TY - JOUR A1 - Rurack, Knut A1 - Schulz, Burkhard A1 - Reck, Günter A1 - Resch-Genger, Ute A1 - Bricks, J. A1 - Maus, M. T1 - Substituted 1,5-Diphenyl-3-benzothiazol-2-yl-Delta2-pyrazolines - Synthesis, X-ray Structure, Photophysics, and Cation Complexation Properties N2 - The spectroscopic properties of 1-phenyl-3-benzothiazol-2-yl-5-(4-R-phenyl)-2-pyrazolines are strongly dependent on both the electronic nature of the substituent R and solvent polarity. As revealed by spectroscopic studies as a function of solvent polarity as well as temperature, for electron-rich amino donor substituents in polar solvents, deactivation of the strongly emissive charge transfer (CT) state of the basic 1-phenyl-3-benzothiazol-2-yl-2-pyrazoline chromophore has to compete with a fast intramolecular electron transfer (ET) quenching reaction. In the case of the dimethylamino derivative (R = DMA), the rate constant of ET in acetonitrile was determined to ket = 3 × 1010 s-1. This ET process can be utilized for metal ion sensing by introducing nitrogen containing aza crown ether receptor units to the 4-position of the 5-phenyl group. The spectroscopically determined ET rates of the 5-(N-alkyl)anilino substituents, a DMA, a tetrathia- (AT415C5), and a tetraoxa-monoaza-15-crown-5 (A15C5) group, correlate with electrochemical data and increase in the order AT415C5 < A15C5 < DMA. The metal ion sensing abilities of the two crowned derivatives are presented, and the different signaling mechanisms include binding to the crown ether in the 4-R-position, chelate formation in the 3-benzothiazol-2-yl-2-pyrazoline moiety, and electrophotochemical detection. Furthermore, the rigid "pseudo spiro" geometry of the molecules, which holds the three substituents of the central 2-pyrazoline ring in a fixed prearrangement, was confirmed by X-ray structure analysis. KW - Farbstoff KW - Fluoreszenz KW - Kationen KW - Photophysik PY - 2000 DO - https://doi.org/10.1021/jp993404q SN - 1089-5639 SN - 1520-5215 VL - 104 IS - 26 SP - 6171 EP - 6188 PB - Soc. CY - Washington, DC AN - OPUS4-841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Bricks, J. L. A1 - Reck, Günter A1 - Radeglia, Reiner A1 - Resch-Genger, Ute T1 - Chalcone-analogue dyes emitting in the near-infrared (NIR) - influence of donor-acceptor substitution and cation complexation on their spectroscopic properties and X-ray structure N2 - The photophysical properties of several newly synthesized 1-benzothiazole-3-(4-donor)-phenyl-substituted prop-2-en-1-ones (substituted chalcones) are studied as a function of solvent polarity, temperature, and metal ion by employing steady-state and time-resolved spectroscopy. To investigate the effect of bulkiness and donor strength of the anilino moiety on the spectroscopic properties of these dyes, the spectroscopic behavior of the 4-N-dimethylamino (DMA), the 4-N-tetraoxa-monoaza-15-crown-5 (A15C5), and the 4-N-tetrathia-monoaza-15-crown-5 (AT415C5) derivatives as well as the 3-julolidino (Jul) analogue is compared. Absorption and fluorescence measurements reveal that the strength of the intramolecular charge transfer (ICT) process increases on the order of AT415C5 < A15C5 ~ DMA < Jul. The slight but significant differences between the two crowned dyes are well-supported by the results of the X-ray structure analysis, where oxa aza and thia aza crowns show essentially different geometries. For both fluoroionophores, this variation of heteroatom substitution pattern of the receptor induces specific cation selectivities. The spectroscopic effects accompanying complexation and the different binding sites are studied by steady-state and time-resolved optical spectroscopy as well as NMR spectroscopy. Whereas the probe carrying a tetraoxa monoaza 15-crown-5 receptor shows cation-induced fluorescence enhancement in the presence of alkali and alkaline-earth metal ions, its tetrathia analogue binds selectively to HgII, AgI, and CuII in acetonitrile. Moreover, an increase in fluorescence is observed for the latter probe even upon coordination to the widely known fluorescence quencher HgII. Besides receptor complexation, chelate formation in the benzothiazole-carbonyl acceptor part of these intrinsic fluorescent probes is possible, leading to a chromoionophoric signaling behavior in the near-infrared (NIR). PY - 2000 DO - https://doi.org/10.1021/jp994269k SN - 1089-5639 SN - 1520-5215 VL - 104 IS - 14 SP - 3087 EP - 3109 PB - Soc. CY - Washington, DC AN - OPUS4-2088 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López, J.P. A1 - Kraus, Werner A1 - Reck, Günter A1 - Thünemann, Andreas A1 - Kurth, D.G. T1 - Alternating perpendicular 1-D channels in the supramolecular structure of the copper(II) complex [Cu(pyterpy)2](PF6)2 . CH3OH . 