Intermolecular Compounds Research Articles

Syntheses, structures and properties of two Keggin polyoxometalates [H 5PCo(4,4′-bipy)Mo 11O 39][H 3PMo 12O 40]·3.75(4,4′-bipy)·1.5H 2O and [H 3PMo 12O 40]·2(4,4′-bipy)·1.5H 2O

Two novel Keggin polyoxometalates [H 5PCo(4,4′-bipy)Mo 11O 39][H 3PMo 12O 40]·3.75(4,4′-bipy)·1.5H 2O ( 1) and [H 3PMo 12O 40]·2(4,4′-bipy)·1.5H 2O ( 2) (bipy=bipyridine) were prepared by the hydrothermal method for the first time and characterized by elemental analyses, IR spectra and X-ray single crystal diffraction, showing that compound 1 is a novel organic–inorganic hybrid compound which consists of a cobalt-monosubstituted Keggin polyoxoanion [PCo(4,4′-bpy)Mo 11O 39] 5− with one pendant ligand 4,4′-bipy, a well-known Keggin polyoxoanion [PMo 12O 40] 3−, 4,4′-bipy and lattice water molecules. Additionally, the two different heteropolyoxoanions in 1 with alternating alignment, combined with the discrete organic substrates 4,4′-bipy and water molecules by hydrogen bond interactions to afford a pseudo 3D network structure. While compound 2 is an intermolecular compound between polyoxoanion unit [PMo 12O 40] 3− and organic substrate 4,4′-bipy. Furthermore, both the compounds exhibit strong photoluminescence properties in the solid state at room temperature. The catalytic activities of the two compounds were also determined by the oxidation of benzaldehyde to benzoic acid using H 2O 2 as oxidant in a liquid–solid multiphase system. Meanwhile, the catalytic property of the compound 2 was evaluated by the esterification of MeCO 2H (acetic acid) with n-BuOH ( n-butyl alcohol).

Phase behaviour analysis of solid dispersions of loperamide and two structurally related compounds with the polymers PVP-K30 and PVP-VA64.

The purpose of the present study was to investigate the influence of the structure of a poorly water soluble model drug (loperamide) on the phase behaviour in solid dispersions with PVP-K30. Dispersions with PVP-VA64, a less hydrophilic polymer, were investigated as well in order to study the influence of differences in polymer structure and water content of the samples. The solid dispersions of PVP-K30 or PVP-VA64 with loperamide as well as with two fragments of this molecule were prepared by spray drying. The amount of residual solvents and water was determined with GC and thermogravimetric analysis (TGA). The drug loading of the dispersions was determined using high performance liquid chromatography (HPLC). The solid state properties were evaluated using powder-XRD, IR-spectroscopy and MT-DSC. All mixtures containing loperamide proved to be completely amorphous, whereas the dispersions containing the fragments are only amorphous in case the polymer content is high. The phase diagrams that were constructed clearly show that loperamide exhibits a different behaviour in the solid dispersions than its two building blocks. They also point to the presence of specific intermolecular compound--polymer interactions in the dispersions of one of the fragments with the two polymers. This was confirmed by the IR-results. Despite structural similarities, interactions in dispersions containing loperamide are far less important. In dispersions containing high concentrations of the other fragment, the DSC curves give indications for polymorphism whereas IR and XRD-spectra point towards inclusion of solvent in these samples.

Molecular and Crystalline Structure of 6,6'‐Dimethyl‐2,3,4,5,6,7‐Hexahydrobenzo[b]Furan‐3,4‐Dione

Different intermolecular compounds of 6,6'‐dimethyl‐2,3,4,5,6,7‐hexahydrobenzo[b]furan‐3,4‐dione have been investigated by IR spectroscopy and x‐ray structural analysis methods. The relation between changes in the characteristic absorption bands of CH2, CH3, C=O, and C—O—C groups and the properties of the medium surrounding the molecule is established. Crystals of monoclinic syngony, of space group P21/n, are formed from a chloroform‐hexane mixture in crystallization. In the crystalline structure, shortened intermolecular contacts between the atoms of hydrogen of the CH3 and CH2 groups of cyclohexane cycles and the oxygen atom of the furan cycle, and also between the atoms of hydrogen of the CH2 and CH3 groups of both cycles and the oxygen of the cyclohexane cycle are revealed.

Formation of molecular alloys by solid-state vitrification

Formation of a vitreous molecular alloy was observed when a mixture of deoxycholic acid (DCA) and tri- O-methyl-β-cyclodextrin (TMCD) crystals was subjected to mechanical milling at room temperature. Only a single glass transition temperature T g, varying with the composition, was observed by DSC. This means that the vitreous state exhibits a single relaxation process as a whole by forming a molecular alloy. The T g showed a maximum value at the equimolar composition, indicating a strong interaction between the two components. A study of the phase diagram clarified the existence of inter-molecular compounds between them. Thermal conductivity of the milled solid of equimolar mixture exhibited a temperature dependence characteristic of glassy materials. p-Terphenyl and tris(hydroxymethyl)aminomethane crystals could not be vitrified. When each of them was milled with DCA or TMCD, vitreous molecular alloys were obtained in a limited composition range. These alloys exhibited also a single T g and underwent a phase separation on devitrification. Formation of molecular alloys was discussed based on the nature of disorder of the system.

Preparation, characterization and crystal structure of an intermolecular compound based on H3PMo12O40·nH2O and diethylamine

An intermolecular compound, H3PMo12O40·5(CH3CH2)2NH·H2O, between the heteropolymolybdate α-H3PMo12O40 and the organic substrate diethylamine, has been synthesized and characterized. Light yellow crystals of the title compound were crystallized from a mixed solvent of water and acetonitrile with formula H3PMo12O40·5(CH3CH2)2NH·H2O. Spectroscopic data support the presence of a sizable electronic interaction between the organic substrate and the inorganic anion in the solid state. The single crystal x-ray structure analysis of the title compound revealed that it crystallized in the triclinic system, space group P\(\overline 1\) with a = 12.0786(13), b = 12.102(5), c = 21.416(3) A, α = 94.87(2), β = 94.755(9), γ = 113.81(2)°, V = 2830.3(13) A3, and Z = 2.

Thermally-induced transition in aqueous solution of cationic surfactant containing aromatic ring

Heat capacities of aqueous solutions of cetyltrimethylammonium (CTA) salicylate, of CTA m-hydroxybenzoate and of CTA p-hydroxybenzoate were measured using a scanning microcalorimeter. Only the salicylate solution exhibited heat-capacity anomaly around 330 K, depending on the heating rate. The transition enthalpy was 3.5±0.2 kJ mol−1, which was similar to that observed in solution of 1:1 intermolecular compound between CTA bromide (CTAB) and o-iodophenol (OIPh). The enthalpy of formation ΔHf of the 1:1 intermolecular compound from CTAB and OIPh was determined by measuring the enthalpies of solution of the relevant crystals into ethanol. Positive value ΔfH=3.0±0.3 kJ mol−1 was explained from a large difference between the heat capacities of the 1:1 compound and 1:1 mixture of the component crystals.

Measurement and Analysis of the Naphthalene — Octafluoronaphthalene Phase Diagram: Complex Formation in Solid and Liquid

Naphthalene–octafluoronaphthalene room pressure solid–liquid phase diagram has been assessed by means of differential scanning calorimetry and powder X-ray diffraction analyses. Thermodynamic properties are analysed through the associated liquid model. The solid states consists of six crystalline phases with well defined composition: one for naphthalene, two for octafluoronaphthalene and three for an equimolecular intermolecular compound. This complex melts congruently at (406.3±0.3) K, i.e., about fifty degrees higher than its components and the resulting liquid is moderately associated. The solid–solid phase transitions of this complex are strongly energetic. The corresponding overall change of entropy stands for two third times the entropy of fusion. The consecutive increasing of crystalline symmetry and positional disorder is clearly visible on diffraction patterns.

Recent Progress in the Crystallization of Fats

Recent progress in the crystallization of fats, particularly cocoa butter and related triacylglycerols (TAGs) is reviewed. Polymorphism of POP, POS and SOS is compared with that of cocoa butter and polymorphic transformation in tempering in chocolate manufacturing is discussed based on the results of crystallization kinetics obtained by pure TAGs. In place of tempering, a newly developed seeding technique, using BOB (β2) crystal powder and a method for preventing fat blooming at high temperature are discussed. Intermolecular compounds made with SOS and OSO in equal weight were applied to cocoa butter, and unique physical properties of chocolate involving OSO are discussed.

Separation of Close-Boiling Mixtures of 4-Methoxyphenol/Catechol with tert-Butanol

ABSTRACT Solid-liquid equilibrium (SLE) behavior was observed for close-boiling mixtures of 4-methoxyphenol and catechol with tert-butanol. The experimental liquidus lines of binary systems showed that intermolecular complex compounds were formed in both tert-butanol/4-methoxyphenol and tert-butanol/catechol, implying that tert-butanol is a potential medium to serve as an adductive agent for separation of 4-methoxyphenol and catechol. A ternary SLE phase diagram for the tert-butanol/4-methoxyphenol/catechol system was thus prepared and, based on the diagram, the feasibility of such separation processes was discussed. Furthermore, the binary SLE data were correlated with the ideal-chemical model. The model with the determined parameters from binary mixtures was then applied to predict the equilibrium temperatures for the ternary system.

The Mutual Mixing Effect in the LB Films of Merocyanine Dyes

The mutual mixing effect in the LB films of four kinds of merocyanine dyes have been investigated by optical absorption and fluorescence measurements. In single component films, DSe, DS and 6-methyl DS (6Me-DS) can form J-like aggregates but not for DO. In [6Me-DS]-[DO] system, a sharp J-band peak linearly shifts to the longer wavelength for the replacement of 6Me-DS by DO. In [DS]-[DO] system, [DS]:[DO]=1:1 film shows a both sharp J-band absorption and fluorescence peak. The behavior are understood by the formation of the ‘solid solution’ for [6Me-DS]-[DO] and the ‘intermolecular compound’ for [DS]-[DO]. Furthermore, the spectrum of [DO]-[DSe] system shows the presence of the ‘phase separation’. These results would relate to an interesting problem, what we may call a ‘2-dimensional phase diagram’ in J-aggregates.

Clustering of a hydrogen-bonding complex between indole and isoquinoline Correlation with nucleation of intermolecular compounds

Upon crystallization from mixtures containing indole and isoquinoline, intermolecular compounds of 1:1 molecular ratio have been isolated as crystals. This crystallisation process, i.e., molecules→clusters→nucleus was studied in a specially designed mass spectrometer. From the mass spectrometric analysis of clusters isolated from liquid droplets containing indole, isoquinoline and acetonitrile, clusters composed of equimolecular indole and isoquinoline, i.e. (indole) n (isoquinoline) n : n=1, 2, 3,..., were observed as prominent species. This suggested that the hydrogen-bonded complex of indole and isoquinoline works as a unit species for the nucleation of the intermolecular compounds.

Measurement of mass spectrum of clusters that were foemed through adiabatic expansion of liquid droplet : Correlation with mucleation of intermolecular compound

Measurement of mass spectrum of clusters that were foemed through adiabatic expansion of liquid droplet : Correlation with mucleation of intermolecular compound

Clustering of a hydrogen-bonding complex between pyridine and pyrrole: correlation with nucleation of intermolecular compounds

A hydrogen-bonding complex between pyridine and pyrrole aggregates in aqueous solution.

A simple one-step synthesis of alkylation product from cyclic allylic alcohol and resorcinol

The alkylation of resorcinol with cyclic allylic alcohol in non-aqueous acid medium gives intermolecular Friedel-Craft compounds. The products are primary alkylation products. The linkage always occurs between carbon 3 of cyclic allylic alcohol and the position 2, 4, 5 or 6 of the resorcinol.

Effect of pressure on the solid-liquid phase equilibria in (water + sodium sulfate) system

The effect of pressure on the phase diagram of (H 2O + Na 2SO 4) system has been investigated at temperatures from 263 to 343 K and pressures up to 500 MPa. This system forms an intermolecular compound Na 2SO 4·10H 2O. The sodium sulfate decahydrate has an incongruent melting point at 305.5 K at atmospheric pressure. The present study was undertaken to obtain extensive and accurate data concerning the effect of pressure on two kinds of solid-liquid phase equilibria, namely, the solubility curve and the incon-gruent melting point (peritectic point) of Na 2SO 4·10H 2O. The solid-liquid equilibrium measurements were performed by the direct visual observation of the crystal growth and disappearance using a high-pressure optical vessel. The uncertainties in measurements of temperature, pressure, and composition are within 0.1 K, 0.5 MPa and 0.001 mole fraction, respectively. It was found that both the solubility curve and the incongruent melting temperature of Na 2SO 4·10H 2O decrease with increasing pressure. The solid-liquid coexistence curves were correlated by an empirical equation.

Effect of pressure on the solid-liquid phase equilibria of binary organic systems

Solid-liquid phase equilibria of the binary mixtures of the organic liquids have been investigated at temperatures from 278 to 343 K and pressures up to 500 MPa using a high-pressure optical vessel. The systems investigated are as follows: (1) simple eutectic systems-benzene + cyclohexane system and benzene + 2-methyl-2-propanol system; (2) eutectic systems with formation of intermolecular compounds — carbon tetrachloride + p-xylene system and carbon tetrachloride + benzene system; (3) partial solid solution system-α-methylnaphthalene + β-methylnaphthalene system; and (4) complete solid solution system-chlorobenzene + bromobenzene system. The uncertainties of the measurements of temperature, pressure and composition are within ±0.1 K, ± 0.5 MPa, and ±0.001 mole fraction, respectively. The freezing and melting temperatures at a constant composition increase monotonously with pressure. The eutectic mixture becomes richer in the component whose temperature coefficient of the freezing pressure is larger and the eutectic temperature rises monotonously with increasing pressure in the eutectic systems. The pressure-temperature-composition relation of the solid-liquid phase equilibria can be expressed satisfactorily by an equation newly proposed.

Non-aqueous ternary mixtures with ‘island’ miscibility gaps

Liquid—liquid equilibria at 101.3 kPa are determined on four partially miscible systems of the type: carboxylic acid + tertiary amine + hydrocarbon, (1) acetic acid + dimethyl formamide + cyclohexene at 291.15 K, 293.15 K, 295.15 K and 296.15 K, (2) dichloroacetic acid + N-formylpiperidine + cyclohexane at 291.15 K, 293.15 K, 298.15 K, 303.15 K and 305.15 K, (3) dichloroacetic acid + 1-methyl-2-pyrrolidinone + cyclohexene at 273.15 K, 281.15 K, 289.15 K, 291.15 K and 293.15 K, (4) dichloroacetic acid + 1-methyl-2-pyrrolidinone + 1-hexene at 293.15 K, 303.15 K and 313.15 K. All systems exhibit true ‘island’ miscibility gaps with no tendency of the closed binodal curves to touch the sides of the Gibbs phase triangle on lowering of the temperature. A qualitative interpretation of the miscibility gaps in terms of the solvation of the polar intermolecular compounds being formed between the acid and the amine in the molar ratio 1:1 is given.

Raman spectra of intermolecular compounds between antimony trichloride and methyl-group substituted benzenes (2:1)

Raman spectra of intermolecular complexes between antimony trichloride and methyl-group substituted benzene derivatives were recorded to investigate the complexation-induced frequency shifts of vibrations belonging to the aromatic complex partners. The shifts are discussed according to the reduction of electronic charge on the ring framework of the electronic donator molecules and higher amounts of vibrational coupling. Vibrational coupling appears between CC stretching vibrations and internal modes of the substituted methyl groups and between CH stretching vibrations of the ring and the methyl groups. The influence of the charge reduction is directly related to the affections of the CH stretching vibrations and CH out-of-plane vibrations of the ring, as well as the CC stretching vibrations with tangential amplitude directions.

Effect of pressure on the solid-liquid phase equilibria of (carbon tetrachloride + p-xylene) and (carbon tetrachloride+benzene) systems

Solid-liquid phase equilibria of the carbon tetrachloride + p-xylene and the carbon tetrachloride+benzene systems have been investigated at temperatures from 278 to 323 K and pressures up to 500 MPa using a high-pressure optical vessel. The uncertainties in the measurements of temperature, pressure, and composition are within ±0.1 K, ±0.5 MPa, and ±0.001 mole fraction, respectively. In the former system, which has an intermolecular compound with a congruent melting point, the freezing temperature at a constant composition increases monotonously with increasing pressure. The two eutectic points of this system shift to higher temperatures and richer compositions of the compound with increasing pressure. In the latter system, which has two intermolecular compounds with incongruent melting points, the one compound disappears under the present experimental conditions and the incongruent melting point of the other compound changes to the congruent melting point under high pressures. The solid-liquid coexistence curves of these systems can be correlated satisfactorily by the equation previously proposed.

Adhesive properties of cured epoxide resin containing the intermolecular compound of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid

The intermolecular compound of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid was synthesized, and the glass transition temperature and the adhesive properties of the cured epoxide resin containing the above compound were studied. Epoxide reacted with amino groups of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid at the curing conditions of 150 to 180°C for 60 min and formed the cured compounds. The infrared spectra showed that epoxide reacted with isocyanuric acid in the presence of imidazole compounds and converted to 2-oxazolidinone compound on the curing process. The glass transition temperatures of the cured compounds having isocyanurate and 2-oxazolidinone rings in their structures were higher than that of the epoxide resin cured with imidazole and rise as the curing temperature rises, but fall as 2-oxazolidinone ring content increases in their cured compounds. The tensile shear and peel strengths of the steel and steel bonded with the cured compounds and the cured epoxide resin were measured at 25 and 150°C. The adhesive strengths were improved due to isocyanurate and 2-oxazolidinone rings formed in their cured compounds.