TY - JOUR A1 - Comba, P. A1 - Emmerling, Franziska A1 - Jakob, M. A1 - Kraus, Werner A1 - Kubeil, M. A1 - Morgen, M. A1 - Pietzsch, J. A1 - Stephan, H. T1 - Copper(II) chemistry of the functionalized macrocycle cyclam tetrapropionic acid N2 - The CuII complex of H4TETP (H4TETP = 1,4,8,11-tetraazatetradecane-1,4,8,11-tetrapropionic acid) is five-coordinate with a distorted square-pyramidal structure (τ = 0.45; i.e. the geometry is nearly half-way between square-pyramidal and trigonal-bipyramidal) and a relatively long Cu–N and a short Cu–O bond; the comparison between powder and solution electronic spectroscopy, the frozen solution EPR spectrum and ligand-field-based calculations (angular overlap model, AOM) indicate that the solution and solid state structures are very similar, i.e. the complex has a relatively low 'in-plane' and a significant axial ligand field with a dx²-y² ground state. The ligand-enforced structure is therefore shown to lead to a partially quenched Jahn–Teller distortion and to a relatively low complex stability, lower than with the corresponding acetate-derived ligand H4TETA. This is confirmed by potentiometric titration and by the biodistribution with 64Cu-labeled ligands which show that the uptake in the liver is significantly increased with the H4TETP-based system. KW - Copper(II) KW - Chemistry PY - 2013 DO - https://doi.org/10.1039/c2dt32356g SN - 1477-9226 SN - 1477-9234 SN - 1364-5447 VL - 42 IS - 17 SP - 6142 EP - 6148 PB - RSC CY - Cambridge AN - OPUS4-28075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, K. A1 - Weber, M. A1 - Menneken, M. A1 - Kral, A. G. A1 - Mertz-Kraus, R. A1 - Geisler, T. A1 - Vogl, Jochen A1 - Tütken, T. T1 - Diagenetic stability of non-traditional stable isotope systems (Ca, Sr, Mg, Zn) in teeth – An in-vitro alteration experiment of biogenic apatite in isotopically enriched tracer solution N2 - Stable isotope ratios and trace element concentrations of fossil bones and teeth are important geochemical proxies for the reconstruction of diet and past environment in archaeology and palaeontology. However, since diagenesis can significantly alter primary diet-related isotope signatures and elemental compositions, it is important to understand and quantify alteration processes. Here, we present the results of in-vitro Alteration experiments of dental tissues from a modern African elephant molar reacted in aqueous solutions at 30 °C and 90 °C for 4 to 63 days. Dental cubes with ≈ 3 mm edge length, comprising both enamel and dentin, were placed into 2 mL of acidic aqueous solution enriched in different isotopes (25Mg, 44Ca, 67Zn, 86Sr, initial pH 1). Element and isotope distribution profiles across the reacted cubes were measured with LA-(MC-)ICP-MS and EMPA, while potential effects on the bioapatite crystal structure were characterised by Raman spectroscopy. In all experiments isotope ratios measured by LA-(MC-)ICP-MS revealed an alteration of the enamel in the outer ≈ 200–300 μm. In contrast, dentin was fully altered (≈ 1.4 mm) after one week at 90 °C while the alteration did not exceed a depth of 150–200 μm during the 30 °C experiments. Then, the tracer solution started also to penetrate through the enamel-dentin junction into the innermost enamel, however, leaving the central part of the enamel unaltered, even after three months. The Raman spectra suggest an initial demineralisation in the acidic environment while organic matter (i.e. collagen) is still preserved. In the 90 °C experiment, Raman spectra of the v1 PO4) band of the dentin shift over time towards synthetic hydroxylapatite patterns and the Ca (and Sr) concentrations in the respective solutions decrease. This indicates precipitation of newly formed apatite. Isotope and element concentration profiles across the dental tissues reveal different exchange mechanisms for different isotope systems. Magnesium is leached from enamel and dentin, while Zn is incorporated into the apatite crystal structure. However, the distribution of both elements is not affected in the innermost enamel where their concentrations do not change over the whole duration of the experiments. We found no correlation of reaction depth in the cubes and experimental duration, which might be caused by natural variability of the dental material already at the beginning of the experiment. Our alteration experiments in a closed system at high temperatures ≤90 °C and low initial pH demonstrate that at least the central part of mm-thick mammalian enamel apatite seems to be resistant against alteration preserving its pristine bioapatite mineral structure as well as its in-vivo elemental and isotopic composition. The experiments assess diagenetic alteration in a novel multi-proxy approach using in-situ analyses in high spatial resolution. It is demonstrated that the isotopes of Ca, Sr, Zn and Mg in the dentin are prone for diagenetic alteration, while enamel is more resistant against alteration and could be used for dietary and physiological reconstructions in fossil teeth. KW - Bioapatite KW - Isotopes KW - Raman spectroscopy KW - Diagenesis KW - LA-(MC-)ICP-MS KW - EPMA PY - 2021 DO - https://doi.org/10.1016/j.chemgeo.2021.120196 VL - 572 SP - 120196 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-52447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tisato, F. A1 - Refosco, F. A1 - Porchia, M. A1 - Bolzati, C. A1 - Bandoli, G. A1 - Dolmella, A. A1 - Duatti, A. A1 - Boschi, A. A1 - Jung, C. M. A1 - Pietzsch, H.-J. A1 - Kraus, Werner T1 - The Crucial Role of the Diphosphine Heteroatom X in the Stereochemistry and Stabilization of the Substitution-Inert [M(N)(PXP)]2+ Metal Fragments (M = Tc, Re; PXP = Diphosphine Ligand) N2 - The nature of the heteroatom X incorporated in the five-membered PXP-diphosphine bridging chain was found to play a primary unit role both in the overall stability and in the stereochemical arrangement of nitrido-containing [M(N)(PXP)]2+ metal fragments (M = Tc, Re). Thus, by mixing PXP ligands with labile [Re(N)Cl4]- and Tc(N)Cl2(PPh3)2 nitrido precursors in CH2Cl2/MeOH mixtures, a series of neutral M(N)Cl2(PXP) complexes (M = Tc, 1-5; M = Re, 8, 9) was collected. In the resulting distorted octahedrons, PXP adopted facial or meridional coordination, and combination with halide co-ligands produced three different stereochemical arrangements, that is, fac,cis, mer,cis, and mer,trans, depending primarily on the nature of the diphosphine heteroatom X. When X = NH, mer,cis-Tc(N)Cl2(PNP1), 1, was the only isomer formed. Alternatively, when a tertiary amine nitrogen (X = NR; R = CH3, CH2CH2OCH3) was introduced in the bridging chain, fac,cis-M(N)Cl2(PN(R)P) complexes (M = Tc, 2, 3; M = Re, 8f) were obtained. Isomerization into the mer,cis-Re(N)Cl2(PN(R)P), 8m, species was observed only in the case of rhenium when the tertiary amine group carried the less encumbering methyl substituent. fac,cis-Tc(N)Cl2(PSP), 4f, was isolated in the solid state when X = S, but a mixture of fac,cis-Tc(N)Cl2(PSP) and mer,trans-Tc(N)Cl2(PSP), 4m, isomers was found in equilibrium in the solution state. A similar equilibrium between fac,cis-M(N)Cl2(POP) (M = Tc, 5f; M = Re, 9f) and mer,trans-M(N)Cl2(POP) (M = Tc, 5m; M = Re, 9m) species was detected in POP-containing complexes. The molecular structure of all of these complexes was assessed by means of conventional physicochemical techniques including multinuclear NMR spectroscopy and X-ray diffraction analysis of representative mer,cis-Tc(N)Cl2(PN(H)P), 1, fac,cis-Tc(N)Cl2(PSP), 4f, and mer,cis-Re(N)Cl2(PN(Me)P), 8m, compounds. PY - 2004 DO - https://doi.org/10.1021/ic049139r SN - 0020-1669 SN - 1520-510X VL - 43 IS - 26 SP - 8617 EP - 8625 PB - American Chemical Society CY - Washington, DC AN - OPUS4-5546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kraus, Werner A1 - Walther, M. A1 - Jung, C. M. A1 - Emmerling, Franziska A1 - Pietzsch, H.-J. T1 - Bromotricarbonyl{15-[2-(methylsulfanyl)ethylsulfanyl]pentadecanoic acid-kappa2S,S'}rhenium(I) N2 - The title compound, [ReBr(C18H36O2S2)(CO)3], was synthesized and characterized as a non-radioactive surrogate of a novel Tc-containing fatty acid derivative prepared according to the tricarbonyl/dithioether design with the objective of developing new Tc-based radiopharmaceuticals for the non-invasive diagnosis of myocardial metabolism. The Re chelate contains the metal in the oxidation state +1 and is attached to the terminal position of a fatty acid. The complex formation was accomplished by a ligand exchange reaction using [NBu4]2[Re(CO)3Br3] as starting material. KW - Fatty acid KW - Tc-compound KW - Radio-pharmaceutical PY - 2006 DO - https://doi.org/10.1107/S1600536806024081 SN - 1600-5368 VL - 62 IS - 7 SP - m1660 EP - m1662 PB - Munksgaard CY - Copenhagen AN - OPUS4-12529 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Walther, M. A1 - Jung, C. M. A1 - Bergmann, R. A1 - Pietzsch, J. A1 - Rode, K. A1 - Fahmy, K. A1 - Mirtschink, P. A1 - Stehr, S. A1 - Heintz, A. A1 - Wunderlich, G. A1 - Kraus, Werner A1 - Pietzsch, H.