High Sensitive Molecular Recognition by Monomer and Exciplex Emissions for Endocrine-Disrupting Chemicals and Their Analogs Based on Fluorescent Hetero-Modified Cyclodextrins

A fluorescent molecular sensing for endocrine-disrupting chemicals and their analogs has been investigated by fluorescence spectral change of regio-selective 1-pyrene-ρ-cyanobenzene-modified γ-cyclodextrins on the addition of a guest. These host compounds showed both monomer and exciplex fluorescence at around 378 and 397 nm, and 468nm, respectively. On accommodation of the guests such as dioxin analogs, p-nonylphenol, 2, 4-dichlorophenoxyacetic acid, bisphenol A, and diethylphthalate, the intensities of the guest-induced monomer fluorescence increased or decreased, and those of the guest-induced exciplex emission decreased. The extent of the fluorescence variations with the guest was employed to display the sensing abilities of these hosts. The sensing parameters, ΔIm/I0m and ΔIex/I0ex, were used to describe the sensing ability of the hosts, where Im and I0m, and Iex and I0ex were fluorescence intensities of monomer and exciplex emission, respectively, in the presence and absence of the guest, and ΔIm=I0m-Im, and ΔIex=I0ex-Iex. These hosts particularly exhibited high sensitive and selective molecular recognition ability for 2, 4, 6-trichlorophenol, p-nonylphenol and bisphenol A.