resumo
The inclusion compounds of alpha-, beta- and gamma-cycloclextrins (alpha-CD, beta-CD and gamma-CD) with trans-cinnamic acid (t-CIA), 3-hydroxytrans-cinnamic acid (t-3OHCIA), 4-hydroxy-trans-cinnamic acid (t-4OHCIA) and 3,4-dihydroxy-trans-cinnamic acid (t-3,4OHCIA) were prepared and characterized, in the solid state, by means of thermogravimetry and Raman spectroscopy. The effects of the inclusion process on the guest molecules and on the hydrogen bond interactions of the guest were studied by monitoring sensitive vibrational modes, such as C=O, C=C and ring C-H stretching modes. By combining Raman and TG data with ab initio calculations and information from CSD database on similar compounds, inclusion geometries for the different compounds are proposed. The size of the host cavity and the maximization of host/guest hydrogen-bonding contacts appear to be the main factors determining the inclusion geometries. Copyright (C) 2009 John Wiley & Sons, Ltd.
palavras-chave
CRYSTAL-STRUCTURE; FERULIC ACID; CAFFEIC ACID; SOLID-STATE; VIBRATIONAL MICROSPECTROSCOPY; ANTIOXIDANT ACTIVITY; RAMAN-SPECTROSCOPY; SINGLE-CRYSTALS; PHENOLIC-ACIDS; GALLIC ACID
categoria
Spectroscopy
autores
Nolasco, MM; Amado, AM; Ribeiro-Claro, PJA
nossos autores
Mariela Martins Nolasco
Investigador Auxiliar
Paulo Ribeiro-Claro
Professor Associado com Agregaçãoagradecimentos
The authors would like to thank Wacker Chemie GmbH, Germany, for their kind offer of the cycloclextrin samples, and to the Portuguese Foundation for Science and Technology (FCT) for the financial support. MN (SFRH/BPD/32103/2006) thanks FCT for a research grant. Contract/grant sponsor: Portuguese Foundation for Science and Technology. Contract/grant number: SFRH/BPD/32103/2006.