Antitumor activity of bent metallocenes: electronic structure analysis using DFT computations

The antitumor activities of bent metallocenes [Cp–M–Cp]²⁺ (M = Ti, V, Nb, Mo) and complexes of them with guanine, adenine, thymine and cytosine nucleotides have been probed using electronic structure calculations. DFT/BP86 calculations have revealed that the bent metallocene–nucleotide interaction strongly depends on the stability of the hydrolyzed form of the bent metallocene dichloride [Cp₂M]²⁺ species, and in turn the stability of the [Cp₂M]²⁺ species strongly depends on the electronic structure of [Cp₂M]²⁺. Detailed electronic structure and Walsh energy analyses have been carried out for the hydrolyzed forms of four [Cp–M–Cp]²⁺ (M = Ti, V, Nb, Mo) species to find out why the bent structure is unusually stable. Energy changes that occur during the bending process in frontier molecular orbitals as well as the p(π)–d(π) overlap have been invoked to account for the anticipated antitumor activities of these species. The bonding situation and the interactions in bent metallocene–nucleotide adducts were elucidated by fragment analysis. Of the four nucleotides complexed with the four bent metallocenes, adenine and guanine show better binding abilities than the other two nucleotides. Metallocenes of second-row transition metals exhibit better binding with pyrimidine-base nucleotides. In particular, the Lewis acidic bent metallocenes interact strongly with nucleotides. The antitumor activity is directly related to the binding strength of the bent metallocene with nucleotide adducts, and the computed interaction energy values correlate very well with the experimentally observed antitumor activities.     

Water-soluble titanocene complexes with sulfur-containing aminoacids: synthesis, spectroscopic, electrochemical and Ti(IV)–transferrin interaction studies

Three new water soluble titanocene–aminoacid complexes have been synthesized via the reaction of Cp₂TiCl₂ and two equivalents of aminoacid (L) in methanol, affording [Cp₂TiL₂]Cl₂, L=L-cysteine (2), D-penicillamine (3) and L-methionine (4). These complexes have been characterized by ¹H, IR and UV-Vis spectroscopies, elemental analysis and cyclic voltammetry. Kinetic studies of ligand hydrolysis have been monitored at low pH using UV-Vis and ¹H NMR spectroscopies to assess their stability in aqueous solution. At low pH, aminoacid ligands are lost one order of magnitude faster than cyclopentadienyl. However, at physiological pH, in Tris buffer solution, the complexes decompose rapidly to form an insoluble titanium compound. The affinity of these complexes to apo-transferrin was also investigated to elucidate how the ancillary aminoacid ligands affect the titanium intake by apo-transferrin.Electronic Supplementary Material Supplementary material is available for this article at     

Cobalt-chromium-molybdenum but not titanium-6aluminium-4vanadium alloy discs inhibit human t cell activation in vitro

This study describes the effect of the presence of cobalt-chromium-molybdenum (CoCrMo) and titanium-6aluminium-4vanadium (Ti6AL4V) disc samples on the CD3-mediated in vitro response of human peripheral blood T lymphocyt es. Lymphocyte proliferation in the presence and absence of these metal alloy discs was measured by [³H]thymidine incorporation. Inhibition of lymphocyte proliferation was observed in the presence of CoCrMo disc samples. In contrast, the presence of the Ti6AL4V metal alloy discs had no effect on T cell proliferation. Ultrastructural studies using scanning electron microscopy revealed that the differences in the number of blast cells on uncoated CoCrMo and Ti6AL4V discs from a 4 day culture were consistent with the results observed in the proliferation experiments, i.e. fewer blast cells were seen on the CoCrMo than on the Ti6AL4V discs. In addition, a quantitative analysis of trace elements using total reflection X-ray fluorescence spectrometry in supernatants from 68 h in vitro cultures containing Ti6AL4V or CoCrMo disc samples was performed, revealing differences in the relative metal concentrations in the culture conditions tested. These differences point to the presence of cobalt in the supernatants as a possible determining factor of the inhibition observed. Because cell viability did not appear to change, a more complex mechanism involving the interaction of metals with T lymphocytes may account for the results obtained.     

