Search results for: Nikodem Kuźnik

Items from 1 to 16 out of 16 results

article

Otoczkowanie nawozów saletrzanych modelowymi substancjami chelatowymi

Ryszard Grzesik, Ewa Pankalla, Nikodem Kuźnik

Przemysł Chemiczny > 2022 > T. 101, nr 10 > 810--814

Przedstawiono badania powlekania nawozów saletrzanych wodnymi roztworami chelatów mikroelementowych dostępnych komercyjnie. Doktorat wdrożeniowy zakłada rozszerzenie portfolio produktowego Grupy Azoty ZAK SA o nawozy z zawartością mikroskładników w formach schelatowanych, zarówno w formie ciekłej, jak i stałej.

article

Zastosowanie kompleksów L-cysteiny z mikroelementami do nawożenia roślin

Ryszard Grzesik, Nikodem Kuźnik

Przemysł Chemiczny > 2022 > T. 101, nr 7 > 485--490

Otrzymano chelaty L-cysteiny z metalami przejściowymi stanowiącymi grupę mikroelementów pokarmowych dla większości roślin uprawnych. Podjęto badania w kierunku rozszerzenia portfolio produktowego Grupy Azoty ZAK SA o RSM z zawartością mikroskładników w formach schelatowanych. Wykonano badania fitotronowe 3 produktów kompleksowania związków nieorganicznych L-cysteiną. Badania fitotronowe zostały przeprowadzone...

article

Synthesis of Extended 1,3,4‐Oxadiazole and 1,3,4‐Thiadiazole Derivatives in the Suzuki Cross‐coupling Reactions

Monika Wróblowska, Agnieszka Kudelko, Nikodem Kuźnik, Katarzyna Łaba, more

Journal of Heterocyclic Chemistry > 54 > 2 > 1550 - 1557

New derivatives of 1,3,4‐oxadiazole and 1,3,4‐thiadiazole were synthesized by a palladium catalyzed Suzuki cross‐coupling reaction under the conditions of the phase transfer catalysis. The structure of the products, the absorption and emission spectra were also studied.

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Iron(III) Contrast Agent Candidates for MRI: a Survey of the Structure–Effect Relationship in the Last 15 Years of Studies

Nikodem Kuźnik, Marzena Wyskocka

European Journal of Inorganic Chemistry > 2016 > 4 > 445 - 458

Iron(III) complexes are under investigation as MRI contrast agents, and new challenges have delineated the way they are being developed. This review article describes the enhanced features that have been develolped in the last 15 years of research. The consequences of relaxation theory impose kinetic, thermodynamic, and structural requirements on the potential contrast agent. Iron, as an endogenous...

article

Synthesis of 3-arylquinazolin-4(3H)-imines from 2-amino-N′-arylbenzamidines and triethyl orthoformate

Wojciech Szczepankiewicz, Nikodem Kuźnik

Tetrahedron Letters > 2015 > 56 > 10 > 1198-1199

The synthesis of several 3-arylquinazolin-4(3H)-imines by the simple heating of 2-amino-N′-arylbenzamidines in triethyl orthoformate solution at 100°C is described.

article

Fe3+ ions anchored to Fe@O-MWCNTs as double impact T2 MRI contrast agents

Nikodem Kuźnik, Mateusz M. Tomczyk, Sławomir Boncel, Artur P. Herman, more

Materials Letters > 2014 > 136 > C > 34-36

Fe3+ ions were anchored via complexation onto the oxidized multiwall carbon nanotubes containing encapsulated iron-based nanoparticles (Fe@O-MWCNTs) yielding hybrids Fe(III)/Fe@O-MWCNTs for application as MRI contrast agents. After washing, no free Fe3+ ions were observed in the solution. A 120 mg Fe3+ was coordinated by each 1 gram of Fe@O-MWCNTs with a formation of stable hybrids. Relaxation times...

article

A study on the synthesis and properties of substituted EHBG-Fe(III) complexes as potential MRI contrast agents

Nikodem Kuźnik, Grażyna Szafraniec-Gorol, Lidia Oczek, Artur Grucela, more

Journal of Organometallic Chemistry > 2014 > 769 > Complete > 100-105

Mono- and disubstituted EHBG (HBED) ligands of different kind: forming hydrogen bonds (p-OMe, p-NHAc) and of high lipophilicity (3,4-Me ₂ , p-Ph) were obtained. The ligands were complexed with Fe(III). Complexes so obtained were studied for their stability in different pH environments; and r ₁ relaxivity, which turned out the highest for Fe-EHBG-NHAc, i.e. 0.95 mM ⁻¹ s ...

article

An approach for disaccharide chiron synthesis using a Ferrier-type rearrangement

Katarzyna Komor, Wiesław Szeja, Tadeusz Bieg, Nikodem Kuźnik, more

Tetrahedron Letters > 2014 > 55 > 27 > 3709-3712

We report a new approach for the synthesis of new chiral synthons in which two unsaturated sugars are linked via a glycosidic bond. The di-unsaturated disaccharide can be further functionalized using effective, highly selective methods and used in convergent syntheses of relatively complex glycoconjugates. Our approach utilizes in situ generation of active glycosyl donors via Ferrier-type rearrangement...

article

A new class of bioactivable self-immolative N,O-ligands

Nikodem Kuźnik, Arkadiusz Chrobaczyński, Małgorzata Mika, Patrycja Miler, more

European Journal of Medicinal Chemistry > 2012 > 52 > Complete > 184-192

A hexadentate ligand built on an amine-bis(phenol) skeleton with an aminal, self-immolative moiety is presented. Synthesis of the ligand is convenient and relatively high yielded. Moreover, it enables synthesis of many derivatives, both in the amino-phenol and aminal fragment (various heterocycles). Once the final hexadentate ligand is synthesized via the Katritzky reaction, it becomes prone to hydrolysis...

article

3-Triphenylphosphonio-2,5-piperazinediones as new chiral glycine cation equivalents

Tadeusz Gorewoda, Roman Mazurkiewicz, Wojciech Simka, Grzegorz Mlostoń, more

Tetrahedron: Asymmetry > 2011 > 22 > 8 > 823-833

3-Triphenylphosphonio-2,5-piperazinediones were effectively synthesized from homochiral valine or proline via Boc-Val-Gly-OMe, Boc-Pro-Gly-OMe or Cbz-Pro-Gly-OMe. Retention of configuration of the primary stereogenic center of the valine and proline moieties was observed. Diastereoselective nucleophilic substitution of the triphenylphosphonium group in 2,5-piperazinediones with S-, N-, P- and C-nucleophiles...

article

A new method for the synthesis of mixed orthoesters from O-allyl acetals

Stanisław Krompiec, Robert Penczek, Piotr Bujak, Ewelina Kubik, more

Tetrahedron Letters > 2009 > 50 > 11 > 1193-1195

Two new methods for the synthesis of orthoesters and compounds containing an orthoester moiety (dihydroisoxazoles) are presented. Mixed orthoesters of general formulas RC(OR ¹ )(OR ² ) ₂ and RC(OR ¹ )(OR ² )(OR ³ ) were prepared via addition of ROH (R=Bu or m-methylphenyl) to O-allyl acetals (acrolein acetals: diethyl or cyclic, i.e., 2-vinyl-1,3-dioxanes...

article

Transition metal complexes as catalysts of double-bond migration in O-allyl systems

Nikodem Kuźnik, Stanisław Krompiec

Coordination Chemistry Reviews > 2007 > 251 > 1-2 > 222-233

This review provides a literature survey of the double-bond migration in O-allyl systems catalyzed by transition metal complexes: allyl aryl, allyl alkyl ethers, cyclic ethers, such as 2,5-dihydrofurane and cyclic acetals, e.g. 4,7-dihydro-1,3-dioxepine derivatives and allyl silyl ethers. The most frequently used catalysts are ruthenium and rhodium phosphine complexes, but other compounds, such as...

article

A selective and convenient ruthenium mediated method for the synthesis of mixed acetals and orthoesters

Stanisław Krompiec, Robert Penczek, Nikodem Kuźnik, Jan Grzegorz Małecki, more

Tetrahedron Letters > 2007 > 48 > 1 > 137-140

Addition of alcohols and phenols to O-allyl compounds (allyl ethers and acrolein acetals), catalyzed by [RuCl ₂ (PPh ₃ ) ₃ ], was examined. Intramolecular addition of an OH group, leading to the formation of cyclic acetals and orthoesters, was also investigated. As a result, a new, selective and convenient method for the synthesis of symmetrical and unsymmetrical (mixed) acetals...

article

Isomerization of alkyl allyl and allyl silyl ethers catalyzed by ruthenium complexes

Stanisław Krompiec, Nikodem Kuźnik, Magdalena Urbala, Józef Rzepa

Journal of Molecular Catalysis. A, Chemical > 2006 > 248 > 1-2 > 198-209

The results of double-bond migration in alkyl allyl and allyl silyl ethers catalyzed by ruthenium complexes [RuClH(CO)(PPh ₃ ) ₃ ] and in situ forming catalytic system {[RuCl ₂ (cod)] _x } with hydride and a phosphine) are presented. The conversion of allyl to 1-propenyl ethers is quantitative. The mechanism of double-bond migration has been investigated on deuterated...

article

Highly selective isomerization of N-allylamides catalyzed by ruthenium and rhodium complexes

Stanisław Krompiec, Mariola Pigulla, Nikodem Kuźnik, Michał Krompiec, more

Journal of Molecular Catalysis. A, Chemical > 2005 > 225 > 1 > 91-101

Isomerization of N-allylamides catalyzed by ruthenium and rhodium complexes to corresponding 1-propenyl derivatives is described. The first catalytic system containing a precursor ({[RuCl ₂ (1,5-COD)] _x }), tris(2,4-di-t-butylphenyl)phosphite and CaH ₂ for highly (Z)-selective isomerization of allylamides is presented. It has been shown that the double bond migration catalyzed...

article

Highly selective synthesis of (E)-N-aryl-N-(1-propenyl) ethanamides via isomerization of N-allyl ethanamides catalyzed by ruthenium complexes

Stanislaw Krompiec, Mariola Pigulla, Wojciech Szczepankiewicz, Tadeusz Bieg, more

Tetrahedron Letters > 2001 > 42 > 40 > 7095 - 7098

A convenient and highly selective method of synthesis of (E)-N-aryl-N-(1-propenyl)ethanamides via isomerization of respective N-allyl-N-arylethanamides catalyzed by [RuClH(CO)(PPh ₃ ) ₃ ] has been described. N-Allyl-N-arylethanamides have been obtained by allylation of respective N-arylethanamides under PTC conditions. It is proposed that the observed selectivity of the double bond...

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