TY - JOUR A1 - Zottnick, Sven H. A1 - Sprenger, Jan A. P. A1 - Finze, Maik A1 - Müller‐Buschbaum, Klaus T1 - Statistic Replacement of Lanthanide Ions in Bis‐salicylatoborate Coordination Polymers for the Deliberate Control of the Luminescence Chromaticity JF - ChemistryOpen N2 - Based on the strand‐like coordination polymer (CP) type \(^{1}\)\(_{∞}\)[Ln(BSB)\(_{3}\)(py)\(_{2}\)], [BSB]−=bis‐salicylatoborate anion, mixed Eu/Tb‐containing compounds of the constitution \(^{1}\)\(_{∞}\)[Eu\(_{x}\)Tb\(_{1-x}\)(BSB)\(_{3}\)(py)\(_{2}\)] were synthesised ionothermally for a phase width of (x=0.25–0.75) and characterized regarding structure and optical properties. Previously, known only for other lanthanides, the mixed 1D−Eu/Tb‐CPs show excellent options for statistic replacement of the Ln‐cations during synthesis yielding solid solutions. The products are highly luminescent, with the chromaticity being a direct function of the amount of the respective Ln‐ions. Corresponding to an overall addition of emission intensities, the green Tb\(^{3+}\) emission and the red Eu\(^{3+}\) emission allow for a chromaticity control that also includes yellow emission. Control of the luminescence colour renders them suitable examples of the versatility of statistic replacement of metal ions in coordination chemistry. In addition, crystallization of [EMIm]\(_{2}\)[YCl\(_{5}\)(py)] illuminates possible other products of the ionothermal reactions of [EMIm][BSB] with LnCl\(_{3}\) constituted by components not being part of the main CPs. KW - borates KW - coordination polymers KW - ionic liquids KW - lanthanides KW - luminescence Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239953 VL - 10 IS - 2 SP - 164 EP - 170 ER - TY - JOUR A1 - Zhang, Xiaolei A1 - Friedrich, Alexandra A1 - Marder, Todd B. T1 - Copper-Catalyzed Borylation of Acyl Chlorides with an Alkoxy Diboron Reagent: A Facile Route to Acylboron Compounds JF - Chemistry—A European Journal N2 - Herein, the copper-catalyzed borylation of readily available acyl chlorides with bis(pinacolato)diboron, (B\(_{2}\)pin\(_{2}\)) or bis(neopentane glycolato)diboron (B\(_{2}\)neop\(_{2}\)) is reported, which provides stable potassium acyltrifluoroborates (KATs) in good yields from the acylboronate esters. A variety of functional groups are tolerated under the mild reaction conditions (room temperature) and substrates containing different carbon-skeletons, such as aryl, heteroaryl and primary, secondary, tertiary alkyl are applicable. Acyl N-methyliminodiacetic acid (MIDA) boronates can also been accessed by modification of the workup procedures. This process is scalable and also amenable to the late-stage conversion of carboxylic acid-containing drugs into their acylboron analogues, which have been challenging to prepare previously. A catalytic mechanism is proposed based on in situ monitoring of the reaction between p-toluoyl chloride and an NHC-copper(I) boryl complex as well as the isolation of an unusual lithium acylBpinOBpin compound as a key intermediate. KW - boronate KW - catalysis KW - borylation KW - carbonyl KW - copper Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318318 VL - 28 IS - 42 ER - TY - JOUR A1 - Zhang, Fangyuan A1 - Radacki, Krzysztof A1 - Braunschweig, Holger A1 - Lambert, Christoph A1 - Ravat, Prince T1 - Zinc-[7]helicenocyanine and its discrete π-stacked homochiral Dimer JF - Angewandte Chemie International Edition N2 - In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×10\(^6\) M\(^{−1}\) and 3.42×107 M\(^{−1}\) in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn\(^{-7}\)HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state. KW - organic chemistry KW - supramolecular assembly KW - chirality KW - helicenes KW - homochiral dimer KW - phthalocyanines Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256534 VL - 60 ER - TY - JOUR A1 - Zhang, Chonghe A1 - Liu, Xiaocui A1 - Wang, Junyi A1 - Ye, Qing T1 - A Three-Dimensional Inorganic Analogue of 9,10-Diazido-9,10-Diboraanthracene: A Lewis Superacidic Azido Borane with Reactivity and Stability JF - Angewandte Chemie N2 - Herein, we report the facile synthesis of a three-dimensional (3D) inorganic analogue of 9,10-diazido-9,10-dihydrodiboraantracene, which turned out to be a monomer in both the solid and solution state, and thermally stable up to 230 °C, representing a rare example of azido borane with boosted Lewis acidity and stability in one. Apart from the classical acid-base and Staudinger reactions, E−H bond activation (E=B, Si, Ge) was investigated. While the reaction with B−H (9-borabicyclo[3.3.1]nonane) led directly to the 1,1-addition on N\(_{α}\) upon N\(_{2}\) elimination, the Si−H (Et\(_{3}\)SiH, PhMe\(_{2}\)SiH) activation proceeded stepwise via 1,2-addition, with the key intermediates 5\(_{int}\) and 6\(_{int}\) being isolated and characterized. In contrast, the cooperative Ge−H was reversible and stayed at the 1,2-addition step. KW - E-H bond activation KW - boracycle KW - azido borane KW - lewis superacid KW - structure elucidation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318322 VL - 61 IS - 36 ER - TY - JOUR A1 - Zapf, Ludwig A1 - Radius, Udo A1 - Finze, Maik T1 - 1,3-bis(tricyanoborane)imidazoline-2-ylidenate anion - a ditopic dianionic N-heterocyclic carbene ligand JF - Angewandte Chemie International Edition N2 - The 1,3-bis(tricyanoborane)imidazolate anion 1 was obtained in high yield from lithium imidazolate and B(CN)\(_3\)−pyridine adduct. Anion 1 is chemically very robust and thus allowed the isolation of the corresponding H\(_5\)O\(_2\)\(^+\) salt. Furthermore, monoanion 1 served as starting species for the novel dianionic N-heterocyclic carbene (NHC), 1,3-bis(tricyanoborane)imidazoline-2-ylidenate anion 3 that acts as ditopic ligand via the carbene center and the cyano groups at boron. First reactions of this new NHC 3 with methyl iodide, elemental selenium, and [Ni(CO)\(_4\)] led to the methylated imidazolate ion 4, the dianionic selenium adduct 5, and the dianionic nickel tricarbonyl complex 6. These NHC derivatives provide a first insight into the electronic and steric properties of the dianionic NHC 3. Especially the combination of properties, such as double negative charge, different coordination sites, large buried volume and good σ-donor and π-acceptor ability, make NHC 3 a unique and promising ligand and building block. KW - inorganic chemistry KW - N-heterocyclic carbene KW - anioniccarbene KW - boron KW - cyanoborate KW - imidazolate Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256498 VL - 60 IS - 33 ER - TY - JOUR A1 - Zapf, Ludwig A1 - Peters, Sven A1 - Bertermann, Rüdiger A1 - Radius, Udo A1 - Finze, Maik T1 - Tricyanoborane‐Functionalized Anionic N‐Heterocyclic Carbenes: Adjustment of Charge and Stereo‐Electronic Properties JF - Chemistry – A European Journal N2 - The 1‐methyl‐3‐(tricyanoborane)imidazolin‐2‐ylidenate anion (2) was obtained in high yield by deprotonation of the B(CN)3‐methylimidazole adduct 1. Regarding charge and stereo‐electronic properties, anion 2 closes the gap between well‐known neutral NHCs and the ditopic dianionic NHC, the 1,3‐bis(tricyanoborane)imidazolin‐2‐ylidenate dianion (IIb). The influence of the number of N‐bonded tricyanoborane moieties on the σ‐donating and π‐accepting properties of NHCs was assessed by quantum chemical calculations and verified by experimental data on 2, IIb, and 1,3‐dimethylimidazolin‐2‐ylidene (IMe, IIa). Therefore NHC 2, which acts as a ditopic ligand via the carbene center and the cyano groups, was reacted with alkyl iodides, selenium, and [Ni(CO)\(_{4}\)] yielding alkylated imidazoles 3 and 4, the anionic selenium adduct 5, and the anionic nickel tricarbonyl complex 8, respectively. The results of this study prove that charge, number of coordination sites, buried volume (%V\(_{bur}\)) and σ‐donor and π‐acceptor abilities of NHCs can be effectively fine‐tuned via the number of tricyanoborane substituents. KW - N-heterocyclic carbene KW - anionic carbene KW - boron KW - cyanoborate KW - imidazolate Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287200 VL - 28 IS - 39 ER - TY - JOUR A1 - Zapf, Ludwig A1 - Finze, Maik T1 - The crystal structure of poly[(μ \(_3\)-imidazolato-κ \(^3\) N:N:N′)(tetrahydrofuran- κ \(^1\) O)lithium(I)], C\(_7\)H\(_{11}\)LiN\(_2\)O JF - Zeitschrift für Kristallographie - New Crystal Structures N2 - C\(_7\)H\(_{11}\)LiN\(_2\)O, monoclinic, P2\(_1\)/c (no. 14), a = 8.9067(1) angstrom, b = 8.6975(1) angstrom, c = 10.2398(1) angstrom, beta = 101.900(3)degrees, V = 770.491(15) angstrom(3), Z = 4, R-gt (F) = 0.0338, wR(ref) (F\(^2\)) = 0.0925, T = 100 K. KW - acid sphingomyelinase KW - antidepressants KW - major depression KW - regulatory T cells KW - sphingolipids Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-260745 VL - 236 IS - 5 ER - TY - JOUR A1 - Wu, Zhu A1 - Roldao, Juan Carlos A1 - Rauch, Florian A1 - Friedrich, Alexandra A1 - Ferger, Matthias A1 - Würthner, Frank A1 - Gierschner, Johannes A1 - Marder, Todd B. T1 - Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP) JF - Angewandte Chemie N2 - Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)\(_{3}\) does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP. KW - boric acid KW - room-temperature phosphorescence (RTP) KW - optical materials Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318308 