TY - JOUR A1 - Ritter, B. A1 - Haida, P. A1 - Fink, F. A1 - Krahl, T. A1 - Gawlitza, Kornelia A1 - Rurack, Knut A1 - Scholz, G. A1 - Kemnitz, E. T1 - Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF2, SrF2 and BaF2 nanoparticles – structure and luminescence N2 - A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu3+ and Tb3+ doped CaF2, SrF2 and BaF2 particles via the fluorolytic sol–gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3–20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials. From CaF2:Eu10 via SrF2:Eu10 to BaF2:Eu10 a steady increase of the luminescence intensity and lifetime occurs by a factor of ≈2; the photoluminescence quantum yield increases by 29 to 35% due to the lower phonon energy of the matrix. The fast formation process of the particles within fractions of seconds is clearly visualized by exploiting appropriate luminescence processes during the synthesis. Multiply doped particles are also available by this method. Fine tuning of the luminescence properties is achieved by variation of the Ca-to-Sr ratio. Co-doping with Ce3+ and Tb3+ results in a huge increase (>50 times) of the green luminescence intensity due to energy transfer Ce3+ → Tb3+. In this case, the luminescence intensity is higher for CaF2 than for SrF2, due to a lower spatial distance of the rare earth ions. KW - Luminescence materials KW - Alkaline earth metal fluorides KW - Fluorolytic sol–gel synthesis PY - 2017 DO - https://doi.org/10.1039/C6DT04711D VL - 46 IS - 9 SP - 2925 EP - 2936 PB - Royal Society of Chemistry AN - OPUS4-39286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Röhr, Holger A1 - Trieflinger, C. A1 - Rurack, Knut A1 - Daub, J. T1 - Proton- and Redox-Controlled Switching of Photo- and Electrochemiluminescence in Thiophenyl-Substituted Boron-Dipyrromethene Dyes N2 - A luminescent molecular switch in which the active thiol/disulfide switching element is attached to a meso-phenyl-substituted boron-dipyrromethene (BDP) chromophore as the signalling unit is presented. The combination of these two functional units offers great versatility for multimodal switching of luminescence: 1) deprotonation/protonation of the thiol/thiolate moiety allows the highly fluorescent meso-p-thiophenol-BDP and its nonfluorescent thiolate analogue to be chemically and reversibly interconverted, 2) electrochemical oxidation of the monomeric dyes yields the fluorescent disulfide-bridged bichromophoric dimer, also in a fully reversible process, and 3) besides conventional photoexcitation, the well separated redox potentials of the BDP also allow the excited BDP state to be generated electrochemically (i.e., processes 1) and 2) can be employed to control both photo- and electrochemiluminescence (ECL) of the BDP). The paper introduces and characterizes the various states of the switch and discusses the underlying mechanisms. Investigation of the ortho analogue of the dimer provided insight into potential chromophore-chromophore interactions in such bichromophoric architectures in both the ground and the excited state. Comparison of the optical and redox properties of the two disulfide dimers further revealed structural requirements both for redox switches and for ECL-active molecular ensembles. By employing thiol/disulfide switching chemistry and BDP luminescence features, it was possible to create a prototype molecular ensemble that shows both fully reversible proton- and redox-gated electrochemiluminescence. KW - Boron-dipyrromethene KW - Electrochemiluminescence KW - Fluorescence KW - Molecular switches KW - Redox chemistry KW - Thiol/disulfide chemistry KW - Fluoreszenz KW - Elektrochemilumineszenz KW - Redox-Kontrolle KW - Molekulare Sensoren PY - 2006 DO - https://doi.org/10.1002/chem.200500729 SN - 0947-6539 SN - 1521-3765 VL - 12 IS - 3 SP - 689 EP - 700 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-12175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Kollmannsberger, M. A1 - Daub, J. T1 - A highly efficient sensor molecule emitting in the near infrared (NIR): 3,5-distyryl-8-(p-dimethylaminophenyl)-difluoroboradiaza-s-indacene N2 - The spectroscopic properties and the photophysical behaviour of difluoroboradiaza-s-indacene 1, especially designed for the near infrared (NIR) spectral region and equipped with a p-dimethylaminophenyl group at the meso-position, were studied by steady-state