Aliphatic Polyamines Research Articles

Polyfunctional ion-exchangers based on wood

α-Oxide wood derivatives were synthesized by O-alkylation of wood with a bifunctional epoxide oligomer in the presence of Et3N catalyst. Polyfunctional ion-exchangers were prepared by subsequent amination of them by aliphatic polyamines.

Epoxy nanocomposites curing by microwaves

AbstractIn this work, chemically modified sodium montmorillonite and epoxy monomer were used to prepare nanocomposites in two consecutive stages. In the first stage, dodecylamine, octadecylamine, hexadecylamine, and hexadecyltrimethyl ammonium bromide were used to prepare various organophilic clays. In the second stage, the bisphenol‐A based epoxy monomer and predetermined amounts of organoclay were mixed together and then cured by an aliphatic polyamine for 20 min under microwave at 400 W. Furthermore, α‐ω diacrylate poly(dimethylsiloxane) was added to the mixture before the curing process to modify the toughness of the samples. The mixture was poured into the poly(tetrafluoroethylene) mold; the epoxy resin/curing agent ratio was maintained as 2/1. The clear films formed after microwave irradiation were removed from the mold, cooled, and then stored in a cool and dry medium until characterization. The samples were analyzed by wide angle X‐ray diffraction, differential scanning calorimetry, and mechanical tests. Surfaces of the cold fractured samples were also observed under the scanning electron microscope. The results revealed that microwave curing of the samples of 5% organoclay and 5% siloxane showed improvement in mechanical properties. POLYM. ENG. SCI. 46:1104–1110, 2006. © 2006 Society of Plastics Engineers

Structure of the copper (II) perchlorate complex with Schiff base ligand containing pyridine N-oxide fragments and propylene bridges: Solvatochromic effect

Abstract The copper (II) perchlorate complexes with Schiff base ligands were investigated by X-ray single crystal analysis, electron spectroscopy, infrared and electron paramagnetic spectroscopy. The Schiff bases were obtained as condensation products of 2-pyridinecarboxaldehyde N-oxide with dipropylenetriamine (L1) and triethylenetetramine (L3), respectively. The structure of the complex [CuL2](ClO4)2 was solved. In the structure, the ligand exists in the form of aliphatic polyamine containing two Schiff bases in contrary to the free form of this ligand with one pyrimidine ring and one Schiff base. Electronic spectra of the copper (II) perchlorate complexes of both ligands in different solvents were measured including time dependences. Vivid solvatochromic effect was observed for the complexes of both ligands. It was suggested that similar solvents cause similar equilibrium in the system and at least two different ways of isomerisation of the ligand during complexation exist.

Capillary electrophoresis coupled to mass spectrometry from a polymer modified poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip

Hybrid capillary-poly(dimethysiloxane)(PDMS) microchips with integrated electrospray ionization (ESI) tips were directly fabricated by casting PDMS in a mould. The shapes of the emitter tips were drilled into the mould, which produced highly reproducible three-dimensional tips. Due to the fabrication method of the microfluidic devices, no sealing was necessary and it was possible to produce a perfect channel modified by PolyE-323, an aliphatic polyamine coating agent. A variety of different coating procedures were also evaluated for the outside of the emitter tip. Dusting graphite on a thin unpolymerised PDMS layer followed by polymerisation was proven to be the most suitable procedure. The emitter tips showed excellent electrochemical properties and durabilities. The coating of the emitter was eventually passivated, but not lost, and could be regenerated by electrochemical means. The excellent electrochemical stability was further confirmed in long term electrospray experiments, in which the emitter sprayed continuously for more than 180 h. The PolyE-323 was found suitable for systems that integrate rigid fused silica and soft PDMS technology, since it simply could be applied successfully to both materials. The spray stability was confirmed from the recording of a total ion chromatogram in which the electrospray current exhibited a relative standard deviation of 3.9% for a 30 min run. CE-ESI-MS separations of peptides were carried out within 2 min using the hybrid PDMS chip resulting in similar efficiencies as for fused silica capillaries of the same length and thus with no measurable band broadening effects, originating from the PDMS emitter.

