Synthesis And Photophysical Properties Of Perylenetetracarboxylic Diimide Derivatives Linked With Spirobifluorene

Perylenetetracarboxylic diimide (PDI) derivatives are important optical function materials that in recent years they have generated more and more attention, and gradually become a research hotspot. Due to their low light and thermal fading rates, high luminescence efficiencies, wide absorption and emission bands in visible region, they have been used in liquid crystal materials, electroluminescence, solar energy conversion and biological fluorescent probes and so on.Recently, the modification on molecular structure of PDI aimed at changing the photophysical properties has attracted a lot of research interest in the past years. By this way PDI can content to the demands of diverse applications. To create a new PDI dye with outstanding photophysical and photochemical properties, the combination of PDI and multifunctional groups in one molecule is a rational design. So, in this paper, we described the synthesis and properties of a series of novel PDls wich has never been reported in literature..In chapter1, the research of synthesis, properties and applications of these perylene diimide derivatives have been reviewed.In chapter2, we synthesize a series of compounds consisted of four diphenoxyl groups substituted PO-PDI named Spiro-PDI1, three PO-PDI and one dipyrrolidinyl group substitutued5PDI called Spiro-PDI2, one PO-PDI and one5PD1called Spiro-PDI3which all covalently linked by spiro-linkage. This kind of compound is expected to exhibit unique photophysical properties due to their relative orthogonal orientations, which may cause special interactions between the PDI units at different positions. For comparison, we also synthesized two compounds linked by fluorene with PO-PDI and5PDI, F-PDI4and F-PDI5.In chapter3, The photophysical properties of these compounds were investigated by the steady state electronic absorption and fluorescecne spectra and the lifetime measurements. The ground state absorption spectra revealed no interactions between the PDIs. The fluorescence spectra suggest efficient energy transfer from diphenoxyl groups substituted PO-PDI units to the perpendicular arranged dipyrrolidinyl group substitutued PDI (5PDI), which accompanied by an less efficient electron transfer from5PDI to PO-PDI within the compound. The kinetics of the energy transfer process has been deduced from the transient absorption spectra. The efficient energy transfer from PO-PDI to the perpendicular arranged5PDI conflicts with the predication of Foster theory and therefore it is extraordinary..In chapter4, we synthesised and charactered two other PDI compounds linked with an extended spiro-bridge.We found that the properties of these compounds change obviously from that of the compounds in last chapter. The absorption and fluorescence spectra of these new spiro-linked ompounds show relatively larger dependence on the solvents. Efficient energy transfer from PO-PDI units to5PDI was flund in this compounds, but no electron transfer from5PDI to PO-PDI was found. All the results indicated that the energy transfer is less dependent on the distance=between the PO-PDI and5PDI than the electronic transfer in these compounds.