VL - 61 IS - 15 ER - TY - JOUR A1 - Wu, Zhu A1 - Nitsch, Jörn A1 - Marder, Todd B. T1 - Persistent room-temperature phosphorence from purely organic molecules and multi-component systems JF - Advanced Optical Materials N2 - Recently, luminophores showing efficient room-temperature phosphorescence (RTP) have gained tremendous interest due to their numerous applications. However, most phosphors are derived from transition metal complexes because of their intrinsic fast intersystem crossing (ISC) induced by strong spin–orbit coupling (SOC) constants of the heavy metal. Metal-free RTP materials are rare and have become a promising field because they are inexpensive and environmentally friendly. This review summarizes organic molecular materials with long triplet lifetimes at room temperature from the perspective of whether they stem from a molecular or multi-component system. Among purely organic phosphors, heteroatoms are usually introduced into the backbone in order to boost the singlet–triplet ISC rate constant. In multi-component systems, useful strategies such as host–guest, polymer matrix, copolymerization, and supramolecular assembly provide a rigid matrix to restrict nonradiative pathways thus realizing ultralong RTP. KW - inorganic chemistry KW - non-radiative decay KW - polymer matrix KW - intersystem crossing KW - luminescence KW - photophysics Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256415 VL - 9 IS - 20 ER - TY - JOUR A1 - Wu, Zhu A1 - Dinkelbach, Fabian A1 - Kerner, Florian A1 - Friedrich, Alexandra A1 - Ji, Lei A1 - Stepanenko, Vladimir A1 - Würthner, Frank A1 - Marian, Christel M. A1 - Marder, Todd B. T1 - Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature JF - Chemistry—A European Journal N2 - Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T\(^M_1\) state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T\(^A_1\) state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently. KW - AIE KW - luminescence KW - phosphorescence KW - triarylborane KW - triplet Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318297 VL - 28 IS - 30 ER - TY - JOUR A1 - Witte, Robert A1 - Arrowsmith, Merle A1 - Lamprecht, Anna A1 - Schorr, Fabian A1 - Krummenacher, Ivo A1 - Braunschweig, Holger T1 - C−C and C−N Bond Activation, Lewis‐Base Coordination and One‐ and Two‐Electron Oxidation at a Linear Aminoborylene JF - Chemistry – A European Journal N2 - A cyclic alkyl(amino)carbene (CAAC)‐stabilized dicoordinate aminoborylene is synthesized by the twofold reduction of a [(CAAC)BCl\(_{2}\)(TMP)] (TMP=2,6‐tetramethylpiperidyl) precursor. NMR‐spectroscopic, X‐ray crystallographic and computational analyses confirm the cumulenic nature of the central C=B=N moiety. Irradiation of [(CAAC)B(TMP)] (2) resulted in an intramolecular C−C bond activation, leading to a doubly‐fused C\(_{10}\)BN heterocycle, while the reaction with acetonitrile resulted in an aryl migration from the CAAC to the acetonitrile nitrogen atom, concomitant with tautomerization of the latter to a boron‐bound allylamino ligand. One‐electron oxidation of 2 with CuX (X=Cl, Br) afforded the corresponding amino(halo)boryl radicals, which were characterized by EPR spectroscopy and DFT calculations. Placing 2 under an atmosphere of CO afforded the tricoordinate (CAAC,CO)‐stabilized aminoborylene. Finally, the twofold oxidation of 2 with chalcogens led, in the case of N\(_{2}\)O and sulfur, to the splitting of the B−C\(_{CAAC}\) bond and formation of the 2,4‐diamino‐1,3,2,4‐dichalcogenadiboretanes and CAAC‐chalcogen adducts, whereas with selenium a monomeric boraselenone was isolated, which showed some degree of B−Se multiple bonding. KW - bond activation KW - boraselenone KW - dicoordinate borylene KW - one-electron oxidation KW - push-pull stabilization Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312491 VL - 29 IS - 16 ER - TY - JOUR A1 - Wirthensohn, Raphael A1 - Finze, Maik T1 - The crystal structure of trimethylsulfonium tris(trifluoromethylsulfonyl)methanide, C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\) JF - Zeitschrift für Kristallographie - New Crystal Structures N2 - C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\), orthorhombic, P2\(_1\)2\(_1\)2\(_1\) (no. 19), a = 8.80180(10) Å, b= 10.96580(10) Å, c = 16.91360(10) Å,V= 1632.48(3) Å\(^3\), Z= 4, R\(_{gt}\)(F) = 0.0222, wR\(_{ref}\)(F\(^2\)) = 0.0604, T = 100 K. KW - chemistry Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231358 VL - 236 IS - 2 ER - TY - JOUR A1 - Wildervanck, Martijn J. A1 - Hecht, Reinhard A1 - Nowak-Król, Agnieszka T1 - Synthesis and strong solvatochromism of push-pull thienylthiazole boron complexes JF - Molecules N2 - The solvatochromic behavior of two donor-π bridge-acceptor (D-π-A) compounds based on the 2-(3-boryl-2-thienyl)thiazole π-linker and indandione acceptor moiety are investigated. DFT/TD-DFT calculations were performed in combination with steady-state absorption and emission measurements, along with electrochemical studies, to elucidate the effect of two different strongly electron-donating hydrazonyl units on the solvatochromic and fluorescence behavior of these compounds. The Lippert–Mataga equation was used to estimate the change in dipole moments (Δµ) between ground and excited states based on the measured spectroscopic properties in solvents of varying polarity with the data being supported by theoretical studies. The two asymmetrical D-π-A molecules feature strong solvatochromic shifts in fluorescence of up to ~4300 cm\(^{−1}\) and a concomitant change of the emission color from yellow to red. These changes were accompanied by an increase in Stokes shift to reach values as large as ~5700–5800 cm\(^{−1}\). Quantum yields of ca. 0.75 could be observed for the N,N-dimethylhydrazonyl derivative in nonpolar solvents, which gradually decreased along with increasing solvent polarity, as opposed to the consistently reduced values obtained for the N,N-diphenylhydrazonyl derivative of up to ca. 0.20 in nonpolar solvents. These two push–pull molecules are contrasted with a structurally similar acceptor-π bridge-acceptor (A-π-A) compound. KW - solvatochromism KW - donor–acceptor KW - fluorescence KW - hydrazone KW - Lippert–Mataga plot KW - push–pull thienylthiazole KW - tetracoordinated boron Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286186 SN - 1420-3049 VL - 27 IS - 17 ER - TY - JOUR A1 - Weiser, Jonas A1 - Cui, Jingjing A1 - Dewhurst, Rian D. A1 - Braunschweig, Holger A1 - Engels, Bernd A1 - Fantuzzi, Felipe T1 - Structure and bonding of proximity‐enforced main‐group dimers stabilized by a rigid naphthyridine diimine ligand JF - Journal of Computational Chemistry N2 - The development of ligands capable of effectively stabilizing highly reactive main‐group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity‐enforced group 13–15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8‐naphthyridine (napy) core. We show that the redox‐active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element‐element interaction modes, the latter ranging from isolated, element‐centered lone pairs (e.g., E = Si, Ge) to cases where through‐space π bonds (E = Pb), element‐element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI‐E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy‐based ligands in main‐group chemistry. KW - bond theory KW - computational chemistry KW - density functional calculations KW - main group elements KW - N ligands Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312586 VL - 44 IS - 3 SP - 456 EP - 467 ER - TY - JOUR A1 - Wei, Yuxiang A1 - Wang, Junyi A1 - Yang, Weiguang A1 - Lin, Zhenyang A1 - Ye, Qing T1 - Boosting Ring Strain and Lewis Acidity of Borirane: Synthesis, Reactivity and Density Functional Theory Studies of an Uncoordinated Arylborirane Fused to o‐Carborane JF - Chemistry – A European Journal N2 - Among the parent borirane, benzoborirene and ortho‐dicarbadodecaborane‐fused borirane, the latter possesses the highest ring strain and the highest Lewis acidity according to our density functional theory (DFT) studies. The synthesis of this class of compounds is thus considerably challenging. The existing examples require either a strong π‐donating group or an extra ligand for B‐coordination, which nevertheless suppresses or completely turns off the Lewis acidity. The title compound, which possesses both features, not only allows the 1,2‐insertion of P=O, C=O or C≡N to proceed under milder conditions, but also enables the heretofore unknown dearomative 1,4‐insertion of Ar−(C=O)− into a B−C bond. The fusion of strained molecular systems to an o‐carborane cage shows great promise for boosting both the ring strain and acidity. KW - borirane KW - carborane KW - fused boracycles KW - Lewis acidity KW - ring strain Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312089 VL - 29 IS - 5 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Tastenoy, M. A1 - Camus, J. A1 - Christophe, J. A1 - Strohmann, C. A1 - Linoh, H. A1 - Zilch, H. A1 - Tacke, Reinhold A1 - Mutschler, E. A1 - Lambrecht, G. T1 - Binding and functional properties of antimuscarinics of the hexocyclium/sila-hexocyclium and hexahydro-diphenidol/hexahydro-sila-diphenidol type to muscarinic receptor subtypes N2 - l In an attempt to assess the structural requirements for the musearlnie receptor selectivity of hexahydro-diphenidol (hexahydro-difenidol) and hexahydro-sila-diphenidol (hexahydro-sila-difenidol), a serles of structurally related C/Si pairs were investigated, along with atropine, pirenzepine and methoctramine, for their binding affinities in NB-OK 1 cells as well as in rat heart and pancreas. 