Analytical Sciences

Photo-responsive Retention Behavior of Azobenzene-modified Cyclodextrin Stationary Phase in Micro-HPLC

Tatsuro NAKAGAMA,  Kazuya HIRASAWA, Katsumi UCHIYAMA, and Toshiyuki HOBO

Division of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, 1-2 Minami-osawa, Hachioji, Tokyo 192-0397, Japan

An azobenzene-modified gamma-cyclodextrin stationary phase (Azgamma-CDSP) was prepared and its photo- and temperature-responses for the retention of perylene and pentacene were investigated using a mixture of methanol and water as the mobile phase in micro-HPLC. The retention of perylene slightly increased, whereas that of pentacene significantly decreased by UV light irradiation to Azgamma-CDSP. These retentions recovered upon irradiation with visible light. Both retentions decreased upon an increase in the column temperature. It was presumed that the trans-azobenzene moiety acts as a preventive cap for perylene and a spacing for pentacene in filling the CD cavity. An azobenzene-modified stationary phase changed its retention behavior with the column temperature and the light irradiation. An improvement in the micro-HPLC system and the optimization of the molecular structure of the photo-responsive stationary phase would provide selective retention control by the irradiation of light in micro-separation systems.

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