Ivana A. Janković

New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M−1 have been determined.

Synthesis and Characterization of Rutile TiO 2 Nanopowders Doped with Iron Ions

Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence.

Surface modification of anatase nanoparticles with fused ring catecholate type ligands: a combined DFT and experimental study of optical properties

Surface modification of nanocrystalline TiO(2) particles (45 Å) with catecholate-type ligands consisting of an extended aromatic ring system, i.e., 2,3-dihydroxynaphthalene and anthrarobin, was found to alter the optical properties of the nanoparticles in a similar way to modification with catechol. The formation of inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and the reduction of the band gap upon the increase of the electron delocalization on the inclusion of additional rings. The binding structures were investigated by FTIR spectroscopy. The investigated ligands have the optimal geometry for binding to surface Ti atoms, resulting in ring coordination complexes of catecholate type (binuclear bidentate binding-bridging) thus restoring the six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, stability constants in methanol/water = 90/10 solutions at pH 2 of the order 10(3) M(-1) have been determined. Quantum chemical calculations on model systems using density functional theory (DFT) were performed to obtain vibrational frequencies of charge transfer complexes, and the calculated values were compared with the experimental data.

Influence of AlOOH nanoparticles on the oxidation of iodide by persulphate

Abstract The oxidation of iodide by persulphate has been studied in the presence of the AlOOH nanoparticles. The rate of this reaction is significantly higher in the presence of the AlOOH nanoparticles than when it takes place in an aqueous medium. The dependence of the rate constant on the AlOOH content, temperature, ionic strength and pH has been examined. The results are interpreted in terms of electrostatic interaction between negatively charged reactant species and surface charge of the AlOOH nanoparticles. The sensitivity of the rate constant to the pH provides convenient method for precise detection of the point of zero charge of dispersed material.

New microsatellite markers for Campanula pyramidalis (Campanulaceae) and cross-amplification in closely related species

Premise of the study: Microsatellite markers were identified and characterized to study the genetic diversity and structure, conservation status, taxonomy, and biogeography of subspecific taxa and populations of Campanula pyramidalis (Campanulaceae). Methods and Results: Eleven microsatellite markers were developed from genomic libraries enriched for di- and trinucleotide repeats. A total of 80 alleles were observed in the tested natural population. The number of alleles per locus, observed heterozygosity, and expected heterozygosity ranged from four to 13, 0.217 to 0.913, and 0.521 to 0.895, respectively. Conclusions: The new microsatellite markers will be useful for studying genetic diversity and structure as well as for better assessing the conservation status of subspecific taxa and populations of C. pyramidalis. Furthermore, a set of seven loci was successfully cross-amplified in C. secundiflora and C. versicolor and will be of great value for addressing unsolved taxonomic and biogeographic issues within the C. pyramidalis species complex.

Towards the bryophyte flora of the Sutjeska National Park (the Republic of Srpska, Bosnia and Herzegovina)

Old literature data together with recent field research were combined in order to present bryophyte checklist of the Sutjeska National Park. A total of 261 taxa were found within the park area, out of which 40 are liverwort and 221 moss taxa. Bearing in mind a huge lack of bryological research in Bosnia and Herzegovina during last decades, 41 species were refound after more than fifty years, and 92 new for the park area as well. Additionally, seven species are included in the candidate list of the new Red data book of European bryophytes. These are: Anoectangium aestivum, Buxbaumia viridis, Cinclidotus aquaticus, Fontinalis hypnoides, Orthotrichum patens, Pseudocampylium radicale and Schistidium helveticum.