Temperature-induced intermicellization and contraction in aqueous mixtures of sodium dodecyl sulfate and an amphiphilic diblock copolymer

Aqueous solutions of a thermoresponsive amphiphilic diblock copolymer, containing poly(N-isopropylacrylamide), in the presence of the anionic sodium dodecyl sulfate (SDS) surfactant can undergo a temperature-induced transition from loose intermicellar clusters to collapsed core–shell nanostructures. The polymer–surfactant mixtures have been characterized with the aid of turbidity, small-angle neutron scattering (SANS), intensity light scattering (ILS), dynamic light scattering (DLS), shear viscosity, and rheo-small angle light scattering (rheo-SALS). In the absence of SDS, compressed intermicellar structures are formed at intermediate temperatures, and at higher temperatures further aggregation is detected. The SANS results disclose a structure peak in the scattered intensity profile at the highest measured temperature. This peak is ascribed to the formation of ordered structures (crystallites). In the presence of a low amount of SDS, a strong collapse of the intermicellar clusters is observed at moderate temperatures, and only a slight renewed interpolymer association is found at higher temperatures because of repulsive electrostatic interactions. Finally, at moderate surfactant concentrations, temperature-induced loose intermicellar clusters are detected but no shrinking was registered in the considered temperature range. At a high level of SDS addition, large polymer–surfactant complexes appear at low temperatures, and these species are compressed at elevated temperatures. The rheo-SALS results show that the transition structures are rather fragile under the influence of shear flow.     

Estimation of Critical Temperature of Thermal Explosion for Nitrosubstituted Azetidines Using Non-isothermal DSC

Based on reasonable hypothesis, two general expressions and their six derived formulae for estimating the critical temperature (T_b) of thermal explosion for energetic materials (EM) were derived from the Semenov's thermal explosion theory and eight non‐isothermal kinetic equations. We can easily obtain the values of the initial temperature (T_0i) at which DSC curve deviates from the baseline of the non‐isothermal DSC curve of EM, the onset temperature (T_ei), the exothermic decomposition reaction kinetic parameters and the values of T₀₀ and T_e0 from the equation T_{0i or ei}=T_{00 or e0}+a₁β_i+a₂β_i²+···+a_L?2β_i^L?2, i=1, 2, ;···, L and then calculate the values of T_b by the six derived formulae. The T_b values for seven nitrosubstituted azetidines, 3,3‐dinitroazetidinium nitrate ( 1 ), 3,3‐dinitroazetidinium picrate ( 2 ), 3,3‐dinitroazetidinium‐3‐nitro‐1,2,4‐triazol‐5‐onate ( 3 ), 1,3‐bis(3′,3′‐dinitroazetidine group)‐2,2‐dinitropropane ( 4 ), 1‐(2′,2′,2′‐trinitroethyl)‐3,3‐dinitroazetidine ( 5 ), 3,3‐dinitroazetidinium perchlorate ( 6 ) and 1‐(3′,3′‐dinitroazetidineyl)‐2,2‐dinitropropane ( 7 ), obtained with the six derived formulae are agreeable to each other, whose differences are within 1.5%. The results indicate that the heat‐resistance stability of the seven nitrosubstituted azetidines decreases in the order 6 > 7 > 5 > 4 > 3 > 2 > 1 .     

Polyvinylpyrrolidone as an Efficient Stabilizer for Silver Nanoparticles

Aggregation of nanoparticles is a serious problem in their applications. In this article, stability of biosynthesized silver nanoparticles (AgNPs) was initially studied with different concentrations of sodium chloride (NaCl). Surfactant screening showed that polyvinylpyrrolidone (PVP) was an ideal stabilizer, which not only was effective at a low concentration (0.1%, V/V), but also could protect silver colloids from aggregation for a long period at 1 mol·L^?1 NaCl, and 6 h even at 3 mol·L^?1 NaCl. However, some other surfactants, such as sodium dodecyl (SDS), Triton X‐100, Tween‐20, and Tween‐80, could not prevent AgNPs from aggregation even at a high concentration up to 0.5% (V/V). This AgNPs stabilizer is simple and convenient for a variety of applications compared with others.     

