25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Stability of Diphosphates and Diphosphonates in Si-O-P Compounds - A Solid-State NMR Study

Not scheduled
4h
Harnack House and Henry Ford Building

Harnack House and Henry Ford Building

Board: 487
Poster Posters

Speaker

Ms Christine Viehweger (TU Bergakademie Freiberg, Institute of Analytical Chemistry)

Description

In general, Si-O-P compounds are structurally interesting materials because they possess many different structural motives including higher coordinated silicon atoms. Well-known examples are crystalline silicophosphates like SiP2O7.[1] These and other Si-O-P compounds can be synthesized by different reaction routes at ambient pressure. We established a so-called “water-free” sol-gel route,[2,3] which can be adapted as a general synthetic procedure to obtain various Si-O-P compounds by using diphosphoric or diphosphonic acids instead of crystalline phosphoric acid.

Here, the reaction of tetraethoxysilane with either diphosphoric acid (SiOP1) or 1-hydroxyethane 1,1-diphosphonic acid (SiOP2) yielded amorphous products. The local structure of these Si-O-P materials could be elucidated primarily by solid-state NMR spectroscopy. The evidence for higher coordinated silicon atoms was given by 29Si MAS NMR spectroscopy due to chemical shift data.[4] Additionally, 13C and 31P MAS NMR spectra could verify the existence of diphosphate and diphosphonate structures. Furthermore, FSLG-HETCOR and 31P-29Si CP-REDOR experiments were able to deliver, inter alia, detailed information about 1H-29Si and 1H-31P heteronuclear correlations and the first coordination sphere of the phosphate and phosphonate groups. In the case of SiOP1, the phosphorous atoms of the main structure are connected via oxygen to three silicon atoms.[5]

[1] H. Rabaâ, F. Bkiri, Can. J. Chem. 2006, 84, 1024–1030.
[2] S. Jähnigen, E. Brendler, U. Böhme, G. Heide, E. Kroke, New J. Chem. 2014, 38, 744–751.
[3] S. Jähnigen, E. Brendler, U. Böhme, E. Kroke, Chem. Commun. 2012, 48, 7675–7677.
[4] T. R. Krawietz, P. Lin, K. E. Lotterhos, P. D. Torres, D. H. Braich, A. Clearfield, J. F. Haw, J. Am. Ceram. Soc. 1998, 120, 8502–8511.
[5] J. Kowalke, C. Arnold, I. Ponomarev, C. Jäger, P. Kroll, E. Brendler, E. Kroke, Eur. J. Inorg. Chem. 2019, 2019, 828–836.

Primary authors

Ms Christine Viehweger (TU Bergakademie Freiberg, Institute of Analytical Chemistry) Ms Janine Kowalke (TU Bergakademie Freiberg, Institute of Inorganic Chemistry) Prof. Christian Jäger (BAM Federal Institute for Materials Research and Testing, Division I.3) Dr Ilia Ponomarev (University of Texas at Arlington, Department of Chemistry and Biochemistry) Dr Peter Kroll (University of Texas at Arlington, Department of Chemistry and Biochemistry) Prof. Edwin Kroke (TU Bergakademie Freiberg, Institute of Inorganic Chemistry) Dr Erica Brendler (TU Bergakademie Freiberg, Institute of Analytical Chemistry)

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