The mechanism of Mo-/Cu-dependent CO dehydrogenase

Density functional theory computations at the B3LYP/SDDp//B3LYP/Lanl2DZ level were performed on model complexes derived from [(Me₂C₂S₂)Mo(O)₂-S-CuSMe]²⁻ or its oxo protonated form to gain insight into the reaction steps involved in substrate oxidation of a Mo-/Cu-dependent CO dehydrogenase. Only the bisoxo but not the hydroxo oxo complex was found to oxidize CO exothermically. A thiocarbamate complex structurally characterized as the reaction product of the enzyme with the inhibitor n-butylisonitrile corresponds to a thermodynamic well on the potential energy surface. For the formation of the analogous thiocarbonate complex from CO oxidation, however, we do not find a significant thermodynamic driving force. In the protein matrix of the enzyme this species should be further destabilized, as it requires the metal centers to move apart considerably from each other.Electronic Supplementary Material Supplementary material is available for this article at .     

Synthesis,Ti(IV) intake by apotransferrin and cytotoxic properties of functionalized titanocene dichlorides

Functionalization of cyclopentadienyl (Cp) ligands and incorporation of these into a Ti(IV) center require careful design and selection of the appropriate synthetic routes to obtain the desired product in reasonably good yields. As part of our research efforts in the area of titanocene antitumor agents, we have revisited the synthesis of Cp rings with electron-withdrawing groups and their corresponding titanocene dichlorides, (Cp-R)₂TiCl₂ and (Cp-R)CpTiCl₂, where R is CO₂CH₃ and CO₂CH₂CH₃. These complexes were characterized by elemental analysis and ¹H and ¹³C NMR and IR spectroscopies. This report presents the first detailed synthetic route for (Cp-CO₂CH₂CH₃)CpTiCl₂ and provides an alternate route for synthesis of (Cp-R)₂TiCl₂ complexes. The ability of these complexes to deliver Ti(IV) to apotransferrin was investigated to elucidate how the functionalized Cp ligands affect the titanium intake by apotransferrin. The subject complexes transfer Ti(IV) to human apotransferrin, loading both N- and C-lobes. The antitumor activity of these complexes against HT-29 cancer colon cells was determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Carboethoxy Cp functionalization results in complexes with a toxicity comparable to that of titanocene dichloride. The carbomethoxy-functionalized complexes proved to be nonactive at the time intervals studied here, regardless of their ability to donate the titanium atom to human apotransferrin.     

Vanadocene complexes of amino acids containing secondary amino group: The first evidence of O,O-bonded carboxylic group to vanadocene(IV) moiety

Reaction of vanadocene dichlorides (Cp₂VCl₂ and (η⁵-C₅H₄Me)₂VCl₂) with amino acids containing secondary amino groups gives three types of complexes: a) compounds with N,O-bonded amino acid, b) O-bonded amino acids and c) O,O-bonded amino acid. The complexes with N,O-bonded amino acid and O-bonded amino acids were observed in the case of l-proline and N-methylglycine (NMG). Reactions with N-phenylglycine (NPG) give O,O-chelates as the sole products. All three types of the complexes were characterized by spectroscopic methods. Structures of [(η⁵-C₅H₄Me)₂V(O-Pro)][BPh₄], [Cp₂V(O-Pro)₂][PF₆]₂, [Cp₂V(N,O-NMG)][BPh₄]·MeOH, [(η⁵-C₅H₄Me)₂V(N,O-NMG)][BPh₄]·MeOH, [Cp₂V(O-NMG)₂][Cl]₂·2H₂O, [(η⁵-C₅H₄Me)₂V(O-NMG)₂][Cl]₂·H₂O and [(η⁵-C₅H₄Me)₂V(O,O-NPG)][BPh₄] were determined by X-ray crystallography.     