基于一个四羧酸配体构筑的具有(4,8)-连接的镧系金属-有机框架材料及对小分子的检测试验

以3,3'',5,5''-四-（羧基苯基）联苯为配体（H₄L）,与镧系金属Ln（Ⅲ）盐反应,自组装形成了5个具有三维孔洞结构的镧系金属-有机框架材料：{[Ln₃L₂(H₂O)₇]·(OH)·10DMA}_n(Ln=Gd (1a); Ln=Ho(2a), {[Ln₃L₂(H₂O)₃]·(OH)·mDMA}_n (Ln=Er,m=10(1b); Ln=Yb, m=9(2b); Ln=Lu, m=10(3b))。单晶X射线衍射分析表明,这些MOFs属于2种系列的类质同晶化合物,分别属于正交晶系Ccca空间群和单斜晶系C2/c空间群。有机小分子溶剂交换荧光研究发现,2b对小分子二氯甲烷和甲苯荧光有增强效应,表现出良好的荧光探测功能。     

PVC matrix membrane sensor for potentiometric determination of dodecylsulfate

The construction and performance characteristics of a new potentiometric PVC membrane sensor for the determination of sodium dodecyl sulfate (SDS) are described. The sensor was based on the use of an N-cetyl-N,N,N trimethyl ammonium (CTA) dodecyl sulfate (DS) ion pair as ion exchange sites in PVC matrix in the presence of o-nitrophenyl octylether as plasticiser. The sensor exhibited a fast, stable, and near-Nernstian response for SDS over the concentration range of 1 × 10^?3 to 10^?6 M at 25°C and the pH range 4–8.5 with anionic slope of 52.5 ± 0.5 mV decade^?1. The lower detection limit was 3 × 10^?6 M, and the response time was 25 s. Selectivity coefficients of SDS with respect to a number of different species were investigated. There were negligible interferences caused by most of the investigated anions. The determination of 1.0–280.0 µg mL^?1 of SDS in aqueous solutions showed an average recovery of 99.1%, and the mean relative standard deviation was 1.4 at 100 µg mL^?1. The results obtained in the determination of SDS in liquid soap, water and in some pharmaceutical preparations compared favourably with those obtained by the Methylene Blue active substance method (MBAS). In the present investigation, the DS sensor has been used as an end-point indicator electrode for some precipitation titration reactions, e.g. titration of SDS with CTMABr and cetylpyridinium chloride with SDS.     

基于一个四羧酸配体构筑的具有(4,8)-连接的镧系金属有机框架材料及对小分子的检测试验

以3,3’,5,5’-四-(羧基苯基)联苯为配体(H₄L),与镧系金属Ln(Ⅲ)盐反应,自组装形成了5个具有三维孔洞结构的镧系金属-有机框架材料：{[Ln₃L₂(H₂O)₇]·(OH)·10DMA}_n(Ln=Gd(1a);Ln=Ho(2a),{[Ln₃L₂(H₂O)3]·(OH)·mDMA}_n(Ln=Er,m=10(1b);Ln=Yb,m=9(2b);Ln=Lu,m=10(3b))。单晶X射线衍射分析表明,这些MOFs属于2种系列的类质同晶化合物,分别属于正交晶系Ccca空间群和单斜晶系C2/c空间群。有机小分子溶剂交换荧光研究发现,2b对小分子二氯甲烷和甲苯荧光有增强效应,表现出良好的荧光探测功能。     

