Organic molecule-modulated phase evolution of inorganic mesostructures

The involvement of alkane in the P123-TEOS-NH4F-H3O+ synthesis system alters the phase behavior of the complex emulsion system dramatically. Changing one of the reaction parameters (such as the initial reaction temperature, IRT) will result in diverse solution mesostructures. With subsequent condensation of silicate species, interesting inorganic materials with various mesostructures are obtained. The present work is aimed at understanding the phase evolution behavior of this complex alkane (C6-C12)-P123-TEOS-NH4F-H3O+ emulsion system, with emphasis on the influence of alkane chain number (ACN) and IRT. HREM (high-resolution electron microscopy), XRD (X-ray diffraction), nitrogen sorption, FFEM (freeze-fracture electron microscope), and interfacial tension techniques have been used to investigate the phase behavior of the emulsion system and the structure of the inorganic products. A linear relationship between the phase-transformation temperature (PTT) and ACN has been established, which could be attributed to the modification of alkane with respect to the hydrophobic-hydrophilic properties of the complex emulsion system. Moreover, the right combination of reaction temperature, ACNs, and thus-induced swelling of hydrophobic PPO blocks as well as the modification of hydrophilicity of PEO brushes by silicate oligmers is the driving force in altering the packing parameter/geometry of the copolymers surfactant (P123) aggregates. This leads to the diverse structures of the obtained mesoporous silicas. A temperature-induced phase-transformation mechanism has also been proposed and discussed.     

Sorption of cobalt on organic and inorganic intercalated clays

A Mexican montmorillonite clay was intercalated on the one hand with aluminium or zirconium polyhydroxications, and on the other with two organic compounds. Radioactive cobalt was used to study the Co²⁺ sorption curves in the original and pillared clays. It was found that pillaring in general does not favour the diffusion of cobalt between the layers specially the organic pillared clays. In equilibrium, the cobalt retention reached the highest level, around 0.7 meq/g in the Zr pillared clay.     

Sorption of anti-infective organic molecules from aqueous solutions onto zirconium phosphate

Amorphous zirconium phosphate (ZP), an inorganic ion exchange material of tetravalent metal acid (tma) salt, is synthesized by the sol-gel method and characterized by elemental analysis (ICP-AES), thermal analysis (TGA, DSC), FT-IR and X-ray diffraction studies. The resistivity of the material to acids, bases and organic solvents is assessed. The sorption behavior of the dyes acriflavin (AF) and brilliant green (BG) toward ZP was studied at 313, 323 and 333 K and the kinetic and thermodynamic parameters evaluated. Adsorption isotherms [Langmuir and Fruendlich], breakthrough capacity and elution behavior of these dyes are also studied. The sorption affinity of dyes towards ZP is BG > AF.     

Sorption of organic molecules by graphitic acid and methylated graphitic acid: A preliminary study

Summary Interlamellar sorption complexes formed by graphitic acid and methylated graphitic acid have been studied. The latter forms complexes less readily with amines, more readily with fatty acids; for nitriles and alcohols the differences are minor. We believe this is due to the reduction in the acid nature on methylation. An important rôle in sorption is also ascribed to the number of active points per unit area of substrate.A liquid-solid transition is believed to occur in the sorbed film. Evidence is presented that the states concerned are not as sharply demarcated as for the free substance, and that the transition may occur at a lower temperatue for the sorbed film than the free substance.Mixtures of similar substances (amines) give a linear variation of interlayer spacing with composition. Mixtures of dissimilar substances may give complicated curves for this variation, from which conclusions may be drawn regarding the segregation (de-mixing) of sorbed molecules.

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Zusammenfassung Sorptionskomplexe der Zwischenschicht der Graphitsäure und der methylierten Graphitsäure wurden untersucht. Letztere bildet nur ziemlich schwer Komplexe mit Aminen, dagegen viel leichter mit Fettsäuren; die beobachteten Unterschiede für Nitrile und Alkohole sind klein. Wir denken, daß dies in Verbindung mit einer Verminderung des sauren Charakters der Graphitsäure infolge der Methylierung steht. Eine wichtige Rolle bei dem Sorptionsprozeß spielt wahrscheinlich auch die Anzahl von aktiven Zentren per Flächeneinheit.Wir glauben, einen Übergang flüssig-fest in der sorbierten Schicht beobachtet zu haben. Gewisse experimentelle Tatsachen weisen darauf hin, daß der Unterschied dieser beiden Zustände weniger bemerkbar bei der sorbierten Schicht als bei der freien Substanz ist. Der Übergang tritt im letzteren Fall auch bei einer niedrigeren Temperatur auf.Mischungen gleichartiger Substanzen (Amine) ergeben eine lineare Änderung der Zwischenschichtaufweitung mit der Zusammensetzung. Mischungen ungleichartiger Substanzen dagegen zeigen kompliziertere Kurven, die gewisse Folgerungen über die Ausscheidung der Molekeln in den Schichten ermöglichen.

