The Photophysics and Photochemistry of a series of Phthalocyanines as Potential Photosensitisers in Photodynamic Therapy

Van Leeuwen, Magda (2013) The Photophysics and Photochemistry of a series of Phthalocyanines as Potential Photosensitisers in Photodynamic Therapy. Doctoral thesis, University of East Anglia.

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The photophysical and photochemical measurements have been made
on 3 series of novel alpha octa(alkyl-substituted) phthalocyanines.
Each series is defined by the distinct non-metal or metal ion centre,
silicon hydroxide, zinc(II) and palladium(II). It is well documented
that the phthalocyanine molecule possesses several distinct properties,
including absorption in the red, low fluorescence and high triplet
quantum yields that make it an ideal candidate as a potential
photosensitiser in photodynamic therapy. Photodynamic therapy is an
alternative treatment to cancer using a photosensitiser, which is
preferentially absorbed by malignant cells and remains dormant until
activated by red light. This results in the formation of singlet delta
oxygen via the excited state of the photosensitiser. The generation of
singlet oxygen leads to cell death.
Fluorescence quantum yields and lifetimes, triplet quantum yields,
lifetimes and energies and singlet delta oxygen quantum yields were
measured in 1% v/v pyridine in toluene. The effects of alkyl
substitution, with increasing chain length, variation of metal ion centre
and the core modification of the phthalocyanine unit are investigated
and compared relative to the unsubstituted parent molecules, SiPc,
ZnPc and PdPc.
All substituted phthalocyanines exhibited a typical phthalocyanine
absorption spectrum with significant red-shift of the Q-band maxima.
Q-band maxima for all compounds ranged between 660 – 712 nm and
extinction coefficients of the Q-band between 10-4 – 10-5 M-1 cm-1. All
compounds also exhibited triplet quantum yields in the range 0.52 –
0.96 and singlet delta oxygen quantum yields of 0.49 – 0.94,
illustrating promising photophysical and photochemical properties for
photodynamic therapy.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Users 2259 not found.
Date Deposited: 05 Mar 2014 11:52
Last Modified: 05 Mar 2014 11:52


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