Soluble porphyrin-containing polymide : synthesis and optical properties

Abstract

Polyimides containing porphyrin moieties were synthesized by condensation polymerization of two diamino monomers, either 5,10-bis(4-aminophenyl)-10, 20-diphenylporphyrin(cis-DATPP) or 5,15-bis(4-aminophenyl)-10, 20-diphenylporphyrin (trans-DATPP) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (PFMB) and a dianhydride, 4,4'-hexafluoroisopropylidenediphthalic anhydride (6FDA) at 1:1 ratio. The content of cis-DATPP or trans-DATPP in diamino monomer part was varied in the range of 5-30% by mole. The incorporation of Zn metal in the porphyrin moieties of these polyimides was also carried out. The structures of these four types of polyimides, containing cis-DATPP, trans-DATPP, cis-ZnDATPP and trans-ZnDATPP, were confirmed by ATR-IR and H1-NMR. All polyimides were soluble in polar aprotic solvents, THF, DMAc and CH2Cl2 and had higher viscosity than the polyimides without porphyrin moiety. UV-vis and fluorescence spectroscopy of these polyimides in CH2Cl2 and DMAc were investigated. The rate constants for electron transfer of polyimides containing the highest content of cis-DATPP and trans-DATPP, PI-C4 and PI-T4, were 1.50x10[superscript 7] and 1.48x10[superscript 7] s[superscript -1] and the corresponding metalloporphyrins, PI-ZnC4 and PI-ZnT4, were 9.25x10[superscript 7] and 8.90x10[superscript 7] s[superscript -1] in CH2Cl2, respectively. Fluorescence quenching of the porphyrin monomers and porphyrin polyimides by anthraquinone as an electron acceptor involved both static and dynamic quenching mechanisms. In addition, all of these polyimides displayed good thermal stability as determined by thermogravimetric analysis