Res. Chem. Intermed.
, Vol. 34, No. 2–3, pp. 229–239 (2008)
Koninklijke Brill NV, Leiden, 2008.
Also available online - www.brill.nl/rci
The synthesis and characterization of novel
coumarin-containing cyanine dyes via “Click” chemistry
WEN-HAI ZHAN, JIAN-LI HUA, YING-HUA JIN, XIN TENG and HE TIAN
Lab for Advanced Materials & Institute of Fine Chemicals, East China University of Science &
Technology, Shanghai 200237, P. R. China
Received 20 November 2006; accepted 18 January 2007
Abstract—Four novel cyanine dye derivatives (C-Cy(1–4)) in which a coumarin moiety is attached
to benzoindole ring of asymmetric trimethine cyanine dyes or hemicyanine dye by 1,2,3-triazole have
been successfully synthesized via “Click” reaction between the corresponding alkyl-end cyanine dyes
and 3-azidocoumarin. Six reaction systems were employed to ﬁnd the suitable “Click” conditions of
cyanine dyes. It was found that the combination of DMF, CuI and di-i-propylethylamine (DIPEA)
was the most excellent system for “Click” reaction. All of the compounds were characterized by
H-NMR, MS, UV and FL.
Keywords: “Click” chemistry; cyanine dye; coumarin; synthesis.
Cyanine dyes are intensely colored compounds that are widely used, initially as
photographic sensitizers. Cyanines have found many applications as biological
stains and ﬂuorescent labels and probes due to their high ﬂuorescence quantum
yields, as well as their sensitivity to environmental factors such as temperature,
polarity and viscosity. The general dye structure consists of two heteroaromatic
rings connected by a polymethine linker. Variation of the heterocycle and bridge
length allows for tuning of the absorption and emission wavelengths. Cyanine dyes
are currently available with absorption and ﬂuorescence spectra that span the visible
Carbocyanine dyes are known to have high molar extinction coefﬁcients with ε
values between 100 000 and 250 000 M
, being less affected by the chemical
environment. When adsorbed on the nanocrystalline TiO
ﬁlm, cyanine dyes can
form J- and H-aggregates which broadens the absorption spectra of the electrode
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