Synthesis And Properties Of Several Perylene Fluorescent Probes

Perylene diimides(PDIs)are red vat dyes with exceptional chemical,photo,thermal,and weather stability,and so they have been applied to pigments such as fluorescent light collectors,materials for single molecule spectroscopy,laser dyes,and automotive finishes.Also,PDIs show strong fluorescence with high photostability and wide visible ranges,which indicates they could be good materials for fluorescent sensors.However,PDIs display poor solubility and thus show very weak fluorescence owing to aggregation of perylene chromophores,which is a disadvantage that limits their applications.However,the perylene tetra-(alkoxycarbonyl)(PTAC)that is structurally related to PDIs but with four electron deficient carboxylic ester groups attached,is more soluble in organic solvents and show excellent fluorescence.Incorporating heteroatoms into the perylene skeleton can dramatically change the electronic structures and photochemical properties of these heterocyclic annulated perylenes.Furthermore,highly ?-extended heteroarenes would also induce a variety of intermolecular interactions,such as van der Waals interactions and heteroatom-heteroatom interactions.Based on the current investigation of perylene derivatives,this thesis develops several new synthesis methods and designs a fluorescent probe to H+and two novel fluorescence sensors to fluoride ion,also reports the self-assembly of two five membered heterocyclic annulated perylene diimides.The main contents are as follows:1.pH-sensitive perylene tetra-(alkoxycarbonyl)probes for live cell imagingA fluorescent pH-sensitive probe of 1-hydroxyl-3,4;9,10-tetra(n-butoxyloxycarbonyl)perylene(HPTBAC)was synthesized and used for pH sensing in chemical system and living cells.The probe exhibits fluorescence emission characteristics with pKa 7.9 and linear response to the very improtant pH range of 6.7-8.9.We designed the probe for binding of O-of hydroxyl in the perylene skeleton with H+to be responsible for the probe ability to determine acidity to weak base pH.The pH sensitivity is introduced via the O-moiety upon either protonation or deprotonation.In deprotonation form,HPTBAC exhibit very weak emission due to strong electron-donating groups of O-.HPTBAC was successfully applied as a high-performance fluorochrome for living A549 cells(human lung cancer)and E.coli cells imaging.The resultsdemonstrate that HPTBAC is a good candidate for monitoring pH fluctuations in living cells as a pH probe.The hydroxyl modified pH probe which was chosen in this chapter is favorable to the most important pH response range in biological system.In addition,proton of phenolic structure can dissociate more easily than the amides.Therefore it has higher sensitivity.2.Two new chemosensors for fluoride ion based on perylene tetra-(alkoxycarbonyl)derivativesTwo novel fluorescence sensors(1 and 2)based on perylene tetra-(alkoxycarbonyl)derivative(PTAC)were designed and synthesized.The properties of sensors were detected by absorption,fluorescence spectra and electrochemical response.Test results indicated that the sensors had specific selectivity and high sensitivity for fluoride ion(F-)among the halide anions examined(F-,Cl-,Br-and I-).The absorption and fluorescence emission properties of the sensors arise from the intermolecular proton transfer(IPT)process between a hydrogen atom on the amide N position of sensor and the fluoride ion.Corresponding orbital electron distribution and molecular geometry configurations of the compounds were predicted by density functional theory(DFT).Moreover,sensor-based test strips can conveniently detect F-without any additional equipment.Incorporating S atom into perylene tetra esters 2 led to modified aromatic systems while retaining planarity and large conjugated ?-bonds,amide ortho's chlorine substitution enhanced the sensitivity and such molecular tailoring approach would be helpful for designing and synthesizing novel ratio metric fluorescent perylene chemosensors for F-.3.Self-assembly,optical and electrical properties of five membered O-or S-heterocyclic annulated perylene diimidesIn this work,mono five-membered S-heterocyclic annulated perylene diimide(S-PDI)and a new mono five-membered O-heterocyclic annulated perylene diimide(O-PDI)have been synthesized.The compounds O-PDI and S-PDI self-assembled into nanoneedle and nanosheet,respectively.Photophysical,electrochemical and thermal properties were investigated by UV–vis absorption,fluorescence,cyclic voltammetric,thermogravimetric and differential scanning calorimetry techniques.Optical,fluorescence,scanning and transmission electron microscopies were employed in the molecular self-assembly studies.Due to significant electronic coupling between their heterocycles and perylene diimide(PDI)cores,the intermolecular ?-? actions are neglectable,providing high luminescence efficiency.At the same time,the space betweenperylene chromophores is still very short(3.3 ? for O-PDI and 3.23 ? for S-PDI),which is favorable for the hopping transportation of charge carrier from one molecule to a neighboring one.These compounds could be candidate materials for acquiring well defined organic nanostructures with both excellent charge-transporting and good light-emitting capabilities.