Formation Of Molecular Aggregates Research Articles

Cyclomaltooligosaccharide-assisted spectroscopic discrimination of phthalimido-derived amino acids through the formation of molecular aggregates

Spectroscopic evidence was used to demonstrate the formation of molecular associates in an aqueous solution of phthalimido tryptophan. These molecular associates are loosely formed through π–π aromatic stacking, properties that are not sufficient to cause NMR spectroscopic enantiomeric discrimination. A cyclomaltooligosaccharide with a larger cavity, such as cyclomaltooctaose (γ-cyclodextrin), is capable of forming a ternary complex with these molecular associates and enhances π–π aromatic stacking interactions, resulting in NMR enantiomeric discrimination. Electrospray-ionization mass spectroscopy (ESIMS) and NOESY two-dimensional NMR spectroscopic methods were used to study these complexes. Association constants and thermodynamic data for these cyclomaltooligosaccharide complexes were also estimated.

Hydrohysteretic Phenomena of “Extremely Diluted Solutions” Induced by Mechanical Treatments: A Calorimetric and Conductometric Study at 25 ∘C

The purpose of this study was to obtain information about the influence of successive dilutions and succussions (violent shaking) on the structure of water. “Extremely diluted solutions” (EDS) are solutions obtained through the iteration of two processes: 1:100 dilution and succussion. Those two processes are repeated until extreme dilutions are reached, so that the chemical composition of the end solution is identical to that of the solvent. We measured the heats of mixing and the electrical conductivity of basic solutions of such EDS, and compared these results with the analogous heats of mixing and electrical conductivity of the untreated solvent. The measurements were carried out as a function of the age of the samples. We found some relevant exothermic excess heat of mixing, and higher electrical conductivity than those of the untreated solvent, also in function of time. The measurements show a good linear correlation between the two independent physico-chemical quantities, implying a single cause for this behavior of the extremely diluted solutions. The slopes of the linear correlation depend on the age of the EDS. Such a phenomenon could result from a variation of the shape of molecular aggregates that characterize the two different supramolecular structures of the water of different ages. This behavior could provide important support for understanding the nature of the phenomena described herein. A really intriguing phenomenon is the evolution of some physico-chemical properties with time. This hints at a “trigger” effect on the formation of molecular aggregates that result from the succussion procedure. We show that successive dilutions and succussions can permanently alter the physico-chemical properties of the aqueous solvent, the extent of which depends on the age of the samples.

Analytical Techniques for Nucleation Studies in Lipids: Advantages and Disadvantages

ABSTRACT: Crystallization is generally considered a 2‐step process. The 1st step, nucleation, involves the formation of molecular aggregates with a critical size great enough to become stable. During the 2nd step, nuclei grow and develop into crystals. Distinguishing between nucleation and growth constitutes a major challenge in lipid crystallization studies. Thus, it is of great importance to discuss the information obtained from the different techniques that are usually used to study nucleation behavior such as nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), rheological techniques, light‐scattering techniques such as turbidimetry and scanning diffusive light scattering (SDLS), polarized light microscopy (PLM), and laser polarized optical sets such as laser polarizedlight turbidimetry (LPLT). Techniques to describe the nucleation process must be very sensitive to disregard growth. When crystallization is followed by methods such as DSC, NMR, and rheological measurements, at times, small amounts of crystals are present in the melt before any solids are detected. Clearly, at this stage, well beyond the induction time for nucleation (τ), these methods are measuring crystal growth. Techniques of low sensitivity for solid fat contents lower than 0.1% must not be used to evaluate nucleation effects. Sensitive turbidimeters with detectors that saturate below 0.3% solid fat content give good results as do scanning diffusive light‐scattering equipment. Although the PLM technique is sensitive enough for these kinds of studies, an understanding of important basic concepts is essential. Laser optical sets are the most appropriated methods to study nucleation in fats systems.

Theoretical Modeling of TPPS<sub>4</sub> J-Aggregates

The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggregate formation and their geometrical structure are investigated by methods of molecular mechanics and quantum chemistry. J- type aggregates are formed of zwitterionic forms of TPPS4via interaction of their positively charged porphyrin rings and negatively charged SO3- groups. According to ab initio and PM3 calculations it was found that TPPS4zwitterion has asymmetrical structure (parts of porphyrin ring are asymmetrically bent out of plane), although the porphyrin ring of TPPS4molecule in neutral aqueous solution (at pH 7) is flat and the planes of phenyl rings are nearly perpendicular to the porphyrin plane. We propose that asymmetrical porphyrin rings are able to form bent threads. The thread is bent approx. 5° for each monomer, so approximately 60 monomers should form the loop (diameter ~20 nm).

