Sol-gel phase transition of brucine-appended porphyrin gelator:: a study by vibrational circular dichroism spectroscopy

A novel approach to study the sol-gel phase transition of a brucine-porphyrin based gelator, which uses vibrational circular dichroism (VCD) spectroscopy, is described. The gelation process leading to highly ordered chiral supramolecular assemblies was investigated in various solvents at the different temperatures and concentrations. The VCD spectra sensitively reveal the specific parts of molecule whose configuration is influenced by a sol-gel phase transition and chiral supramolecular aggregation and therefore indicate the parts of the molecule responsible for the chiral self-assembly formation. Temperature stability of the organogel studied is discussed on the basis of the VCD and IR absorption spectra. The scanning electron microscopy was used to visualize the structure of brucine-porphyrin conjugate in the gel phase. (C) 2002 Elsevier Science Ltd. All rights reserved.