Synthesis And Properties Of Stiff-Stilbenes Derivatives

Stiff-stilbene,as the structural skeleton of molecular motors,is a space-constrained stilbene fused ring analog.Due to their rigid structure,the alteration of geometric configuration during photoisomerization process,possess high thermal stability and photoisomerization quantum yield,stiff-stilbene derivatives can be widely used in catalysis,biology,controllable self-assembly and ion recognition.In recent years,photoresponsive control-release systems have attracted extensive attention because of their applications in the aspect of drug delivery and ion transport.Therefore,in this study,stiff-stilbenes based on bi-urea groups have been investigated in the application of ion control-release.Subsequently,the effects of substituents in stiff-stilbene on its photoisomerization and photoluminescence properties were studied.This study provides a theoretical basis for the development of stilbene molecular motors with high isomerization efficiency and luminescence efficiency and their applications in intelligent luminescent materials.1.Two forms of stiff-stilbenes(Z-form and E-form)functionalized with bi-urea-groups have been constructed,and the Z-form is similar to the molecular tweezer.It can be proved photoisomerization stimulated by disverse light via examination of their UV-Vis absorption spectra and 1H NMR spectra.Furthermore,NMR titration experiments were performed to demonstrate that the Z-form stiff-stilbene has the functions of selective recognition and control-release of CH3CO2-and H2PO4-.Finally,by the fluorescence spectral change upon irradiation at diverse UV light,it was affirmed that the stiff-stilbenes can be conducted as a new type of fluorescent switch.2.16 stiff-stilbene derivatives with different substituent groups have been designed and synthesized.Their photoisomerization behaviors in different solvents were studied via UV-Vis absorption spectra and 1H NMR spectra.Furthermore,they can generate photoisomerization under different wavelengths of ultraviolet light except the compounds with nitro group.Noteworthily,the stiff-stilbenes with-OCH3,-CH3,and-H possess high photoisomerization yield(over 98%)and relatively high photoreaction quantum yield from Z-form to E-form.Interestingly,the fluorescence of these three Z-form stiff-stilbenes in CH3CN and DMSO is very weak,while the E-forms have strong fluorescence.Additionally,the Z-forms and E-forms can be trans form each other with good photoisomerization performance and reversibility.Therefore,they are excellent fluorescent switches,and they can provide new texturess for the development of intellegent light-emitting materials.