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

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 hydrated crystalline calcium carbonate phase: Calcium carbonate hemihydrate.

Hydrous CaCO 3 gets a new structure Calcium carbonate (CaCO 3 ) forms important minerals on Earth and is a model system for understanding crystal nucleation. Three different structures of CaCO 3 are known, along with two structures that are hydrated. Zou et al. found a third hydrated CaCO 3 structure formed from amorphous CaCO 3 in the presence of magnesium ions. The discovery illustrates the importance of amorphous precursors for producing new materials. Science , this issue p. 396

Korrosion von Kulturgut: Entdeckung einer kollagenartigen Tripelhelix in der Kristallstruktur von Calciumacetat‐Hemihydrat

CCDC 1958904: Experimental Crystal Structure Determination

Related Article: Sebastian Bette, Jörg Stelzner, Gerhard Eggert, Thomas Schleid, Galina Matveeva, Ute Kolb, Robert E. Dinnebier|2020|Angew.Chem.,Int.Ed.|59|9438|doi:10.1002/anie.202001609