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 - Sperlich, Jörg A1 - Becht, Joachim A1 - Mühleisen, Mathias A1 - Wagner, Stephan A. A1 - Mattern, Günter A1 - Tacke, Reinhold T1 - Zwitterionische Bis[vic-arendiolato(2-)][(morpholinio)alkyl]silicate: Synthese sowie strukturelle Charakterisierung in Lösung und im Kristall N2 - No abstract available. KW - Silicate KW - Bis[1,2-benzendiolato(2-)][(morpholinio)alkyl]silicates KW - Bis[2,3-naphthalenediolato(2-)][(morpholinio)alkyl]silicates KW - Zwitterionic [lambda]5-Spirosilicates Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-73153 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 - Eltze, M. A1 - Ullrich, B. A1 - Mutschler, E. A1 - Moser, U. A1 - Bungardt, E. A1 - Friebe, T. A1 - Gubitz, C. A1 - Tacke, Reinhold A1 - Lambrecht, G. T1 - Characterization of muscarinic receptors mediating vasodilation in rat perfused kidney N2 - The muscarinic receptor mediating vasodilation of resistance vessels in the rat isolated, constant-pressure perfused kidney (preconstriction by w- 7 M cirazoline) was characterized by subtype-preferring agonists and se]ective antagonists. The agonists produced vasodi1ation with the fol1owing rank order of potency: arecaidine propargy] ester (APE) > 5-methylfurtrethonium = methacholine = oxotremorine > (S)-aceclidine > arecaidine 2-butyne-1,4-diyl bisester > 4-Cl-McN-A-343 = (R)-nipecotic acid ethyl ester = N-ethyl-guvacine propargyl ester- (R)-aceclidine = (S)-nipecotic acid ethyl ester > McN-A-343. Agonist-induced vasodilation disappeared after destruction of the endothelium with detergent. Highly significant correlations of agonist potencies for vasodilation were found between rat kidney and guinea-pig ileum submucosal arterioles as weH as agonist potencies at smooth muscle muscarinic M\(_3\) receptors of the guinea-pig ileum. The rank order of antagonist potencies (4-diphenylacetoxy-Nmethylpiperidine methiodide (4-DAMP) > (R)-hexahydro-difenidol - hexahydro-sila-difenidol > pirenzepine - p-fluorohexahydro- sila-difenidol- himbacine- AF-DX 384- AQ-RA 741 > (S)-hexahydro-difenidol) to attenuate vasodilation to APE in rat kidney, correlated significantly with affinities at M\(_3\) receptors in submucosal arterioles and in smooth muscle of the guinea-pig ileum, but differed from those at M\(_1\) and M\(_2\) receptors in rabbit vas deferens. The agonist and antagonist potencies suggest that vasodilation elicited by muscarinic stimuli in endothelium-intact rat renal vasculature is mediated by functional muscarinic M\(_3\) receptors. KW - Anorganische Chemie KW - Kidney (perfused KW - rat) KW - Muscarinic receptor agonists KW - Muscarinic receptor antagonists KW - Arterioles (submucosal) KW - Ileum; Atrium KW - Vas deferens Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64283 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 - Tacke, Reinhold A1 - Lopez-Mras, A. A1 - Becht, J. A1 - Sheldrick, W. S. T1 - Synthese sowie Kristall- und Molekülstruktur von Tetrafluoro[2-(pyrrolidinio)ethyl]silicat T1 - Synthesis and Crystal and Molecular Structure of Tetrafluoro[2-(pyrrolidinio)etbyl]silicate N2 - Das zwitterionische Tctratluoro[2-(pyrrolidinio) ethyl]silicat (4) wurde durch Reaktion von Trimethoxy( 2-pyrrolidinoethyl)silan (5) mit Fluorwasserstoff in einem Ethanol/Flußsäure-Gemisch bei 0 °C synthetisiert. Die Kristall- und Molekülstruktur von 4 wurde bei - 100 °C mittels einer Einkristall-Röntgenstrukturanalyse untersucht. Außerdem wurde 4 durch NMR-Untersuchungen in Lösung charakterisiert (CD\(_3\)CN: \(^1\)H, \(^{13}\)C). N2 - The