Synthesis, electrochemical and spectroscopic studies of multidodecylated liquid crystalline phthalocyanine-ferrocenylethoxide conjugates for biochemical applications

[摘要] English: This thesis is concerned with the synthesis and characterisation of some ferrocenyl and phthalocyanine derivatives. Symmetrically dodecylated phthalocyanines were obtained by the cyclisation of 3,6-bis(dodecyl)phthalonitrile. Unsymmetrically dodecyl-phthalocyanineferrocenylethoxideconjugates were obtained by the statistical condensation of 3,6-bis(dodecyl)-phthalonitrile and 4-(2'-ferrocenylethoxy)phthalonitrile. The anchoring of the ferrocenylfragment, which itself is an antineoplastic entity, onto a phthalocyanine was accomplishedutilising an ether bond.The electrochemical behaviour of the ferrocenyl and selected phthalocyanine derivatives isreported. Most of the ferrocenyl compounds undergo a one-electron reversible process. Fourring-based electron transfer processes for the metal-free phthalocyanines were observed,whereas the ferrocenyl-phthalocyanine conjugate showed an additional, fifth, redox coupleassociated with the ferrocenyl moiety.UV/VIS spectroscopy of the non-peripherally dodecyl substituted phthalocyanines showed a redshift in absorption Qmax-band, which holds some advantages for irradiation with low-energydiode lasers during photodynamic cancer therapy. The new phthalocyanines also obeyed theBeer-Lambert law for the concentration range 78-163 )µM (Q-band data) in THF, thus showingno aggregation.The new symmetrical octadodecylated phthalocyanines as well as the hexadodecylphthalocyanine-ferrocenylethoxide conjugates exhibited liquid crystalline mesophase behaviour,which was studied using polarised light optical microscopy and differential scanningcalorimetry. The zinc-containing ferrocenyl-phthalocyanine conjugate displayed mesophasebehaviour over a larger temperature range (30.9-269.9°C) than the metal-free conjugate(30.4-185.3°C). Variable temperature UVNIS spectra of thin films (ca. 1000 A thick) of thephthalocyanine derivatives cast on glass is also reported for each mesophase.

[发布机构] University of the Free State