Formation Of Inclusion Compounds Research Articles

Structural chemistry and guest inclusion of a new supramolecular material showing sensitivity to organic solvent vapors

Clathrate formation—the formation of crystalline inclusion compounds—is one approach to chemical sensing of vapors and gases. The synthesis of a new diol host compound is described and absorptive clathrate formation and thermal clathrate decomposition are reported for acetone as the guest. It is shown that the sorptive uptake of a guest vapor by the crystalline host compound is not merely surface adsorption but true clathrate formation, involving a solid‐state transformation. It is suggested that the use of the host as a chemical sensor is not far off.

ChemInform Abstract: Crystalline Diol Hosts Featuring a Bulky Biphenyl Framework ‐ Host Synthesis and Formation of Inclusion Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Optional Formation of “Parallel or Antiparallel” β-Sheet-like Structures in (R)-(1-Naphthyl)glycyl-(R)-phenylglycine Crystals

Abstract (R)-(1-Naphthyl)glycyl-(R)-phenylglycine forms inclusion compounds with ethers (tetrahydrofuran and diethyl ether) or allylic alcohols (2-propen-1-ol and 2-methyl-2-propen-1-ol). X-ray crystallographic study showed that the dipeptide has the ability to optionally form “parallel or antiparallel” β-sheet-like structures by the choice of ethers or allylic alcohols, respectively, as the guest molecules.

96/04605 Formation and thermolysis of coal inclusion compounds with alkali metal hydroxides

96/04605 Formation and thermolysis of coal inclusion compounds with alkali metal hydroxides

Eicosapentaenoic acid (20∶5n‐3) from the marine microalgaPhaeodactylum tricornutum

AbstractEicosapentaenoic acid (EPA, 20∶5n‐3) was obtained from the marine microalgaePhaeodactylum tricornutum by a three‐step process: fatty acid extraction by direct saponification of biomass, polyunsaturated fatty acid (PUFA) concentration by formation of urea inclusion compounds, and EPA isolation by semipreparative high‐performance liquid chromatography (HPLC). Alternatively, EPA was obtained by a similar two‐step process without the PUFA concentration step by the urea method. Direct saponification of biomass was carried out with two solvents that contained KOH for lipid saponification. An increase in yield was obtained because the problems associated with emulsion formation were avoided by separating the biomass from the soap solution before adding hexane for extraction of insaponifiables. The most efficient solvent, ethanol (96%) at 60°C for 1 h, extracted 98.3% of EPA. PUFA were concentrated by the urea method with a urea/fatty acid ratio of 4∶1 at a crystallization temperature of 28°C and by using methanol and ethanol as urea solvents. An EPA concentration ratio of 1.73 (55.2∶31.9) and a recover yield of 78.6% were obtained with methanol as the urea solvent. This PUFA concentrate was used to obtain 93.4% pure EPA by semipreparative HPLC with a reverse‐phase, C18, 10 mm i.d.×25‐cm column and methanol/water (1% acetic acid), 80∶20 w/w, as the mobile phase. Eighty‐five percent of EPA loaded was recovered, and 65.7% of EPA present inP. tricornutum biomass was recovered in highly pure form by this three‐step downstream process. Alternatively, 93.6% pure EPA was isolated from the fatty acid extract (without the PUFA concentration step) with 100% EPA recovery yield. This two‐step process increases the overall EPA yield to 98.3%, but it is only possible to obtain 20% as much EPA as that obtained by three‐step downstream processing.

