Pimelic Acid Research Articles

Synthesis and Structural Characterization of Inorganic-Organic-Inorganic Hybrids of Dipalladium-Substituted γ-Keggin Silicodecatungstates

Three inorganic-organic-inorganic hybrids of dipalladium-substituted γ-Keggin silicodecatungstates with organic linkers of different lengths, TBA8[{(γ-H2SiW10O36Pd2)(O2C(CH2)nCO2)}2] (n = 1 (II), 3 (III), and 5 (IV), TBA = [(n-C4H9)4N](+)), were synthesized by exchange of the acetate ligands in TBA4[γ-H2SiW10O36Pd2(OAc)2] (ITBA) with malonic, glutaric, and pimelic acids, respectively. The X-ray crystallographic analysis of II, IIIA (IIIA: III with DCE, DCE = 1,2-dichloroethane), and IVA (IVA: IV with 10DCE) revealed that the anion parts of II, IIIA, and IVA were inorganic-organic-inorganic hybrids composed of two dipalladium-substituted γ-Keggin silicodecatungstates connected by two dicarboxylate ligands. In the crystal structure of IVA, 10 DCE molecules per polyanion were present in the vicinity of polyanions. Compound IVB (IVB: IV with 0.2DCE) was obtained by the evacuation of IVA. The DCE sorption-desorption isotherms of IVB showed that the amount of DCE sorbed was saturated at 10.5 mol mol(-1), of which the amount was close to that (10 mol mol(-1)) of crystallographically assigned DCE molecules. In the DCE sorption-desorption isotherms, a low-pressure hysteresis was observed probably because of hydrogen-bonding interaction between DCE molecules and polyanions. The powder X-ray diffraction (XRD) pattern of IVA changed with decrease in the relative DCE vapor pressure to form IVC (IVC: IV with 0.7DCE) at P/P0 = 0.0. The in situ powder XRD study showed reversible structure transformation between IVA and IVC driven by the sorption-desorption of DCE.

A novel montmorillonite with β-nucleating surface for enhancing β-crystallization of isotactic polypropylene

Montmorillonite (MMT) generally has α-nucleating ability for isotactic polypropylene (iPP). A novel MMT with β-nucleating surface (β-MMT) supported by chemically calcium pimelate (CaA) was prepared through the chemical reaction between pimelic acid (HA) and calcium ion on the surface of MMT in the first time. Infrared spectrometry and thermogravimetric analysis confirmed the formation of CaA on the surface of MMT. The differential scanning calorimeter and X-ray diffraction illustrated that the iPP nanocomposites filled by MMT and β-MMT exhibit different heterogeneous nucleation. The heterogeneous nucleation of the prepared MMT surface has changed from α-nucleation into β-nucleation and a novel MMT with β-nucleating surface is obtained. Even, the heterogeneous β-nucleating ability of β-MMT is much stronger than that of CaA. Addition of MMT with β-nucleating surface into iPP matrix significantly increased the spherulite nuclei density and decreased the spherulite size, and can easily prepare the β-iPP nanocomposites with high relative β-phase content.

The β-nucleating effect of wollastonite-filled isotactic polypropylene composites

Wollastonite (W) with β-nucleating effect (β-W100) for iPP crystallization was obtained through reaction between Ca2+ in wollastonite and pimelic acid (PA) and the β-iPP composites filled by different content of β-W100 were prepared. The effect of PA and wollastonite contents on β-nucleation, crystallization and melting behavior, and crystalline morphology of W and β-W100-filled iPP composites was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and polarizing optical microscopy. The results indicated that incorporation of W and β-W100 increase the crystallization peak temperature of iPP due to its heterogeneous nucleating ability. And iPP/W composites predominantly crystallize in the α-phase iPP and iPP/β-W100 composites in the β-phase iPP. The results of DSC multi-scanning in same and different melting temperatures showed that β-W100 not only has strong heterogeneous β-nucleating effect but also DSC multi-scanning in same and different melting temperatures has no influence on the heterogeneous β-nucleating effect of β-W100. The β-iPP containing high wollastonite content with high β-phase content can be easily prepared.

Synthesis and Characterization of Supramolecular Hydrogen-Bonded Liquid Crystals Comprising of p-n-Alkyloxy Benzoic Acids with Suberic Acid and Pimelic Acid

Two series of supramolecular hydrogen-bonded liquid crystalline complexes have been designed and synthesized. A successful attempt has been made to form hydrogen bond between Suberic acid (SA) and Pimelic acid (PA) with p-n-alkyloxy benzoic acids (nBAO) by varying the respective alkyloxy carbon number. The first homologous series comprises of Suberic acid and p-n-alkyloxy benzoic acids (SA+nBAO), while the another series is formed between Pimelic acid and p-n-alkyloxy benzoic acids (PA+nBAO), where n represents the alkyloxy carbon number which varies from 5 to 12. These two homologous series are analyzed by polarizing optical microscope, differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), and proton NMR studies. The formation of intermolecular hydrogen bond is evinced through FTIR and 1H-NMR. An interesting feature of PA+nBAO homologues series is the inducement of tilted smectic C phase with increasing carbon chain length. In the SA+nBAO homologues series odd–even effect is observed at isotropic to nematic transition temperatures. Phase diagrams of the above complexes are constructed and compared.

Physicochemical properties of imidazo-pyridine protic ionic liquids

A new class of protic ionic liquids (PILs) were prepared by reacting imidazo-[1,2a]-pyridine (ImPr) with benzene-1,2-dithiol (BDT), oxalic acid (Ox), phthalic acid (Phth), pimelic acid (Pim), and sulfuric acid. [ImPr][HSO4] was determined to be the most thermally stable PIL with a decomposition temperature of 326 °C and could potentially be used as an electrolyte in fuel cells and lithium ion batteries. X-ray crystallography on oxidized [ImPr][BDT] indicated the formation of the first reported disulfide PIL. [ImPr][Pim] and [ImPr][Phth] showed fragile behaviour. A Walden plot indicated ionic behaviour close to ideal for [ImPr][Phth].

Engineering Chitosan Using <i>α</i>, <i>ω</i>-Dicarboxylic Acids—An Approach to Improve the Mechanical Strength and Thermal Stability

The current scenario in tissue engineering research demands materials of requisite properties, viz., high porosity, mechanical stability, thermal stability, biocompatibility and biodegradability for clinical applications. However, bringing these properties in single biomaterial is a challenging task, which needs intensive research on suitable cross-linking agents. In the present study, 3D scaffold was prepared with above said properties using chitosan and oxalic (O), malonic (M), succinic (S), glutaric (G), adipic (A), pimelic (P), suberic (SU), azelaic (AZ) and sebacic (SE) acid (OMS- GAP-SAS) individually as a non covalent cross-linkers as well as the solvent for chitosan. Assessment on degree of cross-linking, mechanical strength, FT-IR analysis, morphological observation, thermal stability, binding interactions (molecular docking), in vitro biocompatibility and its efficacy as a wound dressing material were performed. Results revealed the degree of cross-linking for OMSGAP-SAS engineered chitosan were in the range between ≈55% - 65% and the biomaterial demonstrated thermal stability more than 300°C and also exhibited ≥3 - 4 fold increase in mechanical strength compared to chitosan alone. The bioinformatics studies evidently proved the chemistry behind the interaction of OMSGAP-SAS with chitosan. OMSGAP-SAS played dual role to develop the chitosan biomaterial with above said properties, thus matching the requirements needed for various applications.

Structure, hydrogen bond network and proton conductivity of new benzimidazole compounds with dicarboxylic acids

Dicarboxylic acids are interesting for crystal engineering due to their ability of hydrogen bond formation. To find a relationship between the molecular structure and the properties of proton conducting materials, we synthesized two compounds of benzimidazole with dicarboxylic acids of different chain length: glutaric and pimelic acids. The structure of the compounds was determined by X-ray diffraction and compared with molecular arrangement studied by 13C CP/MAS NMR spectroscopy supported by Density Functional Theory computations for benzimidazole. Benzimidazole was found to form salt with glutaric acid in a 1 : 1 ratio and monoclinic layer-type structure with P21/n space group. Flat layers, parallel to (−102) plane, are built of glutaric acid molecules linked into rectangular-type chains by O–H⋯O bonds and benzimidazole molecules attached to the chains by N–H⋯O bonds. The molecule of the benzimidazole compound with pimelic acid contains two benzimidazole rings and one pimelic acid chain. The structure with alternating layers, built of two groups of benzimidazole dimers and layers of pimelic acid chains, belongs to P21/n space group. The acid layers are built of pimelic acid molecules linked by O–H⋯O hydrogen bonds into chains parallel to [30−1] direction and the benzimidazole dimers are linked to the acid layers by N–H⋯O bonds. Impedance spectroscopy studies in wide frequency and temperature range of pellets made of powdered compounds enabled to separate the contributions of crystalline and grain boundary parts to the electric conductivity. The conductivity (averaged over all directions) of the crystalline compounds of benzimidazole with glutaric and pimelic acid is characterized by activation energy of 2.5 eV and 1.6 eV, respectively, which is in an agreement with the hydrogen bond network in the materials.

