| This thesis mainly focus on the synthesis of novel bidirectional photoswitchable photochromic[2]rotaxanes,whose dual spectral variation properties as well as distinctive visible light stable features for the light-activated colored states were studied systematically.Firstly,two bistable[2]rotaxanes of R1 and R2 which composed of dumbbell-shaped axises and electron-deficient tetravalent macrocycles(CBPQT4+)were synthesized through linear end-capping approaches.Whereas the axis of R1contains a stiff stilbene?SB?unit and an electron-rich 1,5-dioxophthalene?DNP?unit as two recognition sites,a SB unit and a biphenyl?BP?unit were incorporated as two recognition sites in the axis of R2.The chemical structures of R1 and R2 were undualtablly characterized by 1H NMR,13C NMR as well as high resolution mass spectroscopies,respectively.Then,the photochromic behaviors and the dual absorption spectra variations of R1 and R2 in methanol were systematically investigated in methanol by using NMR and UV/Vis spectroscopic experiments.The results showed that the CBPQT4+macrocycles in the R1 and R2 prefered to complex with the E-SB units in their non-excited states.Upon the irradiation with alternative UV lights??=340 nm/375 nm?,the revesible E/Z photoisomerization of the SB units could triggered,leading to the shuttling of the CBPQT4+rings on the dumbbell.This made the contents of the charge-transfer complexes of E-SB@CBPQT4+and DNP@CBPQT4+(or BP@CBPQT4+)varied between different photostaionary states,which resulted in unique dual spectral as well as solution color changes to the naked eyes.More importantly,the UV-irradiated corlored states for both R1 and R2 were stable under visible light condition,owning to the distinctive bidirectional UV lights activated photochromic mechanisms.We believe that these novel[2]rotaxanes are expected to be applied in the field of new information display and data storage materials. |
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