2 The action of these antagonists at musearlnie receptors mediating negative inotropic responses in guinea-pig atrla and ileal contractions has also been assessed. 3 Antagonist binding data indicated that NB-OK 1 cells (M\(_1\) type) as weil as rat heart (cardiac type) and pancreas (glandularjsmooth muscle type) possess different muscarinic receptor subtypes. 4 A highly significant correlation was found between the binding affinities of the antagonists to muscarinic receptors in rat heart and pancreas, respectively, and the affinities to muscarinic receptors in guinea-pig atria and ileum. This implies that the musearlnie binding sites in rat heart and the receptors in guinea-pig atrla are essentially similar, but different from those in pancreas and ileum. 5 The antimuscarinic potency of hexahydro-diphenidol and hexahydro-sila-diphenidol at the three subtypes was inftuenced differently by structural modifications (e.g. quaternization). Different selectivity profiles for the antagonists were obtained, which makes these compounds useful tools to investigate further muscarinic receptor heterogeneity. lndeed, the tertiary analogues hexahydrodiphenidol (HHD) and hexahydro-sila-diphenidol (HHSiD) bad an M\(_1\) = glandularjsmooth muscle > cardiac selectivity profile, whereas the quaternary analogues HHD methiodide and HHSiD methiodide were M\(_1\) preferring (M\(_1\) > glandularjsmooth muscle, cardiac). KW - Anorganische Chemie Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63944 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Mutschler, E. A1 - Strohmann, C. A1 - Tacke, Reinhold A1 - Schjelderup, L. A1 - Aasen, A. A1 - Lambrecht, G. A1 - Christophe, J. T1 - Stereoselective interaction of procyclidine, hexahydro-difenidol, hexbutinol and oxyphencyclimine, and of related antagonists, with four muscarinic receptors N2 - Wc invcstigatcd thc binding properlies of thc (R)- and (Sl-cnantiomcrs of thc muscarinic antagonists trihcxyphcnidyl, procyclidinc, hcxahydro-difcnidol. p-fluoro-hcxahydro-difcnidol. hcxbutinol, p-fluoro-hcxbutinnl. and thcir corrcsponding methiodidcs at muscarinic M\(_1\), M\(_2\)• M\(_3\) and M\(_4\) receptor subtypes. In addition. binding properlies of thc (R)- and (S)-cnantiomcrs of oxyphcncycliminc wcrc studicd. The {R)- cnantiomcrs (cutomcrs} of all the compounds had a grcatcr affinity than the (S)-isomcrs for thc four muscarinic rcccptor subtypcs. Thc binding pattcrns of thc (R)- and (S)-enantiomers wcrc gcncrally different. We did not obscrvc any gcncral corrclation hctwccn thc potcncy of thc high-affinity enantiomer and Lhc affinity ratio (cudismic ratio) of the two cnantiomcrs. Thc rcsuhs arc discusscd in tcrms of a 'four suhsitcs' binding modcl. KW - Anorganische Chemie KW - Muscarinic receptors KW - Hexahydro-difenidol KW - Oxyphencyclimine Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64237 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Mutschler, E. A1 - Strohmann, C. A1 - Tacke, Reinhold A1 - Lambrecht, G. A1 - Christophe, J. T1 - Binding affinities of hexahydro-difenidol and hexahydro-sila-difenidol analogues at four muscarinic receptor subtypes: constitutional and stereochemical aspects N2 - Hexahydro-sila-difenidoJ and eight analogues behaved as simple cumpetitive inhibitors of eHJN·methyl·scopoJamine binding to homogenates frorn human neuroblastoma NB-OK 1 cells (M\(_1\) sites), rat heart (M\(_2\) sites), rat pancreas (M\(_3\) sites), and rat striatum 'B' sites (M\(_4\) sites). Pyrrolidino- and hexamethyleneimino analogues showed the same sekctivity profile as the parent compound. Hexahydro-sila-difenidol methiodide and the methiodide of p-fluoro-hexahydro·sila-difenidol had a fügher affinity but a lower selectivity than the tertiary amines. Compounds containing a p·methoxy, p-chJoro or p-fluoro substituent in the phenyl ring of hexahydro-sila-difenidol showed a qualitative)y similar selectivity profile as the parent compound (i.e., M\(_1\)= M\(_3\) = M\(_4\) >M\(_2\) ), but up to 16-fold lower affinities. o-Methoxy-hexahydro-sila-difenidol has a lower affinity than hexahydro-sila-difeni.:!o! at the four binding sites. lts selectivity profile (M\(_4\) > M\(_1\), M\(_3\) > M\(_2\) ) was different from hexahydro-sila-difenidol. Replacement of the centrat silicon atom of hexahydro-sila-difenidol, p-fluoro-hexahydro-sila-difenidol and thdr quatemary (N-methylated) analogues by a carbon atom did not change their binding affinities significantly. The iour muscarinic receptors showed a higher affinity for the (R)- than for the (S)-enantiomers of hexahydro-difenidol, p-fluorohexahydro-difenidol and their methiodides. The stereoselectivity varied depending on the receptor subtype and drug considered. KW - Anorganische Chemie KW - Muscarinic receptor antagonists (selective) KW - Hexahydro-sila-difenidol analogues KW - p-Fluoro-hexahydro-sila-difenidol KW - Stereoselectivity Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64128 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Mutschler, E. A1 - Strohmann, C. A1 - Tacke, Reinhold A1 - Lambrecht, G. A1 - Christophe, J. T1 - Stereoselectivity of (R)- and (S)-hexahydro-difenidol binding to neuroblastoma M\(_1\), cardiac M\(_2\), pancreatic M\(_3\), and striatum M\(_4\) muscarinic receptors N2 - (R)-Hexahydro-difenidol has a higher affinity for M\(_1\) receptors in NB-OK 1 cells, pancreas M\(_3\) and striatum M\(_4\) receptors (pKi 7.9 to 8.3) than for cardiac M2 receptors (pKi 7 .0). (8)-Hexahydro-difenidol, by contrast, is nonselective (pKi 5.8 to 6.1). Our goal in the present study was to evaluate the importance ofthe hydrophobic phenyl, and cyclohexyl rings of hexahydro-difenidol for the stereoselectivity and reeeptor selectivity of hexahydro-difenidol binding to the four muscarinic receptors. Our results indieated that replacement of the phenyl ring of hexahydro-difenidol by a cyclohexyl group <~ dicyclidol) and ofthe cyclohexyl ring by a phenyl moiety <~ difenidol) indueed a !arge (4- to 80-fold) decrease in binding affinity for all musearlnie receptors. Difenidol had a signifieant preference for M\(_1\) , M\(_3\) , and M\(_4\) over M\(_2\) receptors; dicyclidol, by eontrast, had a greater affinity for M\(_1\) and M\(_4\) than for M\(_2\) and M\(_3\) receptors. The binding free energy deerease due to replacement ofthe phenyl and the cyelohexyl groups of(R)-hexahydro-difenidol by, respectively, a eyclohexyl and a phenyl moiety was almostadditive in the ease of M\(_4\) (striatum) binding sites. In the ease ofthe cardiac M\(_2\), pancreatic M\(_3\) , or NB-OK 1 M\(_1\) receptors the respective binding free energies were not eompletely additive. These results suggest that the four (R)-hexahydro-difenidol ''binding moieties" (phenyl, cyclohexyl, hydroxy, and protonated amino group) cannot simultaneously form optimal interaetions with the M\(_1\), M\(_2\), and M\(_3\) muscarinic receptors. When eaeh of the hydrophobic groups is modified, the position of the whole molecule, relative to the four subsites, was changed to allow an optimal overall interaction with the musearlnie receptor. KW - Anorganische Chemie KW - hexahydro-difenidol enantiomers KW - muscarinic receptor subtypes KW - stereoselective interaction KW - difenidol KW - dicyclidol Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64135 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Lambrecht, G. A1 - Mutschler, E. A1 - Tacke, Reinhold A1 - Christophe, J. T1 - Stereoselectivity of procyclidine binding to muscarinic receptor subtypes M\(_1\), M\(_2\) and M\(_4\) N2 - The goals of the present study were: (1) to investigate thc binding properlies oi (R)- and (S)-procyclidine and two aehiral derivatives of muscarinic M\(_1\)• M\(_2\) and M\(_4\) receptor subtypes and (2) to identify the interaetions which allow these receptors to diseriminate between the two stereoisomers. (R)-Procyclidine showed a higher affinity for human neuroblastoma NB-OK 1 muscarinie M\(_1\) and rat striatum musearinie M\(_4\) receptors. a~ compared to rat cardiac M\(_2\) receptors. (S)-Procyclidine had a 130-iold lower affinity than (R)-procyclidine for M\(_1\) and M\(_4\) receptors. and a 40-fold lower affinity for M\(_2\) receptors. Pyrrinol. the aehiral diphenyl derivative with the eyclohexyl g.roup of (S}-procyclidine replaeed by a phenyl group, has an eight-fold lower affinity for M\(_1\) and M\(_4\) receptors. as eompared to (R)-procyclidine, and a three-fold lower affinity for M\(_2\) receptors. Hexahydro-procyclidine. the eorresponding achiral dicyclohexyl compound, had a 10- to 20-fold lower affinity than (R)-procyclidine for the three reeeptors. The inerease in binding free energy, which is observed when the phenyl and eyclohexyl groups of procyelidine are separately replaeed by cyclohexyJ and phenyl groups, respectively. was additive in the ease of M\(_1\)• M\(_2\) and M\(_4\) receptcrs. This indicates that the musearinic reeeptor s!ereoseleetivity was based on the eoexistence of two binding sites, one preferring a phenylrather than eyclohexyl group and the seeond preferring a cyclohexyl rather than a phenyl group. In addition. there were aiso binding sites for the hydroxy moiety and the protonated amino group of the ligands. The greater affinity and stereoselectivity of M\(_1\) and M\(_4\) muscarinic receptors for (R)-procyelidine reflected the better fit of the eyclohexyl group of (R)-procyclidine to the subsite of M\(_1\) and M\(_4\) as compared to M\(_2\) receptors. KW - Anorganische Chemie KW - Musearlnie M1 KW - receptors KW - Muscarinie M2 receptors KW - Musearinic M4 receptors KW - Pyrrinol KW - Hexahydro-procyclidine KW - Muscarinic receptors Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64034 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Lambrecht, G. A1 - Mutschler, E. A1 - Kropfgans, M. A1 - Sperlich, J. A1 - Wiesenberger, F. A1 - Tacke, R. A1 - Christophe, J. T1 - Thermodynamics of antagonist binding to rat muscarinic \(M_2\) receptors: antimuscarinics of the pridinol, sila-pridinol, diphenidol and sila-diphenidol type JF - British Journal of Pharmacology N2 - 1 We studied the effect of temperature on the binding to rat heart \(M_2\) muscarinic receptors of antagonists related to the carbon/silicon pairs pridinol/sila-pridinol and diphenidol/sila-diphenidol (including three germanium compounds) and six structurally related pairs of enantiomers [(R)- and (S)-procyclidine, (R)- and (S)-trihexyphenidyl, (R)- and (S)-tricyclamol, (R)- and (S)-trihexyphenidyl methiodide, (R)- and (S)-hexahydro-diphenidol and (R)- and (S)-hexbutinol]. Binding affinities were determined in competition experiments using \([^3H]\)-N-methyl-scopolamine chloride as radioligand. The reference drugs were scopolamine and N-methyl-scopolamine bromide. 2 The affinity of the antagonists either increased or decreased with temperature, van 't Hoff plots were linear in the 278–310°K temperature range. Binding of all antagonists was entropy driven. Enthalpy changes varied from large negative values (down to \(−29 kJ mol^{−1}\)) to large positive values (up to \(+ 30 kJ mol^{−1}\)). 3 (R)-configurated drugs had a 10 to 100 fold greater affinity for \(M_2\) receptors than the corresponding (S)-enantiomers. Enthalpy and entropy changes of the respective enantiomers were different but no consistent pattern was observed. 4 When silanols \((R_3SiOH)\) were compared to carbinols \((R_3COH)\), the affinity increase caused by C/Si exchange varied between 3 and 10 fold for achiral drugs but was negligible in the case of chiral drugs. Silanols induced more favourable enthalpy and less favourable entropy changes than the corresponding carbinols when binding. Organogermanium compounds \((R_4Ge)\) when compared to their silicon counterparts (R4Si) showed no significant difference in affinity as well as in enthalpy and entropy changes. 5 Exchange of a cyclohexyl by a phenyl moiety was associated with an increase or a decrease in drug affinity (depending on the absolute configuration in the case of chiral drugs) and generally also with a more favourable enthalpy change and a less favourable entropy change of drug binding. 6 Replacement of a pyrrolidino by a piperidino group and increasing the length of the alkylene chain bridging the amino group and the central carbon or silicon atom were associated with either an increase or a decrease of entropy and enthalpy changes of drug binding. However, there was no clear correlation between these structural variations and the thermodynamic effects. 7 Taken together, these results suggest that hydrogen bond-forming OH groups and, to a lesser extent, polarizable phenyl groups contribute significantly to the thermodynamics of interactions between these classes of muscarinic antagonists and \(M_2\) muscarinic receptors. KW - entropy KW - binding KW - M2 muscarinic receptors KW - thermodynamics KW - van 't Hoff plot KW - enthalpy Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128439 VL - 109 IS - 2 ER - TY - JOUR A1 - Waelbroeck, M. A1 - Camus, J. A1 - Tastenoy, M. A1 - Feifel, R. A1 - Mutschler, E. A1 - Tacke, R. A1 - Strohmann, C. A1 - Rafeiner, K. A1 - Rodrigues de Miranda, J. F. A1 - Lambrecht, G. T1 - Binding and functional properties of hexocyclium and sila-hexocyclium derivatives to muscarinic receptor suhtypes JF - British Journal of Pharmacology N2 - 1 We have compared the binding properties of several hexocyclium and sila-hexocyclium derivatives to muscarinic Ml receptors (in rat brain, human neuroblastoma (NB-OK I) cells and calf superior cervical ganglia), rat heart M2 receptors, rat pancreas M3 receptors and M4 receptors in rat striatum, with their functional antimuscarinic properties in rabbit vas deferens (Ml/M4-like), guinea-pig atria (M2), and guinea-pig ileum (M3) muscarinic receptors. 2 Si la-substitution (C/Si exchange) of hexocyclium (~ sila-hexocyclium) and demethyl-hexocyclium (~demethyl-sila-hexocyclium) did not significantly affect their affinities for muscarinic receptors. By contrast, sila-substitution of demethoxy-hexocyclium increased its affinity 2 to 3 fold for all the muscarinic receptor subtypes studied. 3 The p-fluoro- and p-chloro-derivatives of sila-hexocyclium had lower affinities than the parent compound at the four receptor subtypes, in binding and pharmacological studies. 4 In binding studies, o-methoxy-sila-hexocyclium (Ml = M4 ~ M3 ~ M2) had a much lower affinity than sila-hexocyclium for the four receptor subtypes, and discriminated the receptor subtypes more poorly than sila-hexocyclium (Ml = M3> M4> M2)' This is in marked contrast with the very clear selectivity of demethoxy-sila-hexocyclium for the prejunctional MtlM4-like heteroreceptors in rabbit vas deferens. 5 The tertiary amines demethyl-hexocyclium, demethyl-sila-hexocyclium and demethyl-o-methoxy-silahexocyclium had 10 to 30 fold lower affinities than the corresponding quaternary ammonium derivatives. KW - Hexocyclium/sila-hexocyclium derivatives KW - o-methoxy-sila-hexocyclium KW - muscarinic receptor subtypes KW - structure/ affinity relationships KW - binding/functional correlations KW - muscarinic receptor antagonists Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128265 VL - 112 ER - TY - JOUR A1 - Verspohl, E. J. A1 - Tacke, Reinhold A1 - Mutschler, E. A1 - Lambrecht, G. T1 - Muscarinic receptor subtypes in rat pancreatic islets: binding and functional studies N2 - Cholinergie agents arepotent modulators of insulin release that aet via musearinie reeeptors. We now investigated the muscarinic receptor subtype present in rat panereatic islets in binding and funetional studies. Binding of 5 nM [ \(^3\)H]N-methylscopolamine ([\(^3\)H]NMS) was half maximal at 30 min. At 60 min, the maximal total bindingwas 1.29% and the non-specifie binding (presence of 100 ,uM atropine) was 0.18% of the total radioaetivity per 10 f.'g islet protein. Unlabelled atropine inhibited [\(^3\)H]NMS binding with an IC50 of ca. 30 nM. The rank order of antagonist high-affinity binding was atropine > sila-hexocyelium methyl sulfate (SiHC; M\(_1\) > M\(_3\) > M\(_2\) ) > pirenzepine (M\(_1\)> M\(_2\) = M\(_3\) ) = methoctramine (M\(_2\) > M\(_1\) > M\(_3\) ). The high-affinity K\(_d\)s were 8.5, 56, 1300 and 1300 nM, respectively. The high affinity Kd of the muscarinie receptor agonist, arecaidine propargyl ester (APE), was 8.1 nM. The EC\(_{50}\) for the biologieal effects of APE on insulin and glucagon secretion was 3.2 and 2.3 nM. The rank order for the high-affinity biological effects of antagonists (inhibition of APE-mediated insulin/ glucagon release) was almost the same as for binding. The data indicate that rat pancreatie islets contain neither an M\(_1\) subtype (high-affinity for pirenzepine) nor an M\(_2\) subtype (high-affinity for methoctramine) receptor. However, the data evidence an M\(_3\) receptor subtype, since SiHC in the absence of the M\(_1\) receptor subtype shows a relatively high affinity to the receptors in rat panereatic islets. KW - Anorganische Chemie KW - Muscarinic receptor subtypes KW - Islets of Langerhans (rat) KW - Insulin KW - Glucagon Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63993 ER - TY - JOUR A1 - Tumir, Lidija-Marija A1 - Pavlović Saftić, Dijana A1 - Crnolatac, Ivo A1 - Ban, Željka A1 - Maslać, Matea A1 - Griesbeck, Stefanie A1 - Marder, Todd B. A1 - Piantanida, Ivo T1 - The nature of the (oligo/hetero)arene linker connecting two triarylborane cations controls fluorimetric and circular dichroism sensing of various ds-DNAs and ds-RNAs JF - Molecules N2 - A series of tetracationic bis-triarylborane dyes, differing in the aromatic linker connecting two dicationic triarylborane moieties, showed very high submicromolar affinities toward ds-DNA and ds-RNA. The linker strongly influenced the emissive properties of triarylborane cations and controlled the fluorimetric response of dyes. The fluorene-analog shows the most selective fluorescence response between AT-DNA, GC-DNA, and AU-RNA, the pyrene-analog’s emission is non-selectively enhanced by all DNA/RNA, and the dithienyl-diketopyrrolopyrrole analog’s emission is strongly quenched upon DNA/RNA binding. The emission properties of the biphenyl-analog were not applicable, but the compound showed specific induced circular dichroism (ICD) signals only for AT-sequence-containing ds-DNAs, whereas the pyrene-analog ICD signals were specific for AT-DNA with respect to GC-DNA, and also recognized AU-RNA by giving a different ICD pattern from that observed upon interaction with AT-DNA. The fluorene- and dithienyl-diketopyrrolopyrrole analogs were ICD-signal silent. Thus, fine-tuning of the aromatic linker properties connecting two triarylborane dications can be used for the dual sensing (fluorimetric and CD) of various ds-DNA/RNA secondary structures, depending on the steric properties of the DNA/RNA grooves. KW - triarylborane KW - fluorescent probe KW - circular dichroism KW - DNA recognition KW - RNA recognition Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-319322 SN - 1420-3049 VL - 28 IS - 11 ER - TY - JOUR A1 - Tinajero-Trejo, Mariana A1 - Rana, Namrata A1 - Nagel, Christoph A1 - Jesse, Helen E. A1 - Smith, Thomas W. A1 - Wareham, Lauren K. A1 - Hippler, Michael A1 - Schatzschneider, Ulrich A1 - Poole, Robert K. T1 - Antimicrobial Activity of the Manganese Photoactivated Carbon Monoxide-Releasing Molecule [Mn(CO)\(_3\)(tpa-kappa\(^3\)N)]\(^+\) Against a Pathogenic Escherichia coli that Causes Urinary Infections JF - Antioxidants & Redox Signaling N2 - Aims: We set out to investigate the antibacterial activity of a new Mn-based photoactivated carbon monoxide-releasing molecule (PhotoCORM, [Mn(CO)\(_3\)(tpa-kappa\(^3\)N)]\(^+\)) against an antibiotic-resistant uropathogenic strain (EC958) of Escherichia coli. Results: Activated PhotoCORM inhibits growth and decreases viability of E. coli EC958, but non-illuminated carbon monoxide-releasing molecule (CORM) is without effect. NADH-supported respiration rates are significantly decreased by activated PhotoCORM, mimicking the effect of dissolved CO gas. CO from the PhotoCORM binds to intracellular targets, namely respiratory oxidases in strain EC958 and a bacterial globin heterologously expressed in strain K-12. However, unlike previously characterized CORMs, the PhotoCORM is not significantly accumulated in cells, as deduced from the cellular manganese content. Activated PhotoCORM reacts avidly with hydrogen peroxide producing hydroxyl radicals; the observed peroxide-enhanced toxicity of the PhotoCORM is ameliorated by thiourea. The PhotoCORM also potentiates the effect of the antibiotic, doxycycline. Innovation: The present work investigates for the first time the antimicrobial activity of a light-activated PhotoCORM against an antibiotic-resistant pathogen. A comprehensive study of the effects of the PhotoCORM and its derivative molecules upon illumination is performed and mechanisms of toxicity of the activated PhotoCORM are investigated. Conclusion: The PhotoCORM allows a site-specific and time-controlled release of CO in bacterial cultures and has the potential to provide much needed information on the generality of CORM activities in biology. Understanding the mechanism(s) of activated PhotoCORM toxicity will be key in exploring the potential of this and similar compounds as antimicrobial agents, perhaps in combinatorial therapies with other agents. KW - intracellular hydrogen-peroxide KW - campylobacter-jejuni KW - oxygen-metabolism KW - deficient mutant KW - oxidative stress KW - aqueous-solution KW - metal caponyls KW - RU(CO)(3)CL(GLYCINATE) KW - bacteria KW - enzyme Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188910 VL - 24 IS - 14 ER - TY - JOUR A1 - Thiess, Torsten A1 - Mellerup, Soren K. A1 - Braunschweig, Holger T1 - B–B Cleavage and Ring-Expansion of a 1,4,2,3-Diazadiborinine with N-Heterocyclic Carbenes JF - Chemistry - A European Journal N2 - A 1,4,2,3‐diazadiborinine derivative was found to form Lewis adducts with strong two‐electron donors such as N‐heterocyclic and cyclic (alkyl)(amino)carbenes. Depending on the donor, some of these Lewis pairs are thermally unstable, converting to sole B,N‐embedded products upon gentle heating. The products of these reactions, which have been fully characterized by NMR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction, were identified as B,N‐heterocycles with fused 1,5,2,4‐diazadiborepine and 1,4,2‐diazaborinine rings. Computational modelling of the reaction mechanism provides insight into the formation of these unique structures, suggesting that a series of B−H, C−N, and B−B bond activation steps are responsible for these “intercalation” reactions between the 1,4,2,3‐diazadiborinine and NHCs. KW - B,N-heterocylcles KW - B-B bond activation KW - diazadiborinines KW - NHCs KW - ring-expansion reactions Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-206173 VL - 25 IS - 59 ER - TY - JOUR A1 - Thiess, Torsten A1 - Ernst, Moritz A1 - Kupfer, Thomas A1 - Braunschweig, Holger T1 - Facile Access to Substituted 1,4‐Diaza‐2,3‐Diborinines JF - Chemistry – A European Journal N2 - Several bis(dimethylamino)‐substituted 1,4‐diaza‐2,3‐diborinines (DADBs) were synthesized with variable substituents at the backbone nitrogen atoms. By reaction with HCl or BX\(_{3}\) (X=Br, I), these species were successfully converted into their synthetically more useful halide congeners. The high versatility of the generated B−X bonds in further functionalization reactions at the boron centers was demonstrated by means of salt elimination (MeLi) and commutation (NMe\(_{2}\) DADBs) reactions, thus making the DADB system a general structural motif in diborane(4) chemistry. A total of 18 DADB derivatives were characterized in the solid state by X‐ray diffraction, revealing a strong dependence of the heterocyclic bonding parameters from the exocyclic substitution pattern at boron. According to our experiments towards the realization of a Dipp‐substituted, sterically encumbered DADB, the mechanism of DADB formation proceeds via a transient four‐membered azadiboretidine intermediate that subsequently undergoes ring expansion to afford the six‐membered DADB heterocycle. KW - azadiboretidines KW - B,N-heterocycles KW - diazadiborinines KW - diboranes KW - ring expansion Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214650 VL - 26 IS - 13 SP - 2967 EP - 2972 ER - TY - JOUR A1 - Tendera, Lukas A1 - Schaub, Thomas A1 - Krahfuss, Mirjam J. A1 - Kuntze‐Fechner, Maximilian W. A1 - Radius, Udo T1 - Large vs. Small NHC Ligands in Nickel(0) Complexes: The Coordination of Olefins, Ketones and Aldehydes at [Ni(NHC)\(_{2}\)] JF - European Journal of Inorganic Chemistry N2 - Investigations concerning the reactivity of Ni(0) complexes [Ni(NHC)\(_{2}\)] of NHCs (N‐heterocyclic carbene) of different steric demand, Mes\(_{2}\)Im (= 1,3‐dimesitylimidazoline‐2‐ylidene) and iPr\(_{2}\)Im (= 1,3‐diisopropyl‐imidazoline‐2‐ylidene), with olefins, ketones and aldehydes are reported. The reaction of [Ni(Mes\(_{2}\)Im)\(_{2}\)] 1 with ethylene or methyl acrylate afforded the complexes [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐C\(_{2}\)H\(_{4}\))] 3 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐(C,C)‐H\(_{2}\)C=CHCOOMe)] 4, as it was previously reported for [Ni\(_{2}\)(iPr\(_{2}\)Im)\(_{4}\)(µ‐(η\(^{2}\):η\(^{2}\))‐COD)] 2 as a source for [Ni(iPr\(_{2}\)Im)\(_{2}\)]. In contrast to 2, complex 1 does not react with sterically more demanding olefins such as tetramethylethylene, 1,1‐diphenylethylene and cyclohexene. The reaction of [Ni(NHC)\(_{2}\)] with more π‐acidic ketones or aldehydes led to formation of complexes with side‐on η\(^{2}\)‐(C,O)‐coordinating ligands: [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH\(^{t}\)Bu)] 5, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CHPh)] 6, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CMePh)] 7, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CPh\(_{2}\))] 8, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(4‐F‐C\(_{6}\)H\(_{4}\))\(_{2}\))] 9, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(OMe)(CF\(_{3}\)))] 10 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CHPh)] 11, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(CH(CH\(_{3}\))\(_{2}\)))] 12, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(4‐NMe\(_{2}\)‐C\(_{6}\)H\(_{4}\)))] 13, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(4‐OMe‐C\(_{6}\)H\(_{4}\)))] 14, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CPh\(_{2}\))] 15 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(4‐F‐C\(_{6}\)H\(_{4}\))\(_{2}\))] 16. The reaction of 1 and 2 with these simple aldehydes and ketones does not lead to a significantly different outcome, but NHC ligand rotation is hindered for the Mes\(_{2}\)Im complexes 3, 4 and 11–16 according to NMR spectroscopy. The solid‐state structures of 3, 4, 11 and 12 reveal significantly larger C\(_{NHC}\)‐Ni‐C\(_{NHC}\) angles in the Mes\(_{2}\)Im complexes compared to the iPr\(_{2}\)Im complexes. As electron transfer in d\(^{8}\)‐ (or d\(^{10}\)‐) ML\(_{2}\) complexes to π‐acidic ligands depends on the L–M–L bite angle, the different NHCs lead thus to a different degree of electron transfer and activation of the olefin, aldehyde or ketone ligand, i.e., [Ni(iPr\(_{2}\)Im)\(_{2}\)] is the better donor to these π‐acidic ligands. Furthermore, we identified two different side products from the reaction of 1 with benzaldehyde, trans‐[Ni(Mes\(_{2}\)Im)\(_{2}\)H(OOCPh)] 17 and [Ni\(_{2}\)(Mes\(_{2}\)Im)\(_{2}\)(µ\(_{2}\)‐CO)(µ\(_{2}\)‐η\(^{2}\)‐C,O‐PhCOCOPh)] 18, which indicate that radical intermediates and electron transfer processes might be of importance in the reaction of 1 with aldehydes and ketones. KW - Nickel Complexes KW - N‐Heterocyclic Carbenes KW - NHC Complexes KW - Olefin Complexes KW - Aldehyde Complexes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-216058 VL - 2020 IS - 33 SP - 3194 EP - 3207 ER - TY - JOUR A1 - Tendera, Lukas A1 - Luff, Martin S. A1 - Krummenacher, Ivo A1 - Radius, Udo T1 - Cationic Nickel d\(^{9}\)‐Metalloradicals [Ni(NHC)\(_{2}\)]\(^{+}\) JF - European Journal of Inorganic Chemistry N2 - A series of five new homoleptic, linear nickel d\(^{9}\)‐complexes of the type [Ni\(^{I}\)(NHC)\(_{2}\)]\(^{+}\) is reported. Starting from the literature known Ni(0) complexes [Ni(Mes\(_{2}\)Im)\(_{2}\)] 1, [Ni(Mes\(_{2}\)Im\(^{H2}\))2] 2, [Ni(Dipp\(_{2}\)Im)\(_{2}\)] 3, [Ni(Dipp\(_{2}\)Im\(^{H2}\))\(_{2}\)] 4 and [Ni(cAAC\(^{Me}\))\(_{2}\)] 5 (Mes\(_{2}\)Im=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolin‐2‐ylidene, Mes\(_{2}\)Im\(^{H2}\)=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolidin‐2‐ylidene, Dipp\(_{2}\)Im=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene, Dipp\(_{2}\)Im\(^{H2}\)=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolidin‐2‐ylidene, cAAC\(^{Me}\)=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐yliden), their oxidized Ni(I) analogues [Ni\(^{I}\)(Mes\(_{2}\)Im)\(_{2}\)][BPh\(_{4}\)] 1\(^{+}\), [Ni\(^{I}\)(Mes\(_{2}\)Im\(^{H2}\))\(_{2}\)][BPh\(_{4}\)] 2\(^{+}\), [Ni\(^{I}\)(Dipp\(_{2}\)Im)\(_{2}\)][BPh\(_{4}\)] 3\(^{+}\), [Ni\(^{I}\)(Dipp\(_{2}\)Im\(^{H2}\))\(_{2}\)][BPh\(_{4}\)] 4\(^{+}\) and [Ni\(^{I}\)(cAAC\(^{Me}\))\(_{2}\)][BPh\(_{4}\)] 5\(^{+}\) were synthesized by one‐electron oxidation with ferrocenium tetraphenyl‐borate. The complexes 1\(^{+}\)–5\(^{+}\) were fully characterized including X‐ray structure analysis. The complex cations reveal linear geometries in the solid state and NMR spectra with extremely broad, paramagnetically shifted resonances. DFT calculations predicted an orbitally degenerate ground state leading to large magnetic anisotropy, which was verified by EPR measurements in solution and on solid samples. The magnetic anisotropy of the complexes is highly dependent from the steric protection of the metal atom, which results in a noticeable decrease of the g‐tensor anisotropy for the N‐Mes substituted complexes 1\(^{+}\) and 2\(^{+}\) in solution due to the formation of T‐shaped THF adducts. KW - Alkyl(amino)carbene KW - EPR spectroscopy KW - Metalloradicals KW - Nickel ComplexCyclic Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-293702 VL - 2022 IS - 31 ER - TY - JOUR A1 - Tendera, Lukas A1 - Helm, Moritz A1 - Krahfuss, Mirjam A1 - Kuntze-Fechner, Maximilian W. A1 - Radius, Udo T1 - Case Study of N-\(^{i}\)Pr versus N-Mes Substituted NHC Ligands in Nickel Chemistry: The Coordination and Cyclotrimerization of Alkynes at [Ni(NHC)\(_{2}\)] JF - Chemistry—A European Journal N2 - A case study on the effect of the employment of two different NHC ligands in complexes [Ni(NHC)\(_{2}\)] (NHC=\(^{i}\)Pr\(_{2}\)Im\(^{Me}\) 1\(^{Me}\), Mes\(_{2}\)Im 2) and their behavior towards alkynes is reported. The reaction of a mixture of [Ni\(_{2}\)(\(^{i}\)Pr\(_{2}\)Im\(^{Me}\))\(_{4}\)(μ-(η\(^{2}\) : η\(^{2}\))-COD)] B/ [Ni(\(^{i}\)Pr\(_{2}\)Im\(^{Me}\))\(_{2}\)(η\(^{4}\)-COD)] B’ or [Ni(Mes\(_{2}\)Im)\(_{2}\)] 2, respectively, with alkynes afforded complexes [Ni(NHC)\(_{2}\)(η\(^{2}\)-alkyne)] (NHC=\(^{i}\)Pr\(_{2}\)Im\(^{Me}\): alkyne=MeC≡CMe 3, H\(_{7}\)C\(_{3}\)C≡CC\(_{3}\)H\(_{7}\) 4, PhC≡CPh 5, MeOOCC≡CCOOMe 6, Me\(_{3}\)SiC≡CSiMe\(_{3}\) 7, PhC≡CMe 8, HC≡CC\(_{3}\)H\(_{7}\) 9, HC≡CPh 10, HC≡C(p-Tol) 11, HC≡C(4-\(^{t}\)Bu-C\(_{6}\)H\(_{4}\)) 12, HC≡CCOOMe 13; NHC=Mes\(_{2}\)Im: alkyne=MeC≡CMe 14, MeOOCC≡CCOOMe 15, PhC≡CMe 16, HC≡C(4-\(^{t}\)Bu-C\(_{6}\)H\(_{4}\)) 17, HC≡CCOOMe 18). Unusual rearrangement products 11 a and 12 a were identified for the complexes of the terminal alkynes HC≡C(p-Tol) and HC≡C(4-\(^{t}\)Bu-C\(_{6}\)H\(_{4}\)), 11 and 12, which were formed by addition of a C−H bond of one of the NHC N-\(^{i}\)Pr methyl groups to the C≡C triple bond of the coordinated alkyne. Complex 2 catalyzes the cyclotrimerization of 2-butyne, 4-octyne, diphenylacetylene, dimethyl acetylendicarboxylate, 1-pentyne, phenylacetylene and methyl propiolate at ambient conditions, whereas 1\(^{Me}\) is not a good catalyst. The reaction of 2 with 2-butyne was monitored in some detail, which led to a mechanistic proposal for the cyclotrimerization at [Ni(NHC)\(_{2}\)]. DFT calculations reveal that the differences between 1\(^{Me}\) and 2 for alkyne cyclotrimerization lie in the energy profile of the initiation steps, which is very shallow for 2, and each step is associated with only a moderate energy change. The higher stability of 3 compared to 14 is attributed to a better electron transfer from the NHC to the metal to the alkyne ligand for the N-alkyl substituted NHC, to enhanced Ni-alkyne backbonding due to a smaller C\(_{NHC}\)−Ni−C\(_{NHC}\) bite angle, and to less steric repulsion of the smaller NHC \(^{i}\)Pr\(_{2}\)Im\(^{Me}\). KW - nickel complexes KW - cyclooligomerization KW - cyclotrimerization KW - alkyne complexes KW - N-heterocyclic carbenes Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257137 VL - 27 IS - 71 ER - TY - JOUR A1 - Tanini, Damiano A1 - Pecchi, Tommaso A1 - Ignat’ev, Nikolai V. A1 - Capperucci, Antonella T1 - Ionic liquids-assisted ring opening of three-membered heterocycles with thio- and seleno-silanes JF - Catalysts N2 - Ring opening reactions of strained heterocycles (epoxides, aziridines, thiiranes) by silyl chalcogenides, such as thiosilanes and selenosilanes, can be efficiently performed in a variety of ionic liquids, which can behave as reaction media and in some cases also as catalysts. This protocol enables an alternative access to β-functionalized sulfides and selenides under mild conditions. KW - ring opening reactions KW - ionic liquids KW - silyl sulfides KW - silyl selenides KW - thiolysis KW - selenolysis Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-290350 SN - 2073-4344 VL - 12 IS - 10 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Wuttke, F. A1 - Henke, H. T1 - Zur Stereochemie der mikrobiellen Reduktion von rac-Acetyl( t-butyl)methylphenylsilan mit Trigonopsis variabilis (DSM 70714) und Corynebacterium dioxydans (ATCC 21766): Aufklärung der absoluten Konfiguration der Biotransformationsprodukte (SiR,CR)- und ( SiS ,CR)-t-Butyl( 1-hydroxyethyl)methylphenylsilan N2 - No abstract available KW - Anorganische Chemie Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64176 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Wagner, S. A. A1 - Brakmann, S. A1 - Wuttke, F. A1 - Eilert, U. A1 - Fischer, L. A1 - Syldatk, C. T1 - Synthesis of acetyldimethyl(phenyl)silane and its enantioselective conversion into (R)-(1-hydroxyethyl)dimethyl(phenyl)silane by plant cell suspension culytures of Symphytum officinale L. and Ruta graveolens L. N2 - Starting from chlorodimethyl(phenyl)silane (3), acetyldimethyl(phenyl)silane (l) was prepared by a two-step synthesis in a total yield of 90% [PhMe\(_2\)SiCl (3)-> PhMe\(_2\)SiCCOMe)=CH\(_2\) (4)-> PhMe\(_2\)SiC(O)Me (1)]. The prochiral acetylsilane 1 was transfonned enantioselectively into (R)-(1-hydroxyethyl)dimethyl(phenyl)silane [(R)-2] using plant cell Suspension cultures of Symphytum officinale L. or Ruta graveolens L. Under preparative conditions (300-mg scale, not optimized), (R)-2 was isolated in 15% (Symphytum) and 9% yield (Ruta), respectively. The enantiomeric purities of the products were 81% ee (Syrnphytum) and 60% ee (Ruta), respectively. KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64299 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Strohmann, C. A1 - Sarge, S. A1 - Cammenga, H. K. A1 - Schomburg, D. A1 - Mutschler, E. A1 - Lambrecht, G. T1 - Darstellung und Eigenschaften der Enantiomere des selektiven Antimuscarinikums 1-Cyclohexyl-1-phenyl-4-piperidino-1-butanol (Hexahydro-Difenidol) N2 - No abstract available KW - Anorganische Chemie KW - Difenidol KW - (R)- and (S)-hexahydro- / Antimuscarinic properties / Muscarinic receptor subtypes Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63950 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Sperlich, J. A1 - Becker, B. T1 - Bis[2,3-naphthalenediolato(2-)](pyrrolidinio-methyl)germanate-tetartoacetonitrile, the first zwitterionic \(\lambda_5\)-germanate: synthesis and crystal structure analysis N2 - The zwitterionic spirocyclic \(\lambda_5\)-germanate bis(2,3-naphthalenediolato( 2-)](pyrrolidiniomethyl)germanate (8) was synthesized and the crystal structure of its tetartoacetonitrile solvate 8 · 1/4 CH\(_3\)CN studied by single-crystal X-ray diffraction. Compound 8 was prepared by reaction of (MeO)\(_3\)GeCH\(_2\)NC\(_4\)H\(_8\) (11; NC\(_4\)H\(_8\) = pyrrolidino) with two equivalents of 2,3-naphthalenediol (isolated as 8 · 1/4 CH\(_3\)CN; yield 92%). The coordination polyhedron around the pentacoordi- naphthalenediolatonate germanium atom of 8 · 1/4 CH\(_3\)CN can be described as a strongly distorted trigonal bipyramid (the structure is displaced by 38.9% from the ideal trigonal bipyrarnid towards the ideal square pyramid), the carbon atom occupying an equatorial position. In the crystal lattice of 8 · 1/4 CH\(_3\)CN, the zwitterions form intermolecular N-H ... o hydrogen bonds leading to the formation of dimers. 