Dihexadecyl phosphate

The ITIES with an adsorbed monolayer of surfactant has been studied as a model system of the interface between microphases in a bicontinuous microemulsion [39]. This latter system has important applications in electrochemical synthesis and catalysis [88-92]. Quantitative measurements of the kinetics of electrochemical processes in microemulsions are difficult to perform directly, due to uncertainties in the area over which the organic and aqueous reactants contact. The SECM feedback mode allowed the rate of catalytic reduction of tra 5-l,2-dibromocyclohexane in benzonitrile by the Co(I) form of vitamin B12, generated electrochemically in an aqueous phase to be measured as a function of interfacial potential drop and adsorbed surfactants [39]. It was found that the reaction at the ITIES could not be interpreted as a simple second-order process. In the absence of surfactant at the ITIES the overall rate of the interfacial reaction was virtually independent of the potential drop across the interface and a similar rate constant was obtained when a cationic surfactant (didodecyldimethylammonium bromide) was adsorbed at the ITIES. In contrast a threefold decrease in the rate constant was observed when an anionic surfactant (dihexadecyl phosphate) was used. 

Adsorption Cycle Fig. 2.23 QCM responses on LbL assemblies (a) LbL assembly between dihexadecyl phosphate vesicle and PDDA (b) LbL assembly between anionic cerasome (larger step) and PDDA (smaller step) (c) LbL assembly between anionic cerasome (larger step) and cationic... 

AA Agbodjan, H Bui, MG Khaledi. Study of solute partitioning in biomem-brane-mimetic pseudophases by electrokinetic chromatography dihexadecyl phosphate small unilamellar vesicles. Langmuir 17 2893-2899 (2001). 

Figure 7.7 Schematic representation of the temperature-induced change in the MSP composed of terpy end-capped ditopic monomers and Fe dihexadecyl phosphate. The temperature-induced transition resuits in a distortion of the metal ion coordination geometry, which occurs because of the melting of the amphiphilic counterions, giving rise to a reversible transition from a diamagnetic low spin state to a paramagnetic high spin state (Bodenthin et al. 2005).

Fig. 93. Transmission electron micrograph of electrochemically generated silver particles under dihexadecyl phosphate monolayers kept at a surface area of 45 A2/molecule. The monolayer was floated on a 1.0 x 10-2 M AgN03 solution...

Single-bilayer dihexadecyl phosphate (DHP) vesicles Magnetite particles prepared in situ in vesicles, from Fe2+/Fe3+ and OH Particles were characterized by magnetic birefringence 790... 

Dihexadecyl phosphate [2197-63-9] M 546.9, m 75". Crystd from MeOH [Lukac JACS 106 4387 1984. ... 

Roks, M. F. M. Nolte, R. J. M., (1992) Biomimetic macromolecular chemistry design and synthesis of an artificial ion channel based on a polymer containing cofacially stacked crown ether rings. Incorporation in dihexadecyl phosphate vesicles and study of cobalt ion transport Macromolecules 25, 5398-5407. 

Average value obtained using 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridinio)phenoxide, 1-hexadecyl-4-[(oxocyclohexadienylidene)ethylidene]-l,4-dihydropyridine, l-hexadecyl-5-hydroxyquinoline and l-hexadecyl-6-hydroxyquinoline, average deviation <9 % calculated from [47d]. Abbreviations SDS = sodium dodecyl sulfate DBS = dodecyl benzenesulfonate CTAC = hexadecyltri-methylammonium chloride CTAB = hexadecyltrimethylammonium bromide DTAC = dodecyl-trimethylammonium chloride DTAB = dodecyltrimethylammonium bromide DHP = dihexadecyl phosphate DDDAB = didodecyldimethylammonium bromide DMPC = dimyristoylphosphati-dylcholine DPPC = dipalmitoylphosphatidylcholine POPC = l-palmitoyl-2-oleoylphosphati-dylcholine PCA = phosphatidic acid. 

Sphingomyelin, DCDG , dihexadecyl phosphate, dialkyl dimethyl ammonium salts... 

Polymerized lipids do not occur in natural cell membranes. Nature tends to support fragile membrane structures with polymeric skeletons, i.e. protein cytoskeletons, polysaccharide cell walls etc. Analogous synthetic polymeric nets are simply constructed from polymerizable counterions. Negatively charged dihexadecyl phosphate vesicles can be neutralized with choline methacrylate polymerization of the latter produces a polycationic vesicle coat which is not inserted into the membrane (Figure 4.30). A cytoskeleton at the... 

H. J. D. McManus and L. Kevan, Electron spin resonance, electron spin echo, and electron nuclear double resonance investigations ofthe photoreduction yield of a series of alkylmethylviologens in dihexadecyl phosphate vesicles Effect of added cholesterol, J. Phys. Chem 95, 10172-10178... 

More recently, Fendler and coworkers have used surfactant vesicles as hosts for colloidal semiconductor particles [83]. For instance, dihexadecyl phosphate (DHP) and 2Ci8Br vesicles incorporating CdS, ZnS and mixed CdS-ZnS particles have been obtained and used for the realization of nanoscale photoelectric devices (see later). It is important to point out, however, that the presence of the closed vesicle does not appear, at least with these systems, to be of critical importance for the control of the size of the particles, as similar phenomena also occurs in Langmuir-Blodgett films [84], suggesting that a crucial role in nucleation is played mainly by the surface. 

Vesicles of dihexadecyl phosphate speed electron transfer from photoactivated Ru(bpy)3" to methyl viologen, and it was possible to distinguish between reaction on the inner and outer surface of the vesicle. However although the forward step is very rapid so is the back reaction. A modification of this system in which Ru(bpy) is on the inner surface of a dihexadecyl phosphate vesicle will generate hydrogen, provided that the vesicle contains PtO which catalyzes the decomposition of water [168],... 

The hydrogen-generation photo activity of vesicle-stabilized and catalyst-coated colloidal CdS was first demonstrated for dihexadecyl phosphate (DHP) vesicles with Rh as the catalyst and thiophenol (PhSH) as a sacrificial electron donor [see Fig. 5(a)] [4]. Although CdS could be located selectively at the inner or outer surfaces of the vesicles, the symmetrically organized systems were found to be the easiest to prepare most repro-ducibly. No significant effect of the CdS location on the photochemical activity for the H2 generation was observed. 

Fig. 4.13 Schematic representation of the optical set-up (a) and hemispherical cell (b) forTIR Raman microspectroscopy. TIR Raman spectra of Mn(TMPyP) at the toluene/water interface with two different concentrations of dihexadecyl phosphate (DHP) in the organic phase are shown in (c). The band at 394 cm" corresponds to the symmetric breathing mode of the porphyrin ring. The spectral features were normalized by the toluene band at 520 cm . The spectra were collected with s-polarization. Reprintedwith permission from Ref [33]. Copyright (2003)...

As an extension of Yonezawa s work, Hurst and coworkers reported photo-controlled permeation through a dihexadecyl phosphate (DHP) bilayer containing azobenzene amphiphilic molecules (Lei and Hurst, 1999). The concept... 

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