Establishment of the Chemical Equilibria of Different Types of Pyranoanthocyanins in Aqueous Solutions: Evidence for the Formation of Aggregation in Pyranomalvidin-3-O-coumaroylglucoside-(+)-catechin

• Tipo: Artigo em Revista Científica Internacional
• Data: 2010

Autores

Luis Cruz (Autor) Outra; Petrov, V (Autor) Outra; Teixeira, N (Autor) Outra; Nuno Mateus (Autor) FCUP; Pina, F (Autor) Outra; Victor de Freitas (Autor) FCUP

Revista

Título: Journal of Physical Chemistry B

Vol. 114 Nº 1

Páginas: 13232-13240

ISSN: 1520-6106

Editora: American Chemical Society

Indexação

ISI Web of Knowledge - 45 Citações

Scopus - 46 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia química

CORDIS: Ciências Físicas > Química > Química analítica > Espectroquímica ; Ciências Físicas > Química > Química orgânica

Outras Informações

ID Authenticus: P-003-1TX

DOI: 10.1021/jp1045673

Abstract (EN): The chemical equilibria of the pyranomalvidin-3-glucosides linked to (+)-catechin, (-)-epicatechin, and catechol moieties (and the respective coumaroylglucoside Compounds) were established by means of UV-vis spectroscopy. The conjugated double bonds among pyranic rings C and D provide a higher electronic delocalization that prevents the nucleophilic attack of water at position 2. Consequently, besides flavylium cation (AH(+)), the bases A, A(-), and A(2-) have been identified by increasing pH, and the respective acidity constants were determined by spectrophotometry. The formation of dimers at higher concentration was observed for pyranomalvidin-3-O-coumaroylglucoside-(+)-catechin, and the respective data treated by the exciton model suggests the for-nation of a chiller where the monomers form J-type aggregates with the dipolar moments in opposite directions and rotated by 174 degrees at a distance of 5.2 angstrom (from the center).

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9