Dimeric Carboxylic Acid Research Articles

Monomeric and Dimeric Carboxylic Acid in Crystalline Cavities and Channels of Delta and Epsilon Forms of Syndiotactic Polystyrene.

Delta (δ) and epsilon (ε) co-crystalline forms of syndiotactic polystyrene with a carboxylic acid guest were obtained by sorption of liquid hexanoic acid in syndiotactic polystyrene films exhibiting delta and epsilon nanoporous-crystalline forms. The characterization study is facilitated by axially stretched syndiotactic polystyrene films, used both for polarized FTIR spectra and for WAXD fiber patterns. Particularly informative are two carbonyl-stretching FTIR peaks, attributed to monomeric and dimeric hexanoic acid. The dichroism of these carbonyl peaks indicates that both delta and epsilon phases are able to include hexanoic acid as isolated guest molecules, while only the epsilon phase is also able to include dimeric hexanoic acid molecules in its crystalline channels. The inclusion of both isolated and dimeric hexanoic acid species in the epsilon form crystalline channels produces extremely fast hexanoic acid uptakes by syndiotactic polystyrene epsilon form films.

Parametric Study for Dimeric Anthracene-Based Mechanophore-Embedded Thermoset Polymer Matrix Using Molecular Dynamics

ABSTRACTThis paper presents a parametric study to investigate the effect of relevant design variables on mechanochemical reaction and mechanical properties of a mechanophore-embedded thermoset polymer matrix. Mechanophores emit fluorescence when a specific covalent bond breaks due to external stress, and thus have attracted immense research interest as a damage sensor. Recently, a mechanophore named dimeric 9-anthracene carboxylic acid (Di-AC) was synthesized successfully and incorporated into epoxy-based thermoset polymer matrix to detect damage precursor. However, there is significant potential in modeling the complex mechanochemistry associated with the Di-AC to obtain a better understanding of this mechanophore and its interaction with the host thermoset material. In this study, a hybrid MD simulation methodology is employed to explore this complex mechanochemistry along with the investigation of the effect of design parameters on the mechanophore performance. The hybrid MD simulation method enables the simulation of Di-AC synthesis, epoxy curing, and mechanical loading test; therefore, the experimental process performed can be emulated accurately. Previously, the hybrid MD method showed the capability of capturing experimentally observed phenomena such as early signal detection and yield strength variation between neat epoxy system and epoxy with 5 wt% Di-AC thermoset polymer. In this paper, the effect of curing temperature on mechanophore activation and mechanical properties is investigated. A series of temperatures are used in the curing simulation, which are experimentally achievable. Results show that curing temperature below glass transition temperature maintains early signal detection and yield strength decreases when the curing temperature increases above the glass transition temperature. Good correlation is observed with experimental results.

Cocrystals of Quinoline Derivatives with 5-Aminoisophthalic Acid

The structures of cocrystals of 5-aminoisophthalic acid (AIA) with various quinoline derivatives are investigated. The cocrystals of AIA with isoquinoline are comprised of dimers of carboxylic acids end capped by isoquinoline molecules. The repeat units have length 30.05 Å each. The hydrated cocrystals of AIA with quinoline and 8-hydroxyquinoline are structurally characterized and they have four and six coordination environment around water molecules respectively. The cocrystal of 4-hydroxyquinazoline with AIA has sheet like structure with repeated dimeric carboxylic acids possessing R2 2(14) type of H-bond patterns. In thermogrvimetry, the cocrystals of 5-aminophthalic acid with quinoline or 8-hydroxyquinoline loses the quinoline counterparts followed by decarboxylation of the parent acid, the decarboxylation takes place at 275°C–450°C.

Guest inclusion in cyclic imides containing flexible tethers

Guest inclusion properties of two cyclic imides which have carboxylic acids connected through flexible tether, namely, 4-(1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-cyclohexanecarboxylic acid (1) and 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-cyclohexanecarboxylic acid (2) are studied. The crystals of host 1 containing one molecule of 1, the crystals of 4,4′-bipyridine (bpy) cocrystal of 1 containing one molecule of 1 and half molecule of bpy (1a), the crystals of 1,4-dioxane solvate of 1 containing two molecule of 1 and one and half molecule of 1,4-dioxane (1b) and the crystals of quinoline solvate of 1 containing one molecule of 1 and one molecule of quinoline (1c) in their crystallographic asymmetric units are investigated. Intermolecular hydrogen bonded two dimensional (2D) sheet structure of 1 and 3D channel network of 1b are comprised of cyclic R 2 2 (8) hydrogen bond motifs; whereas cleavage of dimeric carboxylic acid R 2 2 (8) motifs occurs in the structures of 1a and 1c in which 3D host–guest networks are comprised of discrete O–H···N and cyclic R 2 2 (7) interactions, respectively. Various types of weak interactions between the two symmetry nonequivalent host molecule are found to be responsible for the formation of channels (14 × 11 A) filled by guest 1,4-dioxane molecules in the crystal lattice of 1b. Two different solvates of 2 containing one molecule of 2 with a water molecule (2a) and one molecule of 2 with a quinoline molecule (2b) in their crystallographic asymmetric units, respectively, are also crystallized in different space groups. The quinoline molecules are held with host molecules by discrete O–H···N and C–H···O interactions and reside inside the voids formed by 3D repeated hexameric assemblies of host molecules in the crystal lattice of 2b.

Structural Studies on Solvates of Cyclic Imide Tethered Carboxylic Acids with Pyridine and Quinoline

Structures of eight solvates of cyclic imide tethered carboxylic acids and aromatic tetra carboxylic acids with pyridine (solvate I−VI) and quinoline (VII−VIII) are determined. Different types of hydrogen bond motifs (discrete or cyclic) in these solvates are identified. Solvates I and II possess discrete O−H···N interactions, solvates III and VIII possess combinations of cyclic interactions arising from O−H···N and C−H···O interactions, solvates IV, V, and VII have both the above namely discrete and cyclic types of interactions, whereas, solvate VI is an exception which possesses discrete O−H···N as well as R22(8) types of interactions and provides a model system for incomplete cleavage of dimeric assembly of carboxylic acid moiety. On the basis of the results of various hydrogen bond motifs, density functional theory calculations (DFT) on similar motifs generated from formic acid and its interaction with pyridine and quinoline are carried out. In the case of a pyridine formic acid system, DFT calculations show that the energy difference between the cyclic R22(7) motif and the discrete motif is ∼0.6 kcal/mol. Such a small difference accounts for the formation of both types of structural patterns in solvates I−V depending on the steric requirements. The observed motif of VI is established by comparison of theoretical energies between a dimeric carboxylic acid moiety generated from two formic acids interactions and a trimeric moiety that exhibits two formic acids and pyridine interactions. The energy of different types of hydrogen bond motifs formed by the interactions between quinoline and formic acid is also calculated. Calculations based on DFT show that the salt formation between formic acid and pyridine is not a favorable process, but it may occur in the case of quinoline.

Hydrogen bonding in 1:1 proton-transfer compounds of 5-sulfosalicylic acid with 4-X-substituted anilines (X= F, Cl or Br)

The crystal structures of three proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-X-substituted anilines (X = F, Cl and Br), namely 4-fluoroanilinium 5-sulfosalicylate (3-carboxy-4-hydroxybenzenesulfonate) monohydrate, C6H7FN+.C7H5O6S-.H2O, (I), 4-chloroanilinium 5-sulfosalicylate hemihydrate, C6H7ClN+.C7H5O6S-.0.5H2O, (II), and 4-bromoanilinium 5-sulfosalicylate monohydrate, C6H7BrN+.C7H5O6S-.H2O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three-dimensional hydrogen-bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic R(2)(2)(8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic R(3)(3)(8) association involving all three hetero-species is found.

Resorcinarenes with 2-benzimidazolone bridges: Self-aggregation, self-assembled dimeric capsules, and guest encapsulation

The synthesis and spectroscopic characterization of self-assembled dimeric resorcinarenes 1a-d containing four 2-benzimidazolone (cyclic urea) bridges are reported. The nanometer-size capsules are held together by a cyclic array of complementary hydrogen bonds. Unlike the related imide-bridged resorcinarenes reported by Rebek and coworkers [Heinz, T., Rudkevich, D. M. & Rebek, J., Jr. (1998) Nature (London) 394, 764-766], these strongly bound dimers aggregate in chloroform solutions yielding different self-organized structures, depending on the nature and length of the four carbon chains attached at the bottom of each resorcinarene platform, as revealed by transmission electron microscopy. Thus, phenethyl groups (dimer 1c x 1c) produce long fibers, probably arising from tail to tail contacts and subsequent threading of the resulting linear self-assembled polymers, whereas long alkyl chains (dimers 1a x 1a and 1b x 1b) induce formation of large reverse vesicles of 0.8-2.2 microm diameter through side to side extensive stacking. Presumably, the rigidity of the dimer precludes folding of the aggregate into smaller vesicles. On the contrary, dimer 1d. 1d, containing four nine-carbon chains and a cis-double bond, does not substantially aggregate and gives rise to reasonably resolved (1)H NMR spectra. The compound was shown to be dimeric either by matrix-assisted laser desorption ionization-time-of-flight and vapor pressure osmometry. Encapsulation studies were followed by NMR. Propionic or pivalic acid was included in the capsules, probably as head to head hydrogen-bonded dimers in mesitylene-d(12), a solvent too big to be a guest by its own. Longer dimeric carboxylic acids or larger substrates, like 2-adamantyl azide or cyclohexylcarbodiimide, do not encapsulate, but mixtures of a long and a short carboxylic acid (i.e., propionic-adamantyl or propionic-cyclohexyl) yield pairwise complexes.

Comment on ‘A simple method for the matrix isolation of monomeric and dimeric carboxylic acids’. Possible implications of findings, in regard to liquid formic acid

It is suggested that the infrared bands due to a minor species of formic acid (denoted as ‘X’) observed by Halupka and Sander in Ar matrices at 7–10 K, following trapping from a supersonic cold gaseous jet, are due not to higher aggregates but to an open-chain (HCO 2H) 2 species with an energetically favourable arrangement of the two CO dipoles. This species is probably present, as a minor component, also in liquid formic acid.

A simple method for the matrix isolation of monomeric and dimeric carboxylic acids

We have used a supersonic jet to matrix isolate either well defined hydrogen bonded aggregates or the monomeric species of carboxylic acids (formic acid or acetic acid, respectively). By varying several parameters of the pulsed deposition we have shown that the pulse duration has the major influence on the aggregation in the gas phase. This allowed us to generate either the monomer or the dimer from the same gas mixture and to report for the first time the infrared spectra of matrix isolated formic acid cyclic dimers.

Surface and interfacial FT–IR spectroscopic studies of latexes. VI. Orientation and spatial distribution of acid functionalities at the film–substrate interface

AbstractFormation of dimeric carboxylic acid functional groups observed at the film‐substrate interface of ethyl acrylate/methacrylic acid (EA/MAA) and butyl acrylate / methyl meth‐acrylate / methacrylic acid (BA/MMA/MAA) latex films prepared on a high surface tension substrate, such as liquid mercury, is observed when sodium dioctyl sulfosuccinate (SDOSS) is employed as the synthetic emulsifier. To address the acid species assembled at this interface due to the inability of SDOSS to effectively alleviate interfacial tension and to assess the orientation and spatial configuration of acid groups species at the interface, polarized attenuated total reflectance, Fourier‐transform infrared spectroscopy (ATR FT–IR) is employed. It is found that the acid dimer rings adopt an average “on‐edge” configuration at the interface with the hydrogen‐bonded rings perpendicular to the film‐mercury interface. This configuration serves to provide not only the necessary interfacial acid‐dimer layer, but also facilitates favorable ring–ring interactions between groups of opposite polarity on adjacent rings. This study indicates that the on‐edge configuration may also serve to reduce unfavorable interactions between the polar acid functionality and the less polar components present in the bulk of the coalesced latexes. © 1993 John Wiley & Sons, Inc.

