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Janiak A.,Stellenbosch University | Janiak A.,Adam Mickiewicz University | Petryk M.,Adam Mickiewicz University | Petryk M.,Wielkopolska Center for Advanced Technologies | And 3 more authors.
Organic and Biomolecular Chemistry | Year: 2015

Calixsalens, chiral triangular hexaimines are readily synthesized by [3 + 3] cyclocondensation of trans-(R,R)-1,2-diaminocyclohexane with 2-hydroxyisophthalaldehyde derivatives. The usually rigid calixsalen ring is able to invert its conformation as a consequence of steric repulsion between bulky substituents at the C5 positions of the aromatic rings. The steric and electronic nature of the substituents does not affect only the conformation of the macrocycle. Small polar substituents enforce dimeric self-association to form an apohost where each of the monomers simultaneously serves as the host and the guest of its partner. Non-associating calixsalens form assemblies in which two symmetry-related molecules are arranged in a head-to-head fashion to form a capsule, or unimolecular cages that are able to entrap solvent molecules in their intrinsic voids. © 2016 The Royal Society of Chemistry.

Majchrzycki L.,Central Laboratory of Batteries And Cells | Majchrzycki L.,Poznan University of Technology | Majchrzycki L.,Wielkopolska Center for Advanced Technologies | Walkowiak M.,Central Laboratory of Batteries And Cells | And 4 more authors.
Materials Science- Poland | Year: 2016

Nowadays reduced graphene oxide (rGO) is regarded as a highly interesting material which is appropriate for possible applications in electrochemistry, especially in lithium-ion batteries (LIBs). Several methods were proposed for the preparation of rGO-based electrodes, resulting in high-capacity LIBs anodes. However, the mechanism of lithium storage in rGO and related materials is still not well understood. In this work we focused on the proposed mechanism of favorable bonding sites induced by additional functionalities attached to the graphene planes. This mechanism might increase the capacity of electrodes. In order to verify this hypothesis the composite of non-reduced graphene oxide (GO) with multiwalled carbon nanotubes electrodes was fabricated. Electrochemical properties of GO composite anodes were studied in comparison with similarly prepared electrodes based on rGO. This allowed us to estimate the impact of functional groups on the reversible capacity changes. As a result, it was shown that oxygen containing functional groups of GO do not create, in noticeable way, additional active sites for the electrochemical reactions of lithium storage, contrary to what has been postulated previously. © 2016 Wroclaw University of Technology.

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 | Year: 2015

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.

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.
CrystEngComm | Year: 2016

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.

Gorczynski A.,Adam Mickiewicz University | Marcinkowski D.,Adam Mickiewicz University | Marcinkowski D.,University of Life Sciences in Poznań | Pakulski D.,Adam Mickiewicz University | And 6 more authors.
Arabian Journal of Chemistry | Year: 2016

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.

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 | Year: 2015

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.

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 | Year: 2015

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.

Petryk M.,Adam Mickiewicz University | Petryk M.,Wielkopolska Center for Advanced Technologies | Szymkowiak J.,Adam Mickiewicz University | Szymkowiak J.,Wielkopolska Center for Advanced Technologies | And 6 more authors.
Organic and Biomolecular Chemistry | Year: 2016

A one-pot synthesis of chiral [4 + 6] tetrahedral cage compounds containing a salen fragment on each face is presented. The formation of the [4 + 6] products remains in contrast to the reaction of 1,3,5-triformylphloroglucinol with chiral diamines where [2 + 3] keto-enamine pseudocyclophanes are formed exclusively. The presence of OH groups determines the structural and spectroscopic properties of these cage compounds while a change in the reaction conditions facilitates the isolation of the microcrystalline products of the specific surface area varying from 5 to 578 m2 g-1. © The Royal Society of Chemistry 2016.

Gajewy J.,Adam Mickiewicz University | Gajewy J.,Wielkopolska Center for Advanced Technologies | Szymkowiak J.,Adam Mickiewicz University | Szymkowiak J.,Wielkopolska Center for Advanced Technologies | And 2 more authors.
RSC Advances | Year: 2016

Chiral, triangular poly-azamacrocycles (trianglimines) readily available from enantiomerically pure trans-1,2-diaminocyclohexane and various aromatic dialdehydes, differ in their nature and substitution pattern. The highly symmetrical macrocycle having two electron-donating groups attached to the aryl moieties is formed under thermodynamic control that fulfilled the so called entropy of symmetry rule. Conversely, from the 2-nitroterephthaldehyde a kinetic product of trivial C1 symmetry is solely obtained, whereas from 2-methoxyterepthaldehyde a mixture of C3- and C1-symmetrical macrocycles are formed. The factors that contribute to the mechanism of the macrocycle formation were determined on the basis of an experimental/theoretical approach. The non-symmetrical structure of the macrocycle resulted from a symmetrical intermediate that appeared during cyclocondensation. The chiroptical properties of the trianglimines were studied by means of experimental ECD and VCD methods supported by quantum-chemical calculations. The nitro-substituted trianglimine appeared to be a simple, low molecular weight supergelator forming in polar media of stable chiral organogels. The structure of the gel is affected by the nature and chirality of the dopant. The hexaimine macrocycles after reduction of the CN imine bonds formed trianglamines-useful chiral ligands in stereoselective synthesis. The Zn-trianglamine complexes were employed as catalysts for asymmetric hydrosilylation of prochiral ketones, providing products of enantiomeric excess up to 98%. This remains the best result obtained for Zn-diamine catalysed asymmetric hydrosilylation of ketones so far. © 2016 The Royal Society of Chemistry.

Gorczynski A.,Adam Mickiewicz University | Zaranek M.,Adam Mickiewicz University | Zaranek M.,Wielkopolska Center for Advanced Technologies | Witomska S.,Adam Mickiewicz University | And 8 more authors.
Catalysis Communications | Year: 2016

Condensation of 1-methyl-2-imidazolecarboxaldehyde with 2-(1-methylhydrazinyl)pyridine results in the synthesis of new, tridentate Schiff-base ligand L, which readily reacts with CoCl2 to form a monometallic [CoLCl2] complex that, upon reduction, functions as active hydrosilylation catalyst. The ligand and the [CoLCl2] catalyst have been characterized spectroscopically (MS, NMR, FTIR) and by single crystal X-ray diffraction techniques. The results of preliminary catalytic experimentation show that the cobalt complex can induce hydrosilylation and dehydrogenative silylation of olefins, depending upon the hydrosilane substrate used. © 2016 Elsevier B.V. All rights reserved.

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