
K. GHANBARI ET AL.
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has a symmetrical structure, the byproducts are the re-
sults of the reaction of two symmetrical methyls, in two
sides of intermediate molecule with jolulidine carboxal-
dehyde. This byproduct tends to decrease the fluores-
cence efficiency of DCJ, counteracting the effect of re-
duction of concentration quenching, which only has a
very weak fluorescence in the near infra-red region of the
visible spectrum.
In this work, we reported a facile, simple and inexpensive
method for purification of DCJ. It was shown the product
can be purified by column chromatography using hex-
ane-ethyl acetate as an eluent. At first stage, recrystaliza-
tion method seems to be a useful way for byproducts
separation. By using this procedure the ratio of unwanted
byproducts was decreased but not separated completely.
At second stage column chromatography improved our
aim for complete purification. Initially, a more polar ra-
tio of solvents was used. Thin layer chromatography
showed that unwanted byproducts weren’t separated
completely. To improve the purification, we used a less
polar ratio of solvents, then TLC showed unwanted DCJ
dye byproducts were almost removed. Finally, we used a
non-polar ratio of solvents (6:1 n-hexane-ethyl acetate)
and TLC showed that unwanted byproducts were com-
pletely separated. The 1H NMR spectrum of DCJ exhibit
characteristic signals with appropriate chemical shifts
which showed that purification by column chromatogra-
phy was successful.
As expected, both the absorption and fluorescence
spectra of DCJ (Figure 1) exhibited an increase in the
electron donating julolidine group relative to that of
DCM [10]. In other words, DCJ indicated larger quan-
tum efficiency than DCM.
4. Conclusions
One of the DCM type red light emitter, DCJ, was syn-
thesized and successfully purified by a facile and inex-
pensive method. Purification was carried out by column
chromatography instead of HPLC analysis with different
ratio of solvents. We used n-hexane-ethy acetate (6:1) as
an eluent for separation of unwanted DCJ byproduct.
Maximum fluorescence, maximum absorption wave-
length and quantum efficiency of DCJ increased in com-
parison to DCM, because of the existence of the electron
donating julolidine group.
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