Design,Synthesis And Characterization Of Multi-Stimuli Responsive Switches Based On Spiropyran And Benzoxazine

The multi-addressable molecular switch is achieved by linking two or more individual switches into one molecule.Because of the versatile and multi-stimuli responsive properties,it has potential in the applications of multi-color display,high-density information storage and multi-functional intelligent materials which has attracted great attention in recent years.In order to obtain a multi-addressable molecular switch with simple synthesis route and fewer units in structure,we fused spiropyran and benzoxazine molecules on a single molecule by sharing an indole group creatively.It is expected that the dual-addressable molecuar switch can transform to different states upon different stimuli.In the second chapter,a dual-addressable molecular switch(SP-OX-NO₂)containing a light responsive spiropyran and a base responsive benzoxazine was designed and synthesized by sharing with an indole group.Through proper molecular modification with nitro functional groups,both SP and OX forms could be achieved separately upon visible light and base stimuli to give out different colors.Calculation indicated the bidirectional switching property could be observed when the OX isomer was more stable than the deprotonated SP isomer.More importantly,besides the commonly stable states of trans merocyanine?MC?,SP and OX,the lifetime of the metastable cis-MC have been increased to days,which is long enough for characterizations and some applications,and the four states can interconvert into each other upon different stimuli in solution.The structural transition between the four states was proved by UV-vis and NMR spectra.The observation of bidirectional switching property of SP-OX-NO₂ in solution encouraged us to further investigate the multi-color switching property on solid matrix.And the simple dual-addressable molecule has been applied to construct a multicolor reversible display on paper successfully.Based on the atomic efficiency,the dual-addressable molecular switch combined two switches?SP and OX?on one molecule by a sharing indole with the simplest structure.By a simple and effective strategy,this molecule was designed and synthesized,which provides a new thought to realize the multi-stimuli responsive,regulation selective and multi-color display properties of the multi-addressable molecular switches.In the third chapter,in order to obtain more outputs,we added the fluorophore HBT into the fused SP-OX switch with multistate and multi-stimuli responsive properties.We first got the MC isomer with strong red emission.By using different alkalization methods,two kinds of ring-closed form of SP and deprotonated SP were achieved,with yellow emission and no emission.The transformation among the three states could be observed in the solution,solid powder and the PDMS film with the stimuli of acid and base.Which could further be applied in the multi-color display and anti-counterfeiting materials.