Synthesis And Photophysical Properties Of Fluorinated Poly (Aryl Ether) Dendrimer Zinc(Ⅱ) Phthalocyanine-Pyrene Labled Cyclodextrin- Single-Walled Carbon Nanotubes Nanoconjugates

In this paper, two series of poly(aryl ether) fluorinated and non-fluorinated dendrimer phthalocyanine zinc (Ⅱ)-with cyano or ester terminal groups had been synthesized. They were tetra-(2-4-hydroxyphenyl-2-4-cyanobenzyl fluorinated propyl) phthalocyanine Zinc(Ⅱ) [ZnPc(CF3)8(CN)4], tetra-(2-4-hydroxyphenyl-2-4-methoxycarbonyl fluorinated propyl) phthalocyanine Zinc(Ⅱ) [ZnPc(CF3)8(COO-n-Pentyl)4], tetra-(2-4-hydroxyphenyl-2-4-cyanobenzyl propyl) phthalocyanine Zinc(Ⅱ) [ZnPc(CH3)8(CN)4] and tetra-(2-4-hydroxyphenyl-2-4-methoxycarbonyl propyl) phthalocyanine Zinc(Ⅱ) [ZnPc(CH3)8(COO-n-Pentyl)4]. The structures of these dendrimer phthalocyanines were characterized by elemental analysis, IR,1H NMR,13C NMR, ESI-MS and MALDI-TOF-MS methods.The photophysical properties of ZnPc(CF3)8(CN)4、ZnPc(CF3)8(COO-n-Penty4、 ZnPc(CH3)8(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4 were studied by UV/Vis and fluorescence spectroscopic methods. These phthalocyanines mainly existed as a monomer in DMF. The shape and position of Q band of these phthalocyanines do not change with increasing their concentration. Owing the existence of fluorinated substituents (CF3), the photophysical properties of ZnPc(CF3)8(CN)4 and ZnPc(CF3)8(COO-n-Pentyl)4 were greatly photosensitized. The fluorescence intensity, fluorescence lifetimes and molar absorption coefficients of ZnPc(CF3)8(CN)4 and ZnPc(CF3)8(COO-n-Pentyl)4 were higher than that of non-fluorinated dendrimer phthalocyanines (ZnPc(CH3)g(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4). The nature of terminal groups also exerted influence on the fluorescence intensity, fluorescence lifetime and molar absorption coefficient of phthalocyanine bearing fluorinated and non-fluorinated dendritic substituents. The changes of fluorescence intensity, fluorescence lifetime and molar absorption coefficient follow the order:ZnPc(CF3)8(COO-n-Pentyl)4> ZnPc(CF3)8(CN)4; ZnPc(CH3)8(COO-n-Pentyl)4> ZnPc(CH3)8(CN)4. This maybe because the different electron withdrawing abilities of the terminal groups.The photoinduced intermolecular electronic transfer between ZnPc(CF3)s(CN)4、 ZnPc(CF3)8(COO-n-Pentyl)4、ZnPc(CH3)8(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4 and benzoquinones were studied by UV/Vis and steady-state fluorescence spectroscopic methods. The results showed that the fluorescence of these phthalocyanines was greatly quenched by the photoinduced electronic transfer process. This maybe due to the electron was transferred from these dendritic phthalocyanines to benzoquinone. Moreover, the fluorescence quenching efficiency of ZnPc(CF3)8(CN)4 and ZnPc(CF3)8(COO-n-Pentyl)4 were higher than that of ZnPc(CH3)8(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4. As the empty p orbital of CF3 group connected with the p orbital of benzene ring to form larger π conjugate system, the electron was easier to be transfer from dendrimer phthalocyanines to benzoquinone.The photoinduced intramolecular energy transfer of ZnPc(CF3)8(CN)4、 ZnPc(CF3)8(COO-n-Pentyl)4、ZnPc(CH3)8(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4 was studied by fluorescence spectroscopic and UV/Vis methods. The results showed that the intramolecular energy of these phthalocyanines was transferred from dendritic structure to phthalocyanine core. The energy transfer efficiency of ZnPc(CF3)8(CN)4 and ZnPc(CF3)8(COO-n-Pentyl)4 were lower than that of ZnPc(CH3)8(CN)4 and ZnPc(CH3)8(COO-n-Pentyl)4. This maybe due to the existence of CF3 group,the configuration of phthalocyanines bearing fluorinated dendritic substituents becomes more rigidity. With the same dendron structure, the nature of terminal groups also influenced the energy transfer efficiency of these dendritic phthalocyanines. The energy transfer efficiency of ZnPc(CF3)8(CN)4 was higher than that of ZnPc(CF3)8(COO-n-Pentyl)4, and ZnPc(CH3)8(CN)4 higher than ZnPc(CH3)8(COO-n-Pentyl)4.A new series of water soluble SWNT based nanoconjugates was developed by the host-guest interaction between fluorinated and non-fluorinated dendrimer phthalocyanines and pyrene-labeled host attached on the sidewalls of nanotubes via π-π stacking. These nanoconjugates were tetra-(2-4-hydroxyphenyl-2-4-cyanobenzyl fluorinated propyl) zinc phthalocyanine-p-CD-SWNTs(SWNTs-p-CD-DZnPc-F-CN),tetra-(2-4-hydroxyphenyl-2-4-methoxycarbonyl fluorinated propyl) zinc phthalocyanine-p-CD-SWNTs(SWNTs-p-CD-DZnPc-F-Pent), tetra-(2-4-hydroxyphenyl-2-4-cyanobenzyl propyl) zinc phthalocyanine-p-CD-SWNTs(SWNTs-p-CD-DZnPc-CN) and tetra-(2-4-hydroxyphenyl-2-4-methoxy carbonyl propyl) zinc phthalocyanine-p-CD-SWNTs(SWNTs-p-CD-DZnPc-Pent). The structures of nanoconjugates were characterized by SEM, TEM, IR, Raman spectra and TGA methods.The dendrimer phthalocyanines-p-CD-single-wall nanotubes nanoconjugates exhibited excellent stability and solubility in water. The UV/Vis absorption spectra of dendritic phthalocyanines-single-walled nanotubes nanoconjugates were studied. These nanoconjugates exhibited the absorption of Q-band of dendrimer phthalocyanine, p-CD, as well as the van Hove singularities of SWNTs, providing unquestionable evidences that the dendrimer phthalocyanines were successfully nocovalented on the surface of SWNTs. The steady-state fluorescence of this series nanoconjugates was studied. The fluorescence of the nanoconjugates was greatly quenched. This result indicated that the photoinduced electronic transfer process exsited between the dendrimer phthalocyanine and SWNTs.