Abnormal Fluorescence Behavior of Pyrene Functionalized Chitosan Films to Some Quenchers

Investigation of the fluorescence behavior of a pyrene functionalized chitosan film (PSC-CS) to some quenchers,including KI,CH3NO2 and Cu(NO3)2,has revealed that the monomer emission from the PSC-CS film increased rather than decreased,whereas the excimer emission decreased with the increase of time of duration after addition of KI or Cu(NO3)2.Both the increasing and decreasing processes could last as long as 20min to 40min,Unlike that observed in the system containing KI or Cu(NO3)2,for CH3NO2 system,both the monomer emission and the excimer emission increased with introduction of the quencher,but the excimer emission only started to increase after an hour-long induction period.The position of the excimer emission of the PSC-CS film did not change very much with addition of KI or Cu(NO3)2.However,addition of CH3NO2 made the excimer emission blue shifted for at least 20nm indicating formation of distorted excimers opr partially overlapped excimers.The fluorescence response of the film to external additions is sensitive but is low in selectivity.This property may make the film use as a novel sensing material for monitoring the purity of water.

Abnormal Fluorescence Behavior of Pyrene Functionalized Chitosan Films to Some Quenchers

Investigation of the fluorescence behavior of a pyrene functionalized chitosan film (PSC‐CS) to some quenchers, including KI, CH₃NO₂ and Cu(NO₃)₂, has revealed that the monomer emission from the PSC‐CS film increased rather than decreased, whereas the excimer emission decreased with the increase of time of duration after addition of KI or Cu(NO₃)₂. Both the increasing and decreasing processes could last as long as 20 min to 40 min. Unlike that observed in the system containing KI or Cu(NO₃)₂, for CH₃NQ₂ system, both the monomer emission and the excimer emission increased with introduction of the quencher, but the excimer emission only started to increase after an hour‐long induction period. The position of the excimer emission of the PSC‐CS film did not change very much with addition of KI or Cu(NO₃)₂. However, addition of CH₃NO₂ made the excimer emission blue shifted for at least 20 nm indicating formation of distorted excimers or partially overlapped excimers. The fluorescence response of the film to external additions is sensitive but is low in selectivity. This property may make the film use as a novel sensing material for monitoring the purity of water.