(2)與廣島大學合作測量之染料小分子系統，是承襲我們在2017年兩間實驗室共同研究發表之coumarin衍生物分子(出處：Org. Lett. 2017, 19, 2622−2625)並延伸其共軛長度；使其由過去的D-π-D型結構延展至D-π-π-D型。隨著共軛結構的延伸，在實驗中也觀察到了雙光子吸收截面提高了數十倍，這項結果對未來將caged-compound應用於醫療上將會是一大助益。 ;This thesis mainly studies the optical properties of neat-films that fabricated by using our newly synthesized two-photon chromophores in comparison to their optical properties in solution phase. In addition, we also studied the two-photon properties of a film of perovskite quantum dot and a coumarin-containing chromophore in solution phase in order to evaluate its applicability for two-photon uncaging.
We have used four different types of our new chromophore for the film fabrication: Series1: Carbazole-cored multi-branched structure. Series2: Symmetric and asymmetric chromophores derived from oxadiazoles and thiazoles. Series3: Bisarylacetylene-type chromophores based on quinoxaline, fluorene and carbazole units. Series4: Multi-substituted quinoxalinoid chromophores.
For the film samples made from the above-mentioned chromophores, we have found the following optical properties: (1)The two-photon absorption cross-section values of film-phase are generally higher than those of the solution-phase for each chromophore. (2)The two-photon absorption spectra are similar for film and solution samples for each chromophore. We postulate that the close-stacking of molecules has led to a better coplanarity of the molecules, therefore, the two-photon activity values would be higher.
The other two systems of the studied samples are from our collaborators-Prof. Hao-Wu Lin in National Tsing Hua University and Prof. Manabu Abe in Hiroshima University. We have found the following interesting properties: (1)The sample from National Tsing Hua University is a film of perovskite quantum dot. This film exhibits very high fluorescence quantum efficiency. In addition, this film shows a recoverable fluorescence intensity under intermittent irradiation of laser light. (2)The sample from Hiroshima University is an extended version of our previously published chromophore (from: Org. Lett. 2017, 19, 2622−2625). We have modified the conjugated structure from D-π-D to D-π-π-D. We have observed that with the extension of the structure, the two-photon absorption cross-section value can be enhanced over ten times. Such a result has pointed out a possibility to use this structure as a caged-compound for medical application.