Inclusion of nickel(II) and copper(II) complexes with aliphatic polyamines in cucurbit[8]uril

The inclusion compound of macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex containing the tetraazamacrocyclic ligand cyclam, {[Ni(cyclam)]@CB[8]}Cl2··16H2O (1), and the inclusion compounds of CB[8] with the copper(II) bis-ethylene-diamine complex, {trans-[Cu(en)2(H2O)2]@CB[8]}Cl2·{CB[8]}·42H2O (2a) and {trans-[Cu(en)2(H2O)2]@CB[8]}Cl2·17H2O (2b), were synthesized and characterized by X-ray diffraction analysis, IR and ESR spectroscopy, and electrospray mass spectrometry. Guest—host inclusion compounds can be directly synthesized starting from a metal complex and cucurbit[8]uril, as was exemplified by the preparation of compounds 2a and 2b.

A Study on the Modified Lignosulfonate from Lignin

A series of modified lignosulfonates containing aliphatic amide residues were prepared from lignin (wood and straw), the by-products from pulp paper industry, via a modification route, including Mannich reaction with aliphatic polyamine, acylation with aliphatic acyl chloride and sulfomethylation. The results from performance tests show that these modified products are more active than the unmodified lignosulfonates, the surface tension of the product solution at CMC could be as low as 28–38 mN/m. Excellent activity at the interface of crude oil and the solutions was observed. Therefore, it wouldn't be necessary to add other kinds of surfactants, the ultralow interfacial tension could have achieved within a wide range of surfactant concentration and alkalinity. The modified lignosulfonates prepared were found to be the appropriate surfactants in Enhanced oil recovery industry.

Membrane binding and transport of N-aminoethyl-1,2-diamino ethane (dien) and N-aminopropyl-1,3-diamino propane (propen) by rat liver mitochondria and their effects on membrane permeability transition.

This investigation is aimed at defining the structural requirements for aliphatic polyamines to interact with mitochondrial binding sites, which are relevant for the regulation of the permeability transition and for mitochondrial polyamine uptake. The triamines N-aminoethyl-1,2-diaminoethane (dien) and N-aminopropyl-1,3-diaminopropane (propen), both symmetric polyamines, are accumulated to differing extents by an energy-dependent mechanism in liver mitochondria. Propen is also able completely to inhibit the permeability transition of mitochondria, induced by Ca2+ plus phosphate, with the same efficacy as the asymmetric ubiquitary triamine spermidine, whereas dien fails to exhibit this effect. The competitive inhibition of both triamines on spermidine transport demonstrates that they bind to the same site(s) of this polyamine and exploit its transport system. The binding of dien and propen to mitochondrial membrane was studied by applying a thermodynamic model of ligand-receptor interactions developed both for equilibrium and far-from-equilibrium binding processes. Results show the presence of two mono-coordinated binding sites, S1 and S2, for propen, and one monocoordinated binding site for dien, all exhibiting high capacity and low affinity. Comparisons of the binding parameters of these polyamines with those of other natural polyamines reveal that, besides flexibility and hydrophilicity, as previously suggested, protonation of the imino group and the symmetry of the molecules for S1, and the presence of an aminobutyl group for S2, also contribute to the polyamine interactions observed in the two sites.

Elaboration of Transparent Polymeric Films Trapping Copper Ions by Complexation

The aim of this work was to elaborate on a thin polymeric film for coating transparent fluorine-doped tin oxide (FTO) electrode supported on a glass substrate for trapping ions. Possible applications are the easier detection of ions due to complexation on the FTO surface or could be the making up of electrochromic devices using copper(I)-salt based electrolytes to avoid diffusion of ions formed at the anode toward Cu(0) deposited on the cathode. These thin polymeric films proposed here as complexing material candidates toward copper ions belong to polyalkyleneimine polymers. They were obtained by anodic electropolymerization of aliphatic polyamines (with at least two primary amino groups) such as ethylenediamine, 1,3-diaminopropane, or diethylenetriamine on FTO electrode surfaces and characterized by IR attenuated total reflectance spectroscopy. Moreover, we have shown that polyalkyleneimine-type polymers used here present good chelating properties towards ions due to the amino groups they contain. © 2004 The Electrochemical Society. All rights reserved.

