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
A1  - Riemer, Janine
A1  - Holdt, Hans-Jürgen
T1  - A Ratiometric Fluorescent Probe for K+ in Water Based on a Phenylaza-18-Crown-6 Lariat Ether
JF  - Chemistry - a European journal
N2  - This work presents two molecular fluorescent probes 1 and 2 for the selective determination of physiologically relevant K+ levels in water based on a highly K+/Na+ selective building block, the o-(2-methoxyethoxy)phenylaza-18-crown-6 lariat ether unit. Fluorescent probe 1 showed a high K+-induced fluorescence enhancement (FE) by a factor of 7.7 of the anthracenic emission and a dissociation constant (K-d) value of 38mm in water. Further, for 2+K+, we observed a dual emission behavior at 405 and 505nm. K+ increases the fluorescence intensity of 2 at 405nm by a factor of approximately 4.6 and K+ decreases the fluorescence intensity at 505nm by a factor of about 4.8. Fluorescent probe 2+K+ exhibited a K-d value of approximately 8mm in Na+-free solutions and in combined K+/Na+ solution a similar K-d value of about 9mm was found, reflecting the high K+/Na+ selectivity of 2 in water. Therefore, 2 is a promising fluorescent tool to measure ratiometrically and selectively physiologically relevant K+ levels.
KW  - charge transfer
KW  - crown compounds
KW  - fluorescence
KW  - potassium
KW  - ratiometric sensors
Y1  - 2018
U6  - https://doi.org/10.1002/chem.201802306
SN  - 0947-6539
SN  - 1521-3765
VL  - 24
IS  - 40
SP  - 10116
EP  - 10121
PB  - Wiley-VCH
CY  - Weinheim
ER  -