Naphthalimide-Piperazine Derivatives as Multifunctional "On" and "Off" Fluorescent Switches for pH, Hg 2+ and Cu 2+ Ions
Novel 1,8-naphthalimide-based fluorescent probes and were designed and screened for use as chemosensors for detection of heavy metal ions. Two moieties, methylpyridine ( ) and hydroxyphenyl ( ), were attached via piperazine at the C-4 position of the napthalimide core resulting in a notable effect o...
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Published in | Molecules (Basel, Switzerland) Vol. 28; no. 3 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
28.01.2023
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Subjects | |
Online Access | Get full text |
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Summary: | Novel 1,8-naphthalimide-based fluorescent probes
and
were designed and screened for use as chemosensors for detection of heavy metal ions. Two moieties, methylpyridine (
) and hydroxyphenyl (
), were attached via piperazine at the C-4 position of the napthalimide core resulting in a notable effect on their spectroscopic properties.
and
are pH sensitive and show an increase in fluorescence intensity at around 525 nm (switch "on") in the acidic environment, with p
values at 4.98 and 2.91, respectively. Amongst heavy metal ions only Cu
and Hg
had a significant effect on the spectroscopic properties. The fluorescence of
is quenched in the presence of either Cu
or Hg
which is attributed to the formation of 1:1 metal-ligand complexes with binding constants of 3.6 × 10
and 3.9 × 10
, respectively. The
chemosensor can be used for the quantification of Cu
ions in sub-micromolar quantities, with a linear range from 250 nM to 4.0 μM and a detection limit of 1.5 × 10
M. The linear range for the determination of Hg
is from 2 μM to 10 μM, with a detection limit of 8.8 × 10
M. Conversely,
behaves like a typical photoinduced electron transfer (PET) sensor for Hg
ions. Here, the formation of a complex with Hg
(binding constant 8.3 × 10
) turns the green fluorescence of
into the "on" state.
showed remarkable selectivity towards Hg
ions, allowing for determination of Hg
concentration over a linear range of 1.3 μM to 25 μM and a limit of detection of 4.1 × 10
M. |
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ISSN: | 1420-3049 |