Gram-scale purification of eicosapentaenoic acid (EPA, 20:5n-3) from wetPhaeodactylum tricornutum UTEX 640 biomass

Eicosapentaenoic acid (EPA, 20:5n-3) was obtained from the microalgaPhaeodactylum tricornutum following a three-step process: fatty acid extraction by direct saponification of wet biomass, polyunsaturated fatty acid (PUFA) concentration by formation of urea inclusion compounds and EPA isolation by preparative HPLC. Direct saponification of wet biomass was carried out with KOH-ethanol (96% v:v) (1 h, 60 °C), extracting 91% of the EPA. PUFAs were concentrated by the urea method with an urea/fatty acid ratio of 4:1 at a crystallization temperature of 28 °C using methanol as the urea solvent. An EPA concentration ratio of 1.5 (55.2/36.3) and recovery of 79% were obtained. This PUFA concentrate was used to obtain 95.8% pure EPA by preparative HPLC, using a reverse-phase column (C18, 4.7 cm i.d. × 30 cm) and methanol-water (1% AcH) 80:20 w/w as the mobile phase. Ninety-seven per cent of EPA loaded was recovered and 70% EPA present in theP. tricornutum biomass was recovered in a highly pure form by means of this three-step downstream processing. In each of the HPLC preparative runs, 635 mg PUFA concentrate were loaded, obtaining 326 mg of a highly concentrated EPA fraction (2.46 g d−1). Finally, a preliminary cost statement has been calculated.

Inclusion compounds of cholic acid with mixed guests

Abstract Cholic acid is shown to form inclusion compounds with different guest molecules, of diverse chemical nature, in the same crystal. The single crystal structures of the inclusion compounds 2CA·1,2-dichlorobenzene·acetone and 2CA·i-propyl acetate·methyl acetate are elucidated and the guests shown to alternate in an ordered fashion in the channel of the characteristic tubulate clathrate structures.

Solid-state formation of an inclusion compound of cholic acid withp-toluidine

Cholic acid undergoes solid-solid reactions with some aromatic molecules to form inclusion compounds. Simple shaking of a mixture of powdered cholic acid andp-toluidine results in formation of the 1∶1 (host:guest) inclusion compound which has the same structure as that formed by conventional crystallization methods: monoclinic space groupP21 witha=13.577(4),b=8.078(2),c=14.182(6) A, β=114.42(3)°,Z=2 andR 1=0.061 for 2680 unique reflections.

Crystalline diol hosts featuring a bulky biphenyl framework - Host Synthesis and Formation of Inclusion Compounds

Biphenyls having two hydroxy containing benzo condensed oligocyclic substituents in positions 2,2′ were synthesized to yield the crowded diols 5 – 10. These compounds proved successful clathrate hosts. Crystalline inclusion formation is reported and discussed with reference to structural parameters of the host molecules covering the bis-fluorenol analogous host compounds 1–4.

Modification of the face selectivity in asymmetric induction by cyclodextrins through the formation of three-component inclusion compounds

Modification of the face selectivity in asymmetric induction by cyclodextrins through the formation of three-component inclusion compounds

Roof-shaped hydroxy hosts: synthesis, complex formation and X-ray crystal structures of inclusion compounds with EtOH, nitroethane and benzene

A series of crystalline host molecules 1 and 2a–e, based on a characteristic 9,10-dihydro-9,10-ethanoanthracene rigid framework and appended diarylmethanol clathratogenic groups, has been synthesized and studied with regard to their inclusion behaviour. These hosts form crystalline inclusion compounds with a variety of uncharged organic molecules, ranging from protic dipolar to apolar compounds (183 different species), but show a preference for amines and aromatic hydrocarbons. The bis-methanols are largely superior to the mono-methanols, except for the 4-chlorophenyl substituted methanol, which has proved to have equal efficiency.The building principles and the mode of complexation of the host compound 2a(trans-α,α,α′,α′-tetraphenyl-9,10-dihydro-9,10-ethanoanthracene-11,12-dimethanol) with ethanol (protic), nitroethane (aprotic polar) and benzene (aprotic apolar) as guests have been investigated by single crystal X-ray diffraction. The conformation of the host molecule observed in the 1 : 2 (host: guest) EtOH complex is different from that in the nitroethane (1 : 1) or benzene (2 : 1) inclusions. The host–guest contact pattern in 2a·EtOH (1 : 2) features a huge 16-membered loop of H-bonds involving four functional OH groups of both host and guest, with one intra-host H-bond for each of the two host molecules of the 2 : 4 (host:guest) aggregate. On the other hand, in the compounds of 2a with the aprotic guest species nitroethane and benzene the host hydroxys are involved in specific intramolecular OH ⋯π-aryl contact, thus yielding true lattice-type inclusions, although with different organizations. Accordingly, in 2a·nitroethane (1 : 1) the polar guest units fill up the voids between the bulky host molecules, while in 2a·benzene (2 : 1) the host molecules are arranged so as to form tunnels in the crystallographic c direction, where the guests are located.