Vesicles in fatty acid salt–fatty acid stabilized o/w emulsion—emulsion structure and rheology

Texture and rheology properties of fatty acid salt-fatty acid mixture stabilized oil–water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric acid. When these oil and water phases are brought in contact, a portion of lauric acid transforms into sodium laurate in situ via acid–base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate–lauric acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4 M, whilst in the presence of 0.4–0.8 M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8 M NaOH, their size increased with NaOH concentration from 0.8 to 1 M. These observations suggested that sodium laurate–lauric acid concentration ratio that corresponds to 0.6–0.8 M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ ̇ , in the absence of NaOH, the η of the oil solubilized lauric acid was found to be much lower than the η of corresponding sodium laurate–lauric acid stabilized o/w emulsion. Though η( γ ̇ ) profiles of sodium laurate–lauric acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate–lauric acid concentrations (concentration of NaOH in this case). What more is that at any given γ ̇ , the η was observed to be maximum at sodium laurate–lauric acid concentration ratio that corresponded to 0.8 M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8 M NaOH, higher values of σ Y was observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty acid salt vesicles, that under the given set of conditions sodium laurate–lauric acid concentration corresponding to 0.8 M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate–lauric acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate–lauric acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate–lauric acid concentration that corresponded to 0.6–0.8 M NaOH. And not only, in the presence of 0.8 M NaOH, while G″ response of these samples was dominant over G′ response at low ϖ domain, the dynamic moduli crossed-over at around 2 Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate–laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8 M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate–lauric acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8 M. The fact that these emulsion showed smallest δ in the presence of 0.8 M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems.

Thermodynamic Characteristics of a Spherical Molecular Surfactant Aggregate in a Quasi-Droplet Model

The model of spherical molecular aggregate of nonionic surfactant is proposed. This model allows for the maximal (in accordance with packing rules) penetration of water molecules into an aggregate and is an alternative to the droplet model of molecular aggregate. Necessary conditions for the applicability of a model named quasi-droplet model are formulated. Based on this model, the dependence of the work of molecular aggregate formation on the aggregation number and surfactant monomer concentration in solution that plays the key role for the theory of micellization is studied. The equation is derived for the coordinates of maximum and minimum of aggregate formation work on the aggregation number axis arising with an increase in the concentration of micellar solution. Model calculations of the thermodynamic characteristics of the kinetics of micellization are performed. The approximation of the work of molecular aggregate formation allowing for the analytical study is constructed.

Slow dynamics of n -butoxyethanol-water mixture by neutron spin echo technique

We have measured the dynamics of n-buoxyethanol–water mixture of alcohol mole fraction 0.09 by using a neutron spin echo (NSE) technique at 8, 25, and 37 °C, below a lower critical solution temperature (LCST) of 49 °C where n-butoxyethanol–water mixtures undergo phase separation. The diffusion coefficients obtained from intermediate correlation function were determined as 3.3×10-11, 6.6×10-11, and 8.5×10-11 m2 s-1 at 8, 25, and 37 °C, respectively. These values are about 102 times smaller than those of pure water and alcohol, probably reflecting the dynamics of molecular aggregates formed in the mixture, which has been confirmed by previous small-angle neutron scattering. On the other hand, the mutual-diffusion coefficient obtained from dynamic light scattering on the same system decreases with increasing temperature, due probably to an increase in the correlation length of molecular aggregation. The time scale observed by NSE corresponds to that of formation of molecular aggregates, much shorter than that by light scattering. Therefore, it is concluded that the molecular aggregation in the mixture is transitory with a nanosecond lifetime.

2‐Pyridyldimethylsilyl Group as a Removable Hydrophilic Group in Aqueous Organic Reactions: Formation of Molecular Aggregates and Dramatic Rate Enhancement in Diels—Alder Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Visco-elastic properties of reentrant nematic liquid crystalline mixtures

The visco-elastic properties for binary mixtures of 4-n -hexyloxy-4′-cyanobiphenyl (6OCB) and 4-n-octyloxy-4′-cyanobiphenyl (8OCB) are investigated in detail by a light scattering technique. The mixtures exhibit a reentrant nematic (RN) phase between the smectic A (SmA) and crystal phases in the range 22.0–29.5 wt % of 6OCB. The viscosity and the elastic constant increase with cooling in both the nematic and reentrant nematic phases. It is also found that the mixtures exhibit anomalously large values of viscosity and elastic constant near the phase transition, i.e. a pretransitional phenomenon can be observed. The activation energy for viscosity is smaller in the RN phase than in the ordinary nematic phase appearing at higher temperatures, while the normalized elastic constant (defined as the ratio of the elastic constant to the square of the dielectric anisotropy) is larger. Moreover, the visco-elastic behaviour depends on the specific time during which the sample has been kept in the SmA phase. These results confirm that the SmA phase has a strong influence on the formation of molecular aggregates, which plays an important role in the reentrant phenomenon of these systems.

