UCL logo

UCL Discovery

UCL home » Library Services » Electronic resources » UCL Discovery

The Color and Stability of Maya Blue: TDDFT Calculations

Tilocca, A; Fois, E; (2009) The Color and Stability of Maya Blue: TDDFT Calculations. J PHYS CHEM C , 113 (20) 8683 - 8687. 10.1021/jp810945a.

Full text not available from this repository.

Abstract

Car-Parrinello structural optimizations of realistic models of the Maya Blue (MB) hybrid material are combined with TDDFT calculations of the electronic excitation spectra to identify the nature of the fundamental guest-host interactions leading to the unusual stability of this pigment. The comparison with the features of the experimental visible spectrum reveals that the main mode of interaction between the host solid (the palygorskite clay) and the guest molecule (the organic indigo dye) involves the coordination of the carbonyl group of the dye by Al3+ ions exposed at the edge of the palygorskite tunnels. Analogous Mg2+-dye interactions which do not strongly affect the MB visible spectrum can also be present. Thermal treatment used in the preparation of the pigment appears therefore essential to release some of the structural water molecules tightly bound to the Al3+ ions in the internal clay surface, thus leaving them available to coordinate the organic molecule. Moderate heating also favors the oxidation of indigo to dehydroindigo (DHI): the spectral features of the latter complex with Al3+ are in remarkable agreement with the experimental spectrum, thus confirming the substantial role of DHI in the properties of Maya Blue.

Type:Article
Title:The Color and Stability of Maya Blue: TDDFT Calculations
DOI:10.1021/jp810945a
Keywords:MICROPARTICLES APPROACH, MOLECULAR-DYNAMICS, ABSORPTION-SPECTRA, ORGANIC PIGMENT, PALYGORSKITE, INDIGO, VOLTAMMETRY, SEPIOLITE, APPROXIMATION, DEHYDRATION
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

Archive Staff Only: edit this record