title: Coloration phenomenon of mefenamic acid in mesoporous silica FSM-16.
abstract: Coloration of mefenamic acid (MFA) was investigated in the presence of mesoporous silica FSM-16 with 16.0 A (Oc) and 45.0 A (Doc) pore diameter. The color change of MFA/FSM-16 physical mixture from white to deep blue was observed by sealed-heating (SH) and the subsequent humidification (HU). The coloration and the color difference were caused by the changes of chroma and lightness. In the case of MFA/FSM-16 (Oc), coloration was not observed by SH treatment only. Powder X-ray diffraction data indicated that difference of the dispersed states of MFA molecules in FSM-16 mesopore affected the coloration. MFA adsorbed on the silica surface and MFA in the mesopore were differentiated by thermogravimetric analysis. Solid-state (13)C-NMR showed that the molecular mobility of MFA was increased in the dispersed state in FSM-16 mesopores compared to the crystalline state. Structural changes of silanol groups in FSM-16 by humidification were observed by solid-state (29)Si-NMR. MFA adsorption in FSM-16 mesopore by SH as well as changes of the surface state of FSM-16 by HU affected the coloration of MFA.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. moribe@p.chiba-u.ac.jp
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Moribe
authors.forename: Ryo
authors.initials: R
authors.lastname: Kinoshita
authors.forename: Kenjirou
authors.initials: K
authors.lastname: Higashi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tozuka
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D003124:Colorimetry; D009682:Magnetic Resonance Spectroscopy; D008528:Mefenamic Acid / Q000737:chemistry*; D033362:Powder Diffraction; D012822:Silicon Dioxide / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: C481639:FSM 16; D008528:Mefenamic Acid; D012822:Silicon Dioxide