Dissolving alkali metals in zeolites: genesis of the perfect cluster crystal

The interaction of alkali metals with dehydrated zeolites Y and A leads, in a process which bears many similarities to the dissolution of those metals in non-aqueous liquid solvemts, to the formation of inclusion compounds which may be regarded as ordered arrays of closely spaced clusters, and whose properties are dependent on interactions between the clusters. A combined analysis of electron spin resonance, magnetic susceptibility and powder neutron diffraction results enabled us to follow in detail the chemistry behind the formation of sodium- and potassium-based ‘cluster crystals’ in zeolites Y and A respectively.

Cyclodextrin-enhanced degradation of toluene and p-toluic acid by Pseudomonas putida.

Degradation of an immiscible aromatic solvent, toluene, and a water-soluble aromatic compound, p-toluic acid, by a Pseudomonas putida strain in the presence of beta-cyclodextrin (beta-CD) was investigated. The ability of CDs to interact with hydrophobic organics and form inclusion compounds was exploited in this study to remove or alleviate the toxicities of substrates and consequently to enable or enhance degradation. Liquid toluene was found to be highly toxic to P. putida. However, this phase toxicity was removed when crystalline beta-CD-complexed toluene was provided as the substrate. The latter was fully degraded at a concentration of up to 10 g/liter. Degradation of toluene vapors was enhanced in the presence of beta-CD as a result of reduced molecular toxicity and facilitated absorption of the gaseous substrate. Similarly, beta-CD alleviated the inhibitory effect of p-toluic acid on P. putida. This protective effect of CD was remarkably more prominent when the microbial culture was shock loaded with an otherwise toxic dose of p-toluic acid (1.8 g/liter).

Circular dichroism of trans and cis β-lactams and of their inclusion compounds in β-cyclodextrin

The absolute configurations of β-lactams 1, 2 are determined or confirmed based on their CD spectra. The formation of inclusion compounds from 2-azetidinones 1, 2 and β-cyclodextrin 3 is also proved by circular dichroism.

Concentration and purification of stearidonic, eicosapentaenoic, and docosahexaenoic acids from cod liver oil and the marine microalgaIsochrysis galbana

n‐3 Polyunsaturated fatty acids (n‐3 PUFA) from the marine microalgaIsochrysis galbana were concentrated and purified by a two‐step process—formation of urea inclusion compounds followed by preparative high‐performance liquid chromatography. These methods had been developed previously with fatty acids from cod liver oil. By the urea inclusion compounds method, a mixture that contained 94% (w/w) stearidonic (SA), eicosapentaenoic (EPA), plus docosahexaenoic (DHA) acids (4:1 urea/fatty acid ratio and 4°C crystallization final temperature) was obtained from cod liver oil fatty acids. Further purification of SA, EPA, and DHA was achieved with reverse‐phase C18 columns. These isolations were scaled up to a semi‐preparative column. A PUFA concentrate was isolated fromI. galbana with methanol/water (80:20, w/w) or ethanol/water (70:30, w/w). With methanol/water, a 96% EPA fraction with 100% yield was obtained, as well as a 94% pure DHA fraction with a 94% yield. With ethanol/water as the mobile phase, EPA and DHA fractions obtained were 92% pure with yields of 84 and 88%, respectively.

