Ammonium Dibromide Research Articles

Symmetrical ammonium dibromide as an efficient promoter for the ultrasonic irradiation multi-component preparation of pyrrolidine derivatives

In this work, a method has been developed for the formal, multi-component reaction of cyclopropyl dicarboxylates, aldehydes, and amines under ultrasonic irradiation. The symmetrical dibromide salt (A) was prepared from the reaction of 1,2-bis(2-bromoethoxy)ethane with 2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine in toluene under reflux condition. CeCl3 and compound (A) were used as catalyst and promoter and showed a good potential for application in the synthesis of a range of structurally diverse pyrrolidine rings in short reaction times (3–5 h) and excellent yields (89–97 %).

Reversible DNA compaction induced by partial intercalation of 16-Ph-16 gemini surfactants: evidence of triple helix formation.

The interaction between calf thymus DNA and the gemini surfactants N,N'-[α,ω-phenylenebis(methylene)bis [N,N'-dimethyl-N-(1-hexadecyl)]-ammonium dibromide], p-16-Ph-16 (α = 1, ω = 3) and m-16-Ph-16 (α = 1, ω = 2), has been investigated via circular dichroism, fluorescence and UV-vis spectroscopy, zeta potential, dynamic light scattering, and AFM microscopy. Measurements were carried out in aqueous media at different molar ratios, R = (C16-Ph-16)/CDNA and C16-Ph-16 always below the critical micellar concentration (CMC) of the surfactant. Under these conditions, DNA undergoes two reversible conformational changes, compaction and decompaction, due to interaction with the surfactant molecules at low and high molar ratios, respectively. The extent of such conformational changes is correlated with both the degree of surfactant partial intercalation, and the size and charge of the surfactant aggregates formed, in each case. Comparison of the results shows that the para-form of the surfactant intercalates into the DNA to a major extent; therefore, the compaction/decompaction processes are more effective. Among these, the structure of the resulting 16-Ph-16/DNA decompacted complex is worthy of note. For the first time it can be demonstrated that the partial intercalation of the 16-Ph-16 gemini surfactants induces the formation of triplex DNA-like structures at a high R ratio.

Transfection of plasmid DNA by nanocarriers containing a gemini cationic lipid with an aromatic spacer or its monomeric counterpart

This study performed a biophysical characterization (electrochemistry, structure and morphology) and assessment of the biological activity and cell biocompatibility of GCL/DOPE-pDNA lipoplexes comprised of plasmid DNA and a mixed lipid formed by a DOPE zwitterionic lipid and a gemini cationic lipid N-N′-(1,3-phenylene bis (methylene)) bis (N,N-dimethyl-N-(1-dodecyl) ammonium dibromide (12PH12) containing an aromatic spacer or its monomeric counterpart surfactant, N-benzyl-N,N-dimethyl-N-(1-dodecyl) ammonium bromide (12PH). Electrochemical results reveal that i) the gemini cationic lipid (12PH12) and the plasmid pDNA yield effective charges less than their nominal charges (+2 and −2/bp, respectively) and that ii) both vectors (12PH12/DOPE and 12PH/DOPE) could compact pDNA and protect it from DNase I degradation. SAXS and cryo-TEM experiments indicate the presence of a lamellar lyotropic liquid crystal phase represented as alternating layers of mixed lipid and plasmid. Transfection efficiency (by FACS and luminometry) and cell viability assay in COS-7 cells, performed with two plasmid DNAs (pEGFP-C3 and pCMV-Luc VR1216), confirm the goodness of the proposed formulations (12PH12/DOPE and 12PH/DOPE) to transport genetic material, with efficiencies and biocompatibilities comparable to or better than those exhibited by the control Lipofectamine 2000*. In conclusion, although major attention has been paid to gemini cationic lipids in the literature, due to the large variety of modifications that their structures may support to improve the biological activity of the resulting lipoplexes, it is remarkable that the monomeric counterpart surfactant with an aromatic group analyzed in the present work also exhibits good biological activity. The in vitro results reported here indicate that the optimum formulations of the gene vectors studied in this work efficiently transfect plasmid DNA with very low toxicity levels and, thus, may be used in forthcoming in vivo experiments.

Interfacial dynamic properties and dilational rheology of mixed anionic and cationic Gemini surfactant systems at air–water interface

The interfacial dynamic properties and dilational rheology of sulfonate Gemini surfactant (SGS-12), two bisquaternary ammonium dibromides with different carbon chain lengths (BQAS-12, 16), and two mixed anionic and cationic Gemini surfactant solutions (SGS-12/BQAS-12 and SGS-12/BQAS-16) air–water interface were investigated using the drop shape analysis. Results indicate that the adsorption mechanism of surfactants is diffusion-controlled at dilute concentrations, whereas the adsorption process gradually shifts to a mixed kinetic-diffusion control with increasing the surfactant concentration. The surface tension of the mixtures reaches the minimum value when the molar ratios of SGS-12/BQAS-12 and SGS-12/BQAS-16 mixtures are 6:5 and 8:5, respectively. The effects of oscillating frequency and concentration on the dilational properties were also examined. As the dilational frequency increases, the dilational modulus of these surfactants increases gradually, but the phase angle decreases. The dilational elasticity peaks at a certain concentration, which is less than the critical micelle concentration. Moreover, the effects of SGS-12 concentration on the dilational interfacial rheology of the BQAS-12/SGS-12 and BQAS-16/SGS-12 mixtures were studied. The surface activities of these mixtures show positive correlation with the phase angle. Moreover, the surface film mainly exhibits viscosity as the surface tension reaches the minimum.

Solubility and hydrolytic stability of indomethacin in aqueous micellar solutions

The solubility of the indomethacin drug in aqueous micellar solutions of a series of dicationic surfactants was characterized by spectrophotometry. The use of these surfactants can significantly increase the indomethacin content in aqueous solutions without destruction of the drug. The increase in the solubility can be explained by the multifactorial mechanism of the influence of micelles involving the solubilization of the drug and its binding with surfactants due to electrostatic and specific interactions. The use of dicationic surfactants in alkaline solutions was shown to markedly accelerate the hydrolytic cleavage of indomethacin. The highest catalytic effect is observed for N,N´-(hexane-1,6-diyl)bis(2-hydroxyethyl)(methyl)(cetyl)ammonium dibromide: a 1200-fold increase in the reaction rate of alkaline hydrolysis of the drug.

Structure and properties of complexes of α-chymotrypsin with hydroxyl-containing gemini dicationic surfactants with a spacer moiety of varying length

The structure and properties of supramolecular complexes of α-chymotrypsin with hydroxyl-containing alkyl ammonium gemini surfactants (GSs) — α,ω-alkanedyl-bis(hydroxyethylmethylcetyl ammonium dibromides), with a polymethylene spacer of varying length have been studied. IR spectroscopy and tryptophan fluorescence data show that the interaction of GSs with α-chymotrypsin leads to changes of different intensity in the structural state of proteins. The most probable complexation mode of enzyme with GSs have been proposed by the molecular docking method. A correlation is found between the activity of α-chymotrypsin and the length of the GS spacer moiety. The enzyme activity correlates with the change in the substrate concentration in the aqueous phase of the surfactant micellar solution.

Colloidal and biological properties of cationic single-chain and dimeric surfactants

The colloidal and biological properties of the two single-chain surfactants N-benzyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (PH12) and N-cyclohexylmethyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (CH12) and their two dimeric counterparts N,N’-(1,3-phenylenebis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12PH12) and N,N’-(cyclohexane-1,3-diylbis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12CH12) were investigated. The thermodynamic functions of the self-aggregation process were estimated by using calorimetric measurements and the micellization enthalpy values, ΔHM, were examined considering the different enthalpic contributions to ΔHM. In the investigation of the structure-property relationship, it was found that the surfactant structure does not influence practically the foamability of the surfactants, but it plays a key role in their solubilization capacity, antimicrobial activity and biodegradability.