Study of Fuchsin Acid Fading in Micellar Media

The rate constant of alkaline fading of fuchsin acid (FA^2?) was measured in the presence of nonionic (TX‐100), cationic (dodecltrimethylammonium bromide, DTAB), and anionic (sodium dodecyl sulfate, SDS) surfactants. FA^2? has three negatively charged substituents and one positive charge, and this makes the behavior of FA^2– different from dyes such as bromophenol blue. It was observed that the reaction rate constant decreased in the presence of TX‐100, DTAB, and SDS. Binding constants of FA^2? to TX‐100, DTAB, and SDS and the related thermodynamic parameters were calculated by the stoichiometric (classical) model. The results show that the binding of FA^2? to SDS is endothermic in both regions, and the binding of FA^2? to DTAB and TX‐100 is exothermic in one region and endothermic in another region of the used concentration range of these surfactants. Also, the binding constants of FA^2? to surfactant molecules of SDS/TX‐100 and DTAB/TX‐100 mixed micelles were obtained.     

A Comparative Study of the Direct Calorimetric Determination of the Denaturation Enthalpy for Lysozyme in Sodium Dodecyl Sulfate and Dodecyltrimethylammonium Bromide Solutions

The complexes of lysozyme with the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB) have been investigated by isothermal titration calorimetry at pH=7.0 and 27 °C in a phosphate buffer. A new direct calorimetric method was applied to follow the protein denaturation and study the effect of surfactants on the stability of proteins. The extended solvation model was used to represent the enthalpies of lysozyme + SDS interaction over the whole range of SDS concentrations. The solvation parameters recovered from the new equation are attributed to the structural change of lysozyme and its biological activity. At low SDS concentrations, the binding is mainly electrostatic with some simultaneous interaction of the hydrophobic tail with nearby hydrophobic regions of lysozyme. These initial interactions presumably cause some protein unfolding and expose additional hydrophobic sites. The induced enthalpy of denaturation of lysozyme by SDS is 160.81±0.02 kJ⋅mol⁻¹. The lysozyme-DTAB complexes behave very differently from those of the lysozyme-SDS complexes. SDS induces a stronger unfolding of lysozyme than DTAB. The induced enthalpy of lysozyme denaturation by DTAB is 86.46±0.02 kJ⋅mol⁻¹.     

Copper(II) Halide Complexes of 2-Aminopyrimidines: Crystal Structures of [(2-aminopyrimidine) n CuCl2] (n=1,2) and (2-amino-5-bromopyrimidine)2CuBr2

The reaction of CuX₂(X=Cl, Br) with 2-aminopyrimidine in aqueous solution, or 2-amino-5-bromopyrimidine in aqueous acid yields compounds of the forms [LCuCl₂] _n (1), [L₂CuCl₂] (2) and [L'₂CuBr₂] (3) [L=2-aminopyrimidine; L'=2-amino-5-bromo-pyrimidine]. The three compounds all form layered structures in which each copper ion is coordinated to two 2-aminopyrimidine molecules and two halide ions. Common structural threads involve bridging ligation [either by monomeric (1) or hydrogen bonded ligand dimers (2 and 3)], N-H···X and N-H···N hydrogen bonding and π-π stacking interactions as well as semi-coordinate Cu···X bond formation (1 and 2) or Br···Br interactions (3). Compounds 1 and 2 crystallize as two-dimensional coordination polymers with asymmetrically bihalide bridged (CuX₂) _n chains cross-linked into sheets by the 2-aminopyrimidine molecules (1) or by hydrogen bonded L₂ dimers (2). The halide bibridged chains expand their primary copper coordination spheres to give 4 + 2 coordination spheres in 1 and 2. In 3, the layer structure involves coordination of the hydrogen bonded L'₂ dimers and C-Br···Br- interactions. Crystal data: (1): monoclinic, P2₁/m, a=3.929(1), b=12.373(2), c=7.050(1)å, β=91.206(4)°, V=342.7(1)&Aringsup3;, Z=2, D _calc= 2.225Mg/m³, μ=3.878 mm^-1, R=0.0269 for [|I|≥3σ(I)]. For (2): triclinic, P-1, a=4.095(4), b=7.309(5), c=10.123(6) å, α=86.28(6), β=78.44(6), γ=74.55(8)°, V=286.1(4) ų, Z=1, D _calc=1.884 Mg/m³, μ=2.360 mm^-1, R=0.0506 for [|I|≥2σ(I)]. For (3): triclinic, P-1, a=6.074(4), b=7.673(3), c=8.887(3) å, α=108.43(3) β=100.86(5), γ=106.96(4)°, V=357.0(3) ų, Z=1, D _calc=2.657 Mg/m³, μ=12.714mm^-1, R=0.0409 for [|I|≥2σ(I)].     

Hexafluoroisopropanol-induced coacervation in aqueous mixed systems of cationic and anionic surfactants for the extraction of sulfonamides in water samples

Hexafluoroisopropanol (HFIP)-induced coacervation in aqueous mixed systems of catanionic surfactants of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) was described in detail, and its application in the extraction of strongly polar sulfonamides (SAs) was investigated. With 10 % (v/v) HFIP inclusion, coacervation formation and two-phase separation occur in a wide range of SDS/DTAB mole ratios (88:12～0:100 mol/mol) and total surfactant concentrations (10～200 mmol/L). The interactions between HFIP and DTAB play an important role in coacervation formation. The HFIP-induced SDS–DTAB coacervation extraction proves to be an efficient method for the extraction and preconcentration of SAs. Both hydrophobic interaction and polar interactions (hydrogen–bond, electrostatic, and π-cation) contribute to the distribution of SAs into coacervate phase. The proposed HFIP-induced SDS–DTAB coacervation extraction combined with HPLC–UV was employed for the extraction and quantitative determination of SAs in environmental water samples. Limits of detection were 1.4～2.5 ng mL^?1. Excellent linearity with correlation coefficients from 0.9990 to 0.9995 was obtained in the concentration of 0.01～10 μg mL^?1. Relative recoveries were in the range of 93.4～105.9 % for analysis of the lake, underground, and tap water samples spiked with SAs at 0.01, 1.0, and 10 μg/mL, respectively. Relative standard deviations were 0.7～3.2 % for intraday precision and 1.3～4.6 % for interday precision (n?=?3). Concentration factors were 17～49 for three water samples spiked with 0.01 μg/mL SAs. The results demonstrate that the proposed extraction method is feasible for the preconcentration and determination of trace SAs in real water samples. Graphical abstract

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Simultaneous Determination of Phenolic Additives in Cosmetics by Micellar Electrokinetic Capillary Chromatography with Electrochemical Detection

A micellar electrokinetic capillary chromatography method with electrochemical detection (MECC‐ED) has been developed for the simultaneous determination of eight phenolic additives, including propyl gallate (PG), tert‐butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) in cosmetic products. Method development involved optimization of the working electrode, the pH value of running buffer, the concentration of sodium dodecyl sulfate (SDS), the separation voltage, and the sample injection time. Under the optimum conditions, all analytes can be well separated within 26 min at the separation voltage of 18 kV in a 9 mmol·L^?1 sodium dodecyl sulfate (SDS) ?60 mmol·L^?1 borate running buffer (pH 8.0). A 300 μm diameter carbon disk electrode generated good response at +0.90 V (vs. SCE) for all analytes. Linearity of the present method was over three orders of magnitude of analyte concentration with detection limits (S/N=3) ranging from 1.1×10^?7 to 1.2×10^?6 g·mL^?1 for all analytes. This proposed method has been successfully applied to the simultaneous determination of the above additives in commercial cosmetics, and the assay results were satisfactory.     

Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

We have explored the kinetics and mechanism of the reaction between 4‐nitrobenzenediazonium ions (4NBD), and the hydrophilic amino acids (AA) glycine and serine in the presence and absence of sodium dodecyl sulfate (SDS) micellar aggregates by means of UV/VIS spectroscopy. The observed rate constants k_obs were obtained by monitoring the disappearance of 4NBD with time at a suitable wavelength under pseudo‐first‐order conditions. In aqueous acid (buffer‐controlled) solution, in the absence of SDS, the dependence of k_obs on [AA] was obtained from the linear relationship found between the experimental rate constant and [AA]. At a fixed amino acid concentration, k_obs values show an inverse dependence on acidity in the range of pH 5–6, suggesting that the reaction takes place through the nonprotonated amino group of the amino acid. All kinetic evidence is consistent with an irreversible bimolecular reaction with k=2390±16 and 376±7 M ^?1 s^?1 for glycine and serine, respectively. Addition of SDS inhibits the reaction because of the micellar‐induced separation of reactants originated by the electrical barrier imposed by the SDS micelles; k_obs values are depressed by factors of 10 (glycine) and 6 (serine) on going from [SDS]=0 up to [SDS]=0.05M . The hypothesis of a micellar‐induced separation of the reactants was confirmed by ¹H‐NMR spectroscopy, which was employed to investigate the location of 4NBD in the micellar aggregate: the results showed that the aromatic ring of the arenediazonium ion is predominantly located in the vicinity of the C(β) atom of the surfactant chain, and hence the reactive ? N group is located in the Stern layer of the micellar aggregate. The kinetic results can be quantitatively interpreted in terms of the pseudophase kinetic model, allowing estimations of the association constant of 4NBD to the SDS micelles.     

A Femtosecond Study of Solvation Dynamics and Anisotropy Decay in a Catanionic Vesicle: Excitation‐Wavelength Dependence

The structure and dynamics of a catanionic vesicle are studied by means of femtosecond up‐conversion and dynamic light scattering (DLS). The catanionic vesicle is composed of dodecyl‐trimethyl‐ammonium bromide (DTAB) and sodium dodecyl sulphate (SDS). The DLS data suggest that 90 % of the vesicles have a diameter of about 400 nm, whereas the diameter of the other 10 % is about 50 nm. The dynamics in the catanionic vesicle are compared with those in pure SDS and DTAB micelles. We also study the dynamics in different regions of the micelle/vesicle by varying the excitation wavelength (λ_ex) from 375 to 435 nm. The catanionic vesicle is found to be more heterogeneous than the SDS or DTAB micelles, and hence, the λ_ex‐dependent variation of the solvation dynamics is more prominent in the first case. The solvation dynamics in the vesicle and the micelles display an ultraslow component (2 and 300 ps, respectively), which arises from the quasibound, confined water inside the micelle, and an ultrafast component (<0.3 ps), which is due to quasifree water at the surface/exposed region. With an increase in λ_ex, the solvation dynamics become faster. This is manifested in a decrease in the total dynamic solvent shift and an increase in the contribution of the ultrafast component (<0.3 ps). At a long λ_ex (435 nm), the surface (exposed region) of a micelle/vesicle is probed, where the solvation dynamics of the water molecules are faster than those in a buried location of the vesicle and the micelles. The time constant of anisotropy decay becomes longer with increasing λ_ex, in both the catanionic vesicle and the ordinary micelles (SDS and DTAB). The slow rotational dynamics (anisotropy decay) in the polar region (at long λ_ex) may be due to the presence of ionic head groups and counter ions.     

The Role of Chloro Substituents in Solid Inclusion Formation. Crystal Structures Formed by a Bulky Hydroxy Host with Ethyl Acetate (2:1) and Cyclohexylamine (1:2) as Guest