Synthesis and characterization of cyclodextrin/perfluoroalkane inclusion compounds

Acyclic and cyclic perfluoroalkanes associate with α- and β-cyclodextrins (CD) in aqueous solution to varying extents, depending on the structure of both the perfluoroalkane and the cyclodextrin. β-CD readily forms insoluble inclusion compounds, including a β-CD/C 9F 19· complex, prepared from the stable perfluoro-1-ethyl-1,1-diisopropylmethyl radical. Under similar conditions, only trace amounts of inclusion compounds were obtained using α-CD solutions. Three hydrocarbons were compared with the corresponding perfluorocarbons in respect of their tendencies to form inclusion compounds with α-CD and β-CD.

FTi.r. investigation of the inclusion compound formed between trans-1,4-polyisoprene and urea

Several small-molecule hosts form inclusion compounds (ICs) with polymers. In these ICs the guest polymer chains are highly extended and isolated from neighbouring polymer chains by the clathrate wall. Only polymers with extended conformations are narrow enough to reside in the narrow channel. An inclusion compound has been formed between urea and trans-1,4-polysoprene (TPI) and investigated using FTi.r. spectroscopy. Infrared bands observed for this IC indicate that the crystal structure of this IC is most likely different from the usual hexagonal crystal structure. It is also suggested that TPI in the channel adopts a conformation which is similar to bulk TPI with β crystal modification.

Cholic acid inclusion compounds with ketone guests

Cholic acid forms inclusion compounds with acetone, methyl ethyl ketone and diethyl ketone. Crystal structures with these closely related guest molecules indicate variations in packing which result in respectively: unusual 2∶3 host: guest stoichiometry and loss of the 21 screw axis, doubling of the c axis with formation of two different channels and the usualP21 structure with 1∶1 host: guest stoichiometry.

Structural and conformational analysis of six-, seven-, and eight-membered cycloalkanes in tris(5-acetyl-3-thienyl)methane inclusion compounds

Tris(5-acetyl-3-thienyl)methane (TATM) forms inclusion compounds with cyclohexane, -heptane, and -octane in a host/guest ratio of 2:1. The clathrate compounds have been studied by X-ray crystallography. The inclusion compound with cyclohexane crystallizes in two distinct triclinic unit cells of space group [Formula: see text] in the A form, the unit cell dimensions are a = 8.622(2), b = 10.194(2),c = 12.795(2) Å, α = 79.09(1)°, β = 72.74(1)°,γ = 84.89(1)°, V = 1053.9(4) Å3(220 K); for the B form, a = 11.668(4), b = 13.729(3), c = 14.227(4) Å, α = 89.40(3)°, β = 77.20(4)°, γ = 76.24(4)°, V = 2157(1) Å (room temperature). In the A form the cavity is of the channel type but the guest molecule is located on a centre of inversion while in the B form the cavity is also of the channel type but the guest molecule is in a general position. The inclusion compounds of cycloheptane and cyclooctane crystallize only in the B form. The guest molecules in the B form are disordered. Conformational analyses of the guest molecules have also been performed by a combination of molecular dynamics and energy minimization.

A Study of the Binding of Dimethyldodecylamine Oxide by β-Cyclodextrin Using Surface Tension Measurements

A surface tension method developed previously has been used to investigate the formation of inclusion compounds between dimethyldodecylamine oxide (DDAO) and β-cyclodextrin, at pH values in the range 2 to 8, in the absence and in the presence of added 0.10 M NaCl. Thermodynamic activities of the DDAO are inferred from measurements of surface tension at concentrations lower than the critical micelle concentration of the surfactant. Binding constants are determined directly from the effect of added cyclodextrin on the surface tension vs concentration curves for DDAO in water and in the 0.10 M NaCl solutions. Binding effects are discussed in relation to the charge of the DDAO head group, which can be controlled by varying the pH, and the screening effect of the added electrolyte.