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Address at which this work was performed: Physics Department Queen's College, University of St. Andrews, Dundee, Scotland.     

Sorption of organic vapors by polystyrene

Activity coefficients of benzene, toluene, cyclohexane, carbon tetrachloride, chloroform, and dichloromethane in binary solutions with polystyrene at 23.5°C have been determined using a piezo-electric sorption apparatus. The investigated solvent concentration ranges were 15 to 39 wt % for benzene, 14 to 29 wt % for toluene, 15 to 28 wt % for cyclohexane, 26 to 38 wt % for carbon tetrachloride, 24 to 46 wt % for chloroform, and 21 to 41 wt % for dichloromethane. The polystyrene (weight-averaged) molecular weights were 1.1 × 10⁵ and 6.0 × 10⁵ g/gmole. The weight-fraction activity coefficients (Ω₁ = a₁/w₁) of cyclohexane, toluene, and carbon tetrachloride in polystyrene solutions determined in this work agree within experimental error with previously published values determined by measurement of vapor pressure lowering and vapor absorption by thin films. We find disagreement, at low solvent concentrations, between our results for benzene and chloroform and previously published results. We have analyzed our results using Flory's version of corresponding-states polymer solution theory. The theory can account, qualitatively, for the cyclohexane and carbon tetrachloride results. It cannot account for the toluene, benzene, dichloromethane, or chloroform results.     

Comparison of electronegativities of groups of certain organic and inorganic molecules

For functional groups containing oxygen and sulfur atoms qualitative relationships were obtained and a row of electronegativities was set up within the limits of the “quantum theory of atoms in molecules.” Possibilities of forecasting composition-property correlations on a specified basis were discussed.     

Raman spectroscopic study of hydrophobic hydration of organic molecules in aqueous solution

Raman spectra of several organic molecules which form hydrate clathrates have been measured in aqueous solution, and the hydration structure around those molecules has been investigated from the analysis of Raman linewidth data.     

Sorption of organic dyes by polyurethane foam

The sorption of fifty-nine organic dyes, indicators and stains by polyester and polyether-type polyurethane foams was investigated by use of aqueous solutions and powdered foam material. Comparisons were made with sorption from 50% methanol solutions for some dyes and also with solvent extractions done with diethyl ether or ethyl acetate for several dyes. The R(f) values for the dyes run on cellulose TLC plates in water or a mixed solvent mobile phase were compared to the distribution coefficients with polyurethane foam. The relationship between the structure of the test substances and their sorption is discussed.     

Multifunctional inorganic/organic hybrid microgels

This review summarizes recent research dedicated to hybrid colloids combining inorganic nanoparticles and cross-linked polymer networks. We discuss aspects of synthesis, characterization, and application of systems with different morphologies and properties. Due to the large number of works in the field of composite materials, we focus on materials with responsive polymer components, which are dispersed in aqueous media.     

Protein-templated organic/inorganic hybrid materials prepared by liquid-phase deposition

Organic/inorganic hybrid thin films for protein recognition have been prepared by the liquid-phase deposition (LPD) coupled with template synthesis, i.e., molecular imprinting, where pepsin (Pep) was used as a model protein and titanium oxide was deposited on gold substrates in the presence of Pep-poly-L-lysine (PL) complexes. The complexes remained in the templated film after the deposition, and the binding sites for Pep were constructured after Pep was removed from the film. Surface plasmon resonance signals on the deposited films were measured to examine the binding behaviors toward proteins. The binding of Pep on the templated film was reversible, and the binding isotherm of Pep depicted a saturation curve with a binding constant of 7.3 x 105 M(-1), which was 10 times higher than that of albumin. In contrast, titanium oxide films prepared without PL did not show any selectivity; therefore, the hybridization of PL as the organic binder with the inorganic material is necessary to obtain selective binding sites for Pep. It was also shown that the hybridization process should proceed without denaturing the template protein, in order to obtain selective binding sites for the template. The procedure for preparation of the films was simple to perform, and the process for hybridization of the thin films with nanometer-order thickness was easily controlled by changing the LPD reaction time period. Consequently, the proposed LPD coupled with template synthesis is among the most appropriate methods to prepare hybrid materials with protein recognition ability, which proceeds under mild conditions in aqueous solution.     

Hybrid organic/inorganic epoxy resins prepared by frontal polymerization

The syntheses of hybrid epoxy resins made from different ratios among bisphenol‐A diglycidyl ether, 3‐glycidoxypropyltrimethoxysilane (GPTMS), and diethylenetriamine were successfully performed by using frontal polymerization. Conversions were always almost quantitative, and, because of the use of this alternative convenient technique, materials were prepared in very short times. Samples were characterized by DSC, TGA, IR spectroscopy, and solvent extraction. It was found that those materials containing a relatively high‐Si amount exhibit two different transition temperatures, with the highest one that increases as the content of GPTMS raises. The analogies and the differences with the analogous samples prepared by the classical batch technique are discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Sorption of radionuclides on inorganic sorbents

Inorganic sorbents are often used in separation of metals and radionuclides in radioanalytical application and they were also used in technological scale for separation of radionuclides in cleanup of Three Mile Island NPP. Inorganic sorbents become popular in the last years because no problem with organic contamination, there are stable against radiation, sorption efficiency can be tailor made for selective separation of chosen metal. Contrary to the organic sorbents they have usually lower capacity and chemical stability is limited to narrower pH. Nevertheless of some problems, many good properties of inorganic sorbents make them very attractive for sorption study.     

Light-activated hybrid organic/inorganic antimicrobial coatings

Light-activated antimicrobial coatings were obtained by the covalently immobilizing photo-sensitizers in a hybrid organic/inorganic matrix. These coatings were deposited via sol-gel chemistry using epoxy and methyl functional silanes. The light-activated chromophores used in this study were Methylene Blue, Toluidine Blue O, and Rose Bengal. The immobilized photo-sensitizers did not leach from the coatings. The mechanically durable hybrid coatings comprising 2.5% by weight of Rose Bengal had a good adhesion to the glass surface. These coatings were tested for the photo-deactivation of Escherichia coli and Staphylococcus aureus using illumination by a commercial fluorescent lamp. Log reduction of E. coli and S. aureus were >4 when illuminated by the fluorescent lamp in 1 and 3?h, respectively. Due to its high mechanical durability and chemical resistance, such light-activated hybrid coatings are promising candidates for indoor applications in healthcare facilities.

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Light-controlled organic/inorganic P-N junction nanowires

P-N junctions are of great importance both in modern electronic applications and in understanding other semiconductor devices. Organic/inorganic P-N junction nanowires composed of functional organic molecules and inorganic molecules may be able to realize new or improved chemical and physical properties that were not observed in the individual component on nanosize and their bulk materials. We report herein the fabrication of the organic/inorganic semiconductor P-N junction nanowire and the remarkable performance on the light-controlled diode within a single hybrid P-N junction nanowire. Controlling the conductivity of the P-N junction nanowire by the light irradiation simply to achieve diode work indicates a new way to realize the photoelectric integration in a single nanowire device.     

Structural characterization of a new decavanadate compound with organic molecules and inorganic ions

A new decavanadate compound V₁₀O₂₈[Co(H₂O)₆]₃(C₈H₁₈O₆N₂S₂)₂ (I) is synthesized and characterized by single crystal X-ray diffraction, thermogravimetric analysis, FT-IR spectroscopy, and scanning electron microscopy. The sizes of the monoclinic unit cell are as follows: a = 13.2851(16) ?, b = 22.769(3) ?, c = 13.1883(16) ?, ??= 117.555(2)°, V = 3536.7(7) ?³, C2/m space group, Z = 2. The studies revealed that different moieties in the compound show a three-dimensional framework structure, in which {CoO₆}, the decavandate cluster anions, and 1,4-piperazinediethanesulfonic acid (PIPES) interact with each other by intermolecular forces and strong hydrogen bonding. Bond valence calculations were used to calculate the valence states of the atoms.     

Network structure of inorganic/organic hybrid gels

Two series of inorganic/organic hybrid gels were prepared by the sol-gel reaction of triethoxysilyl-terminated poly(tetramethylene oxide) and tetraethoxysilane. The structure of hybrid gels was observed by small-angle X-ray scattering, and the scattered profiles were analysed by assuming a priori the density correlation functions. The results suggest that the hybrid gel is composed of organic-rich, inorganic-rich and organic/inorganic mixed regions. The size and structure of respective regions were discussed in terms of the correlation lengths evaluated from the scattering profiles.     

Stabilization of inorganic nanocrystals by organic dendrons

A series of hydrophilic organic dendron ligands was designed and synthesized for stabilizing high-quality semiconductor and noble metal nanocrystals. The focal point of the dendron ligands is chosen to be a thiol group which is a universal coordinating site for compound semiconductor and noble metal nanocrystals. The methods for binding these dendron ligands onto the surface of the nanocrystals are simple and straightforward. The thin, about 1-2 nm, but closely packed and tangled ligand shell provides sufficient stability for the "dendron-protected nanocrystals" to withstand the rigors of the coupling chemistry and the standard separation/purification techniques. The chemistry presented can be immediately applied for the development of a new generation of biomedical labeling reagents based on high-quality semiconductor nanocrystals. It also provides an alternative path to apply noble metal nanocrystals for developing sensitive detection schemes for chemical and biochemical purposes. The concept may further provide an optimal solution for many other problems encountered in nanocrystal-related research and development, for which the stability of the nanocrystals is a critical issue. Furthermore, the experimental results confirmed that the photochemical stability of colloidal semiconductor and noble metal nanocrystals is the key for developing reliable and reproducible processing chemistry for these nanocrystals.