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Conducting polymers with anion binding sites for potential sensing
applications
Krzysztof Bąk, Michał J. Chmielewski *
Conducting polymers are highly promising materials for sensing applications, in part because
their conjugated, molecular wire-like structures offer high potential for signal amplification. Yet, their
potential in anion sensing is largely underdeveloped.
1,8-Diaminocarbazole is a new, particularly attractive building block for the construction of anion
receptors, developed in our laboratory. It combines enhanced hydrogen bonding ability (compared to
pyrrole), rigidity and outstanding synthetic versatility with the presence of chromophore and
fluorophore. Moreover, it undergoes facile electropolymerisation into a π-conjugated, conducting
polymer with highly promising properties. Thus, appropriately functionalised derivatives of 1,8diaminocarbazole,
having both an anion binding site and free amino group which is necessary for
polymerisation, may serve as precursors of conducting polymers with anion sensing properties.
Interestingly, such polymers may function as triple channel sensors, displaying colorimetric,
fluorescent and electrochemical response to anionic guests.
Selective protection of only one amino group of 1,8-diaminocarbazole was achieved in ca.
50% yield using (Boc)2O in THF. This opened an easy access to a variety of amide, urea and thiourea
derivatives with one amino group free and ready for polymerisation. Preliminary electrochemical
investigations confirmed successful electropolymerisation of a simple benzamide derivative.
i/A
8.0µ
7.0µ
6.0µ
5.0µ
4.0µ
3.0µ
2.0µ
1.0µ
0.0
-1.0µ
-2.0µ
-3.0µ
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
E/V
i/A
2.0µ
1.6µ
1.2µ
800.0n
400.0n
0.0
-400.0n
-800.0n
-1.2µ
-0.4 -0.2 0.0 0.2 0.4
E/V
On the left: voltamperogram received
during polymerization proving the
formation of conducting polymer.
On the right: electrical answer of the
system obtained during preliminary
electrochemical studies.