Long-chain Alkylamines Research Articles

Sphingosine induces the aggregation of imine-containing peroxidized vesicles

Lipid peroxidation plays a central role in the pathogenesis of many diseases like atherosclerosis and multiple sclerosis. We have analyzed the interaction of sphingosine with peroxidized bilayers in model membranes. Cu2+ induced peroxidation was checked following UV absorbance at 245nm, and also using the novel Avanti snoopers®. Mass spectrometry confirms the oxidation of phospholipid unsaturated chains. Our results show that sphingosine causes aggregation of Cu2+-peroxidized vesicles. We observed that aggregation is facilitated by the presence of negatively-charged phospholipids in the membrane, and inhibited by anti-oxidants e.g. BHT. Interestingly, long-chain alkylamines (C18, C16) but not their short-chain analogues (C10, C6, C1) can substitute sphingosine as promoters of vesicle aggregation. Furthermore, sphinganine but not sphingosine-1-phosphate can mimic this effect. Formation of imines in the membrane upon peroxidation was detected by 1H-NMR and it appeared to be necessary for the aggregation effect. 31P-NMR spectroscopy reveals that sphingosine facilitates formation of non-lamellar phase in parallel with vesicle aggregation. The data might suggest a role for sphingosine in the pathogenesis of atherosclerosis.

Dispersibility of reduced alkylamine-functionalized graphene oxides in organic solvents

The alkylamine functionalization of graphene oxide is well known as an efficient approach to prepare reduced functionalized graphene oxide (RFGO) that is highly dispersible in organic solvents. Herein, we systematically investigated the effects of long-chain alkylamine functionalization of graphene oxide on the organic solvent dispersibility and electrical conductivity of RFGO. Three kinds of alkylamines, octylamine, dodecylamine and hexadecylamine, were chosen as functionalization agents. The alkylamine functionalization of graphene oxide was characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and X-ray diffraction. RFGO using octylamine exhibited the best electrical conductivity of greater than 180S/m. All of the RFGOs had excellent dispersibility, up to 3.0mg/mL, in organic solvents, with Hansen solubility parameters in the range of 6.3<(δp+δh)<13.7.

Massive-exfoliation of magnetic graphene from acceptor-type GIC by long-chain alkyl amine

Graphene can be prepared from a graphite intercalation compound (GIC) with acceptor-type intercalator, FeCl3. When the FeCl3–GIC is treated with primary amines at 90 °C for 6 h, the GIC expands to a few layers. The expansion is further facilitated, as the alkyl chain of primary amines becomes longer, while tertiary amines cannot penetrate inside the GIC because of their structural steric hindrance. The primary amine adsorbed in the GIC is oriented to form a bilayer by an indirect reactions among FeCl3–graphene–amine, and this process plays an important role in the expansion of the GIC, in contrast to the reaction of primary amines with donor-type GICs. Then the expanded-GIC is sonicated to exfoliate the graphene sheets. The obtained material exhibited a superparamagnetic property due to the remaining iron compounds. This approach using FeCl3–GIC and primary amine is preferable for the mass production of graphene because of the mild reaction conditions and the short treatment time for exfoliation from the chemically stable FeCl3–GIC. Moreover, the magnetization of graphene nano-composites could be useful for magnetic-recovery processes, electromagnetic heating, and the other applications.

Oleylamine-Stabilized Gold Nanostructures for Bioelectronic Assembly. Direct Electrochemistry of Cytochrome c

Methods to prepare ultrathin gold nanowires and monodisperse nanoparticles based on the intrinsic property of gold(I) ions to form aurophilic interactions stabilized by oleylamine and long-chain alkylamine have been widely explored. Due to the low thermodynamic stability of the high aspect ratio nanostructures, their conjugation and assembly into functional nanosystems have not been explored so far. One of the reasons for this is that the surface of the nanostructures is insulated by stabilization compounds, which preserve the integrity of the nanostructures but at the same time form an insulating barrier in electronic and electrochemical systems in contact areas and for the charge transfer reactions. Conjugation of a metalloprotein cytochrome c (Cyt c) with oleylamine-stabilized gold ultrathin nanowires and nanoparticles into a bioelectrochemically active nanoarchitecture is presented here for the first time. Methods of preparing and assembling the ultrathin nanowires and nanoparticles on the thin-film g...

