu 3D topology, based on pillaring of dimer-based [Cd2(33dmg)2]n layers by pairs of dpa ligands. Luminescent behavior in 1–4 is attributed to intra-ligand molecular orbital transitions within the dpa aromatic pyridyl rings. The new phases were also surveyed for the ability to detect nitroaromatics in ethanol suspension, with 4 providing optimum response for nitrobenzene detection. Thermal decomposition behavior is also discussed herein.