Urea Inclusion Complex Research Articles

Scalable production of high-quality carbon nanotube dispersion in aqueous solution using cellulose as dispersant by a freezing/thawing process

Carbon nanotube (CNT) dispersion, which enables scalable fabrication of printed and flexible electronic materials, has brought a revolutionary improvement in CNT-based devices. To progress from the laboratory to commercial applications, it will be necessary to develop simple and scalable methods to produce high-quality CNT dispersions. Here, we propose a freezing/thawing strategy assisted by cellulose to produce high-quality CNT dispersion in an aqueous solution on a large scale. The freezing/thawing process simultaneously serves two purposes: (1) one is to cleave CNTs from their bulk via water-freezing expansion force; (2) the other is to dissolve cellulose in NaOH/urea aqueous solution, facilitating the wrapping of cellulose on the surface of CNTs to improve the stability of the dispersion. The obtained cellulose-dispersed CNT (CDCNT) dispersion is highly homogeneous and stable because of the formation of CNT/cellulose/NaOH/urea inclusion complexes. Importantly, the freezing/thawing strategy using cellulose promises scalable production, including a high CNT concentration of 11.3 mg/mL, high yield of 75%, high production capacity, and unlimited system size, much superior to common ultrasonication. Furthermore, it is demonstrated that the CDCNT dispersion can be used as a precursor solution for fabricating different CNT-based materials via various techniques, such as spinning, dyeing, screen printing, and 3D printing, indicating versatile applications.

Thladiantha Seed Oils - New Source of Conjugated Fatty Acids: Characterization of Triacylglycerols and Fatty Acids.

In this study, seed oils of Thladiantha nudiflora and Thladiantha dubia were found to contain 55.5 and 44.4% mole of conjugated octadecatrienoic fatty acids, respectively. The presence of moieties of conjugated fatty acids was confirmed by a series from physical methods: UV, IR, 1H and 13C NMR. The triacylglycerols (TAGs) isolated of the seed oils were studied by RP-HPLC with diode array and mass spectrometric detections. It was shown that all 15 TAGs of Thladiantha dubia contain moieties of conjugated fatty acids - punicic, (9Z,11E,13Z)-octadeca-9,11,13-trienoic acid (35.6% mole) and 8.9% mole α-eleostearic, (9Z,11E,13E)-octadeca-9,11,13-trienoic acid. Meanwhile, 24 TAGs of Thladiantha nudiflora seed oil contain both acids in approximately equal proportions (27.4:28.2 % mole). The enrichment for polyunsaturated fatty acids of the hydrolysis product of the seed oils due to urea inclusion complex formation was discussed.

Preparation of Monoacylglycerol Derivatives from Indonesian Edible Oil and Their Antimicrobial Assay against Staphylococcus aureus and Escherichia coli

In the present work, linoleic acid and oleic acid were isolated from Indonesian corn oil and palm oil and they were used to prepare monoacylglycerol derivatives as the antibacterial agent. Indonesian corn oil contains 57.74% linoleic acid, 19.88% palmitic acid, 11.84% oleic acid and 3.02% stearic acid. While Indonesian palm oil contains 44.72% oleic acid, 39.28% palmitic acid, 4.56% stearic acid and 1.54% myristic acid. The oleic acid was purified by using Urea Inclusion Complex (UIC) method and its purity was significantly increased from 44.72% to 94.71%. Meanwhile, with the UIC method, the purity of ethyl linoleate was increased from 57.74% to 72.14%. 1-Monolinolein and 2-monoolein compounds were synthesized via two-step process from the isolated linoleic acid and oleic acid, respectively. The preliminary antibacterial assay shows that the 1-monolinolein did not give any antibacterial activity against Staphylococcus aureus and Escherichia coli, while 2-monoolein showed weak antibacterial activity against Staphylococcus aureus.

Enrichment of Polyunsaturated Fatty Acids from Phyllanthus emblica L. Seed Oil by Urea Inclusion

Polyunsaturated fatty acids are essential to human nutrition. Phyllanthus emblica L. seed oil serves as a source of enrichment for the preparation of polyunsaturated fatty acids by urea inclusion technique. Under optimal conditions (6 g urea per 3 mL free fatty acids, crystallization temperature of −6°C, and crystallization time of 19 h), the purity of polyunsaturated fatty acids was up to 98.47% and the yield was 71.85%. The urea-polyunsaturated fatty acids inclusion complex was analyzed using differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy/energy, and dispersive X-ray spectroscopy. The results showed that polyunsaturated fatty acids can be successfully separated by urea inclusion fractionation. The filled and hollow hexagonal prisms of urea crystal were clearly observed. In addition, the macroscopic and microscopic morphology of palmitic acid-urea inclusion were studied after washing with solvents using scanning electron microscopy and X-ray diffraction analysis to understand the involvement of guest molecules in the hexagonal crystal structure. The results showed that washing with solvents could not remove all the palmitic acid in the hexagonal structure of the urea inclusion complex, and the formation of hexagonal structure needed the support of involved guest molecules.

