Mössbauer Spectroscopic Investigation of Fe<sup>II</sup> and Fe<sup>III</sup> 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks

Wagner, F. E.; Lerf, A.

doi:10.1002/zaac.201500532

Cited by 12 publications

(24 citation statements)

References 15 publications

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“…In agreement with Lerf and Wagner [14,15], the data gathered show that the main chromophore in the iron-gall inks we reproduced is not based on a carboxylate-iron binding, as suggested in previous literature, including the recent work by Ponce et al [6,11,12]. As an alternative to iron-carboxylate binding, colour may be developed through the catechol ring, with 2 OH or galloyl with 3 OH groups providing binding sites for metal ions to chelate, as has already been proposed in different scientific areas of research [38; also see 4,7,8,13].…”

Section: Microftir Spectroscopysupporting

confidence: 89%

“…From polyphenol research, it has been shown that "tannins" are found in galls largely as polygalloyl esters of glucose depicted in Fig. 2 [10], however the models used by the scientific community to describe the iron complexes assume that gallic or tannic acids are available in the gall extracts to bind iron [6,[11][12][13][14][15] (Fig. 2 and Additional file 1: Fig.…”

Section: Polyphenol Metal Ion Complex: the Ligandsmentioning

confidence: 99%

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New insights into iron-gall inks through the use of historically accurate reconstructions

et al. 2018

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Iron-gall inks have been described as complexes of iron ions with gallic or tannic acids, available in gall extracts. To assess this working hypothesis, we have prepared medieval inks using ingredients and methods appropriate to the fifteenth to seventeenth centuries. The five historical inks studied were selected based upon research into Iberian written sources of medieval techniques. Results are supported by comparison with iron complexes with a well-characterized phenol counterpart: gallic, ellagic, and tannic acids as well as digalloyl and pentagalloyl glucose; as either precipitates or prepared as inks by adding gum arabic. Raman and infrared spectroscopies show that medieval writing inks could not have been represented solely by iron complexes with gallic acid. Overall, writing inks display the infrared signature of gallotannins, indicating that complexes of Fe 3+-polygalloyl esters of glucose are also formed. Our results also show that the commercial tannic acid solution is far more complex than the gall extracts, and cannot be used to represent a gall extract (as described in historic written sources). High-performance liquid chromatographyelectrospray ionisation, HPLC-ESI-MS, reveals that the concentration of gallic acid varies in the gall extracts, depending on the extraction method and ink recipe. Importantly, in certain recipes, gallic acid is found as a minor compound, when compared with the galloyl esters of glucose.

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Section: Microftir Spectroscopysupporting

confidence: 89%

Section: Polyphenol Metal Ion Complex: the Ligandsmentioning

confidence: 99%

New insights into iron-gall inks through the use of historically accurate reconstructions

et al. 2018

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“…Whereas the structure and magnetic properties of these transition metal based solids were thoroughly studied, 23,27 no information about their adsorptive properties was available. Nitrogen sorption experiments carried out at 77 K on the Mg derivative indicated that this solid is microporous, although the small size of the pores and their high polarity, associated with the presence of remaining acidic protons on the ligand, accounted for strong diffusion kinetics limitation at low temperature.…”

Section: Introductionmentioning

confidence: 99%

Small-Pore Gallates MOFs for Environmental Applications: Sorption Behaviors and Structural Elucidation of Their High Affinity for CO₂

et al. 2020

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The ability of two structurally related small pore Metal Organic Frameworks (MOFs) to capture CO2 was investigated by a combination of gas sorption measurements, X-ray powder diffraction (XRPD) analysis, microcalorimetry experiments and Ideal Adsorbed Solution Theory (IAST) calculations. The title solids, formulated Mg(H2gal) and Fe(Hgal) (H4gal = gallic acid) are made of a naturally occurring ligand, and were both prepared on the multigram scale under mild conditions. They both present very similar structures, with identical channels of ca 3.5 Å diameter, but present different amounts of acidic protons on the surface of the pores. These compounds were found to be extremely hydrophilic, and exhibit a moderate stability towards water. Whilst their ability to adsorb CH4 and N2 is very limited, they both adsorb significant amounts of CO2 even at atmospheric pressure (3 and 5 mmol g-1 at 303 K for the Fe and Mg derivatives respectively). As a consequence, these compounds present high CO2/N2 and CO2/CH4 selectivities (380-910 and 190-460 respectively) together with good working capacities, making them of interest for the capture of CO2 from flue gas or for landfill gas upgrading in pressure swing adsorption or vacuum swing adsorption processes. Finally, the analysis of the Mg derivative by X-Ray Diffraction (XRD) and adsorption microcalorimetry revealed that its high affinity for CO2 relies on a strong and specific site of adsorption involving double hydrogen bonds between the CO2 molecules and the acidic protons of the framework.

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“…This suggests that the state of the iron even on freshly written manuscripts is mainly the result of the reaction of the cellulose of the paper and the unreacted iron sulfate of the ink. The concentration of complexes of iron with phenolic ligands is, at least in most cases, too low to be seen in the Mössbauer spectra [40]. In the course of time, and depending on the conditions of storage, iron oxalate or iron oxy-hydroxides may form from the iron compounds formed initially with the cellulose of the paper.…”

Section: Discussionmentioning

confidence: 99%

“…It is also possible that polyphenol complexes of the inks decompose to Fe(II)-oxalate with iron from the iron sulfate. For example, a ferrous component found as a byproduct in the synthesis Fe(III)-gallate(2) from ferrous sulfate and gallic acid at about 100 °C [40] is clearly ferrous oxalate. The exact conditions under which ferrous oxalate forms in old documents still need clarification, but prolonged storage in a warm and moist environment may be favorable for its formation.…”

Section: Papers With Applied Inkmentioning

confidence: 99%

Mössbauer Study of Iron Gall Inks on Historical Documents

Lerf

Wagner

Dreher

et al. 2020

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Iron gall ink was used as a permanent writing material already in late Roman times and throughout the Middle Ages, until it became obsolete in the 20th century. There is much interest in non-destructive experimental methods to determine the state of the ink and its degradation products on historical documents. Mössbauer spectroscopy is such a method, and it has the particular advantage to be sensitive to the chemical bonding of iron, but this method has only rarely been applied to historical documents. In this paper we present Mössbauer data for two damaged documents from a Library in Granada and a handwritten German book from the 18th century. These new results are discussed in the context of previously published Mössbauer data. In one of the investigated documents Fe-(II)-oxalate, FeC2O4·2H2O, was observed. The assignment of the various Fe3+ sites in the different documents is rather difficult and often there is a superposition of various species. These species can be remains of the Fe-tannin complexes of the ink, complexes of Fe3+ with the cellulose of the paper and different iron oxide or hydroxide nanoparticles.

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Mössbauer Spectroscopic Investigation of Fe^II and Fe^III 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks

Cited by 12 publications

References 15 publications

New insights into iron-gall inks through the use of historically accurate reconstructions

New insights into iron-gall inks through the use of historically accurate reconstructions

Small-Pore Gallates MOFs for Environmental Applications: Sorption Behaviors and Structural Elucidation of Their High Affinity for CO₂

Mössbauer Study of Iron Gall Inks on Historical Documents

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Mössbauer Spectroscopic Investigation of FeII and FeIII 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks

Cited by 12 publications

References 15 publications

New insights into iron-gall inks through the use of historically accurate reconstructions

New insights into iron-gall inks through the use of historically accurate reconstructions

Small-Pore Gallates MOFs for Environmental Applications: Sorption Behaviors and Structural Elucidation of Their High Affinity for CO2

Mössbauer Study of Iron Gall Inks on Historical Documents

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Product

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Mössbauer Spectroscopic Investigation of Fe^II and Fe^III 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks

Small-Pore Gallates MOFs for Environmental Applications: Sorption Behaviors and Structural Elucidation of Their High Affinity for CO₂