-J. A1 - Kropp, J. A1 - Deussen, A. A1 - Spies, H. T1 - Synthesis and Biological Evaluation of a New Type of 99mTechnetium-Labeled Fatty Acid for Myocardial Metabolism Imaging PY - 2007 SN - 1043-1802 SN - 1520-4812 VL - 18 SP - 216 EP - 230 CY - Washington, DC AN - OPUS4-14514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Walther, M. A1 - Matterna, M. A1 - Juran, S. A1 - Fähnemann, S. A1 - Stephan, H. A1 - Kraus, Werner A1 - Emmerling, Franziska T1 - Imidazole-containing bispidine ligands: synthesis, structure and Cu(II) complexation N2 - The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine Skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, Crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state. KW - Piperidone KW - Bispidine KW - Copper(II) KW - Configuration isomerism PY - 2011 SN - 0932-0776 SN - 0340-5087 SN - 0044-3174 VL - 66b SP - 721 EP - 728 PB - Verl. d. Zeitschrift für Naturforschung CY - Tübingen AN - OPUS4-24091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kubeil, M. A1 - Zarschler, K. A1 - Pietzsch, J. A1 - Kraus, Werner A1 - Comba, P. A1 - Stephan, H. T1 - Copper(II) cyclam complexes with N-propionic acid pendant arms N2 - Four cyclam (1,4,8,11-tetraazacyclotetradecane) ligands with different numbers of N-substituted propionic acid groups lead to pentacoordinate copper(II) complexes that adopt trans-I configurations (4+1 geometry), that is, the complexes have a dx2-y2 ground state with significant rhombic distortion. From the structural data (X-ray diffraction analysis and electron paramagnetic resonance, UV/Vis and IR spectroscopy), as the number of secondary amine groups of the macrocyclic ring substituted with propionic acid groups increases, the distortion from square pyramidal to trigonal bipyramidal increases, and this is expected to lead to relatively low complex stabilities. This is confirmed by in vitro studies with superoxide dismutase (SOD) and human serum challenge experiments as well as by biodistribution data with the 64Cu-labelled complexes. The 64Cu-labelled complexes with cyclam monopropionic and dipropionic acid show high in vitro and in vivo stabilities, and the latter provides a comparable biodistribution profile to that of 64Cu–TETA (TETA = 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid). KW - Copper KW - Chelates KW - Macrocyclic ligands KW - Radiopharmaceuticals KW - Diagnostic and therapy KW - Copper complexes PY - 2015 DO - https://doi.org/10.1002/ejic.201500510 SN - 1434-1948 SN - 1099-0682 IS - 24 SP - 4013 EP - 4023 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-33993 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simoes, R. A1 - Bernades, C. A1 - Joseph, A. A1 - Piedade, F. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Diogo, H. A1 - da Piedade, M. T1 - Polymorphism in simvastatin: Twinning, disorder, and enantiotropic phase transitions N2 - : Simvastatin is one of the most widely used active pharmaceutical ingredients for the treatment of hyperlipidemias. Because the compound is employed as a solid in drug formulations, particular attention should be given to the characterization of different polymorphs, their stability domains, and the nature of the phase transitions that relate them. In this work, the phase transitions delimiting the stability domains of three previously reported simvastatin forms were investigated from structural, energetics, and dynamical points of view based on single crystal X-ray diffraction (SCXRD), hot stage microscopy (HSM), and differential scanning calorimetry (DSC) experiments (conventional scans and heat capacity measurements), complemented with molecular dynamics (MD) simulations. Previous assignments of the crystal forms were confirmed by SCXRD: forms I and II were found to be orthorhombic (P212121, Z′/Z = 1/4) and form III was monoclinic (P21, Z′/Z = 2/4). The obtained results further indicated that (i) the transitions between different forms are observed at 235.9 ± 0.1 K (form III → form II) and at 275.2 ± 0.2 K (form II → form I) in DSC runs carried out at 10 K min−1 and close to these values when other types of techniques are used (e.g., HSM). (ii) They are enantiotropic (i.e., there is a transition temperature relating the two phases before fusion at which the stability order is reversed), fast, reversible, with very little hysteresis between heating and cooling modes, and occur under single crystal to single crystal conditions. (iii) A nucleation and growth mechanism seems to be followed since HSM experiments on single crystals evidenced the propagation of an interface, accompanied by a change of birefringence and crystal contraction or expansion (more subtle in the case of form III → form II), when the phase transitions are triggered. (iv) Consistent with the reversible and small hysteresis nature of the phase transitions, the SCXRD results indicated that the molecular packing is very similar in all forms and the main structural differences are associated with conformational changes of the “ester tail”. (v) The MD simulations further suggested that the tail is essentially “frozen” in two conformations below the III → II transition temperature, becomes progressively less hindered throughout the stability domain of form II, and acquires a large conformational freedom above the II → I transition. Finally, the fact that these transitions were found to be fast and reversible suggests that polymorphism is unlikely to be a problem for pharmaceutical formulations employing crystalline simvastatin because, if present, the III and II forms will readily convert to form I at ambient temperature. KW - Polymorphism KW - Twinning KW - Disorder KW - Simvastatine PY - 2018 DO - https://doi.org/10.1021/acs.molpharmaceut.8b00818 SN - 1543-8384 SN - 1543-8392 VL - 15 IS - 11 SP - 5349 EP - 5360 PB - American Chemical Society CY - Washington, DC AN - OPUS4-46927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stephan, H. A1 - Walther, M. A1 - Fähnemann, S. A1 - Ceroni, P. A1 - Molloy, J.K. A1 - Bergamini, G. A1 - Heisig, F. A1 - Müller, C.E. A1 - Kraus, Werner A1 - Comba, P. T1 - Bispidines for dual imaging N2 - The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY-substituted bispidine 3 combines a coordination site for metal ions, such as radioactive 64CuII, with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X-ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: CuII quenches the BODIPY fluorescence, whereas NiII and ZnII ions do not affect it. It follows that, in imaging applications with the positron emitter 64CuII, residues of its origin from enriched 64Ni and the decay products 64NiII and 64ZnII, efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the 64CuII–3 complex is investigated by transmetalation experiments with ZnII and NiII, using fluorescence and radioactivity detection, and the results confirm the high stability of 64CuII–3. In addition, metal complexes of ligand 3 with the lanthanide ions TbIII, EuIII, and NdIII are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection. KW - Bispidines KW - Chelates KW - Imaging agents KW - Lanthanides KW - Radiolabeling KW - Nuclear medical application KW - Radioactive labelling KW - SPECT PY - 2014 DO - https://doi.org/10.1002/chem.201404086 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 51 SP - 17011 EP - 17018 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-32320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hennig, C. A1 - Ikeda-Ohno, A. A1 - Kraus, Werner A1 - Weiss, S. A1 - Pattison, P. A1 - Emerich, H. A1 - Abdala, P. M. A1 - Scheinost, A.C. T1 - Crystal structure and solution species of Ce(III) and Ce(IV) formates: From mononuclear to hexanuclear complexes N2 - Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)2+ and Ce(HCOO)2+. In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(µ3-O)4(µ3-OH)4(HCOO)x(NO3)y]12–x-y. The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO– results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(µ3-O)4(µ3-OH)4]12+ core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(µ3-O)4(µ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(µ3-O)4(µ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO– ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process. KW - Crystal structure KW - Ce complexes KW - EXAFS KW - XANES PY - 2013 DO - https://doi.org/10.1021/ic400999j SN - 0020-1669 SN - 1520-510X VL - 52 IS - 20 SP - 11734 EP - 11743 PB - American Chemical Society CY - Washington, DC AN - OPUS4-29850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -