| Summary: | 碩士 === 國立中央大學 === 化學學系 === 101 === This research focuses on studying structure-property relationship, exploring two-photon absorption properties and optical power-limiting properties as one of the applications derived from multi-branched triazine. Three new multi-branched triazine compounds : three- and six-branched (compound 1-3) have been designed and synthesized. Their photophysical properties were studied by one-photon fluorescence, fluorescence quantum yield, life-time and two-photon absorption (2PA) cross-section. One-photon fluorescence experimentally was shown that the chromophores (1-3) possess larger Stokes shifts on their fluorescence emission mainly due to intramolecular charge-transfer (ICT). 2PA cross-section measured by two-photon-excited fluorescence (2PEF) technique were determined to be 220.46, 3134.16, and 1873.74 GM for compound 1,2, and 3, respectively at 690 nm. This result indicates that increasing the branch number incorporated to original D-π-A structure frame work could be an effective approach to get the strong molecular 2PA and shown that using a σ-electron pair as bridge might be an efficient way to transfer charge as well as a π-bridge. At the same time, the power-control properties for these chromophores have been investigated by using a tunable nanosecond laser probed at 690 nm and shown that these chromophores have good optical-limiting behavior. These initial results demonstrated that multi-branched triazine chromophores are a highly suitable class of two-photon absorbing materials and would provide attractive potential application in the optical-limiting field.
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