# Study of historical pigments by vibrational and electronic spectroscopy

Sylvie Blanc

► To cite this version:

Sylvie Blanc. Study of historical pigments by vibrational and electronic spectroscopy. Departamento de Química Física, Universidad del País Vasco, Mar 2012, Bilbao, Spain. hal-05367796

HAL Id: hal-05367796

https://univ-pau.hal.science/hal-05367796v1

Submitted on 16 Nov 2025

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Distributed under a Creative Commons Attribution 4.0 International License
# Study of historical pigments
by vibrational and electronic spectroscopy

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Sylvie Blanc

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# Design of hybrid pigments

* to understand the stability of coloured historical materials

* using simple model

* analysing physical deterioration

* studying chemical modification

* to describe and produce new materials

* in archaeology

* in art

* optical applications

* to use non destructive methods

* UV-Visible absorbance, reflectance, fluorescence properties

* IR and Raman spectroscopy

## Maya blue analogues

### Avignon yellow model lakes
# Maya Blue

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## ancient synthetic hybrid material

* indigo from *Indigofera* leaves

* a clay (palygorskite, sepiolite)

* heating

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## extensively used in Mesoamerica (300-1500 AD)

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exceptional stability : acid-resistant (Gettens test)

R.J. Gettens. Am. Antiq. 1962, 27, 557

no biodegradation

stable up to ~300°C
# Why such a chromostability?

## ♦ Matrix

• indigo on the surface of palygorskite clay

Van Olphen H.Science 1966, 154, 645

• indigo in the clay channels

Chiari, G. et al. Eur. J. Mineral. 2003, 15, 21

• occlusion of the channel entrances by indigo

C. Minkowski, G. Calzaferri, Angew. Chem. 2005, 117, 5459

## ♦ Chromophore

• indigo forms hydrogen bonds with host silanol

B. Hubbard et al. Clays and Clay minerals. 2003, 51, 318.

• compexation of indigo with Al of the matrix

Manciu, F.S. et al. J. Raman Spectrosc. 2007, 38, 1193

• presence of dehydro-indigo

Domenech, A. et al. J. Phys. Chem. B 2006, 110, 6027

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⇒ **difficulty to solve the structure**
**of these archaeological composite materials**
# Indigo visible spectroscopy in CHCl<sub>3</sub>

## ♦ Absorption versus concentration

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## ♦ Fluorescence

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→ equilibrium between monomeric and dimeric species

→ emission fluorescence of the monomeric species
## Choice of the matrix

* **palygorskyte**

* fibrous solid

<figure><img src="image_19.png" /></figure>

Chiari, G., Giustetto, R., Druzik, J., Doehne, E., Ricchiardi, G. 2008
Applied Physics A: Materials Science and Processing 90, 3-7.

* **ZSM5**

* Linear and zick-zack channels

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→resistant pigment obtained for zeolites

which pore size matches the width of indigo molecule

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# Synthesis of Maya blue analogs

## Two steps :

* **co-grinding** (to mimic the archeological processes)

* inorganic matrix : MFI zeolites

* organic chromophore : indigo

1 to 10% wt

* **heating up**

* 100-300°C

* from 2h to 15h

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# Maya blue analogs : species versus indigo concentration

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## UV Visible Reflectance

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*ZSM5 mixture heated in air at 200° during 5 h*

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* increasing intensity

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* presence of two species
# Maya blue and analogs : species versus heating time

* in situ fluorescence emission

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2% wt indigo ZSM5 mixture heated in air at 200°

→ Mixing of dimeric and monomeric form of indigo

→ Colour modulation
## Maya blue analogs : acid attack

### indigo

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### ZSM5 2% indigo

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⇒ The colour still persists in pigment analogs under acidic conditions
# Maya Blue components

## ♦ Archeal sample

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frescoes of Cacaxtla Coll. Louvres

⇒ Indigo dilution

## ♦ Colour analogy

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⇒ analogs similar archeal material
for low concentration of indigo
# Yellow of Avignon (Stil-de-grain)

## Characteristics

- Yellow dyes extracted from fruits of *Rhamnus* species

- Tinctorial properties known since the Antiquity

- Employed in artistic paintings as yellow lakes

- Production in the area of Avignon (commercial place)

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<figure><img src="image_35.png" /><figcaption>Livre des Jeux of Alphonse le Sage
1282 Escorial's Library</figcaption></figure>

