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- Mössbauer spectroscopy (2)
- Supramolecular chemistry (2)
- 119mSn-Mössbauer spectroscopy (1)
- 4-Acyl-pyrazolone (1)
- Alpha-helix (1)
- Automated analysis (1)
- Bacterial adhesion (1)
- Biofilm (1)
- Biofilm quantification (1)
- Bis-terpyridine (1)
Organisationseinheit der BAM
Metallosupramolecular coordination polyelectrolytes (MEPEs) based on rigid and flexible ditopic bis-terpyridine ligands and Fe(II) ions are investigated by Mössbauer spectroscopy. We demonstrate the influence of mechanical stress induced by grinding on the structure of MEPE as well as the ability of MEPE to self-repair through recrystallisation.
Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4-propanoyl-2,4-dihydro-5-methyl-2-phenyl-3 H-pyrazol-3-one in the presence of O2 gave the compound cis-dichlorobis(4-propanoyl-2,4-dihydro-5-methyl-2-phenyl-3 H-pyrazol-3-onato) tin(IV) [(C26H26N4O4)SnCl2]. The compound has a six-coordinated SnIV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two-fold axis of inversion for both the ligand anions and the two cis-chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; = 71.59(4), = 79.39(3), = 75.18(4); Z = 2 and Dx = 1.575 g cm-3. The important bond distances in the chelate ring are Sn-O [2.041 to 2.103 Å], Sn-Cl [2.347 to 2.351 Å], C-O [1.261 to 1.289 Å] and C-C [1.401 Å] the bond angles are O-Sn-O 82.6 to 87.7° and Cl-Sn-Cl 97.59°. The UV, IR, 1H NMR and 119Sn Mössbauer spectral data of the compound are reported and discussed.
Systematic 119mSn-Mössbauer spectroscopy studies of three different types of five and six coordinated molybdenum and tungsten stannylidyne complexes are presented. The measured isomer shifts (IS) range from 2.38 to 2.50 mm/s and the quadrupole splittings (QS) from 1.8 to 2.8 mm/s. The values are dependent on the metal centre, the ligand sphere and the charge of the complexes. The influence of the neighbouring metal atoms (Mo, W) and their coordination sphere on the electron density at the tin atom is observed and will be discussed.
Absorption effects and the impact of specimen shape on TXRF analysis has been discussed intensively. Model calculations indicated that ring shaped specimens should give better results in terms of higher counts per mass signals than filled rectangle or circle shaped specimens. One major reason for the difference in signal is shading effects. Full field micro-XRF with a color X-ray camera (CXC) was used to investigate shading, which occurs when working with small angles of excitation as in TXRF. The device allows monitoring the illuminated parts of the sample and the shaded parts at the same time. It is expected that sample material hit first by the primary beam shade material behind it. Using the CXC shading could be directly visualized for the high concentration specimens.
In order to compare the experimental results with calculation of the shading effect the generation of controlled specimens is crucial. This was achieved by 'drop on demand' technology. It allows generating uniform, microscopic deposits of elements. The experimentally measured shadings match well with those expected from calculation.