title: Synthesis of calcium oxalate trihydrate: New data by vibrational spectroscopy and synchrotron X-ray diffraction.
abstract: Calcium oxalate is found in nature in three different crystalline states determined by the number of H2O in the unit formula (whewellite CaC2O4·H2O, COM; weddellite CaC2O4·(2+x)H2O, COD and caoxite CaC2O4·3H2O, COT). The properties of these materials are relevant in the field of biomedicine, cultural heritage and mineralogy. In two previous papers, we have used X-ray diffraction and vibrational spectroscopy (infrared and Raman) to derive information on crystal and molecular structures of COM and COD. In this paper, we complete the synthesis and analysis on the third form, COT, and present a comparative study of the data collected from the three crystalline states. The experiments clearly highlight the role played by the H2O molecules linked within the structure by different kinds of hydrogen bonds. The vibrational assignment of the infrared and Raman bands are critically proposed. The fact relevant for the work in biomedicine, cultural heritage and crystallography is that a simple examination of the spectra allows quickly to determine the chemical nature of the material in an unknown sample even in a minute quantity or in awkward experimental conditions.
authors.affiliation: Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Via Cozzi 53, 20125 Milano, Italy. Electronic address: c.conti@icvbc.cnr.it.
authors.forename: Claudia
authors.initials: C
authors.lastname: Conti
authors.affiliation: Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Via Cozzi 53, 20125 Milano, Italy; DISAT, Università di Milano Bicocca, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Casati
authors.affiliation: Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Via Cozzi 53, 20125 Milano, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Colombo
authors.affiliation: Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Via Cozzi 53, 20125 Milano, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Possenti
authors.affiliation: Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Via Cozzi 53, 20125 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Realini
authors.affiliation: Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Botticelli 23, I-20133 Milano, Italy; Istituto di Cristallografia, CNR, Via G. Amendola 122/o, Bari, Italy.
authors.forename: G Diego
authors.initials: GD
authors.lastname: Gatta
authors.affiliation: Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Botticelli 23, I-20133 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Merlini
authors.affiliation: Dipartimento Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Brambilla
authors.affiliation: Dipartimento Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zerbi
mesh_terms: D002129:Calcium Oxalate / Q000138:chemical synthesis / Q000737:chemistry*; D003460:Crystallization; D008958:Models, Molecular; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D017356:Synchrotrons; D014961:X-Ray Diffraction
chemical_list: C000610370:caoxite; C016189:whewellite; D002129:Calcium Oxalate; C016188:weddellite
keywords: Calcium oxalate trihydrate; Caoxite synthesis; Infrared spectroscopy; Raman spectroscopy; Synchrotron X-ray diffraction