Preparation and Photophysical Properties of Materials Obtained by Co―intercalation of 4―MAA and 2―NSA into Mg―Al―LDH

A pair of chromophores with donor―acceptor properties, 4―methoxyphenylacetic acid (4―MAA) and 2―naphthalene sulfonic acid (2―NSA), were intercalated into the layered double hydroxide (LDH), [Mg0.66Al0.34(OH)2](CO3)0.17·0.67H2O by the method of ion―exchange procedures in ethylene glycol. The obtained co―intercalation compounds were characterized by X―ray diffraction, infrared and thermogravimetry techniques. The photochemical properties of the obtained compounds were studied by UV―Vis absorption and fluorescence spectroscopy. The guest molecular sizes and structures were investigated utilizing an ab initio (HF/6―31G) method by G03w. It was believed that the molecular axis of the interlayer 4―MAA molecule was tilted approximately 45° to the layers, and the molecular axis of the interlayer 2―NSA molecule was perpendicular to the plane of the host layer. Both of them were arranged in monolayer between the metal hydroxide layers. These results indicate that the confinement of the pair of chromophores, 4―MAA―2―NSA, within the interlayer region of hydrotalcites are in favor of guest―host interaction and guest―guest interaction, and that the pair of chromophores, 4―MAA―2―NSA can give rise to energy transfer processes because of the characteristics of their excited states.