Abstract

Two inclusion compounds of the 11-[bis(p‐chlorophenyl)hydroxymethyl]-9,10-dihydro-9,10-ethanoanthracene host (1) have been studied by X-ray diffraction in order to find an explanation of the exceptional clathrate formation ability of the present chloro-containing host as compared with that of closely related chlorine-free host analogues. Crystal data: 1·ethyl acetate (2:1), C₂₇H₂₂OCl₂·½(C₄H₈O₂), M_w = 501.45, P2_1/c, a = 8.9060(5), b = 11.1109(6), c = 25.642(1) Å, β = 99.03(1)°, Z = 4, R = 0.047 for 2029 F values with I>2σ(I); 1·cyclohexylamine (1:2), 2[C₂₉H₂₂OCI₂·2(C₆H₁₃N)], M_w = 1311.50, Pc, a = 12.144(2), b = 12.689(3), c =23.119(8) Å, β = 91.68(1)°, Z = 2, R = 0.054 for 3073 F values with I>2σ(I). Although the two solid inclusion compounds differ in host‐guest stoichiometry, space group symmetry and also in host‐guest recognition mode, both co-crystals are held together by numerous C?H…X (X = O, N or Cl) interactions, in which the chloro-substituents of 1 play a very active role. The observed frequent participation of chlorine in intermolecular interactions in these compounds suggests an ability of the (C?)Cl substituents to effectively enhance the crystal formation in the absence of more dominant forces.     

Vesicle formation induced by layered double hydroxides in the catanionic surfactant solution composed of sodium dodecyl sulfate and dodecyltrimethylammonium bromide

In this paper, it is reported that positively charged Mg₃Al layered double hydroxide (LDH) nanoparticles can induce the spontaneous formation of vesicles in micelle solution of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) with a mass ratio of 8:2. The formation of vesicles was demonstrated by negative-staining transmission electron microscopy observations. The size of the vesicles increased with the increase in the concentration of Mg₃Al-LDH nanoparticles. A composite of LDH nanoparticles encapsulated in vesicles was formed. A possible mechanism of LDH-induced vesicle formation was suggested. The positively charged LDH surface attracts negatively charged micelles or free amphiphilic molecules, which facilitates their aggregation into bilayer patches. These bilayer patches connect to each other and finally close to form vesicles. It was also found that an adsorbed compound layer of SDS and DTAB micelles or molecules on the LDHs surface played a key role in vesicle formation.     

A joint theoretical and experimental structural study of two novel 1,2,4-triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]-1,3,4-thiadiazine derivatives

In this study, two novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine derivatives, 3-[2-(4-methoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 1) and 3-[2-(3,4,5-trimethoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 2), having analgesic–anti-inflammatory activity were synthesized and characterized by IR, ¹H-NMR, and mass spectroscopic techniques besides elementary analysis. Additionally, the structures and molecular packings of the mentioned compounds have been investigated by X-ray single crystal diffraction. The six-membered thiadiazine ring adopts the screw boat conformation in both the compounds. In the crystal packings of the compounds 1 and 2, C–H···N and C–H···O interactions link the molecules into a two-dimensional network and generate infinite chains. Furthermore, C–H···π intermolecular interactions provide further stability to the molecular packing in both the molecules. The conformers have been predicted by the potential energy surface scan employing the AM1 method. Geometry optimizations and electrostatic properties have been obtained using AM1 and ab initio quantum methods.     

Synthesis,Spectral Characterization,and Crystal Structure of Two Polymorphs of o,o’-Dichloro Dibenzyl Disulfide

2-Chlorophenyl methanethiol undergoes air oxidation catalyzed by different selenides and yields the corresponding disulfide 1 in two polymorphic forms, 1a and 1b. In the molecular structures of the two new polymorphs of o,o′-dichloro dibenzyl disulfide, the dihedral angles between the dibenzyl groups are 82.0(1)°, (1a), and 73.7(4)°, (1b), respectively [(1a): P-1, a = 8.424(2) Å, b = 8.838(2) Å, c = 10.5823(19) Å, α = 90.122(18)°, β = 112.19(2)°, γ = 95.19(2)°, V = 725.9(3) ų; (1b): P2₁/n, a = 10.5888(10) Å, b = 9.1590(6) Å, c = 15.2489(14) Å, β = 103.072(9)°, V = 1440.6(2) ų]. MOPAC computational studies yield dihedral angles of 89.6(5)° and 71.9(9)°. Crystal packing is stabilized by weak π-ring (C?H···Cg) intermolecular interactions in both 1a and 1b and by additional weak Cg ··· Cg intermolecular interactions in 1b, which influence the bond distances, bond angles, and torsion angles of the dibenzyl groups in each polymorph. Additional characterization of each polymorph has been carried out by TEM, IR, ¹H and ¹³C NMR spectroscopy, microanalysis, and by FAB mass spectrometry. TEM studies of a sample of 1a show that it contains cigar-shaped crystallites.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

SDS-Based Biomembrane Mimetic Chromatography for Prediction of Human Drug Transport as an in Vitro Technique

The main oral drug absorption barriers are fluid cell membranes, and generally drugs are absorbed by a passive diffusion mechanism. On the other hand, the blood–brain barrier (BBB) is considered to be the main barrier to drug transport into the central nervous system (CNS). The BBB restricts the passive diffusion of many drugs from blood to brain. Biopartitioning micellar chromatography (BMC), a mode of micellar liquid chromatography that uses micellar mobile phases in adequate experimental conditions, can be useful as an in vitro system in mimicking the drug partitioning process into biological systems. In this study, relationships between the BMC retention data of a heterogeneous set of 12 drugs and their pharmacokinetics parameters (human oral drug absorption and BBB penetration ability) are studied and the predictive ability of the models is evaluated. Modeling of log k _BMC of these compounds was established by multiple linear regression in two different concentrations (0.07 and 0.09 M) of sodium dodecyl sulfate (SDS). The results showed a fair correlation between human oral drug absorption and BMC retention data in 0.09 M SDS (R ² = 0.864) and a good correlation between the blood–brain distribution coefficient and BMC retention data in 0.07 M of SDS (R ² = 0.887). Application of the developed models to a prediction set demonstrated that the model is also reliable with good predictive accuracy. The external and internal validation results showed that the predicted values are in good agreement with the experimental value.

     

A synthetic iron phosphate mineral, spheniscidite, [NH4]+[Fe2(OH)(H2O)(PO4)2]?H2O, exhibiting reversible dehydration

Spheniscidite, a synthetic iron phosphate mineral has been synthesized by hydrothermal methods. The material is isotypic with another iron phosphate mineral, leucophosphite. Spheniscidite crystallizes in the monoclinic spacegroupP2₁/n. (a=9·845(1),b=9·771(3),c=9·897(1),β=102·9°,V=928·5(1),Z=4,M=372·2,d _calc=2·02 g cm⁻³ andR=0·02). The structure consists of a network of FeO₆ octahedra vertex-linked with PO₄ tetrahedra forming 8-membered one-dimensional channels in which the NH₄ ⁺ ions and H₂O molecules are located. The material exhibits reversible dehydration and good adsorption behaviour. Magnetic susceptibility measurements indicate that the solid orders antiferromagnetically.     

碱金属硫酸盐-SDS-PEG三维浓度变化对SDS的束缚胶束聚集数的影响

采用稳态荧光猝灭技术测定了三种碱金属(Li, Na或K)硫酸盐-SDS-PEG三元体系中SDS(十二烷基硫酸钠)的束缚胶束聚集数N_b, 考察了SDS浓度c、碱金属硫酸盐浓度c_e及PEG(聚乙二醇)浓度c_p变化时SDS的N_b的变化规律. 对SDS的N_b数据进行二次响应面分析, 得知SDS的N_b是c的线性增大函数、c_e的对数函数以及c_p的反比例函数, 据此对SDS的N_b实验值建立含二次交互作用项的函数表达式. 按上述表达式进行回归, 得到相应于Li₂SO₄, Na₂SO₄或K₂SO₄体系的系数a₀～a₈. 据此计算得到SDS的N_b预期值并与实验值进行比较, 其间的绝对误差在3以内, 相对误差在4%以内. 该结果为用SDS的N_b 预测表面活性剂-大分子软模板的尺寸和化学微环境、并用于调控所制备的金属纳米粒子的大小提供依据.