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Your search keyword '"Kovács, Margit"' showing total 182 results
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182 results on '"Kovács, Margit"'

1. Investigation of Host–Guest Interactions in 2-Ureido-4-ferrocenylpyrimidine Derivatives.

Author

Váradi, Márk, Keszei, Soma J., Gömöry, Ágnes, Kovács, Margit, Kégl, Tamás, Fodor, Lajos, and Skoda-Földes, Rita

Abstract

In the present study, synthesis, conformational behavior, host–guest complex formation, and electrochemical properties of novel 6-substituted-2-ureido-4-ferrocenylpyrimidines were explored. A comprehensive NMR spectroscopic investigation was carried out to confirm the structure and conformational equilibrium of the ureidopyrimidines through studying the temperature- and concentration dependence of NMR spectra. Low-temperature NMR measurements were used to clarify structural changes inflicted by a 2,6-diaminopyridine guest. Association constant (Kassoc) values of host–guest complexes were calculated based on low-temperature titrations. It was shown that the introduction of a pyridin-2-yl substituent in the pyrimidine ring in host 10 induced a considerable change not only in the conformational equilibrium of the host itself but also in that of the host–guest complex. Geometries and relative stabilities of the conformers of host 10 as well as its host–guest complexes were determined by quantum chemical calculations. Electrochemical behavior of ureidopyrimidine hosts and host–guest complexes was investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) measurements. Two ureidopyrimidine derivatives were immobilized on the surface of spectral graphite electrodes, and their electrochemical response on the addition of 2,6-diaminopyridine was compared. These results also supported the importance of the pyridin-2-yl substituent in the efficient sensing of the guest. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Synthesis of 6- or 8-Carboxamido Derivatives of Imidazo[1,2- a ]pyridines via a Heterogeneous Catalytic Aminocarbonylation Reaction.

Author

Nagy, Enikő, Máriás, Attila, Kovács, Margit, and Skoda-Földes, Rita

Subjects
CATALYSTS recycling, PALLADIUM catalysts, CATALYST supports, HETEROGENEOUS catalysts, AMIDE derivatives, IMIDAZOPYRIDINES
Abstract

Imidazo[1,2-a]pyridines and especially their amide derivatives exhibit a wide range of favourable pharmacological properties. In this work, Pd-catalysed carbonylation was used for the first time for the introduction of the carboxamide moiety into positions 6 or 8. A recyclable Pd catalyst, with palladium immobilised on a supported ionic liquid phase decorated with pyridinium ions, was used efficiently for the conversion of 6- or 8-iodo derivatives to the products. In the case of 6-iodo derivatives, a competing mono- and double carbonylation could be observed in the reactions of aliphatic amines as nucleophiles, but under the proper choice of reaction conditions, good-to-excellent selectivities could be achieved towards either the corresponding amides or α-ketomides. The heterogeneous catalyst showed excellent recyclability and low Pd-leaching. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Asymmetric Hydrogenation of Ketones by Simple Alkane-Diyl-Based Ir(P,N,O) Catalysts: A Comparative Study.

Author

Császár, Zsófia, Guóth, Mária, Kovács, Margit, Bényei, Attila C., Bakos, József, and Farkas, Gergely

Subjects
MODULAR construction, LIGANDS (Biochemistry), LIGANDS (Chemistry), BIOCHEMICAL substrates, CATALYTIC activity, HYDROGENATION, TRANSITION metal catalysts
Abstract

The development of new chiral ligands with simple and modular structure represents a challenging direction in the design of efficient homogeneous transition metal catalysts. Herein, we report on the asymmetric hydrogenation of prochiral ketones catalyzed by the iridium complexes of simple alkane-diyl-based P,N,O-type chiral ligands with a highly modular structure. The role of (i) the P-N and N-O backbone in the potentially tridentate ligands, (ii) the number, position and relative configuration of their stereogenic elements and (iii) the effect of their NH and OH subunits on the activity and enantioselectivity of the catalytic reactions are studied. The systematic variation in the ligand structure and the comparative catalytic experiments shed light on different mechanistic aspects of the iridium-catalyzed reaction. The catalysts containing the simple alkane-diyl-based ligands with central chirality provided high enantioselectivities (up to 98% ee) under optimized reaction conditions and proved to be active and selective even at very high substrate concentrations (100 mmol substrate/mL solvent). [ABSTRACT FROM AUTHOR]

Published
2024
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18. The HLA 8.1 ancestral haplotype is strongly linked to the C allele of −429T > C promoter polymorphism of receptor of the advanced glycation endproduct (RAGE) gene. Haplotype-independent association of the −429C allele with high hemoglobin A1C levels in diabetic patients

Author

Laki, Judit, Kiszel, Petra, Vatay, Ágnes, Blaskó, Bernadett, Kovács, Margit, Körner, Anna, Madácsy, László, Blatniczky, László, Almássy, Zsuzsa, Szalai, Csaba, Rajczy, Katalin, Pozsonyi, Éva, Karádi, István, Fazakas, Ádám, Hosszúfalusi, Nóra, Pánczél, Pál, Arason, Gudmundur J., Wu, Yee-Ling, Zhou, Bi, Yang, Yan, Yu, C.-Yung, and Füst, George

Published
2007
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26. The HLA 8.1 ancestral haplotype is strongly linked to the C allele of −429T > C promoter polymorphism of receptor of the advanced glycation endproduct (RAGE) gene. Haplotype-independent association of the −429C allele with high hemoglobinA1C levels in diabetic patients

Author

Laki, Judit, Kiszel, Petra, Vatay, Ágnes, Blaskó, Bernadett, Kovács, Margit, Körner, Anna, Madácsy, László, Blatniczky, László, Almássy, Zsuzsa, Szalai, Csaba, Rajczy, Katalin, Pozsonyi, Éva, Karádi, István, Fazakas, Ádám, Hosszúfalusi, Nóra, Pánczél, Pál, Arason, Gudmundur J., Wu, Yee-Ling, Zhou, Bi, Yang, Yan, Yu, -Yung C., and Füst, George

Published
2007
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38. Synthesis, photophysical and photochemical characterization of novel functionalized 2, 3- distyrylfurans ; Substituent and solvent effects on their photobehaviour

Author

Kikaš, Ilijana, Kovács, Margit, Meščić, Andrijana, Šindler, Marija, Škorić, Irena, and Horváth, Otto

Subjects
3-distyrylfurans, photophysical characterization, substituent and solvent effect, synthesis
Abstract

Furan derivatives are of great importance due to their role in organic chemistry as building blocks in various synthetic routes and because they are involved in numerous natural compounds [1]. Unsaturated furan and benzofuran derivatives are convenient starting materials for photochemical reactions [2]. These types of compounds offer potential applications as fluorescent probes in biology and medicine, in environmental sciences as well as in optoelectronics [3]. Besides, some 2, 3-distyryl-substituted furan derivatives proved to be applicable in electrophotographic photoreceptors as charge transporting agents [4]. In this work, synthesis, photophysical and photochemical study of some novel 2, 3- distyrylfuran derivatives have been realized. In these hexatriene systems with the central double bond incorporated into the furan ring, both the characteristic absorption and the emission bands proved to be significantly influenced by the substituent on the phenyl groups. Solvent polarity strongly affected the quantum yields for both the photochemical reaction and the fluorescence of these compounds, indicating a higher dipole moment of the excited state in these photoinduced processes. [1] Th.L. Gilchrist, Heterocyclic Chemistry, Longman, Singapore, 1997. [2] I. Škorić, N. Basarić, Ž. Marinić, A. Višnjevac, B. Kojić-Prodić, M. Šindler-Kulyk, Chem. Eur. J. 11 (2005) 543-551 and references therein. [3] B. Valeur, Molecular Fluorescence–Principles and Applications, Wiley-VCH, Weinheim, 2002. [4] Z.Z. Song, H.N.C.Wong, Y. Yang, Pure Appl. Chem. 68 (1996) 723–726 ; V. Vuligonda, M.E. Garst, A.S. Chandraratna, Bioorg. Med. Chem. Lett. 9 (1999) 589–594. This work was supported by the Ministry of Science, Education and Sports of the Republic of Croatia and the National Office of Research and Technology (OMFB-01247/2009).

Published
2010

39. Metal-metal bond or isolated metal centers? Interaction of Hg(CN)(2) with square planar transition metal cyanides

Author

Jószai, Róbert, Beszeda, Imre, Bényei, Attila C., Fischer, Andreas, Kovács, Margit, Maliarik, Mikhail, Nagy, Péter, Shchukarev, Andrey, Tóth, Imre, Jószai, Róbert, Beszeda, Imre, Bényei, Attila C., Fischer, Andreas, Kovács, Margit, Maliarik, Mikhail, Nagy, Péter, Shchukarev, Andrey, and Tóth, Imre

Abstract

Three adducts have been prepared from Hg(CN)(2) and square planar M-II(CN)(4)(2-) transition metal cyanides (M = Pt, Pd, or Ni, with d(8) electron shell) as solids. The structure of the compounds K2PtHg(CN)(6)center dot 2H(2)O (1), Na2PdHg(CN)(6)center dot 2H(2)O (2), and K2NiHg(CN)(6)center dot 2H(2)O (3) have been studied by single-crystal X-ray diffraction, XPS, Raman spectroscopy, and luminescence spectroscopy in the solid state. The structure of K2PtHg(CN)(6)center dot 2H(2)O consists of one-dimensional wires. No CN- bridges occur between the heterometallic centers. The wires are strictly linear, and the Pt(II) and Hg(II) centers alternate. The distance d(Hg-Pt) is relatively short, 3.460 angstrom. Time-resolved luminescence spectra indicate that Hg(CN)2 units incorporated into the structure act as electron traps and shorten the lifetime of both the short-lived and longer-lived exited states in 1 compared to K-2[Pt(CN)(4)]center dot 2H(2)O. The structures of Na2PdHg(CN)(6)center dot 2H(2)O and K2NiHg(CN)(6)center dot 2H(2)O can be considered as double salts; the lack of heterometallophilic interaction between the remote Hg(II) and Pd(II) atoms, d(Hg-Pd) = 4.92 angstrom, and Hg(II) and Ni(II) atoms, d(Hg-Ni) = 4.61 angstrom, is apparent. Electron binding energy values of the metallic centers measured by XPS show that there is no electron transfer between the metal ions in the three adducts. In solution, experimental findings clearly indicate the lack of metal-metal bond formation in all studied Hg-II-CN--M-II(CN)(4)(2-) systems (M = Pt, Pd, or Ni).

Published
2005
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47. Frequency of Carriers of 8.1 Ancestral Haplotype and its Fragments in Two Caucasian Populations

Author

Kiszel, Petra, primary, Kovács, Margit, additional, Szalai, Csaba, additional, Yang, Yan, additional, Pozsonyi, Éva, additional, Blaskó, Bernadett, additional, Laki, Judit, additional, Prohászka, Zoltán, additional, Fazakas, Ádám, additional, Pánczél, Pál, additional, Hosszúfalusi, Nóra, additional, Rajczy, Katalin, additional, Wu, Yee-Ling, additional, Chung, Erwin K., additional, Zhou, Bi, additional, Blanchong, Carol A., additional, Vatay, Ágnes, additional, Yu, C. Yung, additional, and Füst, G., additional

Published
2007
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48. The HLA 8.1 ancestral haplotype is strongly linked to the C allele of −429T>C promoter polymorphism of receptor of the advanced glycation endproduct (RAGE) gene. Haplotype-independent association of the −429C allele with high hemoglobinA1C levels in diabetic patients

Author

Laki, Judit, primary, Kiszel, Petra, additional, Vatay, Ágnes, additional, Blaskó, Bernadett, additional, Kovács, Margit, additional, Körner, Anna, additional, Madácsy, László, additional, Blatniczky, László, additional, Almássy, Zsuzsa, additional, Szalai, Csaba, additional, Rajczy, Katalin, additional, Pozsonyi, Éva, additional, Karádi, István, additional, Fazakas, Ádám, additional, Hosszúfalusi, Nóra, additional, Pánczél, Pál, additional, Arason, Gudmundur J., additional, Wu, Yee-Ling, additional, Zhou, Bi, additional, Yang, Yan, additional, Yu, C.-Yung, additional, and Füst, George, additional

Published
2007
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