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This paper introduce a historical geographical study on the process of land cover transformation in the Bükk Region, which can be regarded as a two-faced area concerning its anthropogenic disturbance. Based on historic mapping that began as early as the late 18th century, a database was produced, and the data was interpreted in the context of economic and social processes that took place in the area. Results could be presented in maps using the so-called Anthropogenic Disturbance Index (ADI). These maps demonstrate the peculiar land use pattern in the Bükk Region, namely co-habitation of the significantly transformed margins and the natural or quasi-natural central part. Between them, there are linear areas of intermediate disturbance. These areas, however, due to the foundation and activity of the Bükk National Park and modification of their economic value after the change of the political system, have not increased during the last several decades; rather a re-naturalization of the landscape is aimed.

Since the beginning of landscape research there has been an intent to express and compare the grade of anthropogenic transformation, or even the naturalness of landscapes, by applying objective landscape analytical methods. The most preferred indicator for this kind of landscape study is the state of vegetation or ecosystems. In our study land cover classes and their influences on soil properties were applied to characterize the grade of anthropogenic transformation and their temporal changes in Hungarian micro- and mesoregions. Based on our results, we could point to the spatial extent and differences among micro- and mesoregions, how far they are affected by ongoing abandonment and the extensification of land use and soils, as well as the localization of well-known and widely studied soil- and landscape degradation processes as a consequence of urban and industrial sprawl and intensive agriculture.

The properties of a ferrocenyl ureidopyrimidine derivative, a potential electrochemical sensor for trifluoromethanesulfonic acid and trifluoroacetic acid, were investigated using UV/Vis, NMR and CV measurements. Upon protonation a structural change was found to take place leading to the formation of a proper binding site for the anion of the acid. Anion binding has been proved for both CF3SO3- and CF3CO2-as well as for the BF4- anion by 1H NMR measurements. Moreover, titration experiments carried out with CF3SO3H and CF3CO2H resulted in different responses in the NMR spectra of the pyrimidine host. Cyclic voltammetry was found to be suitable to follow the addition of the acids to the host molecule. DFT calculations and X-ray diffraction were used to explore the properties of anion binding.

Six silica-supported phosphotungstic acid catalysts (PTA/SiO2) of different composition (20–70 wt% PTA content) have been synthesized and characterized by elemental analysis, BET, BJH, NH3-TPD methods, FT-IR spectroscopy of adsorbed pyridine and 1H MAS NMR techniques. The new composite catalysts were first applied in the Friedel–Crafts alkylation of toluene with 1-octene as a benchmark process under batch conditions in order to screen their activity and recyclability. The combined analytical techniques together with the catalytic studies enabled the identification of the main factors affecting the activity of the catalysts. Based on these preliminary experiments, the best performing catalyst system (50 wt% PTA/SiO2) was investigated in continuous flow mode using an in-house-made flow reactor. The thorough screening of the reaction conditions (temperature, toluene/1-octene molar ratio and flow rate) provided firm evidence that the 50 wt% PTA/SiO2 composite is highly active, selective and stable catalyst under mild reaction conditions even at elevated flow rate. Additionally, the catalyst used in the flow mode could successfully be regenerated and reused in the alkylation process.

Thioether-phosphite ligands (SP’s) with axially chiral (S)-H0- or (S)-H8-binaphthyl moiety and their [Rh(COD)(SP)]BF4 complexes have been synthesized to study their coordination chemistry and catalytic features and to compare them to those of the structurally analogous phosphine-phosphites (PP’s). NMR exchange studies on [Rh(COD)(SP)]BF4 complexes showed selective 1,5-cyclooctadiene dynamics. Firm evidence has been found that this fluxional process involves dissociation of the Rh-sulfur bond. Based on in situ NMR studies, SP ligands can form two types of bis-ligated species at ligand-to-metal ratio higher than 1. Unlike bis-ligated phosphine-phosphite complexes, bis-ligated thioether-phosphite Rh-complexes can efficiently catalyze asymmetric hydrogenation reactions due to their distinct coordination chemistry.

