TY - JOUR A1 - Schwarze, Thomas A1 - Sprenger, Tobias A1 - Riemer, Janine T1 - 1,2,3-Triazol-1,4-diyl-Fluoroionophores for Zn2+, Mg2+ and Ca2+ based on Fluorescence Intensity Enhancements in Water JF - ChemistrySelect N2 - Herein, we represent cation-responsive fluorescent probes for the divalent cations Zn2+, Mg2+ and Ca2+, which show cation-induced fluorescence enhancements (FE) in water. The Zn2+-responsive probes Zn1, Zn2, Zn3 and Zn4 are based on o-aminoanisole-N,N-diacetic acid (AADA) derivatives and show in the presence of Zn2+ FE factors of 11.4, 13.9, 6.1 and 8.2, respectively. Most of all, Zn1 and Zn2 show higher Zn2+ induced FE than the regioisomeric triazole linked fluorescent probes Zn3 and Zn4, respectively. In this set, ZN2 is the most suitable probe to detect extracellular Zn2+ levels. For the Mg2+-responsive fluorescent probes Mg1, Mg2 and Mg3 based on o-aminophenol-N,N,O-triacetic acid (APTRA) derivatives, we also found that the regioisomeric linkage influences the fluorescence responds towards Mg2+ (Mg1+100 mM Mg2+ (FEF=13.2) and Mg3+100 mM Mg2+ (FEF=2.1)). Mg2 shows the highest Mg2+-induced FE by a factor of 25.7 and an appropriate K-d value of 3 mM to measure intracellular Mg2+ levels. Further, the Ca2+-responsive fluorescent probes Ca1 and Ca2 equipped with a 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) derivative show high Ca2+-induced FEs (Ca1 (FEF=22.1) and Ca2 (FEF=23.0)). Herein, only Ca1 (K-d=313 nM) is a suitable Ca2+ fluorescent indicator to determine intracellular Ca2+ levels. KW - calcium KW - fluorescence KW - magnesium KW - probes KW - zinc Y1 - 2020 U6 - https://doi.org/10.1002/slct.202003695 SN - 2365-6549 VL - 5 IS - 41 SP - 12727 EP - 12735 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Schneider, Radu A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Fluorescent Probe - Tuning the K+-Complex Stability and the K+/Na+ Selectivity by Varying the Lariat-Alkoxy Unit of a Phenylaza[18]crown-6 Ionophore JF - Chemistry : an Asian journal ; an ACES journal N2 - A desirable goal is to synthesize easily accessible and highly K+/Na+-selective fluoroionophores to monitor physiological K+ levels in vitro and in vivo. Therefore, highly K+/Na+-selective ionophores have to be developed. Herein, we obtained in a sequence of only four synthetic steps a set of K+-responsive fluorescent probes 4, 5 and 6. In a systematic study, we investigated the influence of the alkoxy substitution in ortho position of the aniline moiety in -conjugated aniline-1,2,3-triazole-coumarin-fluoroionophores 4, 5 and 6 [R=MeO (4), EtO (5) and iPrO (6)] towards the K+-complex stability and K+/Na+ selectivity. The highest K+-complex stability showed fluoroionophore 4 with a dissociation constant K-d of 19mm, but the K-d value increases to 31mm in combined K+/Na+ solutions, indicating a poor K+/Na+ selectivity. By contrast, 6 showed even in the presence of competitive Na+ ions equal K-d values (K-d(K+)=45mm and K-d(K+/Na+)=45mm) and equal K+-induced fluorescence enhancement factors (FEFs=2.3). Thus, the fluorescent probe 6 showed an outstanding K+/Na+ selectivity and is a suitable fluorescent tool to measure physiological K+ levels in the range of 10-80mm in vitro. Further, the isopropoxy-substituted N-phenylaza[18]crown-6 ionophore in 6 is a highly K+-selective building block with a feasible synthetic route. KW - crown compounds KW - fluorescence KW - fluorescent probes KW - potassium KW - sodium Y1 - 2016 U6 - https://doi.org/10.1002/asia.201500956 SN - 1861-4728 SN - 1861-471X VL - 11 SP - 241 EP - 247 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 - TY - JOUR A1 - Schwarze, Thomas A1 - Riemer, Janine A1 - Eidner, Sascha A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Two-Photon Fluorescent Probe JF - Chemistry - a European journal N2 - A highly K+-selective two-photon fluorescent probe for the in vitro monitoring of physiological K+ levels in the range of 1-100 mM is reported. The two-photon excited fluorescence (TPEF) probe shows a fluorescence enhancement (FE) by a factor of about three in the presence of 160 mM K+, independently of one-photon (OP, 430 nm) or two-photon (TP, 860 nm) excitation and comparable K+-induced FEs in the presence of competitive Na+ ions. The estimated dissociation constant (K-d) values in Na+-free solutions (K-d(OP)=(28 +/- 5) mM and K-d(TP)=(36 +/- 6) mM) and in combined K+/Na+ solutions (K-d(OP)=(38 +/- 8) mM and K-d(TP)=(46 +/- 25) mM) reflecting the high K+/Na+ selectivity of the fluorescent probe. The TP absorption cross-section (sigma(2PA)) of the TPEF probe+160 mMK(+) is 26 GM at 860 nm. Therefore, the TPEF probe is a suitable tool for the in vitro determination of K+. KW - click chemistry KW - fluorescence KW - fluorescent probes KW - potassium KW - two-photon Y1 - 2015 U6 - https://doi.org/10.1002/chem.201501473 SN - 0947-6539 SN - 1521-3765 VL - 21 IS - 32 SP - 11306 EP - 11310 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Riemer, Janine T1 - Highly K+ selective probes with fluorescence emission wavelengths higher than 500 nm in water JF - ChemistrySelect N2 - Herein, we report on the synthesis of highly K+/Na+ selective fluorescent probes in a feasible number of synthetic steps. These K+ selective fluorescent probes, so called fluoroionophores, 1 and 2 consists of different highly K+/Na+ selective building blocks the alkoxy-substituted N-phenylaza-18-crown-6 lariat ethers (ionophores) and "green" (cf. coumarin unit in 1) or "red" (cf. nile red unit in 2) fluorescent moieties (fluorophores). The fluorescent probes 1 and 2 show K+ induced fluorescence enhancement factors of 4.1 for 1 and 1.9 for 2 and dissociation constants for the corresponding K+ complexes of 43 mM (1+K+) and 18 mM (2+K+) in buffered aqueous solution. The fluorescence signal of 1 and 2 is changed by less than 5 % by pH values in the range of 6.8 to 8.8. Thus, 1 and 2 are capable fluorescent tools to determine extracellular K+ levels by fluorescence enhancements at wavelengths higher than 500 nm. KW - potassium KW - sodium KW - fluorescence KW - selectivity KW - probes Y1 - 2020 U6 - https://doi.org/10.1002/slct.202003785 SN - 2365-6549 VL - 5 IS - 42 SP - 13174 EP - 13178 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Mueller, Holger A1 - Schmidt, Darya A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - Design of Na+-Selective Fluorescent Probes: A Systematic Study of the Na+-Complex Stability and the Na+/K+ Selectivity in Acetonitrile and Water JF - Chemistry - a European journal N2 - There is a tremendous demand for highly Na+-selective fluoroionophores to monitor the top analyte Na+ in life science. Here, we report a systematic route to develop highly Na+/K+ selective fluorescent probes. Thus, we synthesized a set of fluoroionophores 1, 3, 4, 5, 8 and 9 (see Scheme 1) to investigate the Na+/K+ selectivity and Na(+-)complex stability in CH3CN and H2O. These Na+-probes bear different 15-crown-5 moieties to bind Na+ stronger than K+. In the set of the diethylaminocoumarin-substituted fluoroionophores 1-5, the following trend of fluorescence quenching 1 > 3 > 2 > 4 > 5 in CH3CN was observed. Therefore, the flexibility of the aza-15-crown-5 moieties in 1-4 determines the conjugation of the nitrogen lone pair with the aromatic ring. As a consequence, 1 showed in CH3CN the highest Na+-induced fluorescence enhancement (FE) by a factor of 46.5 and a weaker K+ induced FE of 3.7. The Na+-complex stability of 1-4 in CH3CN is enhanced in the following order of 2 > 4 > 3 > 1, assuming that the O-atom of the methoxy group in the ortho-position, as shown in 2, strengthened the Na+-complex formation. Furthermore, we found for the N( o-methoxyphenyl) aza-15-crown-5 substituted fluoroionophores 2, 8 and 9 in H2O, an enhanced Na+-complex stability in the following order 8 > 2 > 9 and an increased Na+/K+ selectivity in the reverse order 9 > 2 > 8. Notably, the Na+-induced FE of 8 (FEF = 10.9), 2 (FEF = 5.0) and 9 (FEF = 2.0) showed a similar trend associated with a decreased K+-induced FE [8 (FEF = 2.7) > 2 (FEF = 1.5) > 9 (FEF = 1.1)]. Here, the Na+-complex stability and Na+/K+ selectivity is also influenced by the fluorophore moiety. Thus, fluorescent probe 8 (K-d = 48 mm) allows high-contrast, sensitive, and selective Na+ measurements over extracellular K+ levels. A higher Na+/K+ selectivity showed fluorescent probe 9, but also a higher Kd value of 223 mm. Therefore, 9 is a suitable tool to measure Na+ concentrations up to 300 mm at a fluorescence emission of 614 nm. KW - crown compounds KW - fluorescence KW - fluorescent probes KW - potassium KW - sodium Y1 - 2017 U6 - https://doi.org/10.1002/chem.201605986 SN - 0947-6539 SN - 1521-3765 VL - 23 SP - 7255 EP - 7263 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 A1 - Garz, Andreas A1 - Teuchner, Klaus A1 - Menzel, Ralf A1 - Holdt, Hans-Jürgen T1 - Two-photon probes for metal ions based on phenylaza[18]crown-6 ethers and 1,2,3-triazoles as pi-linkers JF - ChemPhysChem : a European journal of chemical physics and physical chemistry KW - absorption KW - cations KW - click chemistry KW - dyes/pigments KW - fluorescence Y1 - 2014 U6 - https://doi.org/10.1002/cphc.201402232 SN - 1439-4235 SN - 1439-7641 VL - 15 IS - 12 SP - 2436 EP - 2439 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 - TY - THES A1 - Rosenhauer, Regina T1 - Lichtinduzierte Generierung von optisch anisotropen Filmen auf der Basis von multi-funktionalen Polymeren N2 - Gegenstand der Arbeit ist die lichtinduzierte Orientierung von multifunktionalen Polymeren, die u.a. für die Herstellung von optischen Schichten in Flüssigkristalldisplays verwendet werden können. Dafür wurden Polymere entwickelt, die wenigstens eine mesogene und eine lichtsensitive Gruppe enthalten. Diese Gruppen zeigen Eigenschaften, die für die Orientierung der kompletten Polymerfilme verantwortlich sind. Das Material wird dafür zunächst in einem ersten Schritt kurz mit linear polarisiertem Licht bestrahlt, wobei richtungsabhängig eine photochemische Reaktion an der lichtsensitiven Gruppe erfolgt und dadurch ein "Orientierungskeim" gelegt wird. Durch die thermische Ausrichtung der mesogenen Gruppen an den photochemisch generierten "Orientierungskeimen" erfolgt die komplette Orientierung des Filmes in einem zweiten Schritt. Dadurch wird eine hohe optische Anisotropie erhalten. Dieses Verfahren wurde als Zwei-Stufen-Bulk-Orientierungsprozess bezeichnet. In der vorliegenden Arbeit wurden die Photoreaktionen verschiedener lichtsensitiver Gruppen, wie z. B. Azobenzen, Stilben und Zimtsäureester und deren Orientierungsfähigkeit in flüssigkristallinen Polymeren untersucht. Der Orientierungsprozess wurde durch die Wahl geeigneter Bestrahlungsbedingungen optimiert. Die Effizienz der Orientierung wurde anhand der sich verändernden winkelabhängigen Absorptionseigenschaften und der Doppelbrechung des Materials analysiert. Es wurde gezeigt, dass eine effiziente lichtinduzierte Orientierung bei einer Vielzahl von flüssigkristallinen Polymeren realisierbar ist. So wurde z. B. erstmalig gefunden, dass durch eine Photo-Fries-Orientierung eine hohe optische Anisotropie erhalten werden kann. Außerdem wurde eine neue lichtsensitive Gruppe auf der Basis von Donor-Akzeptor-substituiertem Ethen entwickelt, die farbneutral ist und durch polarisiertes UV-Licht sowohl orientiert als auch re-orientiert werden kann. Es wurden weiterhin Polymere entwickelt, die zusätzlich zu den photosensitiven und flüssigkristallinen Einheiten, fluoreszierende Gruppen enthalten. Die Auswahl geeigneter Fluoreszenzverbindungen erfolgte aufgrund ihrer anisometrischen Form, ihrer Ordnungsparameter in einer niedermolekularen Flüssigkristallmischung und ihrer Photostabilität. Das Orientierungsverhalten von ausgewählten Fluorophoren wurde in sechs Ter- und zwei Copolymeren untersucht. Das Prinzip der Orientierung beruht auf einer kooperativen Ausrichtung der Seitengruppen. Aus diesem Grund kommt dem Nachweis der Kooperativität in der vorliegenden Arbeit eine besondere Stellung zu. Durch lichtinduzierte Bulk-Orientierung wurden Filme erhalten, welche durch eine richtungsabhängige