The Influence Of Bay Substitution On The Melt Crystallization Behavior About C₁₂-PDI-C₁₂

Perylene diimide derivatives are a class of polycyclic aromatic hydrocarbon compounds containing fused conjugated plane with extremely strongπ-πforce,possess unique photophysical and photochemical properties,which is applied in the field of solar energy conversion,electroluminescence and biological fluorescent probe and so on.Over recent two decades,it is meaningful to give PDI molecular and polymer liquid crystal properties by substitution,especially in bay area.On the one hand,it can change the distribution of electron cloud for perylene to improve physical properties.On the other hand,the Bay molecules can form or induced liquid crystal in the balance of rigid and flexible,and it is very important for the application of the semiconductor material.In this paper,initially,side chain dodecylamine and Br-substituted PDI derivatives were synthesized,which were regraded as the row material to compound a series of the displaced products of the bay area by benzene ring,alkyl chains and ethylene glycol oligomer（amphiphilic perylene imide）.The influences of melt induced crystallization,self-assembled behavior in solution and morphology and structure of self-assembled products by length and type of chain were studied systematically and separately.The primary results are below:（1）Based on the previous research of my group,perylene imide derivatives owning dodecyl side chains and bay-substituted by phenol,naphthol or phemethylol,respectively,were synthesized efficiently.UV-Vis Absorption and Fluorescence Emission Spectra of Normalized Solution were used to study the effect of various substituting groups in bay area and photophysical properties.This kind of Phenol substitute group can make perylene ring to form larger conjugate plane by the bay substituted,which is representative of the melt crystallization behavior.DSC,POM and XRD were used to acquire melt crystallization and self-assembled behaviors of modified perylene imide.The conclusion indicated below:1)Although C₁₂-PDI-C₁₂was displaced by benzene derivatives,it did not exist intermediate phase of the liquid crystal phase during the course of uniform cooling.Melt crystallization happened in crystallization temperature range,and the highest temperature is226.6℃、245.9℃、198.7℃,respectively.Compounds which were superseded by Phenol and naphthol formed the same crystal structure with divergence of the multi-branched around the nuclei.However,substitution product replaced by benzyl alcohol generated flake crystals in process of melt crystallization.2)Owing to the electronic properties of Phenol,naphthol,benzyl alcohol substitutes,the absorption and emission wavelength of perylene imide showed red shift.Compared with the intrinsic one,compounds replaced by phenol derivatives augmented fluorescence lifetime.In the slow self-assembly of solution,the tiny changes of molecular structure may cause great discrepancy in self-assembly of solution,which may lead to altering Molecular piling method and angle.Therefore,the crystals holding various morphologies and longer size were observed.（2）Compared to phenyl substituted,Alkyl chain substituted product provided beneficial conditions for the perylene nuclear accumulation in the overall balance of the rigid and flexible process.The perylene imide derivatives having dodecyl side chains in two sides and ethanol,butanol or hexanol respectively at bay-substitution were analyzed by UV-Vis Absorption and Fluorescence Emission Spectra of Normalized Solution.These were used to study the effect of various substituent groups in bay area.DSC,POM and XRD were used to acquire melt crystallization,self-assembled behaviors of modified perylene imide,and crystal size and stacking parameter of modified perylene imide.The conclusion indicated below:1)C₁₂-PDI-C₁₂derivatives occurred in intermediate phase of the liquid crystal phase when displaced by alkyl chain at bay area in disparate length,such as ethanol,butanol,and hexanolall.The structure of liquid phase transfromed from spherulite,branched petaloid to cruciform,respectively.With increment of the length of alkly chain,the formation temperature of middle phase present a growth trend.After being superseded by ethanol,butanol and hexanol,the absorption and emission wavelength of perylene imide derivatives showed red shift trend similarly,which is more conspicuous than phenol-substituted derivatives.The perylene imide derivatives replaced by aloxy-based materials possess longer fluorescence lifetime than the unsubstituted one.Over slow-assembly process of solution,along with the chain in bay area increased,the self-assembled body formed a longer nanoribbon structure.（3）The C-O bond has a higher conformational freedom than the C-C bond,therefore the bay introduction of ethylene glycol molecules can provide Perylenebisamidine molecule with greater flexibility.The compounds including perylene imide derivatives having dodecyl side chain and bay-substituted by TEG,SEG or PEG400 respectively were synthesized.They were analyzed by UV-Vis Absorption and Fluorescence Emission Spectra of Normalized Solution to study the effect of various substituent groups in bay area.DSC,POM and XRD were used to know the process of melt crystallization,self-assembly behaviors,crystal size and stacking parameter of modified perylene imide.The conclusion indicated below:1)C₁₂-PDI-C₁₂displaced by ethylene glycol chain in unlike length（TEG,SEG,PEG400）all performed intermediate phase of the liquid crystal phase,and there were showed different morphologies.On one hand,the liquid crystal phase structure are crescent,pyramidal,multi-branched dendritic,respectively.On the other hand,the formation temperature of interphase may lower as the growth of the ethylene glycol chain.2)Being substituted by TEG,SEG or PEG400,C₁₂-PDI-C₁₂derivatives caused redshift of the absorption and emission wavelength;This shift is more easily to be noticed than phenol-substituted and alkoly-substituted derivatives.Moreover,these perylene imide derivatives with ethylene glycol chains in bay area possess longer fluorescence lifetime than the unsubstituted one.