30181
Accession Number
30961
Title Of Article Chaper
Insight into Framework Destruction in Ultramarine Pigments
Title Of Journal Book
Inorganic Chemistry
Volume
45
Issue
3
Pages
1270-1276
Collation
7 p. : ills.
Reference Bibliography
Includes bibliographic references
Language Of Text
English
Literature Type
Serial
Literature Level
Analytic
Abstract
We report key evidence on the framework destruction in ultramarine pigments upon color fading. Experiments on faded pigments in a fresco painting environment reveal that the paramagnetic chromophores are set free via sodalite framework destruction and are subsequently degraded. Fading in acidic media produces similar results, although a larger number of [beta]-cages appear to be destroyed, and H2S is released. The findings are further supported by studies on natural and synthetic ultramarine pigments of various shades via solid-state resonance-Raman spectroscopy, colorimentry, and solid-state 29Si and 27Al NMR spectroscopy. NMR parameters are shown to correlate well with the intensities of Raman signals corresponding to the S3-· chromophores. A further correlation is established between the colorimetric parameters, L* (lightness) and C* (chroma), and the paramagnetic shift and paramagnetic linebroadening in NMR spectra for both 27Al and 29Si.
Keywords
resonance; raman; radical; anion; solid-state; blue; spectroscopy; chromophore; green; analysis; pigment; ultramarine
pub_id
30181