zwitterionic tetrafluoro[2-(pyrrolidinio) ethyl]silicate (4) was synthesized by reaction of trimethoxy( 2-pyrrolidinoethyl)silane (5) with hydrogen fluoride in elhanollhydrofluoric acid at 0 °C. The crystal and mo1ecular structure of 4 was studied at - 100 °C by singlc-crystal X-ray diffraction. ln addition, 4 was characterized by solution-state NMR sturlies (CD\(_3\)CN: \(^1\)H, \(^{13}\)C). KW - Anorganische Chemie KW - Zwitterionic KW - Lambda5-organofluorosilicate KW - pentacoordinate silicon KW - crystal structure Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64269 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Lopez-Mras, A. A1 - Sperlich, J. A1 - Strohmann, C. A1 - Kuhs, W. F. A1 - Mattern, G. A1 - Sebald, A. T1 - Neue zwitterionische \(\lambda_5\)-Spirosilicate: Synthesen, Einkristall-Röntgenstrukturanalysen und Festkörper-NMR-Untersuchungen T1 - New Zwitterionic \(\lambda_5\)-Spirosilicates: Syntheses, Single-Crystal X-Ray Strudure Analyses, and Solid-State NMR Studies N2 - The zwitterionic spirocyclic \(\lambda_5\) -Silicates bis(3,4,5,6-tetrabromo- 1,2-benzenediolato(2- ))[2-(pyrrolidinio)ethyl]silicate (5; and its monohydrate 5 · H\(_2\)O) and bis[1,2-benzenediolato(2- )][( dimethylammonio)methyl]silicate (6) were synthesized by various methods including Si-C bond cleavage reactions. The crystal structures of 5, 5 · H\(_2\)O, and 6 were investigated by Xray düfraction. Furthermore, 5, 5 · H\(_2\)O, 6, and the related zwitterionic \(\lambda_5\)-spirosilicates 1 · 1/4 CH\(_3\)CN, 2 · CH\(_3\)CN, 3 · CH\(_3\)CN, and 4 were characterized by solid-state NMR spectroscopy (\(^{29}\)Si and \(^{15}\)N CP/MAS). The pentacoordinate silicon atoms of 5, 5 · H\(_2\)O (two crystallographically independent ZWitterions and two crystallographically independent water molecules), and 6 (two crystallographically independent zwitterions) are surrounded by four oxygen atoms and one carbon atom. The coordination polyhedrons around the silicon atoms of 5 and 6 can be described as distorted (5) or nearly ideal (6) trigonal bipyramids, the carbon atoms being in equatorial positions. 5 forms intramolecular and 6 intermolecular (--+ formation of dimeric units) N- H···O hydrogen bonds. The coordination polyhedrons around the two crystallographically independent silicon atoms of 5 · H\(_2\)O can be described as a nearly ideal and slightly distorted square pyramid, respectively, the carbon atoms being in the apical positions. In the crystal lattice of 5 · H\(_2\)O, intermolecular N-H···O and 0-H···O hydrogen bonds between the zwitterions and water molecules are observed. The results obtained by X-ray diffraction and solid-state NMR spectroscopy are consistent for each compound studied. KW - Anorganische Chemie KW - Spirosilicates KW - zwitterionic KW - Silicon KW - pentacoordinate KW - Bond cleavage KW - Si-C I Solid-state NMR KW - 29Si and 15N Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64251 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Lopez-Mras, A. A1 - Sheldrick, W. S. A1 - Sebald, A. T1 - Synthesen, Einkristall-Röntgenstrukturanalysen und \(^{29}\)Si-Festkörper-NMR-Untersuchungen eines zwitter- ionischen \(\lambda_5\)-Spirosilicats und eines käfigartigen Octa(silasesquioxans) : [Professor Hartmut Bärnighausen zum 60. Geburtstage gewidmet] T1 - Syntheses, Single-Crystal x ... Ray Analyses and Solid-State \(^{29}\)Si NMR Studies of a Zwitterionic \(\lambda_5\)-Spirosilicate and a Cage-like Octa(silasesquioxane) N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64243 ER - TY - JOUR A1 - Kaupp, Martin A1 - