Roland Szalay - Academia.edu (original) (raw)
Papers by Roland Szalay
Platinum-complexes permanently play an important role in the medical treatment of tumor cells. Si... more Platinum-complexes permanently play an important role in the medical treatment of tumor cells. Since Pt has a soft-type Lewis acidic character, it forms the most stable complexes with S, P, N and I donor atoms, resulting planar (cisplatine) or octahedral (satraplatine) arrangement of ligands. In our research, new platinum complexes were synthesized with α-glyoximes, such as [Pt(diethyl-glyoxH)2(amine)2], where glyoxH = mono deprotonated glyoxime, amine = imidazole, 2-amino-pyrimidine or 3-hydroxy-aniline, and with Schiff bases, such as [Pt(3-heptanone)2(en)], [Pt(3-heptanone)2(1,2-pn)], [Pt(3-heptanone)2(1,3-pn)] (en = ethylenediamine, pn = propylenediamine). The Schiff bases were obtained with the condensation reaction between 3-heptanone and the corresponding diamines. The molecular structure of our products has been investigated by IR, UV–VIS and NMR spectroscopy, MS, thermoanalytical measurements (TG-DTG-DTA), and powder XRD. The biological activity study of compounds revealed t...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Hyperfine Interactions, 2018
Iron-oxide nanoparticles were prepared by chemical coprecipitation method in inert gas atmosphere... more Iron-oxide nanoparticles were prepared by chemical coprecipitation method in inert gas atmosphere and also in air atmosphere in order to use them as possible nutrition source for plants. The samples were characterized by 57 Fe Mössbauer spectroscopy, electron microscopy and PXRD measurements. The presence of considerable Fe II contributions were indicated by 57 Fe Mössbauer spectra. Furthermore TEM and XRD reflected nanomagnetite in washed and lyophilized samples prepared in inert gas atmosphere while the samples prepared in air atmosphere contained much higher amount of Fe III than characteristic of magnetite. In the case of samples prepared in inert gas, it was also shown that the immediate washing after the coprecipitation has a crucial influence on the Fe II content of the nanomagnetites. Keywords 57 Fe Mössbauer spectroscopy • Iron-oxide nanoparticles • Inert gas atmosphere synthesis • Plant nutrition • Fe(II) oxidation state This article is part of the Topical Collection on
Tetrahedron Letters, 2017
A comparative alcoholysis study of N-silylated derivatives of simple heterocyclic carboxamides (l... more A comparative alcoholysis study of N-silylated derivatives of simple heterocyclic carboxamides (lactams, imides, ureas) is presented. The second-order rate constant values span a range as wide as three orders of magnitude. On the basis of DFT calculations, a good correlation between reactivity and the Si...O distance was found within each family of compounds. The viability of two different reaction pathways was evaluated using a detailed computational mechanistic study of the methanolysis of cyclic urea homologues. Peculiarities in the single-crystal X-ray diffraction structures of the trimethylsilyl and trimethylsiloxy phthalimides are also discussed.
Hyperfine Interactions, 2013
Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethylglyoxime, methyl-isopropyl-gly... more Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethylglyoxime, methyl-isopropyl-glyoxime, [Fe(DioxH) 2 L 2 ] with and without axial ligands have been synthesized. 57 Fe Mössbauer spectroscopy showed different spin states in complexes with short alkyl chain and with branched alkyl chain, respectively. It was shown that the asymmetry observed in the doublet line intensity of ironbis-glyoximes is due to the texture effect. The effect of back-coordination was also studied in the case of iron-bis-dioxime complexes with branched alkyl chains, having different axial ligands.
In our research we synthesized novel [Pd(monophenyl-dioxime)2L2] (L = 2-aminopyrimidine, 3-hydrox... more In our research we synthesized novel [Pd(monophenyl-dioxime)2L2] (L = 2-aminopyrimidine, 3-hydroxi-aniline, lepidine) type complexes and with different Schiff-bases: [Pd(acetonyl-acetone)2(diamine)], [Pd(dibenzoyl-methane)2(diamine)] (diamine = ophenylene-diamine, ethylene-diamine, 1,2-, 1,3-propylene-diamine) by reacting PdCl2, monophenyl-dioxime, respectively Schiff-bases with amine, respectively diamine in the corresponding solvent. We analyzed their physicochemical properties using mass spectrometry, infrared-, NMR-spectroscopy and thermal analysis (TG, DTG and DTA). The Pd-complexes have an important role in many organic chemistry reactions as catalysts [1]. Some of them are used in industry. The Pd precious metal price is high, but compared with Rh, Pt, Ir, or Os is infinitesimal. Regarding the biological activity, they inhibit some enzymes which are important in anti-diabetic therapy. Some of the Pd(II) complexes are anti-glaucoma drug candidates [2]. Due to the similarity be...