Fluoreszenz und Absorption im sichtbaren- oder UV-Bereich charakterisiert sind. Die Fluoreszenz wird durch einige lichtsensitive Verbindungen komplett gelöscht. Die wahlweise erhaltenen anisotropen Filme von farbigen, fluoreszierenden oder farbneutralen Verbindungen, die zudem in kleinen Pixeln von wenigen Mikrometern orientiert werden können, eröffnen vielfältige Möglichkeiten für den Einsatz von multi-funktionalen Polymeren als optische Schichten in Flüssigkristalldisplays. N2 - The work presents the light-induced orientation of multifunctional polymers, which can be used for the preparation of optical films in liquid crystal displays (LCDs). Polymers which contain at least one mesogenic and one photosensitive side group were developed for this approach. The side groups of the specially designed polymers show properties which allow for the orientation of the whole polymer film. Isotropic films of the polymeric material were shortly irradiated with linearly polarised light in a first step. So, a photochemical reaction on the light-sensitive group takes place and results in the generation of "orientational seeds". The complete orientation of the polymer film takes place applying a secondary thermal step which aligns the mesogenic groups near to these "orientational seeds". In this way highly anisotropic films are generated. This method was called two-step-bulk-orientation process. The photoreaction of different light-sensitive groups, such as azobenzene, stilbene, cinnamic ester and their ability to orient liquid crystalline polymers were investigated in this thesis. The orientation process was optimised using suitable irradiation conditions. The efficiency of the orientation was analysed measuring the angular dependent absorbance and the birefringence of the material due to the ordering procedure. It was shown, that a light-induced orientation is practicable in a high amount of different liquid crystalline polymers. So, for the first time it was found, that the generation of a high optical anisotropy is achieved as result of the rearrangement of the Photo-Fries-Reaction. Moreover, a new light-sensitive group based on donor-acceptor substituted ethylene was developed, which is colourless and allow the orientation and reorientation using polarised UV light. Moreover, polymers were developed, which contain fluorescent groups in addition to the photo-sensitive and mesogenic units. The selection of suitable fluorophores was carried out with respect to their anisometric shape, their order parameter in a low molecular liquid crystalline mixture and their photostability. The orientational behaviour of selected fluorophores in six terpolymers and in two copolymers were investigated. The principle of the ordering is based on the cooperative orientation of the side groups. In this way the verification of the cooperativity of the process plays an important role in this work. It was shown, that films can be fabricated by means of the light-induced bulk-orientation, which is characterised by an angular selective fluorescence and absorption in the UV or visible region. The fluorescence was completely quenched by some light-sensitive groups. In this way the anisotropic films became optional coloured, fluorescent or colourless and can be patterned in small anisotropic pixels of some micrometers. So, the developed multifunctional materials and the ordering method open new possibilities for the generation of different types of optical films in LCDs. T2 - Lichtinduzierte Generierung von optisch anisotropen Filmen auf der Basis von multi-funktionalen Polymeren KW - multifunktionale Polymere KW - Anisotropie KW - photosensitiv KW - flüssigkristallin KW - Fluoreszenz KW - Azobenzen KW - Zimtsäureester KW - Stilben KW - Ethen KW - Anthrazen KW - optis KW - multifunctional polymers KW - anisotropy KW - photosensitive KW - liquid crystalline KW - fluorescence KW - azobenzene KW - cinnamic ester KW - stilbene KW - ethylene KW - anthracene KW - op Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001890 ER -