TY  - JOUR
A1  - Schwarze, Thomas
A1  - Sperlich, Eric
A1  - Müller, Thomas
A1  - Kelling, Alexandra
A1  - Holdt, Hans-Jürgen
T1  - Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter
JF  - Helvetica chimica acta
N2  - In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red.
KW  - copper
KW  - fumaronitrile
KW  - ligands
KW  - macrocycles
KW  - maleonitrile
Y1  - 2021
U6  - https://doi.org/10.1002/hlca.202100028
SN  - 1522-2675
VL  - 104
IS  - 6
SP  - e2100028
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schwarze, Thomas
A1  - Kelling, Alexandra
A1  - Sperlich, Eric
A1  - Holdt, Hans-Jürgen
T1  - Influence of regioisomerism in 9-anthracenyl-substituted dithiodicyanoethene derivatives on photoinduced electron transfer controlled by intramolecular charge transfer
JF  - ChemPhotoChem
N2  - In this paper, we report on the fluorescence behaviour of three regioisomers which consist of two 9-anthracenyl fluorophores and of differently substituted dithiodicyanoethene moieties. These isomeric fluorescent probes show different quantum yields (phi(f)). In these probes, an oxidative photoinduced electron transfer (PET) from the excited 9-anthracenyl fluorophore to the dithiodicyanoethene unit quenches the fluorescence. This quenching process is accelerated by an intramolecular charge transfer (ICT) of the push-pull pi-electron system of the dithiodicyanoethene group. The acceleration of the PET depends on the strength of the ICT unit. The higher the dipole moment of the ICT unit, the stronger the observed fluorescence quenching. To the best of our knowledge, this is the first report of a regioisomeric influence on an oxidative PET by an ICT.
KW  - anthracene
KW  - charge transfer
KW  - electron transfer
KW  - fluorescence
KW  - isomerism
Y1  - 2021
U6  - https://doi.org/10.1002/cptc.202100070
SN  - 2367-0932
VL  - 5
IS  - 10
SP  - 911
EP  - 914
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schwarze, Thomas
T1  - Determination of Pd2+ by fluorescence enhancement caused by an off-switching of an energy- and an electron transfer
JF  - ChemistrySelect
N2  - In this paper, we introduce a fluorescent dye 1, which is able to detect selectively Pd2+ by a clear fluorescence enhancement (FE) in THF. In the presence of eight Pd2+ equivalents, we observed a fluorescence enhancement factor (FEF) of 28.3. The high Pd2+ induced FEF can be explained by an off switching of multiple quenching processes within 1 by Pd2+. In the free dye 1 a photoinduced electron transfer (PET) and energy transfer (ET) takes place and quenches the anthracenic fluorescence. The coordination of eight Pd2+ units by the alkylthio-substituted porphyrazine receptor suppresses the PET and ET quenching process and the anthracenic fluorescence is switched on.
KW  - Palladium ion
KW  - electron transfer
KW  - energy transfer
KW  - fluorescence
KW  - porphyrazine
Y1  - 2021
U6  - https://doi.org/10.1002/slct.202003975
SN  - 2365-6549
VL  - 6
IS  - 3
SP  - 318
EP  - 322
PB  - Wiley-VCH
CY  - Weinheim
ER  -