Cocrystals of Active Pharmaceutical Ingredients—Praziquantel in Combination with Oxalic, Malonic, Succinic, Maleic, Fumaric, Glutaric, Adipic, And Pimelic Acids

The combination of racemic praziquantel, (RS)-PZQ, with aliphatic dicarboxylic acids of the homologous series HOOC–(CH2)n–COOH (with n = 0–8) and the unsaturated analogues of succinic acid as cocrystal formers via liquid-assisted grinding provided a total of nine 1:1 and 2:1 cocrystals with oxalic acid, malonic acid, succinic acid (two polymorphic phases), maleic acid, fumaric acid, glutaric acid, adipic acid, and pimelic acid. The cocrystalline phases were identified first by XRPD analysis and then structurally characterized by IR spectroscopy and, as far as possible, by single-crystal X-ray diffraction analysis. Crystals suitable for XRD analysis were obtained for seven cocrystals and, additionally, for (RS)-PZQ. The analysis of the supramolecular interactions in the crystal structures has shown that the dominant hydrogen bonding patterns within the cocrystals are heterodimeric motifs formed through O–H···O hydrogen bonds between PZQ and the dicarboxylic acids, which mostly contain additionally at least...

Isostructurality in three-component crystals achieved by the combination of persistent hydrogen bonding motifs and solvent inclusion

We demonstrate how solution crystallization of lamotrigine with flexible alkane dicarboxylic acids with different chain lengths (adipic acid and pimelic acid) generates a series of four isostructural solvated three-component salts. The analysis of their crystal structures shows that isostructurality is achieved by the combination of robust hydrogen bonding motifs and the incorporation of solvent guest molecules.

Modification of a Dioxygen Carrier, HemoCD, with PEGylated Dendrons for Extension of Circulation Time in the Bloodstream

A supramolecular diatomic receptor, hemoCD, was modified with PEGylated dendrons to extend its circulation time in the bloodstream. The core component was 4-oxo-4-[[4-(10,15,20-tris(4-sulfonatophenyl)-21H,23H-porphin-5-yl)phenyl]amino]butanoic acid (Por-COOH). The building block of the dendrons was Fmoc-4-amino-4-(2-carboxyethyl)heptanedioic acid (FmocTA), which was condensed with α-amino-ω-methoxy-poly(ethylene glycol) (PEG(5000)-NH(2)) to yield an FmocG1-dendron. After deprotection, the G1-dendron was condensed with Por-COOH to yield G1-Por. A precursor (FmocNA) of an FmocG2-dendron was prepared via a condensation reaction of 4-amino-4-(2-t-butoxycarbonylethyl)heptanedioic acid di-t-butyl ester (TA-E) with FmocTA followed by hydrolysis of the resultant nona-carboxylic acid nona-t-butyl ester. Condensation of FmocNA with PEG(5000)-NH(2) yielded an FmocG2-dendron. After deprotection, the G2-dendron was condensed with Por-COOH to yield G2-Por. The ferrous complexes of G1- and G2-Pors formed stable 1:1 inclusion complexes with Py3CD, a per-O-methylated β-cyclodextrin dimer with a pyridine linker, in aqueous solution yielding supramolecular complexes designated as G1-hemoCD and G2-hemoCD, respectively. Both G1- and G2-hemoCDs bound molecular oxygen, with the O(2) affinities (P(1/2)) of hemoCD, G1-, and G2-hemoCDs at pH 7.4 and 37 °C being 22, 20, and 20 Torr, respectively. The modification of hemoCD with the dendrons did not cause destabilization of the O(2) adducts via autoxidation, as indicated by their half-lives (t(1/2)) of 6.8, 6.1, and 5.5 h for hemoCD, G1-, and G2-hemoCDs, respectively. The blood concentration-time curves of G1- and G2-hemoCDs injected into the bloodstream of rats exhibited two phases, with the half-lives of the fast and slow decays being 0.45 and 5.3 h, respectively, for G1-hemoCD, and 0.20 and 12.8 h, respectively, for G2-hemoCD. The half-lives of hemoCD were 0.02 and 0.50 h, respectively. The circulation time of hemoCD was markedly extended by its modification with the PEGylated dendrons, which was very effective in protecting hemoCD against opsonization for uptake by the reticuloendothelial system.

Preparation, structures and properties of shell/polypropylene biocomposites

A novel shell/β-polypropylene (PP) biocomposite was prepared and characterized. Firstly, the waste shell (S) was modified by a stingy amount of pimelic acid (PA) through solution method, and then compounded with PP through melt blending method. The crystalline form, mechanical properties, and morphology of the S/β-PP composites were studied. The results showed that shell modified by PA was a β nucleating agent with high efficiency, resulting in the maximum Kβ value of 0.56 in PP composites. PA modification promoted the dispersion and interfacial bonding of shell powder in PP. The addition of PA-modified shell powder largely increased the impact strength of PP.

Synthon Modularity in 4-Hydroxybenzamide–Dicarboxylic Acid Cocrystals

A family of 4-hydroxybenzamide–dicarboxylic acid cocrystals has been designed and subsequently isolated and characterized. The design strategy follows from an understanding of synthon modularity in crystal structures of monocomponent crystals such as γ-quinol, 4,4′-biphenol and 4-hydroxybenzoic acid. These monocomponent structures contain infinite O–H···O–H···O–H··· cooperative synthons linked with molecular connectors such as phenyl and biphenyl, and supramolecular connectors such as the acid dimer in 4-hydroxybenzoic acid. The cocrystal design was influenced by the anticipation that dicarboxylic acids can form a supramolecular connector mediated by acid–amide synthons with 4-hydroxybenzamide, which can then form the phenol O–H···O–H···O–H··· infinite synthon. Effectively, the acid–amide and phenol synthons are insulated. The short axis of such a structure will be around 5.12 Å and this is borne out in 2:1 cocrystals of 4-hydroxybenzamide with oxalic, succinic, fumaric, glutaric (two forms) and pimelic acids. Hydrated variations of this structure type are seen in the cocrystals obtained with adipic and sebacic acids.

Preparation and β-crystallization of zeolite filled isotactic polypropylene composites

In order to prepare the zeolite filled β-iPP composites, zeolite supported by calcium pimelate as β-nucleator (β-zeolite) was prepared by the interaction between calcified zeolite and pimelic acid. The effects of Ca(Ac)2 solution concentration in the prepared calcified zeolite process and pimelic acid content on β-nucleating ability of β-zeolite were investigated and the crystallization and melting characteristic of zeolite, calcified zeolite and β-zeolite filled iPP composites were compared. DSC and WXAD analysis indicated that the zeolite and calcified zeolite have α-nucleation and the prepared β-zeolite has high β-nucleating ability for iPP crystallization. The β-nucleating ability of prepared β-zeolite is dependent of Ca(Ac)2 solution concentration and pimelic acid content. The prepared β-zeolite content has little influence on the crystallization and melting characteristic and the β-phase content of the filled iPP composites. The zeolite filled β-iPP composites with high β-phase content can be easily obtained by adding β-zeolite into the iPP matrix.

Crystal growth and physical characterization of picolinic acid cocrystallized with dicarboxylic acids

Pharmaceutical cocrystals are multicomponent materials containing an active pharmaceutical ingredient with another component in well‐defined stoichiometry within the same unit cell. Such cocrystals are important in drug design, particularly for improving physicochemical properties such as solubility, bioavailability, or chemical stability. Picolinic acid is an endogenous metabolite of tryptophan and is widely used for neuroprotective, immunological, and anti-proliferative effects within the body. In this paper we present cocrystallization experiments of a series of dicarboxylic acids, oxalic acid, succinic acid, dl-tartaric acid, pimelic acid, and phthalic acid, with picolinic acid. Characterization by FT-IR and Raman spectroscopy, DSC and TG/DTG analysis, and X-ray powder diffraction show that new compounds are formed, including a 1:1 picolinium tartrate monohydrate, a 2:1 monohydrate adduct of picolinic acid and oxalic acid, and a 2:1 picolinic acid–succinic acid monohydrate cocrystal.

Investigations of new barium dicarboxylates

Structures of new barium dicarboxylates (salts of glutaric, adipic, pimelic, suberic, azelaic and dodecanedioic acids {1–6}) were characterized. Structure solution from powder data was performed in the cases of barium adipate {2}, pimelate monohydrate {3} and dodecanedioate {6}. Structures of barium glutarate pentahydrate {1}, suberate {4} and azelate {5} were obtained from single crystal analysis. Even though these compounds are salts of homologus series of dicarboxylic acids [HOOC—CnH2n—COOH; n = (3–10)], the obtained materials are characterized by broad structural diversity. The synthesized salts form layered (2D) or three-dimensional (3D) structures. Coordination polyhedra of BaOn(8 or 9) – create layers or linear systems of polyhedra connected by edges or edges and vertices, or layers formed by isolated polyhedra linked by carboxylic acids. The degree of hydratation ranges from 5 to 0; the obtained materials crystallize in various crystallographic systems, from triclinic to tetragonal.

Crystallization and melting behavior of isotactic polypropylene composites filled by zeolite supported β-nucleator

In order to prepare the zeolite filled β-iPP composites, the calcium pimelate as β-nucleator supported on the surface of zeolite (β-zeolite) was prepared by the interaction between calcified zeolite and pimelic acid. The β-nucleation, crystallization behavior and melting characteristic of zeolite, calcified zeolite and β-zeolite filled iPP composites were investigated by differential scanning calorimetry and wide-angle X-ray diffractometer. The results indicated that addition of the zeolite and calcified zeolite as well as β-zeolite increased the crystallization temperature of iPP. The zeolite and calcified zeolite filled iPP composites mainly crystallized in the α-crystal form and the strong β-heterogeneous nucleation of β-zeolite results in the formation of only β-crystal in β-zeolite filled iPP composites. The zeolite filled β-iPP composites with high β-crystal contents (above 0.90) can be easily obtained by adding β-zeolite into iPP matrix.

Alignment of Organic Crystals under Nanoscale Confinement

Nanocrystals of α,ω-alkanedicarboxylic acids (HO2C(CH2)n−2CO2H, n = 3–13, odd) grown in aligned nanometer-scale cylindrical pores of nanoporous poly(cyclohexylethylene) monoliths (p-PCHE) adopt preferred orientations relative to the pore direction. X-ray diffraction reveals that nanocrystals of malonic acid (n = 3) grown in 14, 30, and 40 nm diameter pores adopted two preferred mutually perpendicular orientations simultaneously, each orientation coinciding with the direction of hydrogen-bonded chains in the solid state. Nanocrystals of glutaric acid (n = 5) embedded within 30 and 40 nm pores adopted orientations with hydrogen-bonded chains coincident with the pore direction, but the chains were perpendicular to the pore direction in 14 nm pores. Pimelic acid (n = 7) nanocrystals were oriented with their hydrogen-bonded chains parallel to the pore direction, but nanocrystals of longer alkane dicarboxylic acids (n = 9, 11, or 13) adopted orientations in which the their hydrogen-bonded chains progressively tilted away from the pore direction as the alkane length was increased. This behavior can be attributed to increasingly strong dispersive interactions between the alkane chains, which alter the ranking of the fast growing crystal directions. The appearance of preferred orientations for embedded nanocrystals argues that critical size effects and surface energy considerations favor precritical nuclei that are oriented with their fast growth axis aligned with the pore direction. This condition permits the nuclei to achieve critical size more readily while minimizing the area of planes with high surface energies, thereby providing a competitive advantage over other orientations during nucleation. The observation in some cases of two orientations simultaneously and size-dependent orientations reveals the delicate balance of free energies among differently oriented nuclei. Collectively, these observations demonstrate the utility of nanoscale confinement for investigating the earliest stages of crystal growth.

Lipid profiling of the Arabidopsis hypersensitive response reveals specific lipid peroxidation and fragmentation processes: biogenesis of pimelic and azelaic acid.

Lipid peroxidation (LPO) is induced by a variety of abiotic and biotic stresses. Although LPO is involved in diverse signaling processes, little is known about the oxidation mechanisms and major lipid targets. A systematic lipidomics analysis of LPO in the interaction of Arabidopsis (Arabidopsis thaliana) with Pseudomonas syringae revealed that LPO is predominantly confined to plastid lipids comprising galactolipid and triacylglyceride species and precedes programmed cell death. Singlet oxygen was identified as the major cause of lipid oxidation under basal conditions, while a 13-lipoxygenase (LOX2) and free radical-catalyzed lipid oxidation substantially contribute to the increase upon pathogen infection. Analysis of lox2 mutants revealed that LOX2 is essential for enzymatic membrane peroxidation but not for the pathogen-induced free jasmonate production. Despite massive oxidative modification of plastid lipids, levels of nonoxidized lipids dramatically increased after infection. Pathogen infection also induced an accumulation of fragmented lipids. Analysis of mutants defective in 9-lipoxygenases and LOX2 showed that galactolipid fragmentation is independent of LOXs. We provide strong in vivo evidence for a free radical-catalyzed galactolipid fragmentation mechanism responsible for the formation of the essential biotin precursor pimelic acid as well as of azelaic acid, which was previously postulated to prime the immune response of Arabidopsis. Our results suggest that azelaic acid is a general marker for LPO rather than a general immune signal. The proposed fragmentation mechanism rationalizes the pathogen-induced radical amplification and formation of electrophile signals such as phytoprostanes, malondialdehyde, and hexenal in plastids.

Different β nucleants and the resultant microstructural, fracture, and tensile properties for filled and unfilled ISO polypropylene

AbstractThis article explores the use of two β nucleants to improve the fracture behavior of filled and unfilled homo‐polypropylene (PP). The first was based upon an organic quinacridone, whereas the second was based upon the inorganic calcium pimelate. Formulations containing various concentrations of nucleant were prepared using single screw extrusion and then characterized by X‐ray diffraction, differential scanning calorimetry (DSC), Izod impact strength, and tensile testing. The quinacridone nucleating agent produced higher levels of β crystallinity and better improvement in strain to failure, whereas the calcium pimelate imparted greater improvement in impact strength regardless of whether the PP was filled or unfilled. No direct relationship between β crystallinity and fracture properties was observed though synergistic enhancement in impact strength was evident. By varying the concentration of calcium carbonate in the calcium pimelate from 10 : 1, 5 : 1, 2 : 1, and 1 : 1 weight composition of calcium carbonate to pimelic acid, similar property enhancements were achieved regardless of composition although the 10 : 1 sample did produce superior elongation to break. The importance of cooling rate on microstructure within each sample was explored via a through the thickness study using DSC and nano‐indenting methods. Variations in the β content through the thickness were related to cooling and found to be independent of sample composition and processing. Elastic properties varied inversely with β content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A Fast Degrading Odd–Odd Aliphatic Polyester-5,7 Made by Condensation Polymerization for Biomedical Applications

A fast enzymatic degradable aliphatic all-odd-polyester-5,7, based on 1,7-heptanedioic acid (pimelic acid) and 1,5-pentanediol, was synthesized by polycondensation. The structural characterization of the polyester was done using 1D- and 2D-NMR spectroscopic techniques. The properties of the resulting polyester-like crystallization behavior, enzymatic degradation, thermal stability, etc., were investigated using differential scanning calorimetry, wide-angle X-ray diffraction, scanning electron microscopy and gel-permeation chromatography. Terahertz time-domain spectroscopy was employed to determine the glass transition temperature, which could not be revealed reliably by conventional thermal analysis. The properties of all-odd-polyester-5,7 were compared with a well-known enzymatic degradable polyester (polycaprolactone). The results indicated that polyester-5,7 has a crystal structure similar to PCL, but a much faster degradation rate. The morphology of polyester-5,7 film during enzymatic degradation showed a fibrillar structure and degradation began by surface erosion.