Enhancement of Thermoelectric Performance of n‐Type PbSe by Cr Doping with Optimized Carrier Concentration

Ti, V, Cr, Nb, and Mo are found to be effective at increasing the Seebeck coefficient and power factor of n‐type PbSe at temperatures below 600 K. It is found that the higher Seebeck coefficients and power factors are due to higher Hall mobility ≈1000 cm² V^?1s^?1 at lower carrier concentration. A larger average ZT value (relevant for applications) can be obtained by an optimization of carrier concentration to ≈10¹⁸–10¹⁹ cm^?3. Even though the highest room temperature power factor ≈3.3 × 10^?3 W m^?1 K^?2 is found in 1 at% Mo‐doped PbSe, the highest ZT is achieved in Cr‐doped PbSe. Combined with the lower thermal conductivity, ZT is improved to ≈0.4 at room temperature and peak ZTs of ≈1.0 are observed at ≈573 K for Pb_0.9925Cr_0.0075Se and ≈673 K for Pb_0.995Cr_0.005Se. The calculated device efficiency of Pb_0.995Cr_0.005Se is as high as ≈12.5% with cold side 300 K and hot side 873 K, higher than those of all the n‐type PbSe materials reported in the literature.     

Essential metals for nitrogen fixation in a free-living N₂-fixing bacterium: chelation, homeostasis and high use efficiency

Biological nitrogen fixation, the main source of new nitrogen to the Earth's ecosystems, is catalysed by the enzyme nitrogenase. There are three nitrogenase isoenzymes: the Mo‐nitrogenase, the V‐nitrogenase and the Fe‐only nitrogenase. All three types require iron, and two of them also require Mo or V. Metal bioavailability has been shown to limit nitrogen fixation in natural and managed ecosystems. Here, we report the results of a study on the metal (Mo, V, Fe) requirements of Azotobacter vinelandii, a common model soil diazotroph. In the growth medium of A. vinelandii, metals are bound to strong complexing agents (metallophores) excreted by the bacterium. The uptake rates of the metallophore complexes are regulated to meet the bacterial metal requirement for diazotrophy. Under metal‐replete conditions Mo, but not V or Fe, is stored intracellularly. Under conditions of metal limitation, intracellular metals are used with remarkable efficiency, with essentially all the cellular Mo and V allocated to the nitrogenase enzymes. While the Mo‐nitrogenase, which is the most efficient, is used preferentially, all three nitrogenases contribute to N₂ fixation in the same culture under metal limitation. We conclude that A. vinelandii is well adapted to fix nitrogen in metal‐limited soil environments.     

Computer graphics applications of electron deformation densities and electrostatic potentials in coordination chemistry

Computer programs have been developed in order to display on a raster scan device electron deformation densities and electrostatic potentials, both as 2D colour-filled contour maps and as 3D solid models. Furthermore, as this quantum chemical model has proved to be adequate for transition metal complexes, the combined use of the Xα formalism and computer graphics is expected to be of value in rationalizing the reactivity of coordination and organometallic compounds. The examples of [Cr(O₂)₄]³⁻, [Mo(O₂)₄]²⁻ and [Nb(O₂)₄]³⁻ are discussed in an attempt to understand the differences in catalytic properties exhibited by parent metal dioxygen complexes.     

Theoretical study on the interaction of titanocene dichloride with deoxyguanosine monophosphate

The completely hydrolyzed titanocene dichloride, [Cp₂Ti(H₂O)₂]²⁺ binding to guanine (G) and phosphate group sites of DNA were investigated by DFT method, with using deoxyguanosine monophosphate (dGMP) as incoming ligand. In the first substitutions, the calculations reveal that the diaquated titanocene binding to O6 shows the lowest activation free energy with 17.9 kcal/mol, closely followed by N7 is 20.5 kcal/mol and the O of phosphate group is 26.3 kcal/mol, respectively. It was also found that all the titanation processes are mildly endothermic. In addition, for the Ti-B(dGMP) in all separated products, the bond dissociation free energies (BDFE) of Ti-O(P, P = phosphate) is higher than those of Ti-N7/O6. In the second substitutions, the reactions leading to the didentate adducts are considered. For bidentate-bridging N7, O6 binding mode, the path of the metal Ti binding to O6 has the lower activation free energy (11.3 kcal/mol) than that of the metal Ti binding to N7 (15.3 kcal/mol). For the bidentate-bridging N7, O(P) binding mode, the path of the metal Ti binding to O(P) has the lower activation free energies (25.3 kcal/mol) than that of the metal Ti binding to N7 (26.2 kcal/mol).     

Over 100‐nm‐Thick MoOx Films with Superior Hole Collection and Transport Properties for Organic Solar Cells

Herein, a novel and effective method to prepare n‐doped MoO_x films with highly improved conductivity is reported. The MoO_x films are readily prepared by spin‐coating an aqueous solution containing ammonium molybdate tetrahydrate and vitamin C (VC). As confirmed by UV–vis absorption, X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy measurements, Mo(VI) is partially reduced to Mo(V) by VC, resulting in the n‐doping of MoO_x. The conductivity of the n‐doped MoO_x (H:V‐Mo) film can be enhanced by four orders of magnitude compared to pristine MoO_x (H‐Mo), that is, from 1.2 × 10⁻⁷ to 1.1 × 10⁻³ S m⁻¹. The device using a 10 nm H:V‐Mo anode interlayer (AIL) exhibits comparable photovoltaic performance to a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐modified device. More importantly, the hole transport and collection properties of the H:V‐Mo AILs show outstanding tolerance to thickness variation, that is, with increasing thickness of the H:V‐Mo AIL from 10 to 150 nm, the V _oc and fill factor values of the devices remain unchanged. The device based on the blade‐coated H:V‐Mo AIL also has a high power conversion efficiency of 10.6%. To the best of the authors' knowledge, this work demonstrates the first example to prepare metal oxide AILs with outstanding tolerance to thickness, which is promising for the future large‐area manufacturing.     

Influence of the coat color on the trace elemental status measured by particle-induced x-ray emission in horse hair

The influence of hair color on the trace elemental status in horse's hair has been studied. A current analytical technique such as particle-induced X-ray emission (PIXE) used in this study has provided reliable, rapid, easy, and relatively inexpensive diagnostic methods. Twenty-eight elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Sr, Ti, V, Y, and Zn) in mane hair were detected by the PIXE method. The gray hair contains significantly greter amounts of Cu, Ti, and Zn, and lower amounts of Br, Ca, Se, and Sr than those in other colored horse hairs (p<0.05). Those results measured in the horse's hair were similar to those found in human and dog hair. When interpreting a result, it should be kept in mind that hair color, especially gray hair, influences the concentrations of some elements in horse hair.     

Catalysis of regioselective reduction of NAD+ by ruthenium(II) arene complexes under biologically relevant conditions

Ruthenium(II) arene anticancer complexes [(η ⁶-arene)Ru(en)Cl]PF₆ (arene is hexamethylbenzene, p-cymene, indan; en is ethylenediamine) can catalyse regioselective reduction of NAD⁺ by formate in water to form 1,4-NADH, at pD 7.2, 37 °C, and in the presence of air. The catalytic activity is markedly dependent on the arene, with the hexamethylbenzene (hmb) complex showing the highest activity. For [(η ⁶-hmb)Ru(en)Cl]PF₆, the rate of reaction is independent of NAD⁺ concentration and shows saturation kinetics with respect to formate concentration. A K _m value of 58 mM and a turnover frequency at saturation of 1.46 h⁻¹ were observed. Removal of chloride and performing the reaction under argon led to higher reaction rates. Lung cancer cells (A549) were found to be remarkably tolerant to formate even at millimolar concentrations. The possibility of using ruthenium arene complexes coadministered with formate as catalytic drugs is discussed.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Reaction behavior of molybdocene dichloride towards ribonucleosides and ribonucleoside monophosphates: Rare example of sugar coordination

The coordination behavior of Cp₂Mo²⁺ towards the ribonucleosides and ribonucleoside monophosphates uridine, adenosine, cytidine, guanosine, 5′-UMP, 5′-AMP, 5′-CMP and 5′-GMP has been studied in solution in the range 4 ? pD ? 9 using NMR spectroscopy. The ribonucleosides were found to bind Cp₂Mo²⁺ exclusively through the ribose moiety giving rise to the chelate complexes [Cp₂Mo(urd-O2′,O3′)], [Cp₂Mo(ade-O2′,O3′)], [Cp₂Mo(cyd-O2′,O3′)], and [Cp₂Mo(gua-O2′,O3′)]. The ribonucleotides form three types of complex with Cp₂Mo²⁺ in neutral solution, namely N,PO-macrochelates, PO,O3′-coordinated species as well as O2′,O3′-chelates, while at pD 9 only sugar coordination is observed.     

Vanadium Requirements and Uptake Kinetics in the Dinitrogen-Fixing Bacterium Azotobacter vinelandii

Vanadium is a cofactor in the alternative V-nitrogenase that is expressed by some N₂-fixing bacteria when Mo is not available. We investigated the V requirements, the kinetics of V uptake, and the production of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium Azotobacter vinelandii. In strain CA11.70, a mutant that expresses only the V-nitrogenase, V concentrations in the medium between 10⁻⁸ and 10⁻⁶ M sustain maximum growth rates; they are limiting below this range and toxic above. A. vinelandii excretes in its growth medium micromolar concentrations of the catechol siderophores azotochelin and protochelin, which bind the vanadate oxoanion. The production of catechols increases when V concentrations become toxic. Short-term uptake experiments with the radioactive isotope ⁴⁹V show that bacteria take up the V-catechol complexes through a regulated transport system(s), which shuts down at high V concentrations. The modulation of the excretion of catechols and of the uptake of the V-catechol complexes allows A. vinelandii to precisely manage its V homeostasis over a range of V concentrations, from limiting to toxic.     

Complexation of oxoanions and cationic metals by the biscatecholate siderophore azotochelin

Azotochelin is a biscatecholate siderophore produced by the nitrogen-fixing soil bacterium Azotobacter vinelandii. The complexation properties of azotochelin with a series of oxoanions [Mo(VI), W(VI) and V(V)] and divalent cations [Cu(II), Zn(II), Co(II) and Mn(II)] were investigated by potentiometry, UV–vis and X-ray spectroscopy. Azotochelin forms a strong 1:1 complex with molybdate (log K = 7.6 ± 0.4) and with tungstate and vanadate; the stability of the complexes increases in the order Mo < V < W (log K _app^Mo = 7.3 ± 0.4; log K _app^V = 8.8 ± 0.4 and log K _app^W = 9.0 ± 0.4 at pH 6.6). The Mo atom in the 1:1 Mo–azotochelin complex is bound to two oxo groups in a cis position and to the two catecholate groups of azotochelin, resulting in a slightly distorted octahedral configuration. Below pH 5, azotochelin appears to form polynuclear complexes with Mo in addition to the 1:1 complex. Azotochelin also forms strong complexes with divalent metals. Of the metals studied, Cu(II) binds most strongly to azotochelin , followed by Zn(II) , Mn(II) and Co(II) . Since very few organic ligands are known to bind strongly to oxoanions (and particularly molybdate) at circumneutral pH, the unusual properties of azotochelin may be used for the separation and concentration of oxoanions in the laboratory and in the field. In addition, azotochelin may prove useful for the investigation of the biogeochemistry of Mo, W and V in aquatic and terrestrial systems. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Bifunctional 3-hydroxy-4-pyridinone derivatives as potential pharmaceuticals: synthesis, complexation with Fe(III), Al(III) and Ga(III) and in vivo evaluation with 67Ga

A series of extra-functionalized 3-hydroxy-4-pyridinone chelators of hard metal ions, containing different side-chains with peptidomimetic groups, was studied to assess the effect of those groups on the physico-chemical properties, the metal-chelating affinity and the in vivo behaviour of the compounds, in view of their potential pharmaceutical applications. Besides the synthesis of the chelators, the study of their properties in aqueous solution alone and in the presence of M ³⁺ (M = Fe, Ga and Al) was performed by potentiometric/spectroscopic techniques. The octanol/water partition coefficient values of these hydroxypyridinone derivatives cover ca. 3 orders of magnitude (1.1 > log P > −2). They all form very stable tris-chelated M(III) complexes, the pFe and pGa values ranging up to five orders of magnitude. The in vivo studies showed the effect of the ligands on the biodistribution of ⁶⁷Ga citrate and also of ⁶⁷Ga-complexes in mice, in view of the potential use of the ligands or complexes as metal decorporating or as imaging agents, respectively. Although almost all these peptidomimetic hydroxypyridinone derivatives present very rapid clearance rate from most organs, the L-ornithine derivative (H₂L⁹) shows to be superior to the others and as good as Deferiprone as metal decontaminant of Ga. Concerning the ⁶⁷Ga complexes, the benzyl-propylamine (H₂L³) shows considerable bone retention, thus suggesting its potential application as imaging agent.Electronic Supplementary Material Supplementary material is available for this article at An erratum to this article can be found at     

Characterization of hypoglycemiant plants by total reflection X-ray fluorescence spectrometry

In this work, synchrotron radiation total reflection X-ray fluorescence spectrometry (SRTXRF) was used to determine trace elements in eight hypoglycemiant plants (Trigonella foenum graecum, Panax ginseng, Pfaffia paniculata, Myrcia speciosa, Zea mays, Harpagophytum procumbens, Syzygium jambolona, and Bauhinia forficate). The elements P, K, Ca, Ti, Mn, Fe, Cu, Zn, Rb, and Sr were detected in all medicinal plants investigated, whereas Si, S, Sc, V, Cr, Co, Ni, Se, Nb, Mo, Sn, Sb, Ba, Hg, and Pb were detected only in some of the samples. The concentration of elements in hypoglycemiant plants varied from 0.15 μg/g of Co to 3.0×10⁴ μg/g of K and the mean of experimental limit of detection for these elements were 0.14 and 3.6 μg/g, respectively.     

Electronic absorption and MCD spectra for octacyanometallate complexes M(CN)8, M=Mo(IV), W(IV), n=4 and Mo(V), W(V), n=3

Electronic absorption and 8.0 T magnetic circular dichroism (MCD) spectra are reported for M(CN)₈ ⁴⁻, M=Mo(IV) and W(IV), in aqueous solution and M(CN)₈ ³⁻, M=Mo(V) and W(V), in acetonitrile solutions. In addition some absorption and MCD spectra are reported for the M(CN)₈ ³⁻ ions embedded in thin poly methyl methacrylate (PMMA) plastic films at temperatures from 295 to 10 K. The temperature dependence of the MCD spectra confirms the presence of C terms. The solution and PMMA spectra for the both Mo and W complexes in either the IV or V oxidation states are remarkably similar to each other for the same oxidation state and are interpreted within a D_2d structural framework for the isotropic environment. The weak bands below 3.0 μm⁻¹ (1 μm⁻¹=10⁴ cm⁻¹) for the M(IV) complexes are assigned as metal-localized ligand field (LF) transitions. LF transitions are also suggested for weaker unresolved absorption between 3.0 and 3.6 μm⁻¹ for the M(V) ions. The intense bands above 3.6 μm⁻¹ for M(IV) and 4.6 μm⁻¹ for M(V) complexes are interpreted as metal to ligand charge transfer (MLCT) from the metal b₁(x²−y²) HOMO to CN⁻-based π * orbitals. The prominent intense bands observed below 4.5 μm⁻¹for the M(V) complexes are assigned as ligand to metal charge transfer (LMCT) from occupied non-bonding or weakly π bonding CN⁻ orbitals to the half-filled b₁(x²−y²) HOMO.     

The cellular distribution and oxidation state of platinum(II) and platinum(IV) antitumour complexes in cancer cells

The cellular distribution of platinum in A2780 ovarian cancer cells treated with cisplatin and platinum(IV) complexes with a range of reduction potentials has been examined using elemental analysis (synchrotron radiation-induced X-ray emission). The cellular distribution of platinum(IV) drugs after 24 h is similar to that of cisplatin, consistent with the majority of administered platinum(IV) drugs being reduced. Micro-X-ray absorption near-edge spectra of cells treated with cisplatin and platinum(IV) complexes confirmed the reduction of platinum(IV) to platinum(II). In cells treated, the most difficult to reduce complex, cis,trans,cis-[PtCl₂(OH)₂(NH₃)₂], platinum(IV) was detected in the cells along with platinum(II). The observations are in accordance with the relative ease of reduction of the platinum(IV) complexes used and support the requirement of reduction for activation of platinum(IV) complexes.Abbreviations en ethane-1,2-diamine - GM growth medium - PBS phosphate buffered saline - RPMI Roswell Park Memorial Institute - SRIXE synchrotron radiation-induced X-ray emission - XAFS X-ray absorption fine structure - XANES X-ray absorption near-edge spectroscopy