Stereoselective Synthesis of Amides Sharing the Guanosine 5′-Monophosphate Scaffold and Umami Enhancement Studies Using Human Sensory and hT1R1/rT1R3 Receptor Assays

Recent studies led to the identification of umami-enhancing (S)-N(2)-(1-carboxyethyl)- and (S)-N(2)-(1-alkylamino)carbonylalkyl)guanosine 5'-monophosphates that, together with their sensorially inactive (R)-stereoisomers, were found to be formed upon Maillard-type glycation of guanosine 5'-monophosphate (5'-GMP) with 1,3-dihydroxyacetone or glyceraldehyde, respectively. As the efficiency of this Maillard-type procedure to generate the amidated derivatives is limited by the low solubility and reactivity of long-chain alkyl amines as well as by the tedious separation of the diastereomers formed, a versatile synthesis for the (R)- and (S)-configured amides of N(2)-carboxyalkylated guanosine 5'-monophosphate was developed. Sensory evaluation of a series of N(2)-(1-alkylamino)carbonylalkyl)guanosine 5'-monophosphates revealed β-values for umami enhancement between 0.1 and 7.7 and identified a strong influence of the stereochemistry as well as the chain length of the N(2)-substituent on the umami-enhancing activity. The observed sensory impact of the (S)-configured isomers was confirmed by recording the enhancing effect of these nucleotides on the l-glutamate-induced response of the functionally expressed T1R1/T1R3 umami receptor in a cell-based assay, thus underscoring the stereospecifity of the umami taste receptor binding site.

Preparation of a Homologous Series of Graphite Alkylamine Intercalation Compounds Including an Unusual Parallel Bilayer Intercalate Arrangement

New ternary graphite intercalation compounds (GICs) containing Na+ and linear alkylamines (Na-Cx-GIC) are reported. The following new GICs with indicated stages and intercalate arrangements are obtained: stage 1, monolayer (C3, C4); stage 1, bilayer (C6, C8); and stage 2 bilayer (C12, C14). Two features new to donor-type GICs found are (i) an intercalate bilayer arrangement with guest alkyl chains parallel to encasing graphene layers, and (ii) the transition from an intercalate bilayer to monolayer arrangement upon evacuation for C6. Although there are many reports on the intercalation of short, medium, and long-chain alkylamines in layered hosts, this is the first example of a homologous compound series for GICs. The products obtained are characterized using powder X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry.

Synthesis of high-quality Al-doped ZnO nanoink

Al-doped ZnO (AZO) nanoparticles (NPs) have been synthesized via the thermal decomposition of metal acetylacetonate precursors in a nonoxygen and nonpolar solvent. Long-chain alkyl amines have been utilized to terminate the growth of AZO NPs and to stabilize them. The NPs have been characterized by a number of techniques as monocrystalline, exhibiting a hexagonal (wurtzite) structure with sizes from 8 to 13 nm. The composition of Al in the resulting NP is related solely to the composition of the reaction mixture and the size is controllable with the temperature of the reaction. The AZO NP dispersion has been proven to be stable over a 24 h period by dynamic light scattering measurements. The influence of the synthetic conditions, such as temperature, reaction time and the Al doping content, on the properties of NPs have also been investigated. An optically transparent AZO thin film was fabricated using the AZO nanoink by spin casting followed by annealing. The resulting film resistivity was measured to be 5.0×10−3 Ω cm.

Esters and amides of hexanoic acid substituted with tertiary amino group in terminal position and their activity as transdermal permeation enhancers

Series of alkyl esters of 6-diethylamino-, 6-(pyrrolidin-1-yl)-, 6- (piperidin-1-yl) and 6-(morpholin-1-yl)hexanoic acids and alkylamides of 6-dimethylamino-, 6-(piperidin-1-yl) and 6-(morpholin-1-yl)hexanoic acids, containing 8-12 carbon atoms in the alkyl chain, were prepared by methods of classical organic synthesis. The appropriate secondary amine was alkylated with ethyl-6-bromohexanoate to give ester of ?-substituted hexanoic acid, except of ethyl-6-dimethylaminohexanoate (1), which was prepared by Eschweiler-Clarke methylation of 6-aminohexanoic acid followed by direct esterification with ethanol. The resulted esters of ?-substituted hexanoic acids underwent direct transesterification with long chain alkanols to yield the desired amino esters, or they were treated with long-chain alkylamines to prepare secondary amides of the appropriate heterocyclic hexanoic acids. These products were in vitro tested on their activity as transdermal permeation enhancers on the strips of the excised human skin with theophylline as the model permeant. The activity was evaluated using parameter enhancement ratio (ER), defined as the ratio between the overall amount of the permeant passing through the skin with the tested enhancer and that without tested substance. Decyl 6-(pyrrolidin- 1-yl)hexanoate (16) with ER = 30 showed the highest activity. The enhancing effects of the esters were generally better than those of the amides.

