Adsorption and entrapment of salicylamide molecules into the mesoporous structure of folded sheets mesoporous material (FSM-16)

Purpose. The aim of this study was to estimate the molecular state of salicylamide on the surface of mesoporous silicas and to investigate the dissolution behavior of salicylamide from the solid dispersion. Methods. Folded sheets mesoporous material (FSM-16) were used as a porous material. The molecular state of salicylamide was estimated by powder X-ray diffractometry, infrared spectroscopy, and fluorescence spectroscopy. Results. The molecular state of salicylamide can be changed by simple blending with FSM-16. When a physical mixture of 25% salicylamide and 75% FSM-16 was heated at 120 degreesC for 3 h, amorphization of salicylamide was observed from the powder X-ray diffraction pattern. The fluorescence emission peak of salicylamide at 433.5 nm shifted to a longer wavelength of 447.5 nm after heating. Changes in fluorescence decay curve suggested that salicylamide molecules were dispersed into the hexagonal FSM-16 channels during the heating process. Enhanced dissolution in the initial stage of salicylamide from the sealed heated sample was observed in comparison with salicylamide crystals. Conclusions. Heat treatment of a physical mixture of salicylamide with FSM-16 gave a solid dispersion in which the salicylamide molecules changed to an amorphous state by adsorption onto the FSM-16 channels. Amorphization of salicylamide contributed to the improvement of dissolution.