Solid-state NMR studies of ultramarine pigments discloration

Eleonora Del Federico, Jacob Newman, Lindsey Tyne, Cyndi O'Hern, Licio Isolani, Alexej Jerschow

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Ultramarines are a family of pigments widely used as colorants in artists' paints, coatings, plastics, cosmetics, and various industrial materials. They are aluminosilicates characterized by a sodalite cage framework which enclathrate paramagnetic (S3, S2) and diamagnetic (S 4 or S3Cl) chromophores responsible for the color of these pigments. Solid-state 27Al MAS NMR studies showed that the fading mechanisms in ultramarine pigments, both in acidic and alkaline environments, is initiated via de-alumination leading to framework destruction which in turn triggers the release of the chromophores. This results in color loss and in the emergence of extraframework aluminum. 29Si MAS studies provide new insight into these processes and suggest that acidic attack leads to the formation of Q1-Q3 silicates and possibly to the emergence of Si(3Al), Si(2Al), Si(1Al) and Si(0Al) fragments indicative of the formation of secondary pores through which the guest chomophores can leave the cage. These findings are important for the design of proper conservation treatments and preservation procedures for artwork containing ultramarine pigments.

Original languageEnglish (US)
Title of host publicationMagnetic Resonance in Material Science
Pages45-50
Number of pages6
Volume984
Publication statusPublished - 2007
Event2006 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 27 2006Dec 1 2006

Other

Other2006 MRS Fall Meeting
CountryUnited States
CityBoston, MA
Period11/27/0612/1/06

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

Cite this

Del Federico, E., Newman, J., Tyne, L., O'Hern, C., Isolani, L., & Jerschow, A. (2007). Solid-state NMR studies of ultramarine pigments discloration. In Magnetic Resonance in Material Science (Vol. 984, pp. 45-50)