In our research project new iron(II) complexes were synthesized with azomethines, such as [Fe(1,4... more In our research project new iron(II) complexes were synthesized with azomethines, such as [Fe(1,4-dibromo-2,3-butane-GlyoxH)2(3-HO-aniline)2], [Fe(1,4-dibromo-2,3-butaneGlyoxH)2(2-amino-pyrimidine)2], [Fe(4-benzyl-2-HO-propiophenone-GlyoxH)2], [Fe(5- methyl-2-hexanone)2(en)], [Fe(5-methyl-2-hexanone)2(1,2-pn)], [Fe(5-methyl-2-hexanone)2 (1,3-pn)], [Fe(5-methyl-2-hexanone)2(o-fen)], [Fe(2,4,5-trimethoxy-acetophenone-SC)2], [Fe(2,4,5-trimethoxy-acetophenone-TSC)2], [Fe(5-methyl-2-hexanone-SC)2], [Fe(5-methyl-2- hexanone-TSC)2], [Fe(Me-Pr-Glyox)3(BOH)2], [Fe(Me-Pr-Glyox)3(BOMe)2], [Fe(Me-i-BuGlyox)3(BOH)2], [Fe(Me-i-Bu-Glyox)3(BOMe)2], [Fe(Me-i-Bu-Glyox)3(BO-n-propyl)2] (en = ethylenedianine, pn = propylenediamine, fen = phenylenediamine, SC = semicarbazone, TSC = thiosemicarbazone), by reacting iron(II)-chloride with different glyoximes, Schiff-bases, semi- or thiosemicarbazones in suitable solvent. The Schiff-bases were obtained with the condensation of 5-methyl-2-hexanone, with diam...
Kutatásunk során új, Schiff-bázisokkal képzett [Fe(4-benzil-2-HO-propiofenon) 2 A], [Fe(2,4,6-tri... more Kutatásunk során új, Schiff-bázisokkal képzett [Fe(4-benzil-2-HO-propiofenon) 2 A], [Fe(2,4,6-trihidroxi-benzil-4-metoxifenil-keton) 2 A], [Fe(ninhidrin) 2 A] (A = etilén-diamin, 1,2-propilén-diamin, 1,3-propilén-diamin, o-fenilén-diamin) típusú komplexeket, állítottunk elő Fe(II)-só és a megfelelő Schiff-bázis reakciója során, a megfelelő oldószerben. A Schiff-bázisokat 4-benzil-2-hidroxi-propiofenon, 2,4,6-trihidroxi-benzil-4-metoxifenil-keton ill. ninhidrin diaminokkal való kondenzációjával nyertük. Rövid irodalmi áttekintés után, mely tartalmazza a vas-komplexek osztályozását és fejlődését, tanulmányoztuk az előállított vegyületek szerkezetét és kémiai sajátosságait FTIR, Mössbauer, UV-VIS, NMR, spektroszkópiai, tömegspektrometriai, termoanalitikai (TG-DTG-DTA), por-röntgen diffrakciós (XRD) módszerekkel, valamint biológiai aktivitásukat. E vegyületcsoport jelentőségét illetően, biokémiai szempontból fontosak, egyes képviselők antibakteriális szerek, valamint potenciális rákellenes gyógyszerek. Célkitűzésünk, az antibakteriális hatás és a rákos sejttenyészetek tanulmányozása a komplexeink jelenlétében.
Hyperfine Interactions, 2021
Dioximes as ligands are used as analytical reagents and serve as models for biological systems as... more Dioximes as ligands are used as analytical reagents and serve as models for biological systems as well as catalysts in chemical processes. A number of novel mixed complexes of the type [Fe(DioxH)2(amine)2] have been prepared and characterised by FTIR, 57Fe Mössbauer and mass spectroscopy by us. We have found strong Fe–N donor acceptor interactions and iron occurred in low-spin FeII state in all complexes. Later, we have also found that the incorporation of branching alkyl chains (isopropyl) in the complexes alters the Fe–N bond length and results in high-spin iron(II) state [1, 2]. The question arises: can the spin state of iron be manipulated generally by replacing the short alkyl chains with high volume demand ones in Fe-azomethine-amine complexes? To answer the question we have synthetized novel iron-bis-glioxime and iron-tris-gloxime complexes when long chain alkyl or aromatic ligands replaced the short alkyl ones and studied by 57Fe Mössbauer spectroscopy, MS, FTIR, UV-VIS, TG-...
Magyar Kémiai Folyóirat, 2020
Molecules, 2021
In this mini-review of our research group’s activity, the application of 57Fe Mössbauer spectrosc... more In this mini-review of our research group’s activity, the application of 57Fe Mössbauer spectroscopy in studies of electronic structure, coordination environment, and magnetic interactions in an interesting series of Fe(II/III) compounds selected is discussed. We selected two prominent phenomena that arose during investigations of selected groups of compounds carried out at different periods of time: (1) very high magnetic hyperfine fields observed at low temperatures; (2) changes in the oxidation state of the central iron atom of complexes in the solid state during interactions with gaseous O2/H2O mixtures, resulting in spin crossover (SCO).
Journal of Nanoparticle Research, 2018
57 Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic-and sa... more 57 Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic-and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic-and salicylic acidcoated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.
![Research paper thumbnail of Magnetic coupling and relaxation in Fe[N(SiPh2Me)2]2 molecular magnet](https://attachments.academia-assets.com/92041296/thumbnails/1.jpg)
](Structural Chemistry, 2016
In Fe[N(SiPh 2 Me) 2 ] 2 molecular magnet, an extraordinary B ≈ 92 T hyperfine field was found in... more In Fe[N(SiPh 2 Me) 2 ] 2 molecular magnet, an extraordinary B ≈ 92 T hyperfine field was found in the 5 K 57 Fe Mössbauer spectrum under an external magnetic field of 0.1 T. This evidences the presence of an unquenched orbital angular moment at the central iron atom. Fe[N(SiPh 2 Me) 2 ] 2 complex is thus shown to represent a further example of lowcoordinate iron complexes where quasi free-ion magnetism visualizes itself through an unquenched orbital moment. Magnetization measurements and hysteresis in magnetization indicated exchange coupling and nanosized magnetic units.
Journal of Radioanalytical and Nuclear Chemistry, 2017
The effect of coating with nine different carboxylic acids (glycolic, propionic, lactic, malic, t... more The effect of coating with nine different carboxylic acids (glycolic, propionic, lactic, malic, tartaric, citric, mandelic, caproic and caprylic) on nanostructured magnetite (D * 10 nm) was studied by Raman and photoacoustic, magnetic and 57 Fe Mössbauer measurements. Mössbauer spectra of frozen suspensions showed dominantly magnetically split envelopes at lower temperatures, which were evaluated by hyperfine field distribution method. Mössbauer and Raman spectroscopy indicated similar variation of relative occurrence of magnetite and maghemite phases. These results are discussed on the basis of the hypothesis that different carboxylic acids can promote either the oxidation or reduction of iron oxide nanoparticles.
![Research paper thumbnail of Preparation and characterization of novel [Fe(methylisopropylglyoximato)2(amine)2] mixed chelates](https://attachments.academia-assets.com/92041291/thumbnails/1.jpg)
](Journal of Radioanalytical and Nuclear Chemistry, 2014
A series of novel [Fe(MeiPrGlyoxH) 2 (amine) 2 ] complexes have been synthesized [(MeiPrGlyoxH 2 ... more A series of novel [Fe(MeiPrGlyoxH) 2 (amine) 2 ] complexes have been synthesized [(MeiPrGlyoxH 2 = methylisopropylglyoxime, amine = 3,5-dimethylpyridine, 4-(dimethylamino)pyridine, 4-(phenylamino)phenol, 2-imidazolidone)] and characterized by 57 Fe Mössbauer, FTIR, UV-Vis spectroscopy, mass spectrometry, AFM and thermoanalytical methods. Quantum chemical (DFT) computations of [Fe(MeiPrGlyoxH) 2 (3,5-dimethyl-Py) 2 ] (Py = pyridine) complex were also performed. The square-planar structure of [Fe(MeiPrGlyoxH) 2 ] moiety is similar to that of [Fe(MeEtGlyoxH) 2 ]. The incorporation of branching alkyl chains (isopropyl) in the complexes alters the Fe-N bond length and results in high-spin iron(II) state.