Molecular dynamics of poly(ethylene glycol)s studied by optical Kerr effect and Brillouin spectroscopy

The optical Kerr effect and Brillouin scattering study of a series of poly(ethylene glycol)s (PEGs) in the function of temperature and molecular weight (MW) have been performed. The obtained results enabled us to determine some macroscopic and microscopic parameters (such as molecular Kerr constant, hypersonic velocity, adiabatic compressibility), of the compounds investigated. The values of these parameters were found to depend strongly on both temperature and PEG's MW. Analysis of the results indicates on the presence of molecular interactions leading to formation of molecular aggregates. The increase in the MW leads to folding of PEG chains and to formation of statistical coils.

2-Pyridyldimethylsilyl Group as a Removable Hydrophilic Group in Aqueous Organic Reactions: Formation of Molecular Aggregates and Dramatic Rate Enhancement in Diels-Alder Reactions

A novel methodology for aqueous organic reactions utilizing a 2-pyridyldimethylsilyl (2-PyMe2Si) group as a removable hydrophilic group has been developed. It was found that 1,3-dienes bearing the 2-PyMe2Si group form molecular aggregates in water when 1.0 equivalent of HCl was added, as evidenced by dynamic light-scattering experiments. The Diels–Alder reaction of 2-PyMe2Si-substituted 1,3-dienes with various dienophiles took place in water at room temperature. The Diels–Alder reaction in organic solvents (Et2O/toluene) under the same reaction temperature and time gave the cycloadduct in much lower yield, indicating the dramatic rate acceleration in water. The removal of the 2-PyMe2Si group was accomplished by desilylation, oxidation, and electrophilic substitution.

Molecular aggregate formation and microphase segregation effects on the photoelectrical and photovoltaic properties of polyimide-perylenediimide composite films

The strong increase of electrophotographic sensitivity, charge carrier photogeneration quantum yield and improved photovoltaic characteristics (sandwich cells with ITO, Al electrodes) are found for films of photoconductive soluble polyimides based on doubled triphenylamine heavily doped by the soluble perylenediimides (with content up to 50-60% wt). It is shown that the effect is due to perylenediimide aggregates of some tens nanometers size which are formed during the film casting at high solvent evaporation rate. The further increase of photoelectric and photovoltaic parameters is achieved by using the films of polymer blends of polyimides with polyetherimides (Ultem-1000 type) also doped with soluble perylenediimides. In this case the effect is due to microphase segregation in doped polymer blend films caused by the partial incompatibility of polymers, that results in the formation of microregions with n- and p-types of photoconductivity contacting with each other and possible appearance of p-n bulk microheterojunctions.

Some Features of the Supramolecular Structures in Petroleum Media

The structure of the disperse phase of crude oils and liquid petroleum products is determined by the characteristics of formation of molecular aggregates of asphaltenes. The characteristics of these processes in dilute solutions of crude oil in toluene were investigated by measuring the proton spin‐spin relaxation time as a function of the concentration of asphaltenes. These measurements allowed explaining the conditions of formation of dimers and more complex aggregates of asphaltene molecules. The data obtained by the NMR‐relaxation method are confirmed by the results of measurements of the viscosity and optical absorption of the petroleum solutions investigated.

Optically induced birefringence in a series of analogous diols

Optically induced birefringence has been analysed in a series of analogous diols containing heteroatoms, such as O, N or S. The presence of a heteroatom in a diol molecule can change the arrangement of hydrogen bonding and, consequently, the arrangement of molecules. This hypothesis was confirmed by the results of our study. The measurements were performed at temperatures from 280 to 350 K. The values of the absolute and molar Kerr constants were calculated. The character and magnitude of the temperature changes of molar Kerr constant depend on the type of the heteroatom. According to the theory of the optical Kerr effect such a temperature behaviour indicates the presence of molecular interactions leading to formation of molecular aggregates. The sign of the calculated values of angular correlation factor indicates the predominant parallel arrangement of molecules in such molecular ensembles.

