RESUMEN
The external sixteenth century wall paintings of St. Dumitru's Church in Suceava (Romania) are suffering visually from deterioration. Fragments of these paintings spallated from the external wall have been studied by micro-Raman microscopy in order to elucidate possible causes of this process. Calcite and alpha-quartz are the components of the substratum indicating that the artists used the Roman fresco technique comprising a limewash putty. No organic binders have been detected in the substrate or pigment application. Amorphous carbon and goethite, alpha-FeOOH, have been identified in areas containing residues of grey and yellow pigments, respectively. Small amounts of gypsum have been detected in the grey areas which we attribute to special attention being given to surface preparation and pigment application in these areas. An abundance of sodium nitrate, nitratine, microcrystals have been observed on the surfaces of many fragments which suggests that a biodeterioration process originating from guano deposits could have been operating in these frescoes.
Asunto(s)
Pinturas , Espectrometría Raman/métodos , Arquitectura , Carbonato de Calcio/análisis , Sulfato de Calcio/análisis , Carbono/análisis , Colorantes/análisis , Compuestos de Hierro/análisis , Minerales , Cuarzo/análisis , Rumanía , Dióxido de Silicio/análisis , Espectrofotometría Infrarroja/métodosRESUMEN
1H-NMR spectra of aqueous solutions of fenbufen and two cyclodextrins (alpha- or gamma-cyclodextrin, respectively) mixtures confirm the formation of an inclusion complex if gamma-cyclodextrin is used, whereas in the case of alpha-cyclodextrin no inclusion complex was obtained. The stoichiometry of the fenbufen/gamma-cyclodextrin complex is of the [2:1] type. The geometry of this supramolecular architecture was established through MM+ molecular mechanics calculations.
Asunto(s)
Fenilbutiratos , alfa-Ciclodextrinas/química , gamma-Ciclodextrinas/química , Antiinflamatorios no Esteroideos , Conformación de Carbohidratos , Secuencia de Carbohidratos , Hidrógeno , Espectroscopía de Resonancia Magnética/métodos , Conformación Molecular , Datos de Secuencia MolecularRESUMEN
An inclusion complex of fenbufen with beta-cyclodextrin (beta-CD) in aqueous solution was characterized by (1)H-NMR spectroscopy. The [1:1] stoichiometry was determined and a stability constant of several 1000s (M(-1)) was calculated. The geometry of the inclusion complex was established based on MM(+) molecular mechanics calculations.
