4 詳細
A fluorogenic reagent, 7-phenylsulfonyl-4-(2,1,3-benzoxadiazolyl) isocyanate for alcohols, with development based on the empirical method for prediction"
S. Uchiyama, T. Santa, S. Suzuki, H. Yokosu and K. Imai
Anal. Chem., 1999, 71, 5367-5371.
■ Abstract
During the course of our studies, we found the relationship between the fluorescence characteristics (the fluorescence intensity and the maximum excitation and emission wavelengths) of benzofurazan compounds and the sum and difference of Hammett substituent constants at the 4- and 7- positions. This prompted us to design a useful fluorogenic derivatization reagent having the benzofurazan skeleton for alcohols along this Line of thought. Accordingly, the fluorogenic derivatization reagents, which have no fluorescence themselves, 7-N,N-dimethylaminosulfonyl-4-(2,1,3-benzoxadiazolyl) isocyanate (DBD-NCO), 7-phenylsulfonyl-4-(2,1,3-benzoxadiazolyl) isocyanate (PSBD-NCO), and 7-methylsulfonyl-4-(2,1,3-benzoxadiazolyl) isocyanate (MSBD-NCO), were synthesized. Among the derivatives derived from the three reagents, that from PSBD-NCO was most strongly fluorescent. PSBD-NCO reacted with l-octanol within 4 h in acetonitrile solution in the absence of a catalyst at 60 degrees C. The derivatives with four alcohols (1-octanol, 1-nonanol, 1-decanol, and 1-undecanol) were separated on a reversed-phase column and detected fluorimetrically at 490 nm with the excitation at 368 nm, The detection limits were at the 10-femtomole level. PSBD-NCO was superior to other fluorescent-labeling reagents with regard to the avoidance of the interfering peaks derived from the reagents themselves and degradation products in the chromatogram, The effectiveness of our approach is disccussed in terms of the development of new fluorogenic reagents.
■ 内容
ベンゾフラザン化合物における置換基のハメット定数と蛍光性の関係を利用して，アルコール用の高感度な蛍光誘導体化試薬を開発したという論文です．
■ ひとこと
Anal. Chem. Minor revision アクセプト．この研究で，一番苦労したのは何といっても試薬の合成です．この論文が完成する２年近く前から試薬自体は設計していたのですが，長らく試薬であるイソシアネートの合成に手こずっていました．そもそも，ホスゲンなんて使えないし，有機系の研究室に質問しに行っても事態は変わらず．と，諦めていたころに東京化成から「合成ができた！」という連絡がありました．実際にこの試薬は，溶液として保存する以外は非常に不安定で，HPLC の移動相に含まれる水によっても分解してしまいます．反応条件や感度は申し分ない試薬ですが，後々から考えてみると，アルコール性水酸基と反応してアミンや水と反応しない試薬なんてそうそう無いはずで，水酸基に選択的な試薬の開発を試みることは実はとんでもなくナンセンスな（＝非科学的な）ことかもしれません．