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Corrosion of Heritage Objects: Collagen-Like Triple Helix Found in the Calcium Acetate Hemihydrate Crystal Structure.

Authors :
Bette S
Stelzner J
Eggert G
Schleid T
Matveeva G
Kolb U
Dinnebier RE
Source :
Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2020 Jun 08; Vol. 59 (24), pp. 9438-9442. Date of Electronic Publication: 2020 Apr 15.
Publication Year :
2020

Abstract

Helical motifs are common in nature, for example, the DNA double or the collagen triple helix. In the latter proteins, the helical motif originates from glycine, the smallest amino acid, whose molecular confirmation is closely related to acetic acid. The combination of acetic acid with calcium and water, which are also omnipresent in nature, materializing as calcium acetate hemihydrate, was now revealed to exhibit a collagen-like triple helix structure. This calcium salt is observed as efflorescence phase on calcareous heritage objects, like historic Mollusca shells, pottery or marble reliefs. In a model experiment pure calcium acetate hemihydrate was crystallized on the surface of a terracotta vessel. Calcium acetate hemihydrate crystallizes in a surprisingly large unit cell with a volume of 11,794.5(3) Å <superscript>3</superscript> at ambient conditions. Acetate ions bridge neighboring calcium cations forming spiral chains, which are arranged in a triple helix motif.<br /> (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Details

Language :
English
ISSN :
1521-3773
Volume :
59
Issue :
24
Database :
MEDLINE
Journal :
Angewandte Chemie (International ed. in English)
Publication Type :
Academic Journal
Accession number :
32065724
Full Text :
https://doi.org/10.1002/anie.202001609