1H- and \(^{13}\C-NMR studies revealed that 8 also exists in solution ([D\(_6\)]DMSO). KW - Anorganische Chemie KW - Lambda5-Germanate KW - zwitterionic KW - Germanium KW - pentacoordinate Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64329 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Saad, S. M. T1 - Silylation of cellulose N2 - Ethane-l:2-diol and propane-l:3-diol reaet with 1: 1:3:3-tetramethyl-l:3-dichlorodisiloxane forming the corresponding rings. However, no ring compounds could be traced tbrough the reaction between butane-l :4-diol, glycerol and the dichlorodisiloxane respectively, where only polymeric compounds are formed. The silylation products of the di- and trihydroxy alcohols, as model compounds, has confirmed that the ring formation during silylation of cellulose with dichlorodisiloxane is uncertain. KW - Anorganische Chemie Y1 - 1977 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-78368 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Rafeiner, K. A1 - Strohmann, C. A1 - Mutschler, E. A1 - Lambrecht, G. T1 - Synthesis of the selective antimuscarinic agent 4-{[cyclohexylhydroxy(2-methoxyphenyl)silyl]methyl}-1,1-dimethylpiperazinium methyl sulfate (o-methoxy-sila-hexocyclium methyl sulfate) N2 - The synthesis of the potent and highly selective silicon-containing antimuscarinic agent o-methoxysila- hexocyclium methyl sulfate and its corresponding tertiary amine (isolated as the dihydrochloride) is described. The quarternary compound is an omethoxy derivative of sila-hexocyclium methyl sulfate, which represents one of the tools currently used in experimental pharmacology for the subclassification of muscarinic receptors. The omethoxy derivative, the pharmacological profile of which differs substantially from tbat of the nonmethoxy compound, is also recommended as a tool for the investigation of muscarinic receptor heterogeneity. KW - Anorganische Chemie KW - o-methoxy-sila-hexocyclium KW - silahexocyclium KW - sila-drugs KW - antimuscarinics KW - muscarinic receptor subtypes Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63930 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Pikies, J. A1 - Wiesenberger, F. A1 - Ernst, L. A1 - Schomburg, D. A1 - Waelbroeck, M. A1 - Christophe, J. A1 - Lambrecht, G. A1 - Gross, J. A1 - Mutschler, E. T1 - Sila-biperiden und endo-Sila-biperiden: Synthesen, Kristallstrukturen und antimuscarinische Eigenschaften N2 - Starting from trichloro(vinyl)silane (Cl\(_3\)SiCH=CH\(_2\)), the musearinic antagonists sila-biperiden [rac-(SiRS,C2SR>-ao-2] and endosila- biperiden [rac-(SiRS,C2SR)-endo-2] were prepared by a seven-step synthesis. Both silanols are configurationally stableininert organic solvents but undergo slow epimerization in aqueous solution (pH 7.4, 32°C) by inversion of the configuration at the silicon atom. The relative configurations of sila-biperiden and endo-sila-biperiden were detennined by single-crystal X-ray diffraction. Both compounds form intennolecular 0-H · · · N hydrogen bonds in the crystal leading to the fonnation of centrosymmetric dimers (sila-biperiden) and infinite chains (endo-sila-biperiden), respectively. Sila-biperiden is a silicon analogue (C/Si exchange) of the antiparkinsonian drug biperiden [rac-(CRS/C2SR}-exo-1]. In functional phannacological experiments, as well as in radioligand competition studies, biperiden, sila-biperiden and endo-sila-biperiden behaved as simple competitive antagonists at muscarinic Ml-, M2-, M3- and M4-receptors. The three compounds displayed the highest affinity for Ml-receptors (pA\(_2\) values: 8.72-8.80; pK\(_i\) values: 8.8-9.1), intermediate affinity for M4- and M3-receptors, and lowest affinity for M2-receptors (pA\(_2\) values: 7.57-7.79; pK\(_i\) values: 7.7-7.8). The affinity profile (Ml >. M4 > M3 > M2) of biperiden, sila-biperiden and endo-sila-biperiden is qualitatively similar to that of the M1-selective muscarinic antagonist pirenzepine. The antimuscarinic properlies of the C/Si analogues biperiden and sila-biperiden are almost identical. N2 - Die Antimuscarinica Sila-biperiden [rac-(SiRS,C2SR)-exo-2] und endo-Sila-biperiden [rac-(SiRS,C2SR)-endo-2] wurden ausgehend von Trichlor(vinyl)silan (Cl\(_3\)SiCH=CH\(_2\)) durch eine siebenstufige Synthese dargestellt. Die beiden Silanoie sind in inerten organischen Solvenzien konfigurationsstabil, unterliegen aber in wässeriger Lösung (pH 7.4, 3ZOC) einer Epimerisierung durch Inversion der Konfiguration am Silicium-Atom. Die relativen Konfigurationen von Sila-biperiden und endo-Sila-biperiden wurden durch Einkristall-Röntgenstrukturanalysen bestimmt. Beide Verbindungen bilden im Kristall intermolekulare 0-H · · · N-Wasserstoff- Brückenbindungen aus, die zum Aufbau von zentrosymmetrischen Dimeren (Sila-biperiden) bzw. unendlichen Ketten (endo-Sila-biperiden) führen. Sila-biperiden ist ein Silicium-Analogon (C/Si-Austausch) des Antiparkinsonmittels Biperiden [rac-(CRS,C2SR>-ao-1). Sowohl in funktionellen pharmakologischen Untersuchungen als auch in Radioligand-Kompetitionsexperimenten erwiesen sich Biperiden, Sila-biperiden und endo-Sila-biperiden als rein kompetitive Antagonisten an muscarinischen M1-, M2-, M3- und M4-Rezeptoren. Alle drei Verbindungen zeigten die höchste Affinität zu den Mt-Rezeptoren (pA\(_2\)-Werte: 8.72-8.80; pKrWerte: 8.8-9.1), eine deutlich geringere Affinität zu den M4- und M3-Rezeptoren und die niedrigste Affinität zu den kardialen M2-Rezeptoren (pA\(_2\)-Werte: 7.57-7.79; pKi-Werte: 7.7-7.8). Das Affinitätsprofil (Ml > M4 > M3 > M2) von Biperiden, Sila-biperiden und endo-Sila-biperiden ist dem des Mt-selektiven Antimuscarinicums Pirenzepin qualitativ sehr ähnlich. Die antimuscarinischen Eigenschaften der C/Si-Analoga Biperiden und Sila-biperiden sind nahezu identisch. KW - Anorganische Chemie KW - Silicon KW - Silanol KW - Sila-biperiden KW - Bioorganosilicon chemistry KW - Muscarinic antagonist KW - Muscarinic receptor subtype Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64303 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Mühleisen, M. A1 - Jones, P. G. T1 - The first zwitterionic, optically active disilicate with pentacoordinate silicon N2 - No abstract available KW - Anorganische Chemie Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64358 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Mühleisen, M. T1 - Bis[benzilato(2-)-O\(^1\),O\(^2\)][2-(dimethylammonio)ethoxy]silicate: synthesis and structural characterization of a zwitterionic \(\lambda^5\)Si-silicate with a SiO\(_5\) framework N2 - No abstract available KW - Anorganische Chemie Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64400 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Mühleisen, M. T1 - Hexacoordinate silicon in a compound with an F\(_5\)SiC unit N2 - No abstract available KW - Anorganische Chemie Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64378 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Mahner, K. A1 - Strohmann, C. A1 - Forth, B. A1 - Mutschler, E. A1 - Friebe, T. A1 - Lambrecht, G. T1 - Cyclohexyl(4-fluorophenyl)(3-piperidinopropyl)silanol (p-fluoro-hexahydro-sila-difenidol, p-F-HHSiD) and derivatives: synthesis and antimuscarinic properties N2 - Four different syntheses of the potent and selective muscanruc antagonist cyclohexyl( 4- fluorophenyl)(3-piperidinopropyl)silanol ( p-fluoro-hexahydro-sila-difenidol, p-F-HHSiD (2b); isolated as hydrochloride 2b· HCl) are described (starting materials: (CH\(_3\)O)\(_2\)SiCH\(_2\)CH\(_2\)CH\(_2\)Cl and Si(OCH\(_3\))\(_4\) ). In addition, the synthesis of the corresponding carbon analogue p-fluoro-hexahydro-difenidol ( p-F-HHD (2a); isolated as 2a· HCI) and the syntheses of three p-F-HHSiD derivatives (3-5), with a modified cyclic amino group, are reported (3: piperidinojpyrrolidino exchange, isolated as 3· HCI; 4: piperidinoj hexamethylenimino exchange, isolated as 4 · HCl; 5: quaternization of 2b with methyl iodide). The chiral compounds 2a, 2b, 3, 4 and 5 were prepared as racemates. In functional pharmacological studies, 3-5 behaved as simple competitive antagonists at musearlnie Ml receptors in rabbit vas deferens, M2 receptors in guinea-pig atria, and M3 receptors in guinea-pig ileal smooth rnuscle. The pyrrolidino (3) and hexamethylenimino (4) analogues of the parent drug p-F-HHSiD (2b) displayed the highest affinity for Ml and M3 receptors (pA\(_2\) values: 7.0-7.4) but exhibited lower affinity for cardiac M2 receptors (pA\(_2\) : 5.9 and 6.0). Their affinity profile (Ml- M3 > M2) is different from that of p-F-HHSiD (2b) (M3 > Ml > M2), but qualitatively very similar tothat of p-F-HHD (2a). The methiodide 5 exhibited the highest affinity for Ml receptors (pA\(_2\) : 8.5) but lower affinity for M2 and M3 receptors by factors of 5.6 and 3.6, respectively. KW - Anorganische Chemie Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64162 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Lopez-Mras, A. A1 - Jones, P. G. T1 - Syntheses, crystal structure analyses, and NMR studies of [2-(dimethylammonio)phenyl]bis[glycolato(2-)-O1,O2]silicate and related zwitterionic spirocyclic \(\lambda_5\)Si-silicates N2 - No abstract available KW - Anorganische Chemie Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64339 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Hengelsberg, H. A1 - Zilch, H. A1 - Stumpf, B. T1 - Enantioselective microbial reduction of 1,1-dimethyl-1-sila-cyclohexan-2-one with growing cells of the yeast Kloeckera corticis (ATCC 20109) N2 - (R)-1,1-Dimethyl-1-sila-cyclohexan-2-ol [(R)-2] was prepared by enantioselective microbial reduction of 1,1-dimethyl-1-sila-cyclohexan-2-one (1) with growing cells of the yeast Kloeckera corticis (ATCC 20109). At a substrate concentration of 0.5 g/1 (temperature 27° C, incubation time 16 h), (R}-2 was obtained on a preparative scale in 60% yield and with an enantiomeric purity of 92% ee. Repeated recrystallization of the biotransformation product from n-hexane raised the enantiomeric purity to 99% ee. KW - Anorganische Chemie Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64010 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Brakmann, S. A1 - Wuttke, F. A1 - Fooladi, J. A1 - Syldatk, C. A1 - Schomburg, D. T1 - Stereoselective microbial reduction of racemic acetyl(t-butyl)methylphenylsilane by Trigonopsis variabilis (DSM 70714) and Corynebacterium dioxydans (ATCC 21766) N2 - (SiR,CR)- and (SiS,CR)-t-butyl(l-hydroxyethyl)methylphenylsilane [(SiR,CR)-2 and (SiS,CR)-3] have been prepared by (R)-selective microbial rcduction of racemic acetyl(t-butyl)methylphenylsilane (rac-1) using resting free cells of the yeast Trigonopsis variabilis (DSM 70714) or the bacterium Corynebacterium dioxydans (ATCC 21766). The biotransfonnations were carried out on a 10 g scale. Afterseparation by column chromatography on silica gel, the optically active diastereomers (SiR,CR)-2 and (SiS,CR)-3 produccd by T. variabilis were obtained in good yields [74% ((SiR,CR)-2). 78% ((SiS,CR)-3)]. The products obtained from the reduction with C. dioxydans were isolated in significantly lower yields [20% ((SiR,CR)-2), 20% ((SiS,CR)-3)]; reaction conditions not optimized). Both bioconversions gave products with high enantiomeric purities (T. variabilis: 91% ee ((SiR,CR)-2), 96% ee ((SiS,CR)-3); C. dioxydons: ~ 991 ee ((SiR,CR)-l), ~ 99% ee ((SiS,CR)-3)). To throw light on the stereochemical aspects of these biotransfonnations, an X-ray diffraction study was carried out on the 3,5-dinitrobenzoate of rac-(SiR,CS/SiS,CR)-3. In addition, 1H NMR spectroscopic stereochemical correlation studies were performed with the (S)-MTPA esters derived from (SiR,CR)-l, (SiS,CR)-3, rac-(SiR,CRjSiS,CS)-2 and rac-(SiR,CSjSiS,CR)-3 [rac-(SiR,CR/ SiS,CS)-2 and rac-(SiR,CS/SiS,CR)-3 were obtained by reduction of rac-1 with LiAIH\(_4\) in diethylether, followed by chromatographic separation of the diastereomers on silica gel]. These stereochemical studies allowed assignment of the absolute configurations and enantiomeric purities of the biotransformation products. KW - Anorganische Chemie Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64109 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Bentlage, Anke A1 - Towart, Robertson A1 - Möller, Eike T1 - Sila-pharmaca, XXV. Sila-analogues of nifedipine-like dialkyl 2,6-dimethyl-4-aryl-1,4 dihydropyridine-3,5-dicarboxylates, III N2 - IS neue C/Si-Analogenpaare (C-Verbindungen und sila- bzw. disila-substituierte Derivate), die sich strukturell vom Nifedipin ableiten, wurden synthetisiert. Diese und einige weitere C/Si-Paare wurden hinsichtlich ihrer physikochemischen und pharmakologischen Eigenschaften vergleichend untersucht. Mittels reversed-phase-Dünnschichtchromatographie wurde gezeigt, daß die Sila- bzw. Disila-Analoga lipophiler sind als die entsprechenden C-Verbindungen. Bezüglich der spasmolytischen in vitra-Aktivitäten zeigen die Si-Verbindungen in erster Näherung ähnliche Struktur-Wirkungs-Beziehungen wie ihre Carba-Analoga. Dagegen konnten hinsichtlich der ill vlva-Effekte (cardiovasculäre und antihypertensive Aktivität) in einigen Fällen große Unterschiede nachgewiesen werden. N2 - 15 new C/Si-analogue pairs (C-compounds and sila- or disila-substituted derivatives, respectively), which are structurally related to nifedipine, have been synthesized. These and some further C/Si-pairs have been investigated comparatively with respect to their physicochemical and pharmacological properties. Using reversed-phase thin-layer chromatography it was shown that both the sila- and disila-analogues are more Iipophilic than the corresponding C-compounds. With respect to the in vitra spasmolytic potencies the Si-compounds show approximately similar structure-activity relationships to their carba-analogues. However, in some cases marked differences in in vivo effects (cardiovascular and antihypertensive activity) could be demonstrated. KW - Anorganische Chemie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-78357 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Becker, B. A1 - Berg, D. A1 - Brandes, W. A1 - Dutzmann, S. A1 - Schaller, S. T1 - Bis(4-fluorophenyl)methyl(1H-1,2,4-triazol-1-yl-methyl)germane, a germanium analogue of the agricultural fungicide flusilazole: synthesis and biological properties N2 - Bis( 4-fluorophenyl)methyl(l H-1,2,4-triazol-1-yl-methyl)germane (2), a germanium analogue of the agricultural fungicide flusilazole (1), has been synthesized from Cl\(_3\)GeCH\(_2\)CI (3) by both a three-step and a four-step synthesis (3-> (p-F-C\(_6\)H\(_4\))\(_2\)Ge(CH\(_2\)Cl)Br (4)-> (p-F-C\(_6\)H\(_4\))\(_2\)Ge(CH\(_2\)CI)CH\(_3\) (S)-> 2; S ~ (p-F-C\(_6\)H\(_4\))\(_2\)Ge(CH\(_2\)I)CH\(_3\) (6)-> l). The fungicidal properties of l have been compared with those of the parent silicon compound 1 (studies on Si/Ge bioisosterism). In various test systems, the SijGe analogues 1 and 2 showed comparable fungicidal properlies (in activity against plant pathogenic fungi: in agar plate diffusion tests and greenhause evaluations; in activity against human pathogenic fungi: in serial dilution tests). In addition, 1 and 2 displayed comparable potencies in respect of sterol biosynthesis inhibition in Sacclulromycopsis üpolytica and Pyricularia oryzae, the mode of action being primarily an inhtbition of oxidative C14-demethylation. KW - Anorganische Chemie Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64224 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Becht, J. A1 - Lopez-Mras, A. A1 - Sheldrick, W. S. A1 - Sebald, A. T1 - Syntheses, X-ray crystal structure analyses, and solid-state NMR studies of some zwitterionic organofluorosilicates N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64272 ER - TY - JOUR A1 - Syldatk, C. A1 - Stoffregen, A. A1 - Wuttke, F. A1 - Tacke, Reinhold T1 - Enantioselective reduction of acetyldimethylphenylsilane: a screening with thirty strains of microorganisms N2 - Thirty strains of microorganisms (bacteria, yeasts, fungi and green algae) were tested as resting free cells for their ability to transform acetyldimethylphenylsilane (1) enantioselectively into (R)-(1-hydroxyethyl) dimethylphenylsilane [(R)-2]. The biotransformations were monitared by GC (packed OV-17 column), and the enantiomeric purities of the products isolated were determined by HPLC (cellulose triacetate column, UV detection). All microorganisms tested were found to reduce 1 enantioselectively to give (R)-2. Under the test conditions used, the yeast Trigonapsis variabilis (DSM 70714) was found to 1 exhibif the highest specific activity (1.5 mg product x g cell wet mass\(^{-1}\) x min\(^{-1}\) ), whereas the highest enantioselectivities were observed for the bacteria Acinetobacter ca lcoaceticus (ATCC 31012) (>95% ee), Brevfbacterium species (ATCC 21860) (90% ee) and Corynebacterium dioxydans (ATCC 21766) (>95% ee), the yeast Candida humico la (OSM 70067) (90% ee), the fungus Cunninghame lla e legans (ATCC 26269) (94% ee), as well as the cyanobacterium Synechococcus leopoliensis (94% ee).· From the green algae tested, Chlamydomonas reinhardii showed the highest.enantioselectivity (85% ee). KW - Anorganische Chemie Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63906 ER - TY - JOUR A1 - Syldatk, C. A1 - Andree, H. A1 - Stoffregen, A. A1 - Wagner, F. A1 - Stumpf, B. A1 - Ernst, L. A1 - Zilch, H. A1 - Tacke, Reinhold T1 - Enantioselective reduction of acetyldimethylphenylsilane by Trigonopsis variabilis (DSM 70714) N2 - Growing and resting cells of the yeast Trigonapsis variabilis (DSM 70714) can be used for the enantioselective reduction of the organosilicon compound acetyldimethylphenylsilane (J) to give optically active (R)-(1-hydroxyethyl)dimethylphenylsilane [(R)-2] in good yields. The enantiomeric purity of the isolated product was determined tobe 62-86% ee depending on the substrate concentration used. Both substrate and product caused an inhibition of the reaction at concentrations higher than 0.35 and 0.5 g/1, respectively. Besides, higher substrate and product concentrations led to increased formation of the by-product 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane. Considering the limiting substrate and product concentrations, it was possible to use the same biomass at least 5 times without significant loss of enzyme activity. 3-Methyl-3-phenyl-2-butanone (5) and acetyldimethylphenylgermane (7), which represent carbon and germanium analogues of 1, were also found to be accepted as substrates by Trigonapsis variabilis (DSM 70714). The reduction rates of the silicon {1) and germanium compound {7) were much higher than the transformation rate of the corresponding carbon analogue 5. KW - Anorganische Chemie Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63836 ER -