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Updated: Jun 16, 2026
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Published on: August 1, 2018
Coloration phenomenon of mefenamic acid in mesoporous silica FSM-16
Kunikazu Moribe1, Ryo Kinoshita, Kenjirou Higashi
1Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. moribe@p.chiba-u.ac.jp
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.
Insights
Mefenamic acid (MFA) changes color to deep blue when mixed with mesoporous silica FSM-16 and heated/humidified. This coloration depends on MFA’s dispersed state within the silica pores and surface changes.
Area of Science:
- Materials Science
- Physical Chemistry
- Nanotechnology
Background:
- Mefenamic acid (MFA) is a non-steroidal anti-inflammatory drug.
- Mesoporous silica materials like FSM-16 offer unique properties for drug delivery and stabilization.
Purpose of the Study:
- To investigate the coloration of mefenamic acid (MFA) when formulated with mesoporous silica FSM-16.
- To understand the influence of FSM-16 pore size and treatment conditions on MFA coloration.
Main Methods:
- Preparation and characterization of MFA/FSM-16 composites with different pore sizes (16.0 Å and 45.0 Å).
- Application of sealed-heating (SH) and humidification (HU) treatments.
- Analysis using Powder X-ray Diffraction (PXRD), Thermogravimetric Analysis (TGA), Solid-state 13C-NMR, and Solid-state 29Si-NMR.
Main Results:
- A distinct color change from white to deep blue was observed in MFA/FSM-16 mixtures after SH and HU treatments.
- Coloration was dependent on the pore size of FSM-16 and the specific treatment applied.
- PXRD data indicated that the dispersion state of MFA within the FSM-16 mesopores influenced coloration.
- TGA differentiated between MFA adsorbed on the surface and MFA within the mesopores.
- Solid-state NMR revealed increased molecular mobility of MFA in FSM-16 and structural changes in silanol groups upon humidification.
Conclusions:
- The coloration of MFA within FSM-16 is a complex phenomenon influenced by MFA adsorption, its dispersed state, molecular mobility, and FSM-16 surface modifications.
- Both the adsorption of MFA into FSM-16 mesopores via SH and the changes in FSM-16 surface state induced by HU contribute to the observed color change.
