W. Spiller et al., Singlet oxygen quantum yields of different photosensitizers in polar solvents and micellar solutions, J PORPHYR P, 2(2), 1998, pp. 145-158
The singlet oxygen luminescence method and the photochemical methods using
1,3-diphenylisobenzofuran (DPBF) or bilirubin ditaurate (BDT) as chemical q
uenchers were employed to determine the single oxygen quantum yields (Phi(D
elta)) of different phthalocyanines and tris(2,2'-bipyridyl)ruthenium(II) d
ichloride in dimethylformamide (DMF) or aqueous micellar solution of 0.1 M
CTAC (cetyltrimethylammonium chloride). Additionally, a perylenetetracarbox
ylic acid diimide derivative was examined in DMF. In a series of tetrasulfo
nated phthalocyanines (PTS) the following order was found: ZnPTS > GaPTS >
AIPTS approximate to H2PTS > CoPTS. In general, he singlet oxygen quantum y
ields are higher in DMF than in 0.1 M CTAC/H2O. The results obtained with t
he photochemical systems are comparable with those obtained by the photophy
sical method.
The photochemical DPBF method results in absolute values of Phi(Delta). How
ever, in micellar solution, chain reactions occur when DPBF is used as chem
ical quencher in the photo-oxidative process. This problem can be overcome
by adding sodium thiosulphate which is able to destroy the endoperoxide ini
tially formed. BDT can be used as quencher in different solvents to determi
ne Phi(Delta) relative to a photosensitizer with known singlet oxygen quant
um yield in the respective solvent.
In comparison to the chemical methods the luminescence method exhibits the
advantage that side reactions of the quencher are excluded. But normally th
e Phi(Delta) values obtained are relative to a reference, since absolute de
terminations need much larger efforts. (C) 1998 John Wiley & Sons, Ltd.