Szczepan Bednarz

Novel efficient fluorophores synthesized from citric acid

A series of novel fluorescent compounds was isolated from condensation mixtures of citric acid and specific β-amines. Their chemical structure was determined using 1H, 13C and HSQC experiments, elemental analysis data, high resolution and fragmentation spectra ESI-MS analyses. These compounds consisted of five-membered ring fused 2-pyridones. The fluorophores exhibited quantum yields as high as 79%.

Application of hydrogen peroxide encapsulated in silica xerogels to oxidation reactions.

Hydrogen peroxide was encapsulated into a silica xerogel matrix by the sol-gel technique. The composite was tested as an oxidizing agent both under conventional and microwave conditions in a few model reactions: Noyori’s method of octanal and 2-octanol oxidation and cycloctene epoxidation in a 1,1,1-trifluoroethanol/Na2WO4 system. The results were compared with yields obtained for reactions with 30% H2O2 and urea-hydrogen peroxide (UHP) as oxidizing agents. It was found that the composite has activity similar to 30% H2O2 and has a several advantages over UHP such as the fact that silica and H2O are the only products of the composite decomposition or no contamination by urea or its derivatives occurs; the xerogel is easier to heated by microwave irradiation than UHP and could be used as both an oxidizing agent and as solid support for microwave assisted solvent-free oxidations.

Fluorescent citric acid-modified silicone materials

Novel transparent and flexible silicone materials with fluorescent properties were developed. Fluorescent derivative of 2-pyridone was incorporated into silicone matrix via condensation of citric acid with α,β-diamine groups. Obtained materials were characterized according to FT-IR spectra, contact angle and fluorescence properties. Possible applications as sensors and silicone material markers were proposed.

Microwave-assisted oxidation of alcohols by hydrogen peroxide catalysed by tetrabutylammonium decatungstate

This work deals with catalytic activity of tetrabutylammonium decatungstate(VI) in the oxidation of selected alcohols with hydrogen peroxide as an oxidant using 1,2-dichloroethane/water or acetonitrile/water as a solvent system. Different forms of heating were compared. The highest conversions of substrates were achieved in the two phase system acetonitrile/water using microwave irradiation combined with elevated pressure. Finally, optimum parameters for these reactions in a microwave pressurised reactor were established and discussed.

Microwave-Assisted Synthesis of Hybrid Polymer Materials and Composites

The fabrication of polymer–inorganic hybrid materials and composites under microwave irradiation benefits from a number of advantages such as reduction in processing time, more uniform heating of materials (i.e., reduced thermal gradient), faster curing of resins, and more efficient crosslinking of composite materials. For polymer hybrid materials, the advantages of microwave-assisted synthesis include smaller particle size, narrower particle size distribution, greater particle density, and higher exfoliation degree, which substantially improve the performance of the final material. A decrease in size of the various components is one of the cornerstones of the push towards improvements in electronic and optical devices, drug delivery, medical scaffolds, biosensors, imaging agents, and analytical technology. This chapter discusses recently published reports on the preparation and characterization of composite materials and polymer hybrids obtained under microwave irradiation using various types of polymer matrix and resins together with inorganic materials such as glass and carbon fibers, carbon black, layered materials (e.g., clays and double hydroxides), metal nanoparticles and nanowires, as well as carbon-based materials (e.g., fullerenes and nanotubes). A survey of past achievements in the preparation of polymer–inorganic hybrid nanocomposites under microwave irradiation can be found in a previously published review paper (Bogdal et al., Curr Org Chem 15:1782, 2011).

Application of Na12[WZn3(H2O)2][ZnW9O34)2] polyoxometalate as a catalyst in oxidation of alcohols under microwave irradiation

In this paper the results of oxidation of alcohols under microwave irradiation using Na12[WZn3(H2O)2][ZnW9O34)2] (ZnPOM) as a catalyst was shown. These reactions were conducted in microwave high-pressure reactor using acetonitryl as organic solvent and 30% hydrogen peroxide as oxidant. Under reaction conditions primary alcohols were oxidized to appropriate acids, secondary alcohols were oxidized to ketones. In case of diols it was found that secondary –OH groups were oxidized in the first instance.