Preparation of Poly(butylene succinate) Crystals with Exceptionally High Melting Point and Crystallinity from Its Inclusion Complex

We successfully developed an effective strategy for preparing poly(butylene succinate) (PBS) material with exceptionally high crystallinity (94.4% from density data) and melting point (∼136 °C) from its urea inclusion complex under normal air pressure for the first time. The strategy consists of three steps: co-electrospinning PBS with urea, thermal treatment, and coalescence of PBS in water. Electrospinning provides well physical mixing between PBS and urea. Thermal treatment causes the assembly of PBS and urea and leads to formation of their inclusion complex, in which PBS chains are separately isolated in urea channels. During the coalescing process the isolated and ordered PBS chains formed crystals with lamellar thickness larger than 26 nm—larger than 5-fold of common PBS crystal—after removing host urea frames. PBS crystals obtained with such high crystallinity and melting point are proved to be the extended-chain crystals (ECCs). Comparative study reveals that the electrospinning and thermal treatm...

Insulated Polyacetylene Chains in an Inclusion Complex by Photopolymerization

ABSTRACTThe properties of a material often depend on the degree of order of their atomic, molecular, or crystalline domain components. This is expected to be especially true for the case of polyacetylene, whose properties are highly anisotropic. For many applications, it may be necessary to have macroscopic order but not necessarily crystalline order. Having polyacetyelene chains fully extended and aligned parallel to each other may be sufficient for these applications even without order of the chains around their long axis. We report here progress in the use of an inclusion crystal containing a photo-reactive precursor to prepare high molecular weight polyacetylene. Raman spectroscopy was performed to probe the resulting conjugated polyene chains. Ultraviolet irradiation of a 1,4-diiodo-1,3-butadiene/urea inclusion complex results in the appearance of new resonance-enhanced Raman modes at 1125 and 1509 cm-1. The Raman spectra of the resulting confined polyene chains are very similar to freestanding isolated trans-polyacetylene prepared by solution methods.

ENRICHMENT OF α-( ALPHA) LINOLENIC ACID OF BASIL SEED OIL, Ocinum Basillium L. BY FRACTIONAL CRYSTALIZATION AND CRYSTALIZATION IN UREA INCLUSION COMPLEXES

Enrichment of α-(alpha) linolenic acid (ALA) of basil seed oil, Ocinum basilicum L. can be done by fractional crystalization and crystalization of fatty acid in urea inclusion complexes (UIC) methods. In this research, the ALA of fatty acid of basil seed oil was fractionated by fractional crystallization in methanol solution at -3, -13 and -25 °C and by crystallization in urea solution (ratio 1:2) at 4, 2, -6 and -8 °C. The ALA percentages were analyzed by GC and GC/MS. The results showed that percentage of ALA obtained from fractional crystallization at -25 °C increase from 65.16 to 91.40, and acquired from UIC is 98.8 at 2 °C

Concise preparation of the (3E,5Z)-alkadienyl system. New approach to the synthesis of principal insect sex pheromone constituents.

A new rapid and low-cost preparation of the (3E,5Z)-3,5-alkadienyl system, encountered in several insect pheromone constituents, was developed. Knoevenagel condensation of (E)-2-alkenals with ethyl hydrogen malonate in dimethyl sulfoxide, in the presence of a catalytic amount of piperidinium acetate, led to a mixture of geometrical isomers of ethyl 3,5-alkadienoates and ethyl 2,4-alkadienoates, from which the (3E,5Z)-3,5-alkadienoate was conveniently separated, by the use of urea inclusion complex formation. The importance of this procedure has been illustrated by the preparation of the (3E,5Z)-3,5-tetradecadienoic acid (megatomoic acid) 1, the (3E,5Z)-3,5-dodecadienyl acetate 2, and the (3E,5Z)-3,5-tetradecadienyl acetate 3. These compounds are the main components of insect sex pheromones and constitute synthetic targets of considerable interest for the semiochemical community.

Oriented n-Alkanes in urea-d4 Inclusion Complexes for Inelastic Neutron Scattering Vibrational Studies

Crystalline urea inclusion complexes (UIC) formed with urea-d4 and hexadecane are used to orient the n-alkane relative to a neutron beam for inelastic neutron scattering studies. Deuteration of the host lattice makes it nearly transparent for neutron studies. Comparison of the results for UIC orientation parallel and perpendicular to the neutron beam permits separation of the low frequency vibrational spectrum into those vibrations that are parallel to the alkane long axis and those perpendicular to the long axis.

Preparation of eicosapentaenoic acid (EPA) concentrate fromPorphyridium cruentum

The polyunsaturated fatty acid eicosapentaenoic acid (EPA) has attracted increased attention due to its pharmaceutical properties. The main source is marine fish oil which contains approximately 15% EPA. However, pharmaceutical applications of EPA will probably require higher concentrations, perhaps as high as 90%. The red microalgaPorphyridium cruentum is a potential source, because its EPA content approaches 44.1% of the total fatty acids. Three methods were attempted for EPA concentration and arachidonic acid (AA) removal from the oil of this alga. Separation of the glycolipids, formation of a urea inclusion complex and reverse phase chromatography on C‐18 Sep‐Pak filters resulted in an EPA concentrate of 97% purity. Similar methods resulted in an AA concentrate of 80% purity.

Synthesis and characterization of all four isomers of methyl 2,4-decadienoate for an investigation of the pheromone components of Pityogenes chaicographus

Methyl (2 E,4 Z)-2,4-decadienoate (1), an important pheromone component of Pityogenes chalcographus, and its three geometrical isomers (2–4) have been synthesized and obtained in 99 % isomeric purity. Urea inclusion complexes were used in the final purification procedures. Spectroscopic data (MS, 1H and 13C NMR) of all four isomers are discussed. A photoisomerization study of the decadienoates is presented.

ChemInform Abstract: A CP‐MAS NMR STUDY OF N‐ALKANES INCLUDED IN UREA: CONFORMATIONAL DEPENDENCES OF THE SUBSTITUENT EFFECTS FOR N‐SUBSTITUTED ALKANES

Abstract Solid state CP-MAS NMR spectra have been obtained for the urea inclusion complexes of the substituted alkanes; tridecane, myristyl alcohol, dioctylamine, myristic acid, and stearonitrile. Changes in the substituent effects on the chemical shift values, on inclusion complex formation, from those of solution NMR spectra are discussed on the assumption that long-chain molecules in urea inclusion complexes have the all- trans conformation.

A CP-MAS NMR study of n-alkanes included in urea: conformational dependences of the substituent effects for n-substituted alkanes

Solid state CP-MAS NMR spectra have been obtained for the urea inclusion complexes of the substituted alkanes; tridecane, myristyl alcohol, dioctylamine, myristic acid, and stearonitrile. Changes in the substituent effects on the chemical shift values, on inclusion complex formation, from those of solution NMR spectra are discussed on the assumption that long-chain molecules in urea inclusion complexes have the all- trans conformation.

Effects of restricted molecular motion on the high-resolution solid-state 13C CP MAS NMR spectrum of the nitrile group of the stearonitrile-urea inclusion complex

The solid-state 13C CP MAS NMR spectra of stearonitrile and its urea inclusion complex were observed at room temperature. The splitting of the nitrile group in the complex was 92 Hz, and was 330 Hz for crystalline stearonitrile. This reduction can be explained by the assumption that the included molecule rotates rapidly (-τ R < 10 −8 s) around the c axis of the complex.

An improved preparation of some insect sex attractants: Synthesis and separation of geometrical isomers by formation of urea complexes

Wittig condensations of aldehydes or ketones with phosphonium salts are frequently used methods for the syntheses of straight-chain or branched alkenes. Suitable choice of reaction conditions may provide the desired geometrical isomer as reaction product. However, we have found that mixtures of geometrical isomers can be conveniently separated on a large scale by the relatively inexpensive method of urea inclusion complex formation. The recovery of both isomers from the separation procedure is almost quantitative. Urea inclusion complexes are formed preferentially withE isomers. Formation of the inclusion complex is affected by the skeletal structure and by the nature of the terminal functional group. By applying this method of separation at a convenient stage, several insect pheromones were prepared without the necessity of a stereoselective step. The technique was used for syntheses of (Z)-11-hexadecenal and (Z)-9-tetradecenal (components of theHeliothis virescens pheromone) and for the synthesis of candidate attractants possessing a trisubstituted double bond.