## History

- Lateran Council of 1215 discrimination of the Jews using yellow dye (until the 18th century)
# Preparation of yellow lakes

## ♦ Marcucci's « recipe »

* Powdering of dried immature *Rhamnus* berries

* Maceration under agitation during 24-48 hours

* Filtration to remove the residues

* Addition of alum ($KAl(SO_4)_2$, 12 $H_2O$)

* Precipitation of the mixture with an alcalinic carbonate

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# Structure, composition?
## Yellow dyes of *Rhamnus catharticus*

### ♦ Separation and identification by HPLC-PDA

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→ quercetin derivatives
# Quercetin in solution

## Acid-base properties

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Several protonation sites

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Absorption spectrum versus pH

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## Al(III) complexation

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Several coordination sites

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Several complexes

1 cation : AlQ, AlQ₂, AlQ₃,

2 cations : Al₂Q, Al₂Q₃

# Solid state properties?
## Yellow lake versus alum concentration

dye in solution + alum + carbonate

### ♦ Natural lake

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### ♦ Quercetine lake

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↔ formation of an inorganic matrix of amorphous aluminium hydroxide including the organic dyes
Quercetin powder

◆ Structure

<caption>➤ Dimer</caption>

<figure><img src="image_49.png" /><figcaption>➤ Dihydrate</figcaption></figure>

◆ DRUV

<figure><img src="image_50.png" /><figcaption>Monomer ↔ dimer</figcaption></figure>
Solid state complexation of quercetin with Al(III)

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Cation

quercetin

+ alun

+ Al(NO₃)₃

+ AlCl₃

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DRUV

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Quercetin [Q]/[Al(III)]=1

⇒ Complexation only with AlCl₃
Solid state Quercetin AlCl₃ complex

♦ Al(III) concentration

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T=24 h

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→ Absorption band characteristic of complexation
Solid state AlCl₃ complex : Raman

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$$ \mathrm{Al}^{3+} \rightleftharpoons \begin{array}{l} \text{water molecules} \\ \text{phenol coordination} \end{array} $$
Solid state AlCl₃ complex and quercetin lake

◆ Classical quercetin Lake :

precipitate obtained by mixing

quercetin +alun+carbonate in solution

◆ Solid state quercetin lake :

$$ (Q + AlCl_3) + Al(OH)_3 $$

$$ [Q]=10^{-3}M; [Alun] = 30g L^{-1} $$

Immediate precipitatipn at pH = 7 (Na₂CO₃)

$$ [Q]=[AlCl_3]=10^{-4} M $$

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Similar UV-Visible reflectance spectrum
## Yellow lake fluorescence

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Al Complex complex emission
Conlusion

♦ Identification of the yellow dyes of Rhamnus catharticus

> Quercetin as chromophore model for Avignon Lake

♦ Quercetin powder

> monomer and dimer observed by DRIFT and DRUV

♦ Solid state complexation of quercetin with AICI3

> observed by DRUV and Raman

> reaction with water molecules showed by Raman

♦ Quercetin lake

> Solid state complexes similar reflectance spectrum as classical quercetin lake

> Fluorescence properties
Perspect

From macroscopic to molecule scale

◆ fluorescence microscopy

Sylvie Blanc

◆ molecular dynamic simulation
COLHYBRI

Sorption process of dye molecules in organic-inorganic complexes :
a route from Maya Blue to novel hybrid colorants

Patrice Bordat

Ross Brown

IPREM CNRS

Université de Pau
et des pays de l'Adour
Pau, France

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Catherine Dejoie

Pauline Martinetto

Pierre Strobel

Michel Anne

Eric Dooryhée

Institut NEEL CNRS

Université Joseph Fourier

Grenoble, France

Philippe Walter

Elsa Van Elslande

Pascale Richardin

C2RMF-Palais du Louvre

Paris, France

Manuel Sanchez del Rio

ESRF Grenoble, France
and University of Mexico

Florence Porcher

LLB CEA Saclay

Gif sur Yvette, France
Tu Khai Nam Nguyen
Kevin Bourhis
Jean-Charles Dupin
Eve Péré

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Institut Pluridisciplinaire de Recherche
sur l'Environnement et les Matériaux

Equipe Chimie Physique

Carole Mathe

Catherine Vieillescazes

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Laboratoire de Chimie Bioorganique et des
Systèmes Moléculaires Vectoriels

Equipe Chimie Appliquée à l'Art et à l'Archéologie