German M. Telbiz

Effect of solvent nature on liquid-phase self-assembly of MEH-PPV/MCM-41 guest–host composites

Guest–host MEH-PPV/MCM-41 composites were prepared by liquid-phase self-assembly via insertion of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) macromolecules inside mesoporous silica. The effect of the solvent nature on the polymer loading and luminescence properties of the composites was explained by retained memory of the chain conformation in the parent solution. The intensity of photoluminescence of the obtained composites was found to be two orders of magnitude greater than that of the neat polymer.

Effect of Aggregation of Rhodamine 6G on the Spectral and Luminescence Characteristics of Hybrid Mesostructured Silica Films

The effect of the concentration of rhodamine 6G and surfactant (Pluronic P123) in a film-forming sol and the method of its deposition (spin or dip coating) on the substrate on the spectral and luminescence characteristics of hybrid mesostructured silica films was determined. Other important factors in the formation of the mesostructured coatings are the condensation rate of the precursor and the evaporation of the solvent. The possibility of controlling the aggregation of rhodamine 6G in the structure of such films was demonstrated.

Optical Manifold of Spatial Localization of Dyes Molecules Self-Organized in the Body of Silica Thin Films

Development of a simple sol-gel-based method for producing high quality mesostructured hybrid films within different concentration Rhodamine 6G is reported. Dip coating or spin coating methods were using for film casting with different optical characteristics. The films have been characterized by UV-Vis absorption spectroscopy and excitation fluorescence spectroscopy. The observed manifold of the optical and fluorescence spectra shows the ability of controlled aggregation of dye molecules owing to time delay of their spontaneous transformation during the process of formation of mesostructured hybrid sol-gel films. Preliminary experiments have shown viability of the composite films for excitation of lasing that is perspective for design of waveguide nanolasers.

2D Hybrid Si-, Ti-Nanocomposites for Optoelectronic Devices Manufactured by the Sol-Gel Method

Nanoscale hybrid SiO2 and TiO2 films manifest a set of properties beneficial for use in sensors, dye lasers, amplifiers, switching devices, solar cells, and OLEDs. With increasing minuteness of these devices, an accurate and homogeneous material structure is of primary importance. We studied factors influencing the characteristics of thin hybrid film which would help to tune the quality of mesoscale patterned surfaces and to developed a self-assemblying technology based on the sol-gel method to fabricate of high-quality hybrid nanocomposite films using network-forming oxides such as silica or titania. The results obtained are expected to promote the manufacturing of 2D mesoscale surfaces with laser dyes incorporated into host materials and to open opportunities for simpler configurations of optoelectronic and sensor device with improved performances.

Functional Titanium Dioxide-Derived Materials of Different Morphology and Metal–Organic Framework Compounds

New approaches are examined for the creation of functional materials derived from composites of mesoporous nanocrystalline TiO2 with nanoparticles of nickel, copper, and silver, dyes, and also nanocomposites of new metal–organic frameworks formed by azamacrocyclic nickel and zinc complexes and aromatic carboxylates with acridine orange dye and iodine. Spectral, luminescent and electrophysical characteristics of these materials were determined. Examples are given for their possible use as photocatalysts, sensitive elements of luminescent sensors, and proton-conducting membranes.

Molecular Aggregation and Deaggregation of Rhodamine 6G in the Formation of Hybrid Sol–Gel Films

Electronic and fluorescence spectroscopy was used to show that the aggregation of rhodamine 6G molecules in a film-forming sol and derived hybrid films is a function of the equilibrium dye concentration and the micelle-forming agent and, as a consequence, the concentration of the micelle-forming agent in the film-forming sol affects the optical characteristics of the hybrid sol–gel films. Dye monomers were found to predominate in the sol, while the formation of nonplanar luminescent H-dimers is possible during film formation as a consequence of geometrical limitations of the dye molecules solubilized within the micelles.

Sol-Gel Approach for Development of the Mesoporous Structures for Creation of the Sensors and Disposal of Low Molecular Weight Toxic Substances from Environmental Objects

Mesoporous sol-gel materials are among the ideal host matrixes for immobilizing enzymes because of their large pore volumes and controllable pore sizes appropriate for inclusion compounds. Although indirect enzyme immobilization in mesoporous materials has been achieved by impregnating of the MCM41 matrix with an enzyme, there are only few reports on one-step direct immobilization of bioactive species in surfactant-templated mesoporous sol-gel materials. We demonstrate here the principle by immobilization of 2,4D herbicide and mycotoxins T2 as model system. With that goal in view, various silica matrices with miscellaneous structural parameters were prepared and characterized.

Sol-Gel Template Synthesis of the Oriented Mesoporous Thin Oxide Films and Nanostructures

In this communication, a different approach to the preparation of mesoporous SiO2 and TiO2 thin films and nanocomposites has been adopted, aimed at preparation of oriented mesoporous thin films with highly stable roughness of the film surface and controlled pore dimension. We describe the preparation and compositional analysis of thin film coatings prepared using sol-gel techniques (thickness 50–500 nm, roughness ± 0.5 nm with pore distribution 2.4–8 nm for silica oxide and up to 300 nm for titanium oxide and porosity 30–50%). Analyses of these systems were based on XRD, AFM, FTIR, and elipsometry porosimetry data. The structural evolution of the film during thermal treatment was observed by FTIR spectroscopy and XRD.