The mechanism of proton transfer in carboxylic acid dimers as studied by 17O quadrupole double resonance

If the 17O quadrupole double resonance results at room temperature for a number of hydrogen-bonded dimeric carboxylic acids, and β-oxalic acid, are interpreted in terms of a proton disorder model, it can be shown that the observed variations are satisfactorily explained in terms of fast concerted two-proton jumps, O 1HO 2 → O 1HO 2 within the dimer, but are inconsistent with rotational disorder. Similar arguments are used to show that the (HCO 3) 2 2− dimer in KHCO 3 is also significantly disordered at room temperature by the same mechanism.

Transition dipole—dipole coupling interactions in the B form of stearic acid single crystals

Raman spectra of the B form of stearic acid single crystals CH 3(CH 2) 16COOH have been recorded for various polarization geometries. Infrared spectra were obtained for the B powder form. A normal coordinate treatment of the crystal has been performed. The group coordinate force field describing the intramolecular potential, a hydroen-bond potential and intermolecular non-bonded atom—atom interactions were used. In addition transition dipole—dipole coupling interactions between the CO bonds in the unit cell were needed in order to explain the observed infrared and Raman bands, contrary to some previous observations concerning the existence of two different conformations of this dimeric carboxylic acid.

Über die Umsetzung von Benzylmalonylchlorid mit verschiedenen Natriumsalzen von Carbonsäuren / The Reaction of Benzylmalonyl Chloride with Sodium Salts of Carboxylic Acids

Benzylmalonyl Chloride reacts in the presence of sodium acetate in boiling benzene to give tribenzyl-phloroglucinol-triacetate, however with sodium chloroacetate to 3,5-dibenzyl-6-phenethylpyran-2,4-dion. In both cases trimerisation of benzylketene or benzylketene carboxylic acid chloride occurs. On the other hand, benzylmalonylchloride reacts with sodium benzoate and sodium phenylacetate via a dimeric benzylketene carboxylic acid chloride under the loss of phosgene to yield cyclopentadienyl derivatives.

The infra-red absorption bands associated with the COOH and COOD groups in dimeric carboxylic acid—II: The region from 3700 to 1500 cm −1

The infra-red spectra of a number of dimeric carboxylic acids and their deutero (COOD) analogues have been investigated in the region of 3700 to 1500 cm −1. The substances were studied in the vapour, liquid, and crystalline solid states, and in solution in carbon tetrachloride. In some cases observations were made over a range of temperature which extended down to that of liquid air. Particular attention was paid to the main broad νOH (νOD) absorption regions centred at 3000 cm −1 (2300 cm −1) and also to the weaker satellite bands to lower frequencies centred near 2650 cm −1 (2100 cm −1). The structure of the satellite bands, the presence of intensity submaxima on the main νOH (νOD) banda, and the general differences in appearance of the νOH and νOD absorption regions have been shown to be reasonably explicable in terms of combination, mostly summation, frequencies involving lower-frequency fundamentals of the COOH (COOD) groups. The summation bands are probably enhanced in intensity by Fermi resonance with the fundamentals responsible for the main νOH (νOD) absorption regions.

The infra-red absorption bands associated with the COOH and COOD groups in dimeric carboxylic acids. I. The region from 1500 to 500 cm -1

The infra-red spectra of a considerable number of carboxylic acids and their COOD derivatives have been investigated between 1500 and 500 cm -1, as dimeric units in the liquid or crystalline solid states. Under these conditions the COOH group is shown usually to give rise to strong absorption bands in the regions 1420 ±20, 1300 ± 15 and 935 ± 15 cm -1 . The first two of these are found to correspond to closely coupled OH deformation and C—O stretching vibrations occurring in the plane of the (COOH) 2 dimeric ring; the latter is caused by the out-of-plane OH deformation vibration. COOD groups have absorption bands in the ranges 1350 ±50, 1050 ± 10 and 675 ±25 cm -1 , which can be assigned respectively to the C—O stretching mode and the in-plane and out-of-plane OD deformation vibrations. Less constant absorption bands of the COOH group between 700 and 575 cm -1 are attributed to O—C = O skeletal deformation vibrations, and the corresponding bands are found at slightly lower frequencies in the spectra of the COOD derivatives. The results of the infra-red investigation are compared with the Raman spectra of such acids and with related infra-red and Raman frequencies of other molecules. Infra-red spectra of some equimolecuiar mixtures of acids with water have also been studied.