Tetrahedron Letters
Single chemosensor for highly selective colorimetric
and fluorometric dual sensing of Cu(II) as well as ‘NIRF’ to acetate ion
Shyamaprosad Goswami a, , Sibaprasad Maity a,b, Avijit Kumar Das a, Annada C. Maity a
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a Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103, West Bengal, India
b Haldia Institute of Technology, Hatiberia, Haldia 721657, West Bengal, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 11 July 2013
Revised 20 September 2013
Accepted 27 September 2013
Available online 3 October 2013
A novel fluorescent probe for the copper(II) ion in mixed aqueous media, based on fluorescence quench-
ing mechanism with noticeable color change from light to dark yellow, was designed and synthesized. It
also exhibited high selectivity for acetate in acetonitrile over other common anions in the near infrared
region (NIR) accompanied with exciting color changes from light yellow to pink. Hence sensor 1 ascer-
tains its dual chemosensing ability toward Cu(II) and acetate ions as evidenced by competitive
experiments.
Keywords:
Dual sensing
NIRF
Ó 2013 Elsevier Ltd. All rights reserved.
Naked eye
Acetate
Cu(II)
Design and development of synthetic fluorescent sensors for
ions and molecules of biological significance remains an important
endeavor in the field of research on chemical sensors. Coordination
to organic dyes induces distinct optical responses, which signal the
presence of the species of interest. Fluorogenic methods in con-
junction with suitable probes are preferable approaches for the
measurement of the analyte because fluorimetry is rapidly per-
formed, nondestructive, highly sensitive, and can afford real infor-
mation on the localization and quantity of the targets of interest.1
Colorimetric probes are also currently attracting increasing atten-
tion, since they can be tailored to allow ‘naked eye’ detection of
the analyte.2–5
Acetate is a critical component of numerous metabolic pro-
cesses. This anion is a possible tracer for malignancies and has
been extensively investigated in prostate cancer and its metasta-
ses.6,7 Carboxylate anions play an important role in nylon industry.
They are also used in the manufacture of paper, plastics, dyes, and
paints. Significant interest has been focused on acetate (CH3COOÀ)-
triggered spectral changes in chromogenic and fluorogenic anion
probes because of the fundamental roles of the acetate ion in many
chemical and biological processes.8
of Cu2+ has attracted considerable attention due to its pivotal role
in a variety of fundamental physiological processes in organisms
including enzyme functions and transcriptional events.12,13 Copper
ion levels are firmly controlled in the cells, as disruption can cause
neurodegenerative diseases like Alzheimer’s disease, Menkes and
Wilson’s diseases14,15 but at the same time, it is an essential trace
element in biological systems. Moreover, in the natural environ-
ment, copper is also considered as a significant pollutant owing
to its high toxicity.
So it is very necessary to synthesize new fluorescent chemosen-
sors to detect acetate and copper ions in biological systems and the
environment. Owing to sensitivity reasons and high order of inter-
ference often caused by the chemically closely related ions during
spectroscopic studies, the development of new highly selective and
sensitive chemosensors for acetate as well as Cu2+ is a continued
interesting and challenging task.
We have recently reported simple naphthalene based colori-
metric sensor selective for acetate.16 Here we disclose the synthe-
sis and binding properties of hydroxybenzene dicarbaldehyde
appended hydroxynaphthalene based sensor which displays extre-
mely selective fluorescence change as well as exciting colorimetric
response not only toward biologically appealing the Cu2+ ion but
also the acetate ion in the near infrared region (NIR), suppressing
the various competing metal ions and anions. Here binding sites
and the optical signaling subunit are covalently bonded in such a
way that the interaction of the anion as well as metal ion with
the binding site induces electronic modulations in the signaling
unit, resulting in color or emission changes. High selectivity can
be attributed to a relatively flexible binding pocket of sensor 1,
The development of synthetic sensors for monitoring heavy and
transition metal ions, especially for cations of biological interest is
also of great importance because of their widespread use in agri-
cultural, chemical, and industrial processes, which are becoming
threats to living organisms.9–11 Among the metal ions, detection
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