Binding of Cationic Single-Chain and Dimeric Surfactants to Bovine Serum Albumin

The interactions between bovine serum albumin (BSA) and the single-chain surfactants N-benzyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (PH12) and N-cyclohexylmethyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (CH12) and their two dimeric counterparts, N,N'-[1,3-phenylenebis(methylene)]bis[N,N-dimethyl-N-(1-dodecyl)]ammonium dibromide (12PH12) and N,N'-[cyclohexane-1,3-diylbis(methylene)]bis[N,N-dimethyl-N-(1-dodecyl)]ammonium dibromide (12CH12), respectively, have been investigated by surface tension, fluorescence, circular dichroism, ζ potential, and atomic force microscopy. The results obtained permit the examination of the way an increase in the number of hydrophobic chains and the substitution of a cyclohexyl ring by a phenyl ring, either in the headgroup of single-chain surfactants or in the spacer of dimeric surfactants, affect BSA-surfactant interactions. The comparison of the fluorescence results with those obtained by ζ potential measurements shows that the sites of binding of the surfactants with aromatic rings to the BSA are somewhat different from those of the surfactants with no aromatic rings.

Physicochemical characterization of bromide mono- and dimeric surfactants with phenyl and cyclohexyl rings in the head group

In this work the two monomeric surfactants N-benzyl- N, N-dimethyl- N-(1-dodecyl)ammonium bromide (PH12,Br −) and N-cyclohexylmethyl- N, N-dimethyl- N-(1-dodecyl)ammonium bromide (CH12,Br −) and their two dimeric counterparts N, N′-(1,3-phenylenebis(methylene))bis( N, N-dimethyl- N-(1-dodecyl)ammonium dibromide (12PH12,2Br −) and N, N′-(cyclohexane-1,3-diylbis(methylene))bis( N, N-dimethyl- N-(1-dodecyl)ammonium dibromide (12CH12,2Br −) were prepared and characterized. The critical micelle concentration, the micellar ionization degree and the average aggregation number were obtained by using different techniques. The results are discussed with the help of 1H NMR two-dimensional, 2D, rotating frame nuclear Overhauser effect spectroscopy measurements, ROESY, which seem to indicate that the phenyl and cyclohexyl rings present in the head groups of the surfactants are bent towards the micellar interior in order to avoid contact with water. The surface activity of the surfactants was studied by means of surface tension measurements. The occurrence of morphological transitions upon increasing surfactant concentration and the variations in the polarity and in the microviscosity of the interfacial region accompanying this sphere-to-rod transition were investigated. It was shown that the formation of spherocylindrical micelles also causes changes in the 1H NMR spectra of the surfactant solutions.

Surface-active, micellar, and antielectrostatic properties of bis-ammonium salts

A series of new cationic surfactants, bis-quaternary ammonium dibromides, were synthesized. The properties of these surfactants were characterized by surface tension measurements, conductivity study, and dynamic light scattering. The surface properties, such as surface excess concentration, Γ cmc , surface area demand per molecule, A min , efficiency in surface tension reduction, p C 20 , the effectiveness of surface tension reduction, γ min , critical micelle concentration, cmc, and standard free energy of micellization, Δ G mic 0 and Δ G ads 0 , were obtained by means of surface tension measurements. The antielectrostatic properties were investigated by measuring the surface resistance, the half-charge decay time, and the maximum voltage induced on polyethylene films and propylene unwoven fabrics. Critical micellar concentrations (cmc) of investigated salts were much lower than those of the monomeric salt DTAC. The results obtained in this work were compared to analogous bis-quaternary ammonium dichlorides and well-known gemini cationic surfactants. It was found that the type of counterion had an impact on the values of the micelle ionization degree and the hydrodynamic diameters. Larger aggregates were found for bis-quaternary ammonium dibromides, which had smaller values of the ionization micelle degree than bis-quaternary ammonium dichlorides. Moreover, the antielectrostatic effect strongly depended on the kind of counterion. All investigated salts had very good antistatic properties.

Fragmentation patterns of novel dispirocyclopiperazinium dibromides with strong analgesic activity under electrospray ionization tandem mass spectrometry conditions.

