Synthesis And Supramolecular Assembly Of Azobenzene-functionalized Pcrylcne Bisimidc Derivatives

In this thesis,a series of novel azobenzene-functionalized perylene bisimide derivatives(PBIs)were synthesized by imidization of 3,4,9,10-perylene tetracarboxylic dianhydride with corresponding amines.The structures of these compounds were characterized by proton nuclear magnetic reasonce(1H NMR)and matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS).Perylene bisimide derivatives can form assemblies under the synergistic interactions of π-πstacking,hydrogen bond and van der Waals force.The effects of different alkyl chain length on the trans-cis photoisomerization of azobenzene groups in perylene bisimide derivatives by irradiation with 365 and 436 nm wavelength light were investigated using ultraviolet-visible(UV-vis)absorption spectroscopy.It is found that the intermolecular interaction force is the key factor affecting the photoisomerization of azobenzene groups in perylene bisimide derivatives.Reversible photoisomerization of azobenzene groups was achieved by alternating irradiation with 365 and 436 nm wavelength light in solution.The morphologies of assemblies in cis-configuration and trans-configuration were monitored by transmission electron microscopy(TEM).For medium-length alkyl chain,the photoisomerization of azobenzene has the most obvious regulatory effect.Their gel properties were also investigated.Subsequently,a novel perylene bisimide derivative with azobenzene as the center linker was synthesized to investigate the effect of the azobenzene photoisomerization behaviour on the morphology of assembly and the effect of acid and base on the luminescence behaviour of assembly..The main research contents of this thesis are roughly described as follows:(1)Three azobenzene functionalized perylene bisimide derivatives with different peripheral alkyl chain length were synthesized by imidization of 3,4,9,10-perylene tetracarboxylic dianhydride with corresponding amines.The structures of the products were characterized by 1H NMR and MALDI-TOF-MS.The effects of alkyl chain length on trans-cis photoisomerization of azobenzene functional perylene bisimide derivatives were investigated in N,N-dimethylformamide(DMF)and 1,2-dichloroethane(DCE),respectively.By comparing the degree of photoisomerization of azobenzene groups in two solvents under the irradiation with 365 and 436 nm wavelength light,it was concluded that the magnitude of intermolecular interaction force is the key factor affecting the photoisomerization of azobenzene groups,and the stronger intermolecular force will have a negative impact on the photoisomerization of azobenzene groups.In DMF,due to the breakage of hydrogen bond,the relatively weak intermolecular interaction facilitated the reversible photoisomerization of the azobenzene groups by alternating irradiation with 365 and 436 nm wavelength light,which showed good reversibility and photocontrollable property.In DCE,the degree of photoisomerization of azobenzene groups decreased due to the stronger intermolecular force.With the extension of testing time,perylene bisimide derivatives self-assembled into large assembly and precipitated out from system,which reduced the ultraviolet-visible absorption value and weakened the reversibility of the photoisomerization of azobenzene groups.The effect of azobenzene photoisomerization on the morphology of the assembly and the influence of alkyl chain length on the assemblies’morphology were investigated by TEM.The results showed that the longer alkyl chain was not conducive to the formation of the fibers.PBI1 and PBI2 with 1 and 6 carbon atom alkyl chain assembled in DMF to form the fibers,while PBI3 with 12 carbon atom alkyl chain could only form the fiber-like assembly.For perylene bisimide derivative PBI2 with medium alkyl chain length,when azobenzene units were in trans-configuration,the short fibers formed.By 365 nm ultraviolet light irradiation,the assembly transformed into a slender willow leaf-like structure due to transformation of trans-to cis-configuration of azobenzene groups.When the solution was irradiated with 436 nm visible light,the azobenzene groups transformed from cis-to trans-configuration,which resulted in re-transformation to the fibers.By reversible trans-cis photoisomerization,the morphology of assembly can be controlled.In addition,the gel properties of the three samples were tested.It was found that PBI1 and PBI2 had a wide range of gelatin solvents at relatively low concentration as compared with PBI3.(2)The central azobenzene functionalized perylene bisimide diploid PBI5 was synthesized by imidization reaction using asymmetric perylene diamide as intermediate.The structure of the compound was characterized by 1H NMR and MALDI-TOF-MS.The acid-base response test showed that by adding a small amount of trifluoroacetic acid(TFA)to the solution,the ultraviolet absorption of the solution increased significantly,and the ultraviolet absorption and fluorescence emission took a red-shift.By adding triethylamine to the solution and making the solution to neutral,the ultraviolet absorption and fluorescence emission of the solution took a blue-shift to the initial position.Continue adding triethylamine and making the solution to alkaline,the fluorescence of the solution was quenched.Under acidic conditions,the solution was purple red,and gave out a yellow light under ultraviolet irradiation.In case of alkaline condition,the solution became orange,and gave out a green light under ultraviolet irradiation.In neutral condition,the solution became orange and can’t give out light under ultraviolet irradiation.The similar response to acid and alkaline condition was also found in PBI derivatives without azobenzene,indicating that the above response is from the interaction between PBI ring and acid or alkali.The photoinduced trans-cis isomerization of azobenzene-bound perylene bisimide diploid under 365 nm pointolite irradiation was investigated in a mixed solvent of DCE and TFA.Under 365 nm pointolite irradiation,along with the trans-cis isomerization of azobenzene group,a red-shift absorption band appeared at 600 nm and a wide blue-shift absorption band appeared at 400-500 nm,indicating the change of perylene aggregation.By heating the solution,the new absorption band could recover slightly and restore again under 365 nm pointolite irradiation.TEM results showed that when azobenzene is intrans-configuration,PBI5 form fibre-like assemblies.When azobenzene is transformed into cis-configuration by 365 nm pointolite irradiation,the morphology of the assemblies is changed into short rods.The control of assemblies’morphology is realized by photoisomerization of azobenzene group.