Thermal and Rheological Characterisation of a Thermoset Matrix for Filament Winding Modelling

Rheo-kinetic behaviour of an epoxy resin, coupled with an aliphatic polyamines hardener, used in fibre reinforced plastics, was analysed comparing experimental data to theoretical models. Then the modelling of technological filament winding process for thermoset matrix composites, developed through a numerical code realized with MATLAB, is reported. The model includes winding and curing phase decoupling the manufacturing process into sub-models. Four sub-models are used: fibre motion, thermal, kinetic and rheological model. Considerable differences are obtained in process condition, using several thermal treatments. The numerical modelling helps to detect the process conditions to optimise the filament winding process.

Uracil as one of the multiple sources of β-alanine in Limonium latifolium, a halotolerant β-alanine betaine accumulating Plumbaginaceae

The metabolic origin of β-alanine has been assessed in Limonium latifolium, a halotolerant Plumbaginaceae, which accumulates β-alanine betaine as an osmoprotectant. It was already known that β-alanine may act as a substrate for β-alanine betaine synthesis in this species and that propionate and spermidine metabolism may serve as putative ways for β-alanine production. The present study reveals that feeding experiments with substrates suspected to be converted to β-alanine bring about preliminary evidences about the multiplicity of the biosynthetic routes leading to this amino acid in L. latifolium. β-Alanine level is shown to be enhanced in roots from hydroponically grown seedlings fed with 1,3-diaminopropane, propionate or N-carbamyl β-alanine. Such precursor–product relationships were only observed in roots. Radiotracer experiments with [5,6- 3H]-uracil supplied to seedlings of L. latifolium and L. sinuatum, a β-alanine betaine non-accumulating species, demonstrate the effectiveness of uracil degradative pathway in β-alanine synthesis via dihydrouracil and N-carbamyl β-alanine in both species. It is demonstrated that this pathway is actually extended to β-alanine betaine only in the betaine accumulating species. The present results suggest that multiple ways deriving from aliphatic polyamines, propionate or uracil may cooperate for β-alanine and β-alanine betaine production in L. latifolium, the contribution of pyrimidine catabolism being highlighted for the first time.

Mechanism and life study on polyaniline anti-corrosion coating

Solvent free polyaniline emeraldine base(EB) corrosion protection coating was prepared, employing aliphatic polyamine as solvent of EB as well as hardener of epoxy resin. This coating passed 2000h of salt fog test when the EB loading was about 1 wt%. The interaction between EB and iron indicated that EB acted as a quasi-catalyst to cause the formation of densed iron oxide film in the interface.

Cu(ii) and Ni(ii) complexes with dipyridine-containing macrocyclic polyamines with different binding unitsElectronic supplementary information (ESI) available: selected bond lengths [Å] and angles [°] for [CuL1](ClO4)2 (Table S1) and for [NiL1](ClO4)2 (Table S2); absorption spectra of L2 in the presence of Cu(ii) (1 ∶ 1 molar ratio) at different pH values (Fig. S1). See http://www.rsc.org/suppdata/dt/b2/b211904h/

The coordination features of the two dipyridine-containing polyamine macrocycles 2,5,8,11,14-pentaaza[15]-[15](2,2′)[1,15]-bipyridylophane (L1) and 4,4′-(2,5,8,11,14-pentaaza[15]-[15](2,2′)-bipyridylophane) (L2) toward Cu(II) and Ni(II) have been studied by means of potentiometric and spectrophotometric UV-vis titrations in aqueous solutions. While in L1 all the nitrogen donor atoms are convergent inside the macrocyclic cavity, in L2 the heteroaromatic nitrogen atoms are located outside. Ligands L1 and L2 form stable mono- and dinuclear complexes with Cu(II). In the case of Ni(II) coordination, only L1 gives dinuclear complexes, while L2 can form only mononuclear species. In the Cu(II) or Ni(II) complexes with L1 the metal(s) are lodged inside the macrocyclic cavity, coordinated to the heteroaromatic nitrogens. As shown by the crystal structure of the [CuL1]2+ and [NiL1]2+ cations, at least one of the two benzylic nitrogens is not coordinated and facile protonation of the complex takes place at neutral or slightly acidic pH values. The particular molecular architecture of L2, which displays two well-separated binding moieties, strongly affects its coordination behavior. In the mononuclear [CuL2]2+ complex, the metal is encapsulated inside the cavity, not coordinated by the dipyridine unit. Protonation of the complex, however, occurs on the aliphatic polyamine chain and gives rise to translocation of the metal outside the cavity, bound to the heteroaromatic nitrogens. In the [NiL2]2+ complex the metal is coordinated by the dipyridine nitrogens, outside the macrocyclic cavity. Thermodynamic and/or kinetic considerations may explain the different behavior with respect to the corresponding Cu(II) complex.

Cooperativity effects in the protonation of aliphatic polyamines

The equilibria between base A and proton H can be calculated in the probability space by means of partition functions Z A and Z H, mathematically represented by binding polynomials. The partition functions are expressed as functions of affinity constants, k j and cooperativity coefficients, b j , specific for each class j of sites. We have undertaken a series of potentiometric measurements of equilibria of polyamines with protons at 25 °C, I=0.1 KCl, in order to calculate these parameters from the experimental data by application of a special computer program. The transformation from the probability space ( Z H (or Z A), k j and exp( b j )), to the free energy space (−Δ G= RT ln Z H (or Z A)) made possible the evaluation of the cooperativity potential Δ μ γ =− RTb i . The cooperativity potential between two amine groups separated by aliphatic chain (CH 2) n  depends on the length of the chain i.e. it decreases exponentially with the increase of the number of methylene groups. On the other hand, the cooperativity coefficient can be brought to the scale of the constants of Hammett equation by dividing b i by 2.303. It is then possible to calculate Taft constants σ* for substituents in primary, secondary and tertiary amines.

Cd(II) complexation in aqueous solution with dipyridine- and phenanthroline-containing polyamine macrocycles

The coordination features toward Cd(II) of four phenanthroline-containing and three dipyridine-containing macrocyclic polyamines have been studied by means of potentiometric and spectrophotometric UV–Vis measurements in aqueous solutions. All ligands form stable 1:1 metal complexes. The stability constants of the Cd(II) are generally lower than those reported for Cd(II) complexes with aliphatic macrocyclic polyamines containing the same number of nitrogen donors. This effect is mainly related to the stiffening of the ligands, due to the insertion of a large and rigid heteroaromatic moiety within the aliphatic polyamine framework. This structural feature does not allow the nitrogen donor to achieve an optimal arrangement around the metal ion. The decreased stability is often accompanied by facile protonation of the complexes, suggesting that some amine groups are not involved in metal binding.

Insights into supramolecular design 2: Analysis of anion coordination geometry of oxoanions in a protonated polyamine matrixPart 1: ref. 1. Electronic supplementary information (ESI) available: Hydrogen bonds for new compounds. See http://www.rsc.org/suppdata/ce/b1/b109449a/

Single-crystal X-ray diffraction analysis of 16 hydrogen bonded structures formed from reaction of 8 aliphatic polyamines with nitric (1), phosphoric (2) and sulfuric acid (3) is reported. The polyamines included are diethylenetriamine, H2N(CH2)2NH(CH2)2NH2 (a), N-(2-aminoethyl)-1,3-propanediamine, H2N(CH2)3NH(CH2)2NH2 (b), spermidine, H2N(CH2)4NH(CH2)3NH2 (c), bis(hexamethylene)triamine, H2N(CH2)6NH(CH2)6NH2 (d), triethylenetetramine, H2N(CH2)2NH(CH2)2NH(CH2)2NH2 (e), N,N-bis(3-aminopropyl)ethylenediamine, H2N(CH2)3NH(CH2)2NH(CH2)3NH2 (f), spermine, H2N(CH2)3NH(CH2)4NH(CH2)3NH2 (g) and 2,2′,2″-triaminotriethylamine, N[(CH2)2NH2]3 (h). The complexes are formed in amine∶anion ratios of 1∶1 to 1∶4. The oxoanions are connected by hydrogen bonds to the protonated amines following specific patterns. These patterns depend on the mode of covalent connectivity of the oxygen within the anion as well as on the distance between the oxygen of interest and the central atom of the anionic species.

Structure of the Lipopolysaccharide Core Region of the Bacteria of the Genus Proteus

The lipopolysaccharide (LPS) core structure was studied in seven rough strains of Proteus and 26 smooth strains belonging to various Proteus O-serogroups. All LPSs share a common heptasaccharide fragment, which includes two Kdo, three Hep, one Glc, and one GalA residue. Core structures differ between strains and within each strain in the presence of a variety of additional monosaccharides and non-sugar substituents. In many strains, the LPS includes a cyclic acetal of GalNAc in the open-chain form, which builds up a new type of linkage between monosaccharides. The covalent linkage of aliphatic polyamines, e.g. putrescine and spermidine, to the LPS was confirmed for the first time and the location of the amines at the carboxyl group of a GalA residue established. Analyses revealed peculiar features of the core structure, which are characteristic of P. mirabilis on one hand and P. vulgaris and P. penneri on the other hand.

IMPROVED PEPTIDE MAPPING BY CAPILLARY ZONE ELECTROPHORESIS USING TRIETHYLENETETRAMINE PHOSPHATE BUFFER AS THE ELECTROLYTE SOLUTION

An acidic separation buffer for peptide mapping by capillary zone electrophoresis (CZE) in both bare fused-silica and acrylamide-coated capillaries is evaluated. The buffer system consists of a mixture of the aliphatic polyamine triethylenetetramine and phosphoric acid in aqueous media. The study has been performed at pH 3.0, which is within the buffering capacity range in the acidic domain determined by the pKa1 values of both the tetramine (3.2) and the polyprotic inorganic acid (2.1). Consequently, the solution resulting by combining phosphoric acid and triethylenetetramine at pH 3.0 is a buffering system exhibiting two conjugate acid-base pairs, both effective at controlling the protonic equilibra at this pH value. The suitability of the triethylenetetramine phosphate buffer at performing efficient peptide mapping by CZE has been evaluated on a tryptic digest of the protein cytochrome c from horse heart. The study is based on the comparison of the tryptic peptide separation performed by CZE with either triethylentetramine phosphate or sodium phosphate buffers, both containing the same concentration of phosphate ions. The results show that both separation performance and electroosmotic flow are greatly influenced by the incorporation of triethylenetetramine in the buffer system. With the triethylenetetramine phosphate buffer, the electroosmotic flow results in being either suppressed or reversed from cathodic to anodic in bare fused-silica and in acrylamide-coated capillaries, respectively. This effect is indicative of the specific adsorption of positively charged molecules of triethylenetetramine into the immobilized region of the electric double layer at the interface between the capillary wall and the electrolyte solution. The improvement of peak shape observed with the triethylenetetramine phosphate buffer is also related to the adsorption of the tetramine evidenced by the variation of the electroosmotic flow. The specific adsorption of cationic triethylenetetramine results in masking the silanol groups and other active adsorption sites on the capillary wall, that are believed to be responsible for the poorer performance obtained with sodium phosphate buffer. Thus, the results demonstrate that besides being an effective component of the buffering system, triethylenetetramine acts as a dynamic coating reagent influencing, significantly, efficiency and resolution of the tryptic peptides.

Coordination properties of a polyamine cryptand with two different binding moieties. A case of a pH-modulated antenna device based on a new Eu(III) cryptate complex.

Protonation and alkali- and alkaline-earth-metal coordination by the dipyridine-containing cryptand L have been studied by means of potentiometric and spectroscopic (UV-vis, (1)H NMR) measurements in aqueous solutions. This ligand is constituted by an aliphatic polyamine chain and a coordinating cleft, delimited by two dipyridine units, where the metal ion is lodged. The resulting complexes are characterized by an unusually high stability. The polyamine chain is not involved, or weakly involved, in metal coordination, and facile protonation can occur on the nitrogen atoms of this moiety. Similar coordination features are found in the Eu(III) complex. A fluorescence emission study reveals that the Eu(III) cryptate shows the characteristic visible emission of the metal, due to the intramolecular energy transfer to the metal ion mainly from the lower energy triplet state of the cryptand. On the other hand, the emission intensity is modulated by pH, giving a maximum at neutral pH and decreasing at both acidic and alkaline pH values.

Aliphatic polyamine oxidation response variability and stability at boron-doped diamond thin-film electrodes as studied by flow-injection analysis

Previously it was shown that four different aliphatic polyamines can be quantitatively electrooxidized at boron-doped diamond thin film electrodes without derivatization or the use of pulsed voltammetric waveforms [Anal. Chem. 71 (1999) 1188; Anal. Chem. 69 (1997) 4041]. The flow injection analysis (FIA-EC) investigation (amperometric detection mode) of cadaverine (CAD), putrescine (PUT), spermine (SPM) and spermidine (SPMD), reported previously [Anal. Chem. 71 (1999) 1188], are updated herein with particular emphasis on the electrode response variability and stability. Most of the measurements were made with a film deposited from a 0.50% methane-to-hydrogen (C/H) volumetric ratio. In general, films deposited with C/H ratios near this value tend to possess the requisite physicochemical properties to support anodic oxygen transfer reactions. The electrode performance was evaluated in terms of the linear dynamic range, limit of quantitation, response variability and response stability. A linear dynamic range from 1.0 μM to 1.0 mM and a limit of quantitation of 1.0 μM or 20 pmol injected (S/N≥3) were found for CAD, PUT, and SPMD. For SPM, a linear dynamic range from 0.32 μM to 1.0 mM and a limit of quantitation of 0.32 μM or 6.4 pmol were observed. The response variability, as low as 2–4%, was observed which is vastly improved over previous results. The improvement was achieved by introducing a 3–6 min delay period between injections. The long-term response stability was good with no evidence for any progressive response attenuation or complete fouling by the reaction product, even though a solid deposit was observed to accumulate on the electrode surface with extended use. The deposit appears to partially reduce the active electrochemical area for polyamine oxidation and to decrease the overpotential for water discharge. Preliminary chromatographic results demonstrated the possibility of separating and detecting the polyamines by a simple reverse-phase scheme at constant applied potential.

Protonation and Zn(II) coordination by dipyridine-containing macrocycles with different molecular architecture. A case of pH-controlled metal jumping outside-inside the macrocyclic cavity.

The synthesis of the macrocyclic ligand 4,4'-(2,5,8,11,14-pentaaza[15])-2,2'-bipyridylophane (L3), which contains a pentaamine chain linking the 4,4'-positions of a 2,2'-dipyridine moiety, is reported. Protonation and Zn(II) complexation by L3 and by macrocycle L2, containing the same pentaamine chain connecting the 6,6'-positions of 2,2'-dipyridine, were studied by means of potentiometric, UV-vis, and fluorescent emission measurements. While in L2 all the nitrogen donor atoms are convergent inside the macrocyclic cavity, in L3 the heteroaromatic nitrogen atoms are located outside. Both ligands form mono- and dinuclear Zn(II) complexes in aqueous solution. In the mononuclear Zn(II) complexes with L2, the metal is coordinated inside the macrocyclic cavity, bound to the heteroaromatic nitrogen donors and three amine groups of the aliphatic chain. As shown by the crystal structure of the [ZnL2](2+) complex, the two benzylic nitrogens are not coordinated and facile protonation of the complex takes place at slightly acidic pH values. Considering the mononuclear [ZnL3](2+) complex, the metal is encapsulated inside the cavity, not coordinated by the dipyridine unit. Protonation of the complex occurs on the aliphatic polyamine chain and gives rise to translocation of the metal outside the cavity, bound to the heteroaromatic nitrogens.