Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam): a novel precursor of calcium oxalate coating for carbonate stone substrates
Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam): a novel precursor of calcium oxalate coating for carbonate stone substrates
Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O-methyl-N-(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w/w) of the title compound with respect to ammonium oxalate (0.4 M, 5% w/w) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w/w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N-(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx.
calcite, conservation, cultural heritage, DFT, limestone, marble, oxamate
Pintus, Anna
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Aragoni, M. Carla
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Carcangiu, Gianfranco
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Caria, Veronica
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Coles, Simon J.
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Dodd, Eleanor
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Giacopetti, Laura
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Gimeno, Domingo
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Lippolis, Vito
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Meloni, Paola
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Murgia, Simone
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Navarro Ezquerra, Antonia
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Podda, Enrico
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Urru, Claudia
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Arca, Massimiliano
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30 July 2023
Pintus, Anna
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Aragoni, M. Carla
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Carcangiu, Gianfranco
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Caria, Veronica
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Coles, Simon J.
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Dodd, Eleanor
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Giacopetti, Laura
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Gimeno, Domingo
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Lippolis, Vito
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Meloni, Paola
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Murgia, Simone
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Navarro Ezquerra, Antonia
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Podda, Enrico
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Urru, Claudia
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Arca, Massimiliano
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Pintus, Anna, Aragoni, M. Carla, Carcangiu, Gianfranco, Caria, Veronica, Coles, Simon J., Dodd, Eleanor, Giacopetti, Laura, Gimeno, Domingo, Lippolis, Vito, Meloni, Paola, Murgia, Simone, Navarro Ezquerra, Antonia, Podda, Enrico, Urru, Claudia and Arca, Massimiliano
(2023)
Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam): a novel precursor of calcium oxalate coating for carbonate stone substrates.
Molecules, 28 (15), [5768].
(doi:10.3390/molecules28155768).
Abstract
Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O-methyl-N-(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w/w) of the title compound with respect to ammonium oxalate (0.4 M, 5% w/w) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w/w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N-(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx.
Text
molecules-28-05768-v3
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More information
Accepted/In Press date: 26 July 2023
Published date: 30 July 2023
Additional Information:
Funding Information:
We thank the Università degli Studi di Cagliari for financial support and CeSAR (Centro Servizi d’Ateneo per la Ricerca) of the University of Cagliari, Italy, for NMR and PXRD measurements. We thank EPSRC (UK) for the provision of single-crystal X-ray diffractometers. CINECA is kindly acknowledged for the computational resources on the GALILEO100 supercomputer accessed within the ISCRA Class C project “A DFT approach to the conservation of cultural heritage: interaction of new consolidating and protecting agents with carbonate stones and mortars” (LithoDFT).
Keywords:
calcite, conservation, cultural heritage, DFT, limestone, marble, oxamate
Identifiers
Local EPrints ID: 481874
URI: http://eprints.soton.ac.uk/id/eprint/481874
ISSN: 1420-3049
PURE UUID: f15e601b-08be-4f9a-b8af-f35b82aec126
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Date deposited: 12 Sep 2023 16:35
Last modified: 18 Mar 2024 02:50
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Contributors
Author:
Anna Pintus
Author:
M. Carla Aragoni
Author:
Gianfranco Carcangiu
Author:
Veronica Caria
Author:
Eleanor Dodd
Author:
Laura Giacopetti
Author:
Domingo Gimeno
Author:
Vito Lippolis
Author:
Paola Meloni
Author:
Simone Murgia
Author:
Antonia Navarro Ezquerra
Author:
Enrico Podda
Author:
Claudia Urru
Author:
Massimiliano Arca
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