Synthesis And Properties Of Novel Multifunctional Groups With Perylene Diimide

Perylene tetracarboxylic diimide(PDI) derivatives are important molecular building blocks that are currently being investigated for use in a variety of photoactive organic materials because of their low light and thermal fading rates,high luminescence efficiency,wide absorption and emission bands in visible region,and optoelectronic properties.They have been used in organic field-effect transistors, light-harvesting solar cells,photovoltaic devices,light emitting diodes,and robust organic dyes that are resistant to photobleaching.These dyes have generated great interest because of their outstanding photochemical and thermal stability,ease of synthetic modification,and desirable optical and redox characteristics.Driven by the demands of diverse applications,the modification on molecular structure of PDI aimed at changing the photophysical properties has attracted a lot of research interest in the past decade.The different substituents in the same position of PDI and the same substituents in the different positions of PDI lead to significant on changes on the photoelectric properties of new dyes greatly.These substituents are either small groups such as phenoxy groups,aryls,cyclic secondary amines,cyano groups,and halogens or large functional moieties such as PDI,Phthalocyanines, porphyrins,BODIPY,cyclodextrin,Fullerene,calixarene,and so on.To create a new PDI dye with novel photophysical and photochemical properties,the combinationof PDI and multifunctional groups in one molecule is a rational design.So,in this paper, we described the synthesis of a series of new PDIs with novel photophysical properties.In chapter 1,the research of synthesis,properties and applications of these perylene diimide derivatives were reviewed.In chapter 2,cyclophanes of perylene tetracarboxylic diimides(PDIs) with different substituents at the bay positions,namely four phenoxy groups at the 1,7-positions,four piperidinyl groups at the 1,7-positions,and eight phenoxy groups at the 1,6,7,12-positions of the two PDI rings,have been synthesized by the condensation of perylene dianhydride with amine in a dilute solution.These novel cyclophanes were characterized by ¹H NMR spectroscopy,MALDI-TOF mass spectrometry,electronic absorption spectroscopy,and elemental analysis.The conformational isomers of cyclophanes substituted with four piperidinyl groups at the 1,7-positions were successfully separated by preparative TLC.The main absorption band of the cyclophanes shifts significantly to the higher energy side in comparison with their monomeric counterparts,which indicates significantÏ€-Ï€interaction between the PDI units in the cyclophanes.Nevertheless,both the electronic absorption and fluorescence spectra of the cyclophanes were found to change along with the number and nature of the side groups at the bay positions of the PDI ring. Time-dependent DFT calculations on the conformational isomers with four piperidinyl groups at the 1,7-positions reproduce well their experimental electronic absorption spectra.Electrochemical studies reveal that the first oxidation and reduction potentials of the PDI ring in the cyclophanes increase significantly compared with those of the corresponding monomeric counterparts,in line with the change in the energy of the HOMO and LUMO according to the theoretical calculations.In chapter 3,three perylene tetracarboxylic diimide(PDI) trimers substituted with different side groups at the bay positions were prepared with the triazine ring as a linkage.The free rotation of C-N-C bonds between the triazine ring and the PDI unit provide these molecules with some flexibility.The UV-vis absorption and fluorescence spectra of these three compounds show different concentration-dependent behaviors,which depend on the side groups at the bay positions. Significant aggregation in organic solvents was revealed by the electronic absorption and emission spectra as well as the fluorescence quantum yield calculation.The aggregation behavior of these compounds in the solid state were investigated by X-ray diffraction(XRD),while the morphology of the aggregates was examined by atomic force microscopy(AFM).The aggregation of trimer 1 with two phenoxy groups at the 1 and 7 positions results in long nanofibers whereas trimers 2 and 3 with dipiperidinyl groups or tetraphenoxyl groups at the bay positions form only particles.The results of this research revealed that PDI trimers with flexible structures can also self-assemble into large ordered aggregates such as those with rigid structure.This information is believed to be useful in the design of novel nanoorganic materials.In chapter 4,two novel fluorescent dyes based on perylene tetracarboxylic diimides synthesized by anhydrous ZnCl₂ catalized condensation between dianhydried and methyl quinoline.Significant features,such as longer wavelength absorption and emission,high fluorescence quantum yields,and strong electron accepting abilities, are observed for these new PDIs.Further reaction of these compounds with BF₃-Et₂O gives two compounds with advantage of both PDI and BODIPY.In chapter 5,several novel fluorescent dyes based on perylene tetracarboxylic diimides(PDIs) were prepared by a catalytic nucleophilic addition of an activated methyl group to carbonyl group.The compounds yield show several significant features compared with the conventional PDIs,such as longer wavelength absorption and emission,high fluorescence quantum yields and strong electron withdrawing abilities.Same side group at different position of the PDI ring will induce significant changes of UV/Vis absorption and fluorescence spectra,which can be ascribed to the different distribution of the frontier molecular orbital.Most importantly,the novel compounds can either reacted with BF₃-Et₂O to form new BODIPY analogues or selectively coordinate with different metal ions accompanied with significant changes on the absorption and fluorescence spectra.These properties make them good candidate for the application as fluorescence sensor.