Molecular States of p-Dimethylaminobenzonitrile Coground with beta-Cyclodextrin Investigated Using Solid-State Fluorescence Spectroscopy

作者：Inoue Yutaka; Hasegawa Nana; Tozuka Yuichi; Yonemochi Etsuo; Oguchi Toshio; Higashi Kenjirou; Moribe Kunikazu; Yamamoto Keiji^*

来源：Chemical & Pharmaceutical Bulletin, 2011, 59(10): 1299-1302.

• solid-state fluorescence
• p-dimethylaminobenzonitrile
• beta-cyclodextrin
• ground mixture
• coprecipitate

Changes in molecular states of p-dimethylaminobenzonitrile (DMABN) coground with beta-cyclodextrin (beta-CD) were examined using solid-state fluorescence measurements. Formation of a DMABN/beta-CD inclusion complex by coprecipitation was confirmed by powder X-ray diffraction measurement. The powder X-ray diffraction pattern of the ground mixture was a halo pattern and differed from the pattern of the mixture prepared by coprecipitation. Solid-state fluorescence measurements revealed emission by DMABN crystals in a twisted intermolecular charge-transfer state at 473 nm. DMABN in the DMABN/beta-CD coprecipitate had a fluorescence emission peak at 393 nm due to its planar structure. In contrast, DMABN in a DMABN/beta-CD ground mixture had an emission peak at 473 nm due to its twisted structure. Grinding time-dependent structural changes in DMABN were evaluated using fluorescence lifetime and relative quantum yield measurements. Structural changes in DMABN in the DMABN/beta-CD coprecipitate from a planar to a twisted structure were observed with grinding. DMABN, dispersed in microcrystalline cellulose (CC) molecules in a DMABN/CC ground mixture, had a fluorescence emission peak at 473 nm. However, the excitation spectrum of a DMABN/beta-CD ground mixture differed from that of DMABN in CC. These results indicated that the molecular state of DMABN accommodated in the beta-CD cavity differs between the coprecipitate and the ground mixture.

• 出版日期2011-10