Über Eisengallustinte

Abstract

Durch Kristallisation in Gelen erhält man aus Gallussäure und Eisen(III)‐chlorid Einkristalle, die einen der wesentlichen Farbstoffe der Eisengallustinte darstellen dürften. Die Struktur besteht aus einem hexagonalen Gallussäure‐Eisen‐1: 1‐Gerüst, in dessen Kanälen Hydronium‐Ionen den Ladungsausgleich bewirken. Die Oxidationsstufe drei des Eisens wurde mit Mössbauer‐ und XANES‐Spektroskopie bestätigt.

DFT calculations of the IR and Raman spectra of anthraquinone dyes and lakes

“…The structure of the aluminum/calcium complexes (the lakes) has been determined by X‐ray measurements only in the case of alizarin and purpurin . The alizarin complex is the main component of madder lake, and the structure is made up by four ligand units, as shown in Figure a.…”

“…Starting from the fractional coordinates obtained by X‐ray measurements, the structure of the alizarin complex has been optimized following the same computational protocol used for anthraquinone and anthraquinone dyes. At the end of the optimization, the structure of the complex stabilizes to a C 2 h symmetry with only minor changes with respect to experimental data, as can be appreciated from Figure b.…”

“…Because Raman spectroscopy is the most adopted technique to study this kind of samples, in the following, only the result of some selected computed active Raman modes are analyzed and discussed. In particular, starting from the structural characterization of the alizarin and purpurin lakes, all the aluminum complexes have been made up by four dyes molecules. Each dye molecule interacts with aluminum through two vicinal OH groups, acting as a bidentate ligand, as shown in Figure , whereas the C=O group is involved in the interaction with Ca 2+ ion.…”

Elucidation of the Fe(III) Gallate Structure in Historical Iron Gall Ink

“…We describe here a series of synthetic, structural, spectroscopic, and aging studies, which unequivocally demonstrate that the primary colorant in IGI is an amorphous form of an octahedral Fe(III) gallate metal organic framework structure that has previously been described by Wunderlich [8][9][10] Unlike the majority of prior studies, we use authentic IGI precursors to prepare both crystalline and amorphous forms of the IGI precipitate and study the crystal-to-amorphous transition by way of XRD, thermal gravimetric analysis (TGA), IR and Raman, Mossbauer, and X-ray photoelectron spectroscopy (XPS). Spectroscopic comparisons with historical documents prove the relevance of the synthetic crystalline and amorphous forms of the model IGI materials to those found in the authentic manuscripts.…”

Towards a new conservation method for ancient manuscripts by inactivation of iron via complexation and extraction

“…It is well known that these kinds of inks were produced by mixing aqueous solutions of iron(II) sulfate with extracts of gall nuts, but usually also variety of different, less important components, were added [13,14,15]. The colour of ink originates, according to Wunderlich [16,17], from the complexes of iron(III) ions with gallic acid and according to Krekel [18] from the complexes with pyrogallol. It was found out that, taking into account the stoichiometry of those compounds, that most ancient iron-gall inks contain an excess of iron [6,7,8,9,10,11,19].…”