Thermodynamic Characteristics of Micellization in the Droplet Model of Surfactant Spherical Molecular Aggregate

The dependence of the work of the molecular aggregate formation on the aggregation number and surfactant monomer concentration in solution that has the key role for the theory of micellization was studied on the basis of a simple realistic droplet model of spherical aggregate composed of surfactant molecules (the o/w micelle type). Analytical formulas were derived for the coordinates of maximum and minimum of aggregate formation work on the aggregation number axis arising with an increase in the concentration of micellar solution. Model calculations of the thermodynamic characteristics of the kinetics of micellization were performed for premicellar and micellar regions of aggregate sizes within a wide range of solution concentration including the critical micellization concentration.

Effects of addition of diacylglycerols on fat crystallization in oil-in-water emulsion

The effects of addition of diacylglycerols (DAGs) on the crystallization behavior of n-hexadecane dispersed in oil-in-water emulsion (oil 20% and water 80%, v/v) were studied by differential scanning calorimetry (DSC) and ultrasonic velocity measurement. In an attempt to modify the crystallization rate of n-hexadecane, five DAGs having the fatty acid moieties of behenic (DAB), stearic (DAS), palmitic (DAP), lauric (DAL) and oleic acid (DAO) were added to n-hexadecane, which was mixed with water and Tween 20 for emulsification. The DSC study showed that the addition of DAB, DAS or DAP (1.0 wt-% with respect to n-hexadecane) increased the crystallization temperature (Tc) of a n-hexadecane/water emulsion from 3 °C (without DAG) to 8 °C, whereas the addition of DAL and DAO showed no effect. The ultrasonic velocity measurement also revealed that the addition of DAGs resulted in increasing the Tc of n-hexadecane in O/W emulsion. These effects were discussed by taking into account the formation of molecular aggregates at the interface due to the addition of DAGs, which act as a template for crystallization of n-hexadecane. The template-assisted crystallization depends on the structure of the fatty acid chains present in the DAG: the longer the fatty acid moiety of DAG, the more is the crystallization of n-hexadecane in O/W emulsion accelerated. La cristallisation de la phase huileuse dans une emulsion huile dans l'eau est une etape importante pour la coagulation de l'emulsion refrigeree, comme par exemple la desemulsification de cremes fouettees ou la congelation de glaces. Les effets de l'addition de diacylglycerols sur la cristallisation de n-hexadecane disperse dans une emulsion huile dans l'eau (20/80% vol.) sont etudies par analyse calorimetrique differentielle et mesure de vitesse de propagation d'ultrasons. On observe que plus la chaine d'acide gras du diacylglycerol est longue, plus la cristallisation du n-hexadecane est rapide.

Molecular characteristics of astaxanthin and β-carotene in the phospholipid monolayer and their distributions in the phospholipid bilayer

The molecular characteristics of the monolayers of astaxanthin with polar group on the β-ionone ring in the molecule and β-carotene without polar group and their interactions in mixed carotenoid–phospholipid monolayers and the effects of carotenoids on the phase behavior of the phospholipid bilayers were examined by the monolayer technique and differential scanning calorimetry (DSC). We found from the monolayer study that β-carotene had an amphiphilic nature. The molecular assembly of astaxanthin in the monolayer at the hydrophobic/hydrophilic interface was more stable than that of β-carotene. Dimyristoylphosphatidylcholine (DMPC) in the monolayer was miscible with astaxanthin in the range of 0–0.4 mol fractions of astaxanthin, but not fully miscible with β-carotene even at low concentrations below 0.1 mol fraction of β-carotene. Surface potential and compression/expansion cycles of β-carotene monolayer indicated the formation of molecular aggregates by itself. DSC study showed that when small amount of astaxanthin was added, the transition temperature of dipalmitoylphosphatidylcholine (DPPC) was markedly shifted to lower temperatures and that the transition peak was asymmetrically broadened, indicative of a significant depression in cooperativity of the gel to liquid–crystalline transition. The asymmetric DSC endothermic bands of DPPC incorporating small amounts of astaxanthin were well fit by deconvolution into two to three domains containing different concentrations of astaxanthin. On the contrary, the incorporation of β-carotene resulted in a small depression of the main transition temperature with a slight broadening of the transition peak, suggesting a small miscibility of β-carotene with the phospholipid bilayer or a formation of aggregates of β-carotene in the membranes. These results suggest that there would be a high localized concentration in the phase separated membrane for astaxanthin or β-carotene to function effectively as scavenger.

Photodynamic and light independent action of 8 to 2 carboxylic free porphyrins on some haem-enzymes

Backgrounds and aims: skin lesions in cutaneous porphyrias appear to be determined by the structural properties of the porphyrins accumulated. To better understand the relationship between the structure and physicochemical properties of porphyrins and their specific effect on protein configuration, the action of a whole range of 8 to 2 carboxylic porphyrins has been studied. Materials and methods: δ-aminolevulinic acid dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D) partially purified from bovine liver, were exposed to 10 μM uroporphyrin (Uro), phyriaporphyrin (Phyria), hexaporphyrin (Hexa), pentaporphyrin (Penta), coproporphyrin (Copro) or protoporphyrin (Proto), either in the dark or under UV light. All experiments were performed in the enzyme solutions after removing the porphyrins. Results: under both illuminating conditions, all porphyrins inactivated the enzymes (20–70% under control values), indicating photodynamic action mediated by oxidative reactions and conformational changes due to direct binding of porphyrins to the protein. Total thiol content in ALA-D was not significantly changed by most porphyrins under UV light, while all porphyrins increase total sulfhydryl groups in PBG-D (23–52% over the control values) indicating changes in the redox status of SH residues. Free amino groups were reduced by all porphyrins in ALA-D (23–56% under controls), instead they were enhanced in PBG-D (23–51% over controls), suggesting protein fragmentation. The formation of molecular aggregates would be the consequence of cross-links between oxidation products, while fragmentation can be attributed to either rupture of disulphur bridges and/or enhancement of free amino groups on the protein enzyme. Conclusions: the effect of the porphyrins on enzyme activity, total SH groups and free amino groups content, was different for ALA-D and PBG-D, even under the same illuminating conditions. On the basis of these results, no correlation between enzyme alterations and the physico-chemical properties of porphyrins could be established.

Time-resolved fluorescence study of isolated and aggregated permethyldecasilanes

Time-resolved fluorescence spectra were measured for two kinds of permethyldecasilanes, Me(SiMe 2) 10Me and Ph(SiMe 2) 10Ph, in fluid solutions at room temperature, in frozen solutions and in vacuum-deposited thin films. Time-dependent red-shifts were clearly observed in fluid solutions but not in dilute frozen solutions, which was discussed in terms of conformational relaxation in the excited states. In concentrated frozen solutions, significantly red-shifted, long-lived fluorescence bands appeared, indicating the formation of molecular aggregates. Temperature dependence of fluorescence lifetimes as well as peak wavelengths for films were discussed with respect to exciton migration followed by trapping in localized sites.

Experimental and theoretical studies of the system n-decyl-β-D-maltopyranoside+water

A class of non-ionic surfactants that is useful for formulating microemulsions, and that is becoming increasingly important for industrial purposes, is the series of alkyl polyglucosides (C X G Y ). These surfactants have x carbons in the hydrophobic alkyl chain and y glucose units in the hydrophilic headgroup, with commercial products typically containing noninteger values of both x and y. Commercial C X G Y blends contain many other compounds besides alkyl-β-D-glucopyranosides, including n-alkyl-α-glucopyranosides, n-alkyl-β-D-maltopyranosides, and other isomers and materials that contain a larger number of glucose units. In this paper, we investigate the physical properties of the system n-decyl-β-D-maltopyranoside (C 10G 2)+water over a wide concentration range, using various experimental techniques (surface tension measurement, rotation rheometer, DSC, polarising microscopy) and a molecular aggregation formation model. The theory is based on calculating the size distribution of the aggregates, which in turn depends on the free energy of forming an aggregate. This free energy is modelled as the sum of several free-energy contributions and an ideal entropy of mixing. For each free-energy contribution, we have highlighted schematically only the relevant characteristics of the surfactant tails or the surfactant heads. The theoretical results are compared to those found in the literature for alkyl-β-D-glucopyranosides (C X G 1) aqueous solutions. In surfactant solutions, rheological behaviour is intimately linked to internal microstructure and micellar architecture. The diluted surfactant system demonstrates Newtonian behaviour and complex non-Newtonian behaviour within the high shear stress regime. In the middle concentration range, the surfactant solutions exhibit an unexpected rheological behaviour, where the viscosities are not dependent on temperature. At high surfactant concentration phase transition, especially liquid-crystalline to isotropic solution, could be followed using rheological experiments. In performing DSC experiments, emphasis is put on the melting behaviour for the dry surfactant and C 10G 2+water systems at high surfactant concentrations. The melting behaviour can be characterised by transitions from a crystalline phase to a liquid crystalline phase and finally to an isotropic solution. The identification of the liquid-crystalline phase was carried out from textural observation, using polarising microscopy. The lyotropic behaviour follows the classical pattern established for the surfactants. Applying polarising microscopy, textures of the hexagonal and lamellar phases could be observed for the system C 10G 2+water.