and time-resolved optical spectroscopy. Solvent-dependent measurements revealed that for 1, excited state deactivation is governed by population of a non-emissive charge transfer excited state (1CT) as the solvent polarity increases, whereas reference compound 2 shows strong fluorescence from a locally excited state (1LE) in all the solvents employed. Accordingly, protonation of 1 completely suppresses the quenching excited state charge transfer process and leads to strong enhancement of fluorescence in the NIR, distinguishing 1 as a very sensitive fluorescent sensor molecule for pH or solvent acidity in this favourable wavelength region. PY - 2001 DO - https://doi.org/10.1039/b007379m SN - 0398-9836 VL - 25 SP - 289 EP - 292 PB - Le Centre National de la Recherche Scientifique CY - Paris AN - OPUS4-1085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut T1 - Flipping the light switch 'ON' - the design of sensor molecules that show cation-induced fluorescence enhancement with heavy and transition metal ions N2 - Real-time and real-space analysis of heavy and transition metal ions employing fluorescent sensor molecules has received much attention over the past few years. Since many of these cations possess intrinsic properties that usually quench the fluorescence of organic dye molecules, a lot of research has lately been devoted to designing fluorescent probes that show complexation-induced fluorescence enhancement. Such an analytical reaction would be highly desirable in terms of increased sensitivity and selectivity. However, in this particular field of sensor research, the photophysical and photochemical mechanisms involved as well as the chemical constitutions of the sensor molecules employed are rather diverse and up to now, very few attempts have been made to establish some general concepts for rational probe design. By analyzing various systems published by other researchers as well as own work, this contribution aims at an elucidation of some of the underlying principles of heavy and transition metal ion-enhanced emission. KW - Fluorescent probes KW - Molecular recognition KW - Fluorescence enhancement KW - Fluorescence quenching KW - Heavy metal ions KW - Transition metal ions PY - 2001 DO - https://doi.org/10.1016/S1386-1425(01)00492-9 SN - 1386-1425 SN - 0370-8322 SN - 1873-3557 SN - 0584-8539 VL - 57 IS - 11 SP - 2161 EP - 2195 PB - Elsevier CY - Amsterdam AN - OPUS4-1182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Towards simple and efficient molecular reporters by combining electron and/or charge transfer processes in fluorescent bifunctional dyes T2 - 57th Southwest Regional Meeting CY - San Antonio, TX, USA DA - 2001-10-17 KW - Donor-Acceptor-Systems KW - Heterocycles KW - Electron Transfer KW - Fluorescence KW - Chelates PY - 2001 VL - 57 SP - 1(?) EP - 2(?) AN - OPUS4-1183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut T1 - Fluoreszenzmarker für Schwer- und Übergangsmetallionen: Selektivität durch gezieltes Rezeptordesign und Ionen-spezifische Fluoreszenzverstärkung KW - Fluoreszenzmarker KW - Schwermetalle KW - Rezeptoren PY - 2000 SN - 0937-1478 SN - 1521-3811 VL - 54 IS - 6 SP - 148 EP - 149 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-1050 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Bricks, J. L. A1 - Reck, Günter A1 - Schulz, Burkhard A1 - Spieles, Monika T1 - Cation coordination of bisamidopyridine-derived receptors as investigated in the solid-state and in solution N2 - A bisamidopyridine-type receptor, N,N'-bis(6-methyl-2-pyridyl)pyridine-2,6-dicarboxamide (1), and its CoIII complex were prepared and their X-ray structures were compared to those of N,N'-diphenylpyridine-2,6-dicarboxamide (2) and CoIII(2)2. Introduction of the two additional coordinative groups resulted in second-order interactions between the central ion and the nitrogen atoms of the terminal pyridine moieties in the crystalline state. Solution studies in acetonitrile revealed the importance of these interactions for the ligand's metal ion recognition ability. Whereas 2 only binds to PbII and CuII, 1 yields complexes with a majority of the heavy and transition metal ions studied, CoII, NiII, CuII, ZnII, FeIII, FeII, HgII, and PbII, respectively. The cation binding properties in solution were investigated by absorption spectroscopy and in the case of 1-MII/III, the