Post agricultural development of traditionally intensively cultivated high fertility soils is a relevant question in surroundings of towns affected by urban sprawl, where extent areas of former cultivated soils are converted into residential, industrial or infrastructural surfaces. Part of these areas will covered by artificially sealed soils, but always extent areas remain for green areas, managed with different intensity, which allows recharge of soil organic carbon stocks and soil regeneration processes. In our study agricultural and post agricultural soils were sampled in a Chernozemic landscape affected by urbanization processes. Besides of other regeneration processes, concerning to the improvement of soil structure, we found that soil organic carbon stocks in the 0-30 cm soil layer are significantly higher in post agricultural soils (9.4±0.5 kg·m-2) as in ploughed (6.4±0.8 kg·m-2) or in ploughed plus irrigated (5.6±0.7 kg·m-2) profiles. The difference was found to be significant not only until the depth of the cultivated layer (30 cm), but until the sampled 70 cm depth throughout (17.8±0.9; 10.8±3.3 and 10.6±2.7 kg·m-2 respectively). Our results point on the high carbon recovery potential of suburban areas converted from fertile cultivated soils.

A cyclometalation motif has been discovered in the unprecedented reaction of Pd(II) precursors with simple pentane-2,4-diyl based aminoalkyl-phosphines. The unique six-membered zwitterionic palladacycles can easily be synthesized in the presence of 1 molar equiv of oxidant in high yields in a pure form. A comparison between the analogous ligands of different tether lengths revealed that the formation of the zwitterionic palladacycles is the exclusive privilege of the six-membered rings.

The configuration of the ligand's N-substituent was found to determine the stoichiometry and strict stereoselectivity of N-coordination in twelve-membered palladium dimers 2a-b. The novel palladium(II)-complexes 2a-b have been synthesized in the reaction of [Pd(COD)Cl2] and optically pure (S,S)-pentane-2,4-diyl based aminoalkyl-phosphine ligands Ph2PCH(CH3)CH2CH(CH3)NHR 1a-b (R = (R)-α-phenylethyl 1a, R = (R)-α-(1-naphthyl)ethyl 1b) with stereogenic nitrogen atom, and studied by various 1D and 2D NMR techniques in solution and in the case of 2a by single-crystal X-ray diffraction. As an unprecedented case, ligands 1a-b were found to yield exclusively 12-membered cyclic dinuclear Pd(II)-complexes with stereospecific coordination of both of the donor nitrogen atoms. Formation of the 12-membered ring is shown to reduce the steric hindrance of the bulky substituents with respect to the six-membered ring.

Quasi-homogeneous nanoparticulate halloysite clay with layered scroll morphology is an ideal material for photochemical activity due to the lack of interference from Fe contaminants and mixed mineral phases. In this work, halloysite was used as a model system for studying the influence of compositional defect sites on the structure and photochemical activity as a result of thermal modifications in the range of 400–480 °C and with 30–180 min exposure. The change in the Al-coordination environment was studied by 27Al, 1H magic-angle spinning (MAS) and cross-polarization (CP)/MAS nuclear magnetic resonance (NMR), and infrared (IR) spectroscopic techniques. The structural and morphological changes were followed by powder X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. Pore structure description was obtained from nitrogen gas adsorption measurements. The amount of residual hydroxide groups was determined by thermogravimetric analysis (TGA). Temperature-controlled desorption (TPD) and 1H MAS NMR techniques were used for the characterization of acid-base properties of thermally created defect sites. These defect sites showed a decrease in Al-coordination number and an increase in the number of acidic sites. However, evidence for the formation of basic sites during long exposure experiments can be seen, which emphasises the impact of the duration of the heat treatment. The emergence of acidic sites was correlated with the increase in photochemical activity. A significantly different photochemical activity was found for thermally treated halloysite than expected from the semiconductor-type photocatalysis model on the basis of the number of hydroxyl radicals generated as a function of the irradiation time.

The asymmetric hydrogenation of benchmark substrates dimethyl itaconate and (Z)-α-acetamidocinnamic acid methyl ester with chiral pentane-2,4-diyl-based phosphine–phosphite Rh complexes immobilized on the support with heteropolyacid (phosphotungstic acid) as anchoring agent has been studied. The complexes have been supported on commercially available Al2O3 by the Augustine method. The novel heterogeneous catalysts were applied in a high-throughput flow reactor. The effect of the pressure, temperature, substrate concentration, and flow rate was thoroughly screened to optimize reaction conditions. The immobilized catalysts proved to be remarkably stable and could be used 6 h in the microfluidic-based reactor without a significant loss of activity and selectivity. Furthermore, under optimized conditions, the hydrogenation product could be obtained with high activity (TOF >2000 h−1) and enantioselectivity (up to 99% ee). As the first precedent, the potential of supported Rh(P-OP)-complexes under flow conditions has been presented.

The asymmetric allylic substitution reaction of rac-1,3-diaryl-2-propenyl acetates with several C- and N-nucleophiles catalyzed by the palladium-complexes of eleven structurally analogous aminoalkyl-phosphines (P,N) with pentane-2,4-diyl backbone is reported. The role of the N-substituents and the influence of the ligand/palladium molar ratio on the activity and enantioselectivity of the catalytic system are studied. The solvent and the temperature dependence of the catalytic reaction were also assessed yielding enantioselectivities up to 95% in alkylation and 90% in amination processes under optimized reaction conditions.

Six-membered chelate complexes of type [Pd(1a-e)Cl2] (2a-e) and [Pd(1a-e)(η3-PhCHCHCHPh)]BF4 (3a-e) of a series of systematically varied chiral phosphine-amine ligands (S,S)-Ph2PCH(CH3)CH2CH(CH3)NHR 1a-e (R = benzyl 1a, R = ethyl 1b, R = (S)-α-phenylethyl 1c, R = isopropyl 1d, R = methyl 1e) have been studied. The complexes 2a-e were characterized by X-ray crystallography, DFT analysis and in solution by 1D and 2D NMR spectroscopy. A very good correlation has been observed between the steric demand of the N-substituent and the distortion of the chelate. Furthermore, it has been proved that sterically more demanding N-substituents are capable of distorting the chelate to a larger extent along one single, well defined conformational pathway. The careful variation of the N-substituent thus allows a precise stereochemical fine tuning of the metal's coordination sphere. As a substantiation of this concept, the investigation of complexes 3a-e revealed that the exo/endo ratio as well as the twisting of the allyl moiety around the Pd-allyl axis can easily be modified by the proper choice of the nitrogen substituent. Furthermore, Pd-catalysts with ligands 1a-e provided high enantioselectivities (up to 96%) in asymmetric allylic alkylation reactions.

Six novel thioether-aminophosphine type ligands with a general formula (Ar1)2PN(R1)CHR2(CH2)nCH(R3)SAr2 has been synthesized. The modular structure of the ligands and the new methodologies developed for their preparation enabled the systematic variation of their bridge length (n = 0 or 1), the substitution pattern of the backbone (R2, R3 = H or Me) as well as the P-, N- and S-substituents (Ar1 = Ph or 3,5-Me2C6H3, R1 = Et or iPr and Ar2 = Ph, 4-MeC6H4, or 4-MeOC6H4, respectively). The ligands proved to be effective in Pd-catalyzed asymmetric allylic etherification reactions providing the products in high yields (up to 95%) and with good enantioselectivities (up to 86%) using unprecedentedly low (0.2 mol%) loadings of the chiral Pd-catalyst. Based on these findings, a new scalable protocol has been developed for the preparation of chiral allylic ethers. Furthermore, the Pd(II) coordination chemistry of the ligands was thoroughly investigated by 1D and 2D NMR methods as well as by X-ray crystallography with special attention to the conformation of the chelate ring and the stereoselectivity of the sulfur coordination. Based on these studies, the main factors determining activity and selectivity of the catalytic system have been identified.

The application of a sol-gel method, starting from N-(4-ferrocenyl-6-phenylpyrimidin-2-yl)-N’-(3-(triethoxysilyl)prop-1-yl)-urea (4), tetraethoxysilane and a structure directing agent, led to the formation of hollow spherical particles with organic moieties concentrated on the inner surface. A similar sol-gel electrodeposition technique was used for the modification of the surface of a spectral graphite electrode. The solid materials were characterized by solid phase NMR and IR measurements, thermal analysis, SEM and TEM. The functional group attached to the ferrocene core offers the possibility to form H-bonds with various guest molecules that makes it a potential electrochemical sensor.

Surface modifications of natural kaolins (Felsőpeteny, Hungary) with iron-content up to 9% (m/m) were carried out by varying acid concentration (5, 8 and 11 M HCl) and treatment time (1, 3 and 6 h) in order to evaluate the influence of treatment conditions on photochemical activity, amount of low coordinate Al defect sites, porosity, and acid/base character of the surface. Nitrogen adsorption and temperature-programmed desorption measurements showed that the acid treatment slightly reduced the pore volume and the surface area, while the average pore diameter and the number of acidic centers were increased. Solid-state 27Al NMR spectroscopy demonstrated the presence of mechanistically relevant Al defect sites. The distribution, concentration, and particle size of the iron oxide co-minerals were found to be influential to photochemical activity. Greater than 90% photochemical degradation efficiency of oxalic acid can be achieved by acid-treated samples upon 3 h exposure to 8 M HCl solution with good reproducibility.

Novel alkane-diyl based heterobidentate P,N and S,N ligands with the general formula R1R2NCH(R3)(CH2)nCH(R4)Q (R1 = Me or iPr; R2 = H or Me; R3, R4 = H or Me; n = 0, 2; Q = PPh2 or SPh) have been prepared starting from cyclic sulfate esters or naturally occurring compounds with C1 symmetry. The length of the ligands’ backbone and the reaction conditions applied strongly affected the stereochemical outcome of the synthesis when using cyclic sulfates as starting materials. Palladium(II)-complexes of the new ligands were characterized by 1D and 2D NMR spectroscopy in solution and in several cases by X-ray crystallography in the solid phase. The structural versatility of the ligands enabled the straightforward comparison of the stereoselectivity of their coordination as a function of their tether length, backbone substitution pattern, donor sets and relative carbon atom configuration in their backbone. The catalytic features of the novel compounds were investigated in asymmetric allylic alkylation reactions where the tether length proved to be a crucial factor in determining enantioselectivity.

Phosphine–phosphoramidite ligands containing a 2,4-pentanediyl backbone, BINOL moieties, and Me, Bn or Ph substituent on the nitrogen were synthesized and fully characterized. The electronic effect of the N -substituents was examined by 31 P NMR of their corresponding seleno-phosphate-amide and phosphine–selenide derivatives. The new ligands together with their earlier reported derivatives were tested in the palladium catalyzed asymmetric allylic alkylation of rac -( E )-1,3-diphenylallyl acetate. Remarkably high activity (up to 1780 h −1 turnover frequency) and first order kinetics were observed by facilitating nucleophile formation. The substituent at the nitrogen and the configuration of chiral moieties had a high impact on the enantioselectivity. The new ligands were also tested in the rhodium-catalyzed asymmetric hydrogenation of methyl ( Z )-α-acetamidocinnammate, dimethyl itaconate (up to 99.9% ee’s) and methyl 2-acetamidoacrylate (up to 99.5% ee).

Phosphine–phosphoramidites (PPAs) are heterobidentate ligands that have been developed in the last two decades and have been used successfully in asymmetric catalytic reactions. A single crystal of the PPA (11bS)-N-[(2S,4S)-4-(diphenylphosphanyl)pentan-2-yl]-N-methyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine, C38H35NO2P2, was prepared and structurally characterized by single-crystal X-ray diffraction and density functional theory (DFT) calculations. Structure elucidation revealed unique features which might have a significant effect in the excellent chemical stability of this type of molecule. The conformation of the molecule provides an optimal chelating structure. Iridium complexes of UPPhos were found to be efficient catalysts in the asymmetric hydrogenation of imines {UPPhos is (11bS)-N-[(2S,4S)-4-(diphenylphosphanyl)pentan-2-yl]-N-(propan-2-yl)dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine}.

The solid-state 13C and 2H NMR spectra of paramagnetic anhydrous trans-bis(L-valinato)copper(II) and cis-aquabis(L-valinato)copper(II) complexes have been obtained. Under the very fast MAS conditions, both the 13C and 2H MAS spectra were well enough resolved to allow the easy distinction between the trans and cis stereoisomers. The conformational disorder observed previously in the X-ray structure of the cis isomer was also reflected in the 13C and 2H MAS spectra. Variable-temperature 2H MAS spectra of differently deuterated ligand species, that is, the copper(II) complexes with L-[D2]valine, L-[D8]valine, and L-[D10]valine, suggested the dynamic nature of this disorder in the aqua cis isomer and confirmed static ND2 deuterons in the anhydrous trans isomer. Quantum chemical DFT/B3LYP calculations of the 13C hyperfine (Fermi contact) shifts of the paramagnetic term were useful as assignment aids in the interpretation of the 13C MAS spectra.

Diastereomers of (4-(diphenylphosphino)pentan-2-yl)- N -isopropyl-{dinaphtho[2,1- d :1′,2′- f ][1,3,2]dioxa-phosphepin-2-yl}-4-amine, ( S )-(2 S ,4 S )- 1 , and ( S )-(2 R ,4 R )- 3 ; the octahydro derivative 4 of ( S )-(2 S ,4 S )- 1 , and derivative 2 of ( S )-(2 S ,4 S )- 1 containing a 1,3-propanediyl backbone, have been synthesized and used for rhodium-catalyzed asymmetric hydrogenations of prochiral olefins in order to study the role of the stereogenic elements in the backbone and in the terminal moiety. The central chirality in the bridge has been found to determine the configuration of the product with a cooperative effect from the terminal groups. Excellent ee’s (up to 99.9%) were obtained in the hydrogenation of methyl ( Z )-α-acetamidocinnamate using a rhodium complex with the matched arrangement ( S )-(2 S ,4 S )- 1 . The hydrogenation is accomplished in a highly enantioselective manner by using green solvents such as propylene carbonate.

Two commercial products—molecular recognition technology (MRT) product AnaLig®Tc-02 gel and extraction chromatography TEVA® resin were successfully tested for the separation of 99Tc. The results obtained for both procedures were compared in terms of activities and recoveries. The demonstrated linear model clearly proves that the residua fulfill the Gaussian model, without any autocorrelation and trend for NPL Alpha–Beta high 2003 intercomparison reference sample.

Excellent enantioselectivities and activities have been obtained in the rhodium catalyzed asymmetric hydrogenation of dimethyl itaconate and several dehydroamino acid esters using a new class of BINOL based phosphine–phosphite ligand. The hydrogenation proceeded efficiently even at a substrate/catalyst molar ratio of 10,000 to give the product with 100% conversion and 99.1% enantioselectivity.

A general and convenient two-step synthetic method has been developed for the preparation of a novel class of aminoalkyl-phosphine type compounds, which involves nucleophilic ring-opening of cyclic sulfate esters. The ring-opening step was performed using several different aliphatic and aromatic amines to produce aminoalkyl sulfates that were reacted with LiPPh 2 to give the corresponding P,N-ligands. The desymmetrization procedure affords an easy route to synthesize enantiomerically pure pentane-2,4-diyl based P,N-ligands with a highly tunable structure. The ligands derived from primary amines have a stereogenic N-atom that can be useful in asymmetric catalytic syntheses.

A general and convenient two-step synthetic method has been developed for the preparation of a novel class of aminoalkyl-phosphine type compounds, which involves nucleophilic ring-opening of cyclic sulfate esters. The ring-opening step was performed using several different aliphatic and aromatic amines to produce aminoalkyl sulfates that were reacted with LiPPh 2 to give the corresponding P,N-ligands. The desymmetrization procedure affords an easy route to synthesize enantiomerically pure pentane-2,4-diyl based P,N-ligands with a highly tunable structure. The ligands derived from primary amines have a stereogenic N-atom that can be useful in asymmetric catalytic syntheses.

1566-7367; Abstract The asymmetric allylic alkylation of rac-1,3-diphenyl-2-propenyl acetate catalyzed by the palladium-complexes of phosphine-phosphite ligands with 1,1'-binaphthyl- or 1,1'-octahydrobinaphthyl- moiety is reported. The roles of (i) the tether length in directly analogous phosphine-phosphite ligands, (ii) the stereogenic elements in the backbone of PC3OP type of ligands, and (iii) the BINOL moiety in the activities and enantioselectivities of the catalysts are studied. The applicability of these ligands was also evaluated in ethylene and propylene carbonates as green solvents obtaining up to 69% ees with good activity. By using directly analogous phosphine-phosphite ligands the catalytic activity increases steadily with the length of the backbone and with the basicity of the phosphine moiety.

A novel chiral ligand is synthesized and successfully applied in the Rh-catalyzed asymmetric hydrogenation of acetamides (I) and dimethyl itaconate (III).

Rhodium complexes derived from axially chiral ligands (I) are efficient catalysts in the asymmetric hydrogenation reactions of dehydroamino acid esters (II) and itaconate (IV), in the latter case even at only 0.01 mol% catalyst loading.

Highly active immobilized hydrogenation catalytic systems were used in the H-Cube™ hydrogenation reactor. “In situ” produced [Rh(COD)((S)-MonoPhos)2]BF4 complex was immobilized on commercially available Al2O3 and mesoporous Al2O3 by means of phosphotungstic acid (PTA), respectively. The optimum reaction conditions were determined and studied at different temperature, pressure, and flow rate values. Furthermore, the effect of the substrate concentration, microstructure of the support, and the stability of the complex were investigated. A continuous-flow reaction system using a stationary-phase catalyst for the asymmetric hydrogenation of methyl acetamidoacrylate was developed and run continuously for 12 h with >99% conversion and 96–97% enantioselectivity.

Holographic interferometry has the advantage of high sensitivity but at practical loads, the fringe systems get soon too dense to be observed conveniently. One special way of overcoming this problem is provided by the comparative methods. In the present paper, comparisons of deformations up to the millimeter region will be reported in difference holographic interferometry and an extension possibility to electronic speckle pattern interferometry will be demonstrated, too. The most direct approach would be to magnify the image to the required great extent and then build up the complete fringe system from the observed tiny parts. A practical method will be suggested here which alleviates this cumbersome procedure. In addition, if the very dense fringes are already washed away by the speckles -- some integration along the fringes proves to be of real help.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

International audience; A series of new phosphine–phosphite ligands P(C)nOP (n = 1–4) have been synthesized and used for rhodium-catalyzed asymmetric hydrogenation of prochiral olefins in order to study the effect of the chelate ring size. Excellent ees (up to 97.5%) were obtained in the hydrogenation of dimethyl itaconate and an increase of activity and enantioselectivity was observed in the hydrogenation of (Z)-α-acetamidocinnamic acid methyl ester with the increasing length of the backbone of the ligands.

A green process for enantioselective hydrogenation of dehydroamino acid derivatives and dimethyl itaconate with a rhodium catalyst modified by a new phosphine–phosphoramidite has been developed providing 97.7–99.8% enantioselectivity in green solvents such as ethylene carbonate and propylene carbonate. The L-DOPA precursor was obtained by simple filtration in 71% yield with 99.5% ee. Dimethyl itaconate was hydrogenated under solvent-free condition at 50 °C with 98.7% ee. The new rhodium complex was heterogenized on a mesoporous Al2O3 support using phosphotungstic acid (PTA) as an anchoring agent and tested in heterogeneous batch and flow reaction modes. The supported catalyst was reused eight times in the batch mode with over 97% ee and used over 12 hours in the flow reaction mode with an average of 97% ee in the asymmetric hydrogenation reaction of (Z)-α-acetamidocinnamic acid methyl ester.