The fragmentation patterns of a series of dispirocyclopiperazinium dibromides with strong analgesic activity are analyzed by positive ion electrospray ionization mass spectrometry in conjunction with tandem mass spectrometry (ESI-MS(n)). Instead of the parent molecular ions, the fragment ions [M-Br](+) are detected as characteristic double peaks and usually the base peaks. Meanwhile, the fragment ions [M-2Br](2+) are unique for this series of diquaternary ammonium dibromides and show high intensity. Besides the common fragmentation patterns around the carbonyl group, elimination of hydrogen bromide from [M--Br](+) ions is another important pathway. Following the elimination, an interesting rearrangement takes place in the unsaturated spirocyclopiperazine and transforms it into a dihydropyrrole structure, whose fragmentations are similar to its precursor ion in the succeeding steps.

Novel polymerizable mono- and divalent quaternary ammonium cationic surfactants: 2. Surface active properties and use in emulsion polymerization

Eight polymerizable monoquaternary ammonium bromide cationic surfactants, and five non-polymerizable analogues have been prepared along with six structurally related polymerizable diquaternary ammonium dibromide cationic surfactants and five non-polymerizable analogues of these. The surface activity properties of all the surfactants have been characterized using surface tension and electrical conductivity measurements. The derived data (critical micelle concentrations, area per molecule at the air/water interface, etc.) have been compared and discussed in terms of the molecular structure of the surfactants and the valency of the salts. All of the surfactants have been employed (singly) as the emulsifier in small scale emulsion polymerizations of styrene and methylmethacrylate. In all cases well defined stable polymer latexes were obtained. The stability of these has also been further probed by the addition of various mono-, di- and trivalent electrolytes. Each emulsion has also been subjected to a freeze-thaw cycle. The stability results are discussed in terms of the molecular structure of the surfactants and, in particular, the efficiency of polymerizable vs non-polymerizable species have been compared and, likewise, the effectiveness of dicationic species vs monocationic ones.

Novel polymerizable mono- and divalent quaternary ammonium cationic surfactants: I. Synthesis, structural characterization and homopolymerization

Abstract Eight novel polymerizable monovalent quaternary ammonium bromide surfactants and five model non-polymerizable structurally analogous surfactants have been synthesized. Methylation of free amine groups in six of the polymerizable monoquaternary ammonium species has yielded the corresponding divalent diquaternary ammonium dibromide surfactants, and likewise, five non-polymerizable divalent diquaternary ammonium dibromides have been prepared. All the new molecules have been characterized structurally by elemental microanalysis and 1 H nuclear magnetic resonance spectroscopy. The solubility, melting behaviour and homopolymerizability of the monomers have been evaluated and the results discussed with those of structurally related systems already in the literature.

ChemInform Abstract: BISQUATERNARY AMMONIUM SALT. PART 3. PREPARATION AND ANTIMICROBIAL ACTIVITY OF SOME NEW BISQUATERNARY AMMONIUM SALTS

A series of new bisquaternary ammonium dibromides of the type N,N'-bis(decyldimethyl)-alpha, omega-alkanediammonium dibromides and N,N'-bis(4-aryloxybutyldimethyl)-1,6-hexane diammonium dibromides has been prepared and screened for antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans. In the first group of compounds the connecting alkyl chain had 2 to 6, 8, 10 and 12 carbon atoms, in the second one in the 4-aryloxybutyl linkage the aryl was phenyl, p-methylphenyl, p-tert-butylphenyl-p-chlorophenyl-1-naphthyl and 2-naphthyl. The effect on the antimicrobial activity of the length of the hydrocarbon chain linking the two nitrogen atoms and the effect of replacing the long alkyl chain with substituted or unsubstituted 4-aryloxybutyl groups was studied.

Pentamethonium as an adjuvant to atropine in the therapy of paraoxon poisoning.

Paton and Perry1 demonstrated a competitive antagonism between acetyl oholine and penta-methyline bis-trimethyl ammonium dibromide (pentamethonium), at ganglia, and this suggested that pentamethonium might be of value in treating poisoning with antioholinesterases such as diethyl 4-nitrophenyl phosphate (paraoxon). Douglas and Matthews2 used pentamethonium in cats poisoned with tetraethyl pyrophosphate (TEPP), and showed that it improved the contractile power of the diaphragm. We now have evidence that pentamethonium bromide significantly increases survival of fully atropinized animals—mice, rabbits and cats— poisoned with paraoxon.