formation of two spectroscopically distinguishable types of complexes was found. Protonation experiments and theoretical considerations helped to gain further insight into possible modes of coordination in solution. KW - Pyridine carboxamides KW - Ion recognition KW - Crystal structure KW - N-coordination PY - 2003 DO - https://doi.org/10.1080/1061027031000078239 SN - 1061-0278 SN - 1029-0478 VL - 15 IS - 3 SP - 189 EP - 197 PB - Gordon and Breach Science Publ. CY - New York, NY AN - OPUS4-2106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Descalzo, Ana B. A1 - Martínez-Mánez, Ramon A1 - Radeglia, Reiner A1 - Rurack, Knut A1 - Soto, J. T1 - Coupling Selectivity with Sensitivity in an Integrated Chemosensor Framework: Design of a Hg2+-Responsive Probe, Operating above 500 nm N2 - For the highly selective and sensitive sensing of Hg2+ in water, a new design concept was realized where the selectivity of the probe's binding site is amplified by electronic properties of the chromophore. The molecular architecture of this phenoxazinone-type sensor molecule combines two potential coordination sites via an amino-keto conjugative backbone. These structural prerequisites allow only the most preferred mercuric ion to bind to the dithia dioxa monoaza crown unit, while other heavy, transition, and main group metal ions as well as protons are trapped at the keto group, inducing opposite spectral effects due to interaction with either the donor (Hg2+) or the acceptor group (other cations) of the probe. Besides these advantageous features, the probe operates well within the visible range of the spectrum and displays rather intense molar absorptivities as well as fluorescence quantum yields. PY - 2003 DO - https://doi.org/10.1021/ja0290779 SN - 0002-7863 SN - 1520-5126 VL - 125 IS - 12 SP - 3418 EP - 3419 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Danel, A. A1 - Rotkiewicz, K. A1 - Grabka, D. A1 - Spieles, Monika A1 - Rettig, W. T1 - 1,3-Diphenyl-1H-pyrazolo[3,4-b]quinoline - A Versatile Fluorophore for the Design of Brightly Emissive Molecular Sensors N2 - The 1,3-diphenyl-1H-pyrazolo[3,4-b]-quinoline chromophore is a versatile building block for the construction of brightly fluorescent molecular sensors. Facile synthetic procedures allow integration of the chromophore into fluorophore-spacer-receptor systems as well as fluoroionophores operating via intramolecular charge transfer. Whereas the former photoinduced electron-transfer probes show strong analyte-induced fluorescence enhancement, the latter exhibit bright ratiometric dual emission. Employing prototype macrocyclic receptors, the favorable signaling features for metal ion recognition are demonstrated. PY - 2002 DO - https://doi.org/10.1021/ol027025i SN - 1523-7060 SN - 1523-7052 VL - 4 IS - 26 SP - 4647 EP - 4650 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - García-Acosta, B. A1 - Albiach-Martí, X. A1 - García, E. A1 - Gil, R. A1 - Martínez-Mánez, Ramon A1 - Rurack, Knut A1 - Sancenón, F. A1 - Soto, J. T1 - Coordinative and electrostatic forces in action: from the design of differential chromogenic anion sensors to selective carboxylate recognition N2 - A new family of differential chromogenic anion chemosensors is described based on anilinopyridine–metal cation coordinative signalling ensembles KW - Differentielle Sensoren KW - Anionen KW - Carboxylat KW - Chromogene Sensoren KW - Koordinative Bindungen KW - Elektrostatische Wechselwirkungen PY - 2004 DO - https://doi.org/10.1039/b314997h SN - 0022-4936 SN - 0009-241x SN - 1359-7345 SN - 1364-548x IS - 7 SP - 774 EP - 775 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-3438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fery-Forgues, S. A1 - Rurack, Knut A1 - Delavaux-Nicot, B. A1 - Lavabre, D. T1 - 1,3-Diphenyl-1H-pyrazolo[3,4-b]-quinoline (DPPQ)-a versatile fluorophore for the design of brightly emissive molecular sensors PY - 2002 SN - 1010-6030 SN - 1873-2666 PB - Elsevier CY - Lausanne AN - OPUS4-2108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Bifunctional Molecular Reporters: Approaches towards Multi-Mode Fluorescence Signaling T2 - Gradulate College on Sensory Photoreceptors: "Sensory Photoreceptors in Natural and Artificial Systems" CY - Regensburg, Germany DA - 2002-01-09 PY - 2002 AN - OPUS4-2962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -