关键词: 荧光化学敏感器, 激基缔合物, 光诱导电子转移, 主客体化学, 单光子记数法

Abstract: The steady and transient state photo physical behaviors of multi pedal naphthyl urea derivatives were studied in this work. It is due to the fact that the interaction between urea groups perturbs the π-π overlap of naphthyl groups resulting in a negative effect on the excimer formation of naphthalene. Experiments show that because the electronic donating group, tertiary amine, exists in the molecule 1, the fluorescence of excited naphthyl group can be quenched via the intra molecular electron transfer process. In this case, although the fluorescence of excimer can be observed by method of spectrum normalization from the steady state spectra of tri podal compound, but the intensity is quite weak. In addition, the pico second single photon counting method is used to measure the fluorescence life time of these compounds. It is found that the decay process of transient species is an tri exponential one. The emission species with the longest life time is attributed to the formation and decomposition of naphthalene excimer. The quantity of the largest life time component in total excited species is just only 4%. This corresponds to the results obtained from the steady state study. The results indicate that for the compound 1, used as a fluorescence chemical sensor, the change of fluorescence of the excimer used as a sensing part for the detection of foreign species is not suitable. On the contrary, if the foreign species introduced is able to affect the degree of intra molecular electron transfer of this compound, and furthermore to affect the fluorescence intensity of naphthalene, it should be a very sensitive way to indicate whether the complexation of guest molecule with host occurs.

Key words: fluorescence chemical sensor, excimer, photoinduced electron transfer, host/guest chemistry, single photon counting method