![Research paper thumbnail of Observation and interpretation of 157.5 T internal magnetic field in Fe[C(SiMe3)3]2 coordination compound](https://attachments.academia-assets.com/92041318/thumbnails/1.jpg)
](Structural Chemistry, 2009
The compound Fe[C(SiMe 3) 3 ] 2 has been prepared and investigated by the means of powder X-ray d... more The compound Fe[C(SiMe 3) 3 ] 2 has been prepared and investigated by the means of powder X-ray diffractometry and 57 Fe Mössbauer spectroscopy. The compound's unique geometry, in which iron is linearly coordinated by the two C(SiMe 3) 3 ligands, results in a unusual electronic structure of iron, which is visualized as an extreme high hyperfine magnetic field of 157.5(8) T as sensed by the 57 Fe nucleus at T = 20 K. In order to obtain information on the electronic structure of iron and on the bonds to the ligands, DFT (density functional theory) calculations were carried out on Fe[C(SiMe 3) 3 ] 2. The high-spin state of iron was found to be energetically favored: an Fe(II) electron configuration of 3d 5.83 4s 0.72 is predicted, where the 4s electron density is only slightly polarized, and most of the unpaired electrons have 3d character. By assuming a linear crystal field, and associated 3d level scheme as a starting point, it is suggested that the extreme high hyperfine magnetic field, observed along with an apparently negative quadrupole splitting, is perpendicular to the C-Fe(II)-C bond axis, and can be decomposed mainly into contact (B c & 44 T), dipolar (B d & 14 T), and orbital (B L & 99 T) hyperfine magnetic field contributions.
![Research paper thumbnail of 157 T internal magnetic field in Fe[C(SiMe3)3]2 compound at 20 K](https://attachments.academia-assets.com/92041298/thumbnails/1.jpg)
](Hyperfine Interactions, 2008
Fe[C(SiMe 3) 3 ] 2 compound, in which iron is coordinated by two carbons, was prepared using the ... more Fe[C(SiMe 3) 3 ] 2 compound, in which iron is coordinated by two carbons, was prepared using the reaction of FeCl 2 with (Me 3 Si) 3 CLi, and investigated by XRD, 57 Fe Mössbauer spectroscopy and DFT calculations. 157.5 T hyperfine magnetic field was found at the site of the iron nucleus of this compound at 20 K. DFT calculations predict the quintet states to be clearly favored energetically over the lower spin states. The population analysis reveals considerable 4s as well as large unpaired 3d electron contributions, which can be responsible for the extremely high hyperfine field.
A kémia központi helyet foglal el a tudományágak hálózatában. Mint az anyag atomi-molekuláris (il... more A kémia központi helyet foglal el a tudományágak hálózatában. Mint az anyag atomi-molekuláris (illetve szupramolekuláris) szerveződésével foglalkozó diszciplína, fogalmainak, módszereinek, ill. elméleteinek kialakításához jelentős mértékben épít az alapozó természettudományokra (fizika, matematika), ugyanakkor számtalan eredménye a legkülönfélébb tudományterületek (pl. a biológia, a földtudományok, az anyagtudomány) ismeretanyagát gazdagítja, illetve strukturálja. A kémia egyben rendkívüli változatossággal is rendelkezik az érdeklődési körébe tartozó objektumok számossága terén: elég csak megemlíteni azt a kb. 200 millió leírt vegyületet, mely a világ legnagyobb ilyen profilú adatbázisában szerepel, továbbá az anyagok között lejátszódó (leírt, illetve lehetséges) miriádnyi kémiai reakciót, melyek legbonyolultabb hálózatával valószínűleg éppen az élő szervezetekben lejátszódó biokémiai folyamatok esetében találkozhatunk. Az előadásban nemcsak a fentiekben idézett, hanem a kémiával a legszélesebb értelemben kapcsolatba hozható hálózatos struktúrák világába nyerünk bepillantást.
Journal of Colloid and Interface Science
A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29... more A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29 silica nanoparticles (29Si-silica NPs) with the purpose of using them as spikes for isotope dilution mass spectrometry (IDMS) quantification of silica NPs with natural isotopic distribution. Si-29 tetraethyl orthosilicate (29Si-TEOS), the silica precursor was prepared in two steps starting from elementary silicon-29 pellets. In the first step Si-29 silicon tetrachloride (29SiCl4) was prepared by heating elementary silicon-29 in chlorine gas stream. By using a multistep cooling system and the dilution of the volatile and moisture-sensitive 29SiCl4 in carbon tetrachloride as inert medium we managed to reduce product loss caused by evaporation. 29Si-TEOS was obtained by treating 29SiCl4 with absolute ethanol. Structural characterisation of 29Si-TEOS was performed by using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. For the NP...
Platinum-complexes permanently play an important role in the medical treatment of tumor cells. Si... more Platinum-complexes permanently play an important role in the medical treatment of tumor cells. Since Pt has a soft-type Lewis acidic character, it forms the most stable complexes with S, P, N and I donor atoms, resulting planar (cisplatine) or octahedral (satraplatine) arrangement of ligands. In our research, new platinum complexes were synthesized with α-glyoximes, such as [Pt(diethyl-glyoxH)2(amine)2], where glyoxH = mono deprotonated glyoxime, amine = imidazole, 2-amino-pyrimidine or 3-hydroxy-aniline, and with Schiff bases, such as [Pt(3-heptanone)2(en)], [Pt(3-heptanone)2(1,2-pn)], [Pt(3-heptanone)2(1,3-pn)] (en = ethylenediamine, pn = propylenediamine). The Schiff bases were obtained with the condensation reaction between 3-heptanone and the corresponding diamines. The molecular structure of our products has been investigated by IR, UV–VIS and NMR spectroscopy, MS, thermoanalytical measurements (TG-DTG-DTA), and powder XRD. The biological activity study of compounds revealed t...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Hyperfine Interactions, 2018
Iron-oxide nanoparticles were prepared by chemical coprecipitation method in inert gas atmosphere... more Iron-oxide nanoparticles were prepared by chemical coprecipitation method in inert gas atmosphere and also in air atmosphere in order to use them as possible nutrition source for plants. The samples were characterized by 57 Fe Mössbauer spectroscopy, electron microscopy and PXRD measurements. The presence of considerable Fe II contributions were indicated by 57 Fe Mössbauer spectra. Furthermore TEM and XRD reflected nanomagnetite in washed and lyophilized samples prepared in inert gas atmosphere while the samples prepared in air atmosphere contained much higher amount of Fe III than characteristic of magnetite. In the case of samples prepared in inert gas, it was also shown that the immediate washing after the coprecipitation has a crucial influence on the Fe II content of the nanomagnetites. Keywords 57 Fe Mössbauer spectroscopy • Iron-oxide nanoparticles • Inert gas atmosphere synthesis • Plant nutrition • Fe(II) oxidation state This article is part of the Topical Collection on
Tetrahedron Letters, 2017
A comparative alcoholysis study of N-silylated derivatives of simple heterocyclic carboxamides (l... more A comparative alcoholysis study of N-silylated derivatives of simple heterocyclic carboxamides (lactams, imides, ureas) is presented. The second-order rate constant values span a range as wide as three orders of magnitude. On the basis of DFT calculations, a good correlation between reactivity and the Si...O distance was found within each family of compounds. The viability of two different reaction pathways was evaluated using a detailed computational mechanistic study of the methanolysis of cyclic urea homologues. Peculiarities in the single-crystal X-ray diffraction structures of the trimethylsilyl and trimethylsiloxy phthalimides are also discussed.
Hyperfine Interactions, 2013
Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethylglyoxime, methyl-isopropyl-gly... more Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethylglyoxime, methyl-isopropyl-glyoxime, [Fe(DioxH) 2 L 2 ] with and without axial ligands have been synthesized. 57 Fe Mössbauer spectroscopy showed different spin states in complexes with short alkyl chain and with branched alkyl chain, respectively. It was shown that the asymmetry observed in the doublet line intensity of ironbis-glyoximes is due to the texture effect. The effect of back-coordination was also studied in the case of iron-bis-dioxime complexes with branched alkyl chains, having different axial ligands.
In our research we synthesized novel [Pd(monophenyl-dioxime)2L2] (L = 2-aminopyrimidine, 3-hydrox... more In our research we synthesized novel [Pd(monophenyl-dioxime)2L2] (L = 2-aminopyrimidine, 3-hydroxi-aniline, lepidine) type complexes and with different Schiff-bases: [Pd(acetonyl-acetone)2(diamine)], [Pd(dibenzoyl-methane)2(diamine)] (diamine = ophenylene-diamine, ethylene-diamine, 1,2-, 1,3-propylene-diamine) by reacting PdCl2, monophenyl-dioxime, respectively Schiff-bases with amine, respectively diamine in the corresponding solvent. We analyzed their physicochemical properties using mass spectrometry, infrared-, NMR-spectroscopy and thermal analysis (TG, DTG and DTA). The Pd-complexes have an important role in many organic chemistry reactions as catalysts [1]. Some of them are used in industry. The Pd precious metal price is high, but compared with Rh, Pt, Ir, or Os is infinitesimal. Regarding the biological activity, they inhibit some enzymes which are important in anti-diabetic therapy. Some of the Pd(II) complexes are anti-glaucoma drug candidates [2]. Due to the similarity be...
In our research project new iron(II) complexes were synthesized with azomethines, such as [Fe(1,4... more In our research project new iron(II) complexes were synthesized with azomethines, such as [Fe(1,4-dibromo-2,3-butane-GlyoxH)2(3-HO-aniline)2], [Fe(1,4-dibromo-2,3-butaneGlyoxH)2(2-amino-pyrimidine)2], [Fe(4-benzyl-2-HO-propiophenone-GlyoxH)2], [Fe(5- methyl-2-hexanone)2(en)], [Fe(5-methyl-2-hexanone)2(1,2-pn)], [Fe(5-methyl-2-hexanone)2 (1,3-pn)], [Fe(5-methyl-2-hexanone)2(o-fen)], [Fe(2,4,5-trimethoxy-acetophenone-SC)2], [Fe(2,4,5-trimethoxy-acetophenone-TSC)2], [Fe(5-methyl-2-hexanone-SC)2], [Fe(5-methyl-2- hexanone-TSC)2], [Fe(Me-Pr-Glyox)3(BOH)2], [Fe(Me-Pr-Glyox)3(BOMe)2], [Fe(Me-i-BuGlyox)3(BOH)2], [Fe(Me-i-Bu-Glyox)3(BOMe)2], [Fe(Me-i-Bu-Glyox)3(BO-n-propyl)2] (en = ethylenedianine, pn = propylenediamine, fen = phenylenediamine, SC = semicarbazone, TSC = thiosemicarbazone), by reacting iron(II)-chloride with different glyoximes, Schiff-bases, semi- or thiosemicarbazones in suitable solvent. The Schiff-bases were obtained with the condensation of 5-methyl-2-hexanone, with diam...
Kutatásunk során új, Schiff-bázisokkal képzett [Fe(4-benzil-2-HO-propiofenon) 2 A], [Fe(2,4,6-tri... more Kutatásunk során új, Schiff-bázisokkal képzett [Fe(4-benzil-2-HO-propiofenon) 2 A], [Fe(2,4,6-trihidroxi-benzil-4-metoxifenil-keton) 2 A], [Fe(ninhidrin) 2 A] (A = etilén-diamin, 1,2-propilén-diamin, 1,3-propilén-diamin, o-fenilén-diamin) típusú komplexeket, állítottunk elő Fe(II)-só és a megfelelő Schiff-bázis reakciója során, a megfelelő oldószerben. A Schiff-bázisokat 4-benzil-2-hidroxi-propiofenon, 2,4,6-trihidroxi-benzil-4-metoxifenil-keton ill. ninhidrin diaminokkal való kondenzációjával nyertük. Rövid irodalmi áttekintés után, mely tartalmazza a vas-komplexek osztályozását és fejlődését, tanulmányoztuk az előállított vegyületek szerkezetét és kémiai sajátosságait FTIR, Mössbauer, UV-VIS, NMR, spektroszkópiai, tömegspektrometriai, termoanalitikai (TG-DTG-DTA), por-röntgen diffrakciós (XRD) módszerekkel, valamint biológiai aktivitásukat. E vegyületcsoport jelentőségét illetően, biokémiai szempontból fontosak, egyes képviselők antibakteriális szerek, valamint potenciális rákellenes gyógyszerek. Célkitűzésünk, az antibakteriális hatás és a rákos sejttenyészetek tanulmányozása a komplexeink jelenlétében.
Hyperfine Interactions, 2021
Dioximes as ligands are used as analytical reagents and serve as models for biological systems as... more Dioximes as ligands are used as analytical reagents and serve as models for biological systems as well as catalysts in chemical processes. A number of novel mixed complexes of the type [Fe(DioxH)2(amine)2] have been prepared and characterised by FTIR, 57Fe Mössbauer and mass spectroscopy by us. We have found strong Fe–N donor acceptor interactions and iron occurred in low-spin FeII state in all complexes. Later, we have also found that the incorporation of branching alkyl chains (isopropyl) in the complexes alters the Fe–N bond length and results in high-spin iron(II) state [1, 2]. The question arises: can the spin state of iron be manipulated generally by replacing the short alkyl chains with high volume demand ones in Fe-azomethine-amine complexes? To answer the question we have synthetized novel iron-bis-glioxime and iron-tris-gloxime complexes when long chain alkyl or aromatic ligands replaced the short alkyl ones and studied by 57Fe Mössbauer spectroscopy, MS, FTIR, UV-VIS, TG-...
Magyar Kémiai Folyóirat, 2020
Molecules, 2021
In this mini-review of our research group’s activity, the application of 57Fe Mössbauer spectrosc... more In this mini-review of our research group’s activity, the application of 57Fe Mössbauer spectroscopy in studies of electronic structure, coordination environment, and magnetic interactions in an interesting series of Fe(II/III) compounds selected is discussed. We selected two prominent phenomena that arose during investigations of selected groups of compounds carried out at different periods of time: (1) very high magnetic hyperfine fields observed at low temperatures; (2) changes in the oxidation state of the central iron atom of complexes in the solid state during interactions with gaseous O2/H2O mixtures, resulting in spin crossover (SCO).
Journal of Nanoparticle Research, 2018
57 Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic-and sa... more 57 Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic-and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic-and salicylic acidcoated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.
Structural Chemistry, 2016
In Fe[N(SiPh 2 Me) 2 ] 2 molecular magnet, an extraordinary B ≈ 92 T hyperfine field was found in... more In Fe[N(SiPh 2 Me) 2 ] 2 molecular magnet, an extraordinary B ≈ 92 T hyperfine field was found in the 5 K 57 Fe Mössbauer spectrum under an external magnetic field of 0.1 T. This evidences the presence of an unquenched orbital angular moment at the central iron atom. Fe[N(SiPh 2 Me) 2 ] 2 complex is thus shown to represent a further example of lowcoordinate iron complexes where quasi free-ion magnetism visualizes itself through an unquenched orbital moment. Magnetization measurements and hysteresis in magnetization indicated exchange coupling and nanosized magnetic units.
Journal of Radioanalytical and Nuclear Chemistry, 2017
The effect of coating with nine different carboxylic acids (glycolic, propionic, lactic, malic, t... more The effect of coating with nine different carboxylic acids (glycolic, propionic, lactic, malic, tartaric, citric, mandelic, caproic and caprylic) on nanostructured magnetite (D * 10 nm) was studied by Raman and photoacoustic, magnetic and 57 Fe Mössbauer measurements. Mössbauer spectra of frozen suspensions showed dominantly magnetically split envelopes at lower temperatures, which were evaluated by hyperfine field distribution method. Mössbauer and Raman spectroscopy indicated similar variation of relative occurrence of magnetite and maghemite phases. These results are discussed on the basis of the hypothesis that different carboxylic acids can promote either the oxidation or reduction of iron oxide nanoparticles.
Journal of Radioanalytical and Nuclear Chemistry, 2014
A series of novel [Fe(MeiPrGlyoxH) 2 (amine) 2 ] complexes have been synthesized [(MeiPrGlyoxH 2 ... more A series of novel [Fe(MeiPrGlyoxH) 2 (amine) 2 ] complexes have been synthesized [(MeiPrGlyoxH 2 = methylisopropylglyoxime, amine = 3,5-dimethylpyridine, 4-(dimethylamino)pyridine, 4-(phenylamino)phenol, 2-imidazolidone)] and characterized by 57 Fe Mössbauer, FTIR, UV-Vis spectroscopy, mass spectrometry, AFM and thermoanalytical methods. Quantum chemical (DFT) computations of [Fe(MeiPrGlyoxH) 2 (3,5-dimethyl-Py) 2 ] (Py = pyridine) complex were also performed. The square-planar structure of [Fe(MeiPrGlyoxH) 2 ] moiety is similar to that of [Fe(MeEtGlyoxH) 2 ]. The incorporation of branching alkyl chains (isopropyl) in the complexes alters the Fe-N bond length and results in high-spin iron(II) state.
Structural Chemistry, 2009
The compound Fe[C(SiMe 3) 3 ] 2 has been prepared and investigated by the means of powder X-ray d... more The compound Fe[C(SiMe 3) 3 ] 2 has been prepared and investigated by the means of powder X-ray diffractometry and 57 Fe Mössbauer spectroscopy. The compound's unique geometry, in which iron is linearly coordinated by the two C(SiMe 3) 3 ligands, results in a unusual electronic structure of iron, which is visualized as an extreme high hyperfine magnetic field of 157.5(8) T as sensed by the 57 Fe nucleus at T = 20 K. In order to obtain information on the electronic structure of iron and on the bonds to the ligands, DFT (density functional theory) calculations were carried out on Fe[C(SiMe 3) 3 ] 2. The high-spin state of iron was found to be energetically favored: an Fe(II) electron configuration of 3d 5.83 4s 0.72 is predicted, where the 4s electron density is only slightly polarized, and most of the unpaired electrons have 3d character. By assuming a linear crystal field, and associated 3d level scheme as a starting point, it is suggested that the extreme high hyperfine magnetic field, observed along with an apparently negative quadrupole splitting, is perpendicular to the C-Fe(II)-C bond axis, and can be decomposed mainly into contact (B c & 44 T), dipolar (B d & 14 T), and orbital (B L & 99 T) hyperfine magnetic field contributions.
Hyperfine Interactions, 2008
Fe[C(SiMe 3) 3 ] 2 compound, in which iron is coordinated by two carbons, was prepared using the ... more Fe[C(SiMe 3) 3 ] 2 compound, in which iron is coordinated by two carbons, was prepared using the reaction of FeCl 2 with (Me 3 Si) 3 CLi, and investigated by XRD, 57 Fe Mössbauer spectroscopy and DFT calculations. 157.5 T hyperfine magnetic field was found at the site of the iron nucleus of this compound at 20 K. DFT calculations predict the quintet states to be clearly favored energetically over the lower spin states. The population analysis reveals considerable 4s as well as large unpaired 3d electron contributions, which can be responsible for the extremely high hyperfine field.
A kémia központi helyet foglal el a tudományágak hálózatában. Mint az anyag atomi-molekuláris (il... more A kémia központi helyet foglal el a tudományágak hálózatában. Mint az anyag atomi-molekuláris (illetve szupramolekuláris) szerveződésével foglalkozó diszciplína, fogalmainak, módszereinek, ill. elméleteinek kialakításához jelentős mértékben épít az alapozó természettudományokra (fizika, matematika), ugyanakkor számtalan eredménye a legkülönfélébb tudományterületek (pl. a biológia, a földtudományok, az anyagtudomány) ismeretanyagát gazdagítja, illetve strukturálja. A kémia egyben rendkívüli változatossággal is rendelkezik az érdeklődési körébe tartozó objektumok számossága terén: elég csak megemlíteni azt a kb. 200 millió leírt vegyületet, mely a világ legnagyobb ilyen profilú adatbázisában szerepel, továbbá az anyagok között lejátszódó (leírt, illetve lehetséges) miriádnyi kémiai reakciót, melyek legbonyolultabb hálózatával valószínűleg éppen az élő szervezetekben lejátszódó biokémiai folyamatok esetében találkozhatunk. Az előadásban nemcsak a fentiekben idézett, hanem a kémiával a legszélesebb értelemben kapcsolatba hozható hálózatos struktúrák világába nyerünk bepillantást.
Journal of Colloid and Interface Science
A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29... more A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29 silica nanoparticles (29Si-silica NPs) with the purpose of using them as spikes for isotope dilution mass spectrometry (IDMS) quantification of silica NPs with natural isotopic distribution. Si-29 tetraethyl orthosilicate (29Si-TEOS), the silica precursor was prepared in two steps starting from elementary silicon-29 pellets. In the first step Si-29 silicon tetrachloride (29SiCl4) was prepared by heating elementary silicon-29 in chlorine gas stream. By using a multistep cooling system and the dilution of the volatile and moisture-sensitive 29SiCl4 in carbon tetrachloride as inert medium we managed to reduce product loss caused by evaporation. 29Si-TEOS was obtained by treating 29SiCl4 with absolute ethanol. Structural characterisation of 29Si-TEOS was performed by using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. For the NP...