β‐シクロデキストリン／２‐ナフチルアルカノール多分子包接系における高エネルギーエキシマー生成

Abstract

In water containing β-cyclodextrin, guest compoun ds 2-naphthylalkanols exhibit, in addition to monomer emission, excimer emission whose emission λmax shifts to the shorter wavelength with increasing branching in the hydroxyalkyl group of the guest molecule, i. e., 400 nm (2-naphthylmethanol), 385 nm (1-(2-naphthyl) ethanol), and 365 nm (2-(2-naphthyl)2-propanol). The depencence of monomer and excimer emission intensities on β-cyclodextrin concentration revealed the initial formation of 1: 1 inclusion compounds and subsequent dimerization to 2: 2 inclusion compounds, the latter leading to formation of excimers upon excitation. The increased steric crowding in the β-cyclodextrin cavity of the 2: 2 inclusion compound appears to prevent entrapped grest molecules from attaining stable sandwich-type excimer configuration, resulting in the observed shift of excimer emissionλmax