Release of DNA Oligonucleotides and Their Conjugates from Controlled‐Pore Glass Under Thermolytic Conditions

The sequential functionalization of long-chain alkylamine controlled-pore glass (CPG) with a 3-hydroxypropyl-(2-cyanoethyl)thiophosphoryl linker and a dinucleoside phosphorotetrazolide leads to a uniquely engineered support for solid-phase synthesis. Unlike conventional succinylated-CPG supports, this support is designed to allow oligonucleotide deprotection and elimination of deprotection side-products to proceed without release of the oligonucleotide. When needed, the DNA oligonucleotide can be thermolytically released in 2 hr under essentially neutral conditions. The modified CPG support has been successfully employed in the synthesis of both native and fully phosphorothioated DNA 20-mers. On the basis of reversed-phase HPLC and electrophoretic analyses, the purity of the released oligonucleotides is comparable to that of identical oligonucleotides synthesized from succinylated-CPG supports, in terms of both shorter-than-full-length oligonucleotide contaminants and overall yields. The detailed preparation of DNA oligonucleotides conjugated with exemplary reporter or functional groups, either at the 3'-terminus or at both 3'- and 5'-termini, is also described.

Nanotech surface networks get functionalized

A new molecule-based compound, N-ethyl-n-butylammonium 3, 5-dinitrobenzoate monohydrate, which undergoes a reversible solid-state phase transition at 197 K (Tc), has been successfully constructed based on long-chain alkylamine. Specific heat capacity and differential scanning calorimetry (DSC) measurements confirm that it is first-order phase transition with a 5 K thermal hysteresis between heating and cooling scans. Dielectric constants exhibit distinct anomalies around Tc accompanied with step-like responses between low and high dielectric states, which further confirm the phase transition. Variable-temperature single-crystal X-ray diffraction analyses illustrate that the phase transition was elucidated from ordering of the flexible N-ethyl-n-butylammonium cations coupled with reorientational motion of the alkylamine chain.

Anaerobic degradation of long-chain alkylamines by a denitrifying Pseudomonas stutzeri

The anaerobic degradation of tetradecylamine and other long-chain alkylamines by a newly isolated denitrifying bacterium was studied. Strain ZN6 was isolated from a mixture of soil and active sludge and was identified as representing Pseudomonas stutzeri, based on partial 16S rRNA gene sequence analysis. Strain ZN6 was a mesophilic, motile, Gram-negative rod-shaped bacterium and was able to grow on a variety of compounds including even-numbered primary fatty amines with alkyl chains ranging from C(4) to C(18) coupled to nitrate reduction. Alkylamines were used as sole carbon, energy and nitrogen source and were completely mineralized. Nitrate was dissimilated by ZN6 to nitrite. When strain ZN6 was grown under nitrate limitation, nitrite was slowly dissimilated further. When cocultivated with the complete denitrifier Castellaniella defragens ZN3, anaerobic degradation under denitrifying of alkylamines by strain ZN6 was slightly faster. Strain ZN3 is a complete denitrifier, unable to convert tetradecylamine, and was copurified from the same enrichment culture as strain ZN6. The proposed pathway for the degradation of alkylamines in strain ZN6 starts with C-N cleavages to alkanals and further oxidation to the corresponding fatty acids.

A Ti-containing Molecular Sieve Assembled from Titanosilicate Precursors with Long-chain Alkylamines

Novel Ti-containing wormlike mesoporous silica (Ti-WMS) had been synthesized through assembly of preformed titanosilicate-1 precursors with long-chain alkylamines at room temperature. The structural and catalytic properties of prepared material were characterized by a variety of techniques including powder X-ray diffraction, transmission electron microscopy, infrared spectroscopy, UV–Visible spectroscopy, N2 physical adsorption and oxidative desulfurization reactions. The hydrothermal stability of Ti-WMS in steam and boiling water was investigated with comparing to the conventional Ti-HMS. It has been shown that Ti-WMS, relative to Ti-HMS, possesses disordered mesostructure, thicker porous walls, improved amount of micropores and higher catalytic activities, which can be attributed to the existence of zeolitic building units in it. However, there is no enhancement in hydrothermal stability of Ti-WMS assembled from zeolite precursors relative to Ti-HMS prepared through conventional process.

Preparation and characterization of TiO2 and polymer nanocomposite films with high refractive index

AbstractNovel nanocomposite films of TiO2 nanoparticles and hydrophobic polymers having polar groups, poly (bisphenol‐A and epichlorohydrin) or copolymer of styrene and maleic anhydride, with high refractive indices, high transparency, no color, solvent‐resistance, good thermal stability, and mechanical properties were prepared by incorporating surface‐modified TiO2 nanoparticles into polymer matrices. In the process of preparing colloidal solution of TiO2 nanoparticles, severe aggregation of particles can be reduced by surface modification using carboxylic acids and long‐chain alkyl amines. These TiO2 nanoparticles dispersed in solvents were found not to aggregate after mixing with polymer solutions. Transparent colorless free‐standing films were obtained by drying a mixture of TiO2 nanoparticles colloidal solution and polymer solutions in vacuum. Transmission electronic microscopic studies of the films suggest that the TiO2 nanoparticles of 3–6 nm in diameter were dispersed in polymer matrices while maintaining their original size. Thermogravimetric analysis results indicate that the nanocomposite film has good thermal stability and the weight fraction of observed TiO2 nanoparticles in the film is in good accordance with that of theoretical calculations. The refractive index of nanocomposite films of TiO2 and poly(bisphenol‐A and epichlorohydrin) was in the range of 1.58–1.81 at 589 nm, which linearly increased with the content of TiO2 nanoparticles from 0 to 80 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Synthesis of ZnSe Quantum Dots and ZnSe–ZnS Core/Shell Nanostructures

Colloidal ZnSe nanocrystals were synthesized in hot mixtures of long-chain alkylamines, fatty acids, and alkylphosphines. It was possible to tune the size of nanocrystals by varying the reaction time. Transmission electron microscope images showed the presence of spherical ZnSe nanocrystals and X-ray diffraction pattern of ZnSe nanocrystals showed the existence of both the crystalline phase, namely, wurtzite and zinc blende. The ZnSe nanocrystals were then passivated with higher band gap ZnS; this lead to a 2.6-fold enhancement in the integrated photoluminescence intensity of ZnSe nanocrystals. We also synthesized the reverse type core/shell ZnS/ZnSe nanocrystals. These exhibited a significant red shift in the absorption edge after coating with a thin ZnSe shell.

Substrate specificity of a long-chain alkylamine-degrading Pseudomonas sp isolated from activated sludge

A bacterium strain BERT, which utilizes primary long-chain alkylamines as nitrogen, carbon and energy source, was isolated from activated sludge. This rod-shaped motile, Gram-negative strain was identified as a Pseudomonas sp. The substrate spectrum of this Pseudomonas strain BERT includes primary alkylamines with alkyl chains ranging from C3 to C18, and dodecyl-1,3-diaminopropane. Amines with alkyl chains ranging from 8 to 14 carbons were the preferred substrates. Growth on dodecanal, dodecanoic acid and acetic acid and simultaneous adaptation studies indicated that this bacterium initiates degradation through a Calkyl–N cleavage. The cleavage of alkylamines to the respective alkanals in Pseudomonas strain BERT is mediated by a PMS-dependent alkylamine dehydrogenase. This alkylamine dehydrogenase produces stoichiometric amounts of ammonium from octylamine. The PMS-dependent alkylamine was found to oxidize a broad range of long-chain alkylamines. PMS-dependent long-chain aldehyde dehydrogenase activity was also detected in cell-free extract of Pseudomonas strain BERT grown on octylamine. The proposed pathway for the oxidation of alkylamine in strain BERT proceeds from alkylamine to alkanal, and then to the fatty acid.

Y2O3:Tb Nanocrystals Self-Assembly into Nanorods by Oriented Attachment Mechanism

Y2O3:Tb nanorods were obtained by self-assembly of nanocrystals using long-chain alkyl amines as the stabilizing agent. Spherical nanoparticles and nanorods can be selectively prepared by varying the synthesis parameters, including the reaction temperature and time or the ratio of yttrium precursors to amine. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) have been employed to characterize the as-prepared Y2O3 nanostructures. Nanobeads like structures provide powerful evidence for the formation of Y2O3 nanorods via an oriented attachment mechanism. Room-temperature photoluminescence (PL) spectra were used to investigate the optical properties of the Y2O3 nanostructures.

Preparation and characterization of poly( l-lactic acid)/TiO 2 nanoparticle nanocomposite films with high transparency and efficient photodegradability

Poly( l-lactic acid)–TiO 2 nanoparticle nanocomposite films were prepared by incorporating surface modified TiO 2 nanoparticles into polymer matrices. In the process of preparing the nanocomposite films, severe aggregation of TiO 2 nanoparticles could be reduced by surface modification by using carboxylic acid and long-chain alkyl amine. As a result, the nanocomposite films with high transparency, similar to pure PLA films, were obtained without depending on the amount of added TiO 2 nanoparticles. A TEM micrograph of the nanocomposite films suggests that the TiO 2 nanoparticles of 3–6 nm in diameter were uniformly dispersed in polymer matrices. Photodegradation of PLA–TiO 2 nanoparticle nanocomposite films was also investigated. The results showed that nanocomposite films could be efficiently photodegraded by UV irradiation in comparison with pure PLA.

Synthesis, Characterization and Catalytic Performance of Ti-Containing Mesoporous Molecular Sieves Assembled from Titanosilicate Precursors

Novel Ti-containing mesoporous materials with wormhole structure (Ti-WMS) can be assembled from preformed titanosilicate-1 precursors with long-chain alkylamines as structure directors. The obtained products were characterized by a series of techniques including powder X-ray diffraction, transmission electron microscopy, FT-infrared spectroscopy, UV−visible spectroscopy, N2 sorption, and hyperpolarized 129Xe NMR at variable temperature. The catalytic properties of the materials were investigated by oxidative desulfurization reactions. The results show that Ti-WMS, whose synthesis utilizes zeolite precursors as total or part of the silica and titanium sources, is a pure mesoporous phase. However, the prepared materials contain additional micropores except the uniform mesopores, which is confirmed by N2 sorption and 129Xe NMR. Infrared spectra indicate that there are zeolitic primary and secondary building units in the pore walls of Ti-WMS. UV−visible spectroscopy results confirm the existence of active Ti4+ species. Ti-WMS is very active in the oxidation of bulky sulfides such as benzothiophene, dibenzothiophene, and 4,6-dimethyl dibenzothiophene, with activities similar to Ti-HMS. However, in thiophene oxidation, which is not diffusion-limited, Ti-WMS exhibits much higher catalytic activity than Ti-HMS because of the presence of micropores and zeolite-like active sites.

Identification of corrosion inhibiting long-chain primary alkyl amines by gas chromatography and gas chromatography–mass spectrometry

Gas chromatography with flame-ionization detection (FID) and gas chromatography–mass spectrometry (GC/MS) has been used to identify long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization (EI) and positive chemical ionization (PCI) mass spectra of trifluoroacetylated derivatives of the identified alkyl amines are presented. The corrosion inhibiting alkyl amines were applied in the investigation of a new anticorrosive and antifouling formulation for water–steam circuit of energy systems in the power industry.

Langmuir−Blodgett Monolayers of Long-Chain NBD Derivatives on Silver Island Films: Well-Organized Probe Layer for the Metal-Enhanced Fluorescence Studies

The metal-enhanced fluorescence (MEF) from the well-organized monolayers of two newly prepared long-chain alkylamine derivatives of nitrobenzoxadiazole (NBD-C16 and NBD-C18) deposited on silver island films (SIFs) has been investigated. The NBD derivatives were conveniently prepared by using a single step procedure in quantitative yields. The monolayers of the probes on SIFs as well as on bare-glass slides were obtained by using the Langmuir-Blodgett (LB) technique. Orientation of the NBD probe molecule in LB monolayer film was measured with polarized absorption spectroscopy. The observed tilt angle of the probe transition dipole moment with respect to the surface normal of approximately 67-68 degrees was evaluated. We observed that the NBD monolayers deposited in close proximity to silver islands show about a 16-fold increase in fluorescence intensity and shortened fluorescence lifetime compared to those on bare-glass, which are due to metal enhanced fluorescence. On the other hand, the corresponding MEF from randomly oriented film obtained by using spin coating of the probes on SIFs was only 2.5-fold. Further, we deposited mixed monolayers of NBD-C16 or NBD-C18 with various molar ratios of stearic acid to understand the polarity effect on MEF. Interestingly, we found a consistent increase in MEF efficiency with increasing molar ratio of stearic acid. Along with MEF, we also found a continuous blue-shift in emission band maxima of the probes with an increasing molar ratio of stearic acid. The observed increase in MEF efficiency is justified based on cooperative effects of (1) the modulations in electronic density of the surface plasmon absorption band of SIFs and (2) defined probe orientation that might lead to preferential excitation.