0.5 CH2Cl2 (pyterpy = 4'-(4'''-pyridyl)-2,2':6',2''-terpyridine) KW - 4´-(4´´´-pyridyl)-2,2´:6´2´´-terpyridine KW - Copper complexes KW - Crystal structure KW - Supramolecular chemistry KW - Pi-pi stacking PY - 2005 SN - 1387-7003 VL - 8 SP - 281 EP - 284 PB - Elsevier CY - Amsterdam AN - OPUS4-6301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López, J.P. A1 - Kraus, Werner A1 - Reck, Günter A1 - Thünemann, Andreas A1 - Kurth, D.G. T1 - Synthesis, structure and reactivity of the homoleptic iron(II) complex of the novel 4'-(4'''-pyridyl-N-oxide)-2,2':6',2''-terpyridine ligand N2 - The new ligand 4´-(4´´´-pyridyl-N-oxide)-2,2´:6´,2´´-terpyridine (pyNoxterpy) and its homoleptic iron(II) complex have been synthesised, and structural and spectroscopic studies have been carried out. The obtained results have been compared with the reported data for the parent ligand 4´-(4´´´-pyridyl)-2,2´:6´,2´´-terpyridine (pyterpy) and its homoleptic iron(II) complex. Significant differences between the spectral and electrochemical properties of the metal complexes have been found, derived from the changes in the electronic properties of the coordinated ligands. KW - Terpyridine KW - Pyridine N-oxide KW - Iron complexes KW - Crystal structure PY - 2005 SN - 0020-1693 SN - 1873-3255 VL - 358 IS - 12 SP - 3384 EP - 3390 PB - Elsevier Sequoia CY - Lausanne AN - OPUS4-10908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Orgzall, I. A1 - Dietzel, B. A1 - Schulz, Burkhard A1 - Reck, Günter A1 - Schulz, B. T1 - Structural studies on trifluoromethyl substituted 2,5-diphenyl-1,3,4-oxadiazoles N2 - Three new compounds have been synthesized based on the molecular motif 2-[2,6-bis(trifluoromethyl)phenyl]-5-phenyl-1,3,4-oxadiazole, with subsequent CF3-substitution in the ortho-positions of the phenylene ring. The crystal structures of the compounds have been determined by single crystal X-ray diffraction. All compounds have a monoclinic structure. The solid state structure of the compounds is influenced by the electronic properties of the fluorine atoms, leading to the occurrence of C–H...F, and C–F...ϖ interactions, partly replacing ϖ–ϖ interactions usually observed in the crystal structures of 2,5-diphenyl-1,3,4-oxadiazole derivatives. Other significant interactions than those involving fluorine appear only in rare cases. The strong impact of the fluorine atoms on the intra- and intermolecular interactions, and the molecular conformation lead to novel inputs for the understanding of molecular recognition, supramolecular assembly, and crystal packing of fluorine containing compounds. KW - Crystal structure KW - 1,3,4-oxadiazole KW - Molecular conformation KW - Weak interactions PY - 2007 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 832 IS - 1-3 SP - 124 EP - 131 PB - Elsevier CY - Amsterdam AN - OPUS4-14644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuchalski, G. A1 - Emmerling, Franziska A1 - Gröger, K. A1 - Hänsicke, A. A1 - Nagel, T. A1 - Reck, Günter T1 - X-ray investigations of nebivolol and its isomers N2 - The molecular and crystal structures of the hydrochlorides of d-nebivolol, dl-nebivolol, and seven nebivolol isomers have been determined by X-ray structure analysis. The absolute configuration of all the compounds could be determined unambiguously using anomal dispersion effects. Two compounds, dl-nebivolol (NEB-1d,l) and the (S,R,S,R) nebivolol isomer (NEB-6), crystallize as racemic mixtures in the centrosymmetric space group P-1. d-Nebivolol and six nebivolol isomers crystallize in space group P212121. The d- and l-nebivolol molecules in NEB-1d and NEB-1d,l adopt a conformation which is significantly different compared with that of all nebivolol isomers. With the exception of dl-nebivolol (NEB-1d,l) numerous intermolecular hydrogen bonds connect the molecules forming molecular layers. KW - X-ray crystal structure KW - Nebivolol PY - 2006 DO - https://doi.org/10.1016/j.molstruc.2006.03.086 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 800 IS - 1-3 SP - 28 EP - 44 PB - Elsevier CY - Amsterdam AN - OPUS4-13800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meißner, T. A1 - Bergmann, R. A1 - Oswald, J. A1 - Rode, K. A1 - Stephan, H. A1 - Richter, W. A1 - Zänker, H. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Reck, Günter T1 - Chitosan-encapsulated Keggin anion [Ti2W10PO40]7-.Synthesis, characterization and cellular uptake studies N2 - The Keggin type polyoxotungstate [Ti2W10PO40]7- forms stable associates with the biopolymer chitosan in the nanometer size range. The cluster compound crystallizes from aqueous solution as K4H3[Ti2W10PO40] · 15H2O having a tetragonal structure. Both, the cluster compound and the chitosan/[Ti2W10PO40] associates show a high hydrolytic stability at pH 7.4. The associates formed between the cluster anion [Ti2W10PO40]7- with the polyaminosaccharide chitosan have been characterized by photon correlation spectroscopy, scanning electron microscopy, filtration, centrifugation and zeta potential measurements. The size of the associates formed is in the range of ca. 5×101 to 5×102 nm. These particles have a defined stoichiometry with 5–6 cluster anions bound per molecule chitosan. The isoelectric point determined by zeta potential measurements was found for a cluster anion to chitosan molar ratio of 5.5, indicating the charge neutralization between protonated chitosan and [Ti2W10PO40]7- anions. Cellular uptake studies with [Ti2W10PO40]7- using tumor cell lines FaDu (human squamous carcinoma) and HT-29 (human adenocarcinoma) showed that the tungsten amount inside the cells is remarkably enhanced in the presence of chitosan. KW - Cluster compound KW - Keggin structure KW - Bipolymer KW - Chitosan PY - 2006 DO - https://doi.org/10.1007/s11243-006-0035-z SN - 0340-4285 SN - 1572-901X VL - 31 IS - 5 SP - 603 EP - 610 PB - Springer CY - Dordrecht AN - OPUS4-12568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Orgzall, I. A1 - Reck, Günter A1 - Schulz, Burkhard A1 - Stockhause, S. A1 - Schulz, B. T1 - Structures of substituted di-aryl-1,3,4-oxadiazole derivatives: 2,5-bis(pyridyl)- and 2,5-bis(aminophenyl)-substitution N2 - Crystal structures of four different di-aryl-1,3,4-oxadiazole compounds (aryl = 2-pyridyl-, 3-pyridyl-, 2-aminophenyl-, 3-aminophenyl-) are determined. Crystallization of di(2-pyridyl)-1,3,4-oxadiazole yielded monoclinic and triclinic polymorphs. The structures are characterized by the occurrence of π–π interactions. Additionally, in case of the aminophenyl compounds intra- as well as intermolecular hydrogen bonds are found that influence the packing motif as well. Since these molecules are often used as ligands in metal–organic complexes similarities and differences of the molecular conformation between the molecules in the pure crystals and that of the ligands in the complexes are discussed. KW - Crystal structure KW - 1,3,4-Oxadiazole KW - Molecular conformation KW - Hydrogen bonds PY - 2006 DO - https://doi.org/10.1016/j.molstruc.2006.03.076 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 800 IS - 1-3 SP - 74 EP - 84 PB - Elsevier CY - Amsterdam AN - OPUS4-13799 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Bricks, J. L. A1 - Resch-Genger, Ute A1 - Kraus, Werner A1 - Schulz, Burkhard A1 - Li, Yanqin A1 - Reck, Günter T1 - Influence of the donor substituent and acceptor alkylation on the structure-analytical properties of mono- and bifunctional biphenyl-type fluorescent reporters N2 - A systematic structural investigation of R-phenyl-substituted 2,2':6',2"-terpyridines, a family of mono- and bifunctional charge transfer (CT)-operated fluorescent reporters for protons and metal ions, is presented. These molecules are equipped with non-binding and analyte coordinating donor substituents R (R = CF3, H, OMe, OH, DMA, A15C5 equaling monoaza-15-crown-5) of various donor strength and display CT-controlled spectroscopic properties and communication of analyte–receptor interactions. The crystal structures of the neutral fluorescent probes are compared to the structures of their terpyridine-alkylated or -protonated counterparts that represent model systems for acceptor protonation or cation coordination. The aim is here a better understanding of the complexation-induced structural and spectroscopic changes and the identification of common packing motifs of bpb-R thereby taking into account the importance of terpyridine building blocks for the construction of supramolecular systems and coordination arrays revealing π–π interactions. KW - Biphenyl KW - Terpyridine KW - Crystal structure KW - Fluorescent probe KW - Charge transfer KW - Bifunctional PY - 2008 DO - https://doi.org/10.1016/j.molstruc.2007.03.025 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 874 IS - 1-3 SP - 14 EP - 27 PB - Elsevier CY - Amsterdam AN - OPUS4-17087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Becker, Roland A1 - Reck, Günter T1 - Mixed crystal of bis(µ2-N,N-di-n-butyldithiocarbamato-S,S,S')-bis(N,N-di-n-butyldithiocarbamato-S,S')-di-zinc(II) and bis(µ2-N,N-di-n-butyldithiopercarbamato-S,O,O')-bis(N,N-di-n-butyldithiocarbamato-S,S')-di-zinc(II) N2 - The title compounds Zn2[S2CN(n-C4H9)2]4 1 and Zn2[(S(SO)CN(n-C4H9)2)(S2CN(n-C4H9)2)]2 3 build mixed crystals in the ratio 0.42: 0.58. Each compound forms dimers, in which the monomer moieties are related via a two-fold axis, coinciding with that of the monoclinic space group C2/c. The lattice parameters are a = 23.581(9), b = 17.112(5), c = 16.372(9) Å, and β = 128.33(3)°. KW - Crystal structure KW - Zinc KW - Dithiocarbamate KW - Dithiopercarbamate PY - 2007 DO - https://doi.org/10.1002/crat.200710956 SN - 0023-4753 SN - 1521-4079 SN - 0232-1300 VL - 42 IS - 10 SP - 1018 EP - 1023 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-17843 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Katrin A1 - Dietzel, B. A1 - Schulz, B. A1 - Reck, Günter A1 - Hoffmann, Angelika A1 - Orgzall, I. A1 - Resch-Genger, Ute A1 - Emmerling, Franziska T1 - Combined structural and fluorescence studies of methyl-substituted 2,5-diphenyl-1,3,4-oxadiazoles - relation between electronic properties and packing motifs N2 - Prerequisite for the rational design of functional organic materials with tailor-made electronic properties is the knowledge of the structure–property relationship for the specific class of molecules under consideration. This encouraged us to systematically study the influence of the molecular structure and substitution pattern of aromatically substituted 1,3,4-oxadiazoles on the electronic properties and packing motifs of these molecules and on the interplay of these factors. For this purpose, seven diphenyl-oxadiazoles equipped with methyl substituents in the ortho- and meta-position(s) were synthesized and characterized. Absorption and fluorescence spectra in solution served here as tools to monitor substitution-induced changes in the electronic properties of the individual molecules whereas X-ray and optical measurements in the solid state provided information on the interplay of electronic and packing effects. In solution, the spectral position of the absorption maximum, the size of Stokes shift, and the fluorescence quantum yield are considerably affected by ortho-substitution in three or four ortho-positions. This results in blue shifted absorption bands, increased Stokes shifts, and reduced fluorescence quantum yields whereas the spectral position and vibrational structure of the emission bands remain more or less unaffected. In the crystalline state, however, the spectral position and shape of the emission bands display a strong dependence on the molecular structure and/or packing motifs that seem to control the amount of dye–dye-interactions. These observations reveal the limited value of commonly reported absorption and fluorescence measurements in solution for a straightforward comparison of spectroscopic results with single X-ray crystallography. This underlines the importance of solid state spectroscopic studies for a better understanding of the interplay of electronic effects and molecular order. KW - Diphenyl-oxadiazoles KW - X-ray structure KW - Packing motif KW - Optical properties KW - Fluorescence quantum yield PY - 2011 DO - https://doi.org/10.1016/j.molstruc.2010.11.071 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 988 IS - 1-3 SP - 35 EP - 46 PB - Elsevier CY - Amsterdam AN - OPUS4-23253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -