Construction of Molecule Sensing Systems and Evaluation of Their Abilities

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Heretofore, we have developed fluorescent cyclodextrins as chemosensors for detecting organic species in aqueous solution. In those cases, the fluorescent moiety attached to cyclodextrin (CD) is excluded from the cavity upon guest accommodation. The object of this study is to produce solid devices containing the fluorescent CDs for application so that they may be used in industry. We used cellulose and glass as solid substrates. As fluorescent CDs, we prepared a novel fluorescent CD (DnsGlu-β-CD), which has dansyl attached glutamic acid bearing free carboxyl group to be reacted with amino group of the substrates. We also prepared another fluorescent CD (DnsC4-β-CD), which was prepared by the reaction between dansylglycine and 1,4-diaminobutane-modified β-CD to be immobilized to cellulose. Cellulose was treated with NaIO_4 and then reacted with 1,6-diaminohexane in the presence of NaCNBH_3. Condensation between carboxyl group of DnsGlu-β-CD and amino group of the modified cellulose gave DnsGlu-β-CD-immobilized cellulose. On the other hand, DnsC4-β-CD was reacted with aldehyde groups of NaIO_4-treated cellulose in the presence of NaCNBH_3 to give DnsC4-β-CD-immobilized cellulose. Both DnsGlu-β-CD- and DnsC4-β-CD-immobilized cellulose membranes decreased the fluorescence intensity upon guest addition in water, indicating that molecule responsive fluorescent papers were produced. On the other hand, we treated glass with 3-aminopropyltorimethoxysilane to introduce amino groups on the surface of the glass. The condensation between the carboxyl group of DnsGlu-β-CD and amino groups of the glass gave DnsGlu-β-CD-immobilized glass, but no guest-induced fluorescence change was observed probably due to adsorption of the dansyl moiety on the surface of the glass. We are exploring the method to overcome this difficulty.