Tetyana Beryozkina

“Hairy” Poly(3-hexylthiophene) Particles Prepared via Surface-Initiated Kumada Catalyst-Transfer Polycondensation

Herein, we present a new paradigm in the engineering of nanostructured hybrids between conjugated polymer and inorganic materials via a chain-growth surface-initiated Kumada catalyst-transfer polycondensation (SI-KCTP) from particles. Poly(3-hexylthiophene), P3HT, a benchmark material for organic electronics, was selectively grown by SI-KCTP from (nano)particles bearing surface-immobilized Ni catalysts supported by bidentate phosphorus ligands, that resulted in hairy (nano)particles with end-tethered P3HT chains. Densely grafted P3HT chains exhibit strongly altered optical properties compared to the untethered counterparts (red shift and vibronic fine structure in absorption and fluorescence spectra), as a result of efficient planarization and chain-aggregation. These effects are observed in solvents that are normally recognized as good solvents for P3HT (e.g., tetrahydrofurane). We attribute this to strong interchain interactions within densely grafted P3HT chains, which can be tuned by changing the surface curvature (or size) of the supporting particle. The hairy P3HT nanoparticles were successfully applied in bulk heterojunction solar cells.

Grafting of Polyfluorene by Surface‐Initiated Suzuki Polycondensation

Graft work: The first surface-initiated and site-specific palladium-catalyzed Suzuki polycondensation that allows selective grafting and patterning of semiconducting and emissive poly[9,9-bis(2-ethylhexyl)fluorene] (1) at room temperature is developed (see scheme). The patterning is demonstrated by AFM (see image).

Surface Engineering Using Kumada Catalyst-Transfer Polycondensation (KCTP): Preparation and Structuring of Poly(3-hexylthiophene)-Based Graft Copolymer Brushes

Poly(4-vinylpyridine)-block-poly(4-iodo-styrene), P4VP-b-PS(I), block copolymers obtained by iodination of readily available P4VP-b-PS block copolymers strongly adhere to variety of polar substrates including Si wafers, glasses, or metal oxide surfaces by a polar P4VP block, forming polymer brushes of moderately stretched PS(I) chains. Kumada catalyst-transfer polycondensation (KCTP) from the P4VP-b-PS(I) brushes results into planar brushes of the graft copolymer in which relatively short ( approximately 10 nm) poly(3-hexylthiophene), P3HT, grafts emanate from the surface-tethered PS(I) chains. Grafting of the P3HT leads to significant stretching of the PS(I) backbone as a result of increased excluded volume interactions. Specific adsorption of the P4VP block to polar surfaces was utilized in this work to pattern the P4VP(25)-b-PS(I)(350) brush. The microscopically structured P4VP(25)-b-PS(I)(350) brush was converted into the respectively patterned P4VP-PS(I)-g-P3HT one using KCTP. We also demonstrated that KCTP from functional block copolymers is an attractive option for nanostructuring with polymer brushes. P4VP(75)-b-PS(I)(313) micelles obtained in selective solvent for the PS(I) block form a quasi-ordered hexagonal array on Si wafer. The P4VP(75)-b-PS(I)(313) monolayer preserves the characteristic quasi-regular arrangement of the micelles even after extensive rinsing with various solvents. Although the grafting of P3HT from the nanopatterned P4VP(75)-b-PS(I)(313) brush destroys the initial order, the particulate morphology in the resulting film is preserved. We believe that the developed method to structured brushes of conductive polymers can be further exploited in novel stimuli-responsive materials, optoectronic devices, and sensors.

Palladium‐Catalyzed Chain‐Growth Polycondensation of AB‐type Monomers: High Catalyst Turnover and Polymerization Rates

Chain-growth catalyst-transfer polycondensations of AB-type monomers is a new and rapidly developing tool for the preparation of well-defined π-conjugated (semiconducting) polymers for various optoelectronic applications. Herein, we report the Pd/PtBu3-catalyzed Negishi chain-growth polycondensation of AB-type monomers, which proceeds with unprecedented TONs of above 100,000 and TOFs of up to 280 s(-1). In contrast, related AA/BB-type step-growth polycondensation proceeds with two orders of magnitude lower TONs and TOFs. A similar trend was observed in Suzuki-type polycondensation. The key impact of the intramolecular (vs. intermolecular) catalyst-transfer process on both polymerization kinetics and catalyst lifetime has been revealed.

High Conductivity in Molecularly p‐Doped Diketopyrrolopyrrole‐Based Polymer: The Impact of a High Dopant Strength and Good Structural Order

[3]-Radialene-based dopant CN6-CP studied herein, with its reduction potential of +0.8 versus Fc/Fc+ and the lowest unoccupied molecular orbital level of -5.87 eV, is the strongest molecular p-dopant reported in the open literature, so far. The efficient p-doping of the donor-acceptor dithienyl-diketopyrrolopyrrole-based copolymer having the highest unoccupied molecular orbital level of -5.49 eV is achieved. The doped films exhibit electrical conductivities up to 70 S cm(-1) .

A Novel Heterocyclic Compound CE-104 Enhances Spatial Working Memory in the Radial Arm Maze in Rats and Modulates the Dopaminergic System.

Various psychostimulants targeting monoamine neurotransmitter transporters (MATs) have been shown to rescue cognition in patients with neurological disorders and improve cognitive abilities in healthy subjects at low doses. Here, we examined the effects upon cognition of a chemically synthesized novel MAT inhibiting compound 2-(benzhydrylsulfinylmethyl)-4-methylthiazole (named as CE-104). The efficacy of CE-104 in blocking MAT [dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter] was determined using in vitro neurotransmitter uptake assay. The effect of the drug at low doses (1 and 10 mg/kg) on spatial memory was studied in male rats in the radial arm maze (RAM). Furthermore, the dopamine receptor and transporter complex levels of frontal cortex (FC) tissue of trained and untrained animals treated either with the drug or vehicle were quantified on blue native PAGE (BN-PAGE). The drug inhibited dopamine (IC50: 27.88 μM) and norepinephrine uptake (IC50: 160.40 μM), but had a negligible effect on SERT. In the RAM, both drug-dose groups improved spatial working memory during the performance phase of RAM as compared to vehicle. BN-PAGE Western blot quantification of dopamine receptor and transporter complexes revealed that D1, D2, D3, and DAT complexes were modulated due to training and by drug effects. The drug’s ability to block DAT and its influence on DAT and receptor complex levels in the FC is proposed as a possible mechanism for the observed learning and memory enhancement in the RAM.

Thermal Rearrangements and Transformations of 1,2,3-Triazoles

This chapter concentrates on the thermal rearrangements and transformations of 1,2,3-triazoles. It also contains data on the ring-chain tautomerism of 1,2,3-triazoles and the substituent effect on the position of the equilibrium between diazoimines and 1,2,3-triazoles. The main part of this review has been devoted to transition-metal-catalyzed denitrogenative transformation of 1,2,3-triazoles.

Copolymerization of zinc-activated isoindigo- and naphthalene-diimide based monomers: an efficient route to low bandgap π-conjugated random copolymers with tunable properties

The present work aims at the extension of the scope of a recently discovered polycondensation of AB-type anion-radical monomers. To this end, we investigate the polymerization of isoindigo-based monomer and its copolymerization with the naphthalenediimide-based monomer. Although polycondensations of parent naphthalenediimide- and perylenediimide-based monomers involve chain-growth mechanism, we found that the corresponding isoindigo-based monomer polymerizes in a step-growth manner under the same reaction conditions. In contrast to Stille, Suzuki and direct arylation polycondensations which require prolonged stirring at high temperatures, the polymerization approach we employed in this study proceeds fast at room temperature. It was found that near statistical copolymerization of isoindigo-based anion-radical monomers with corresponding naphtalenediimide-based monomers proceeds smoothly resulting in a library of copolymers with varying composition and properties depending on the ratio of the monomers.

A novel heterocyclic compound improves working memory in the radial arm maze and modulates the dopamine receptor D1R in frontal cortex of the Sprague-Dawley rat

&NA; A series of compounds have been shown to enhance cognitive function via the dopaminergic system and indeed the search for more active and less toxic compounds is continuing. It was therefore the aim of the study to synthetise and test a novel heterocyclic compound for cognitive enhancement in a paradigm for working memory. Specific and effective dopamine re‐uptake inhibition DAT (IC50 = 4,1 ± 0,8 &mgr;M) made us test this compound in a radial arm maze (RAM) in the rat. CE‐125 (4‐((benzhydrylsulfinyl)methyl)‐2‐cyclopropylthiazole), was tested for dopamine (DAT), serotonin and norepinephrine re‐uptake inhibition by a well‐established system. The working memory index (WMI) was evaluated in male Sprague Dawley rats that were intraperitoneally injected with CE‐125 (1 or 10 mg/kg body weight). In order to evaluate basic neurotoxicity, the open field, elevated plus maze, rota rod studies and the forced swim test were carried out. Frontal cortex was taken at the last day of the RAM test and dopamine receptors D1R and D2R, DAT and phosphorylated DAT protein levels were determined. On the 10th day both doses were increasing the WMI as compared to the vehicle‐treated group. In both, trained and treated groups, D1R levels were significantly reduced while D2R levels were unchanged. DAT levels were comparable between all groups while phosphorylated DAT levels were increased in the trained group treated with 1 mg/kg body weight. CE‐125 as a probably non‐neurotoxic compound and specific reuptake inhibitor was shown to increase performance (WMI) and modulation of the dopaminergic system is proposed as a possible mechanism of action. HighlightsCE‐125 is non‐neurotoxic compound and specific DAT reuptake inhibitor.CE‐125 improvesspatial memoryperformance and increases the WMI in aradial arm maze.CE‐125 modulates the dopamine receptor D1R.

Multicomponent and domino reactions of 3-aroylacrylic acids in the synthesis of heterocycles

This review generalizes the data available on heterocyclizations of 3-aroylacrylic acids and their esters, published over the previous 15 years. Multicomponent, cascade, and domino reactions, as well as cycloaddition and electrocyclization reactions involving 3-aroylacrylic acids and their esters have been used to obtain five- and six-membered aromatic and non-aromatic (including chiral) oxygen- or nitrogen-containing monocyclic heterocycles, spiro compounds, as well as condensed bi- and tricyclic systems.