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Gorczynski A.,Adam Mickiewicz University | Marcinkowski D.,Adam Mickiewicz University | Marcinkowski D.,University of Life Sciences in Poznan | Pakulski D.,Adam Mickiewicz University | And 6 more authors.
Arabian Journal of Chemistry

Four complexes of different Cd(II) salts with 6,6″-dimethyl-2,2':6',2″-terpyridine L have been synthesized of the following structural formulae: [CdL(CH3OH)(ClO4)2] (1) [CdL(Cl/Br)2] (2) [CdLCl2] (2a) [CdL(CH3CO2)2] (3). Their properties have been established through analytical and spectroscopic (ESI-MS, IR, 1H NMR and UV-Visible absorption and emission) methods as well as by X-ray structure determinations. Quite high quantum yield values were obtained for the solution luminescence, despite the fact that presented compounds are 'open species' i.e. are susceptible to the effect of external environment. Titration experiments proved speciation i.e. formation of both 2:1 and 1:1 (L:Cd2+) species in MeCN, yet only the latter ones can be isolated in their crystalline form. In the solid state, there appears to be a correlation between the emission intensity and the stacking arrays in the lattice. There is no evidence that the methyl substituents exert a major influence upon the properties of the complexes, and it is implied however that they might also be responsible for preferential formation of 1:1 complexes in the solid state due to observed intermolecular packing lattices. © 2016 The Authors. Source

Petryk M.,Adam Mickiewicz University | Petryk M.,Wielkopolska Center for Advanced Technologies | Troc A.,Polish Academy of Sciences | Gierczyk Bl.,Adam Mickiewicz University | And 3 more authors.
Chemistry - A European Journal

A procedure for studying "dynamic structural behavior" of large chiral macrocycles is presented. Ion mobility MS, diffusion-ordered NMR spectroscopy (DOSY NMR), and optical rotation (OR) measurements, supported by calculations, are used together as effective complementary methods to study dynamic formation of noncovalent aggregates. It is shown that the monomer-dimer equilibrium is driven by π-π or CH-π interactions and controlled largely by the substitution pattern of the calixsalen skeleton. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kedzierski K.,Poznan University of Technology | Rytel K.,Poznan University of Technology | Majchrzycki L.,Poznan University of Technology | Majchrzycki L.,Wielkopolska Center for Advanced Technologies | Wrobel D.,Poznan University of Technology
Thin Solid Films

While the carbon nanotubes are characterized by excellent electrical, mechanical and thermal properties, which makes them a good candidate for many applications, e.g. as a transparent electrode for photovoltaics, there is still no adequate method for the formation of thin conductive carbon nanotube films. Here we report the Langmuir-Schaefer method for the fabrication of large scale, homogeneous multiwall carbon nanotube layers with good optical and electrical properties. We show that the layers obtained are characterized by optical and electrical anisotropies, which can be controlled by the direction of the barrier and surface pressure during the layer transfer. © 2015 Elsevier B.V. Source

Prusinowska N.,Adam Mickiewicz University | Bendzinska-Berus W.,Adam Mickiewicz University | Szymkowiak J.,Adam Mickiewicz University | Szymkowiak J.,Wielkopolska Center for Advanced Technologies | And 8 more authors.
RSC Advances

A combination of experimental methods (ECD, X-ray diffraction) and theoretical calculations allowed the description of chirality transfer in bis(triphenylacetamides). For the first time it has been shown that effective helicity induction in a trityl chromophore is not only due to the presence of stereogenic center(s) but is also caused by other chirality inductors such as an axis of chirality. For all experimental and computed ECD spectra a uniformly identical sequence of signs of the Cotton effects has been found: negative at around 215 nm and positive below 200 nm. This result can only be explained by the dependence of the ECD spectra on the R absolute configuration of the proximal stereogenic element. The chirality transfer is achieved through a series of weak intramolecular interactions. Helicities of the trityl chromophores and their propeller shapes are influenced by the structure of the chiral inductor and the steric hindrance at amide nitrogen atoms. The stereogenic centers in the diamide unit act independently as chirality inductors and the direct trityl···trityl interactions are only rarely observed. Characteristic for the investigated crystals is the complete hindrance of the amide NH groups and their inability to be involved in any intermolecular interactions as well as their highly restricted ability for the formation of intramolecular hydrogen bonds. This results from the presence of Tr groups, which act as supramolecular NH protecting groups, especially when attached to the rigid carbocycles. © The Royal Society of Chemistry. Source

Petryk M.,Adam Mickiewicz University | Petryk M.,Wielkopolska Center for Advanced Technologies | Biniek K.,Adam Mickiewicz University | Janiak A.,Adam Mickiewicz University | And 2 more authors.

The [3 + 3] cyclocondensation of 2-hydroxyisophthalaldehyde derivatives with racemic trans-1,2-diaminocyclohexane results in formation of triangular vase-like hexaimines called calixsalens. Calixsalen formation is highly stereoselective, yielding racemic mixtures that contain homochiral products with absolute configuration of either all-R or all-S at their stereogenic centres. Calixsalens form tail-to-tail dimers that are assembled into higher-order structures in the solid state. The formation of these dimers is accomplished by enantioselective self-recognition of chiral calixsalen units driven by non-covalent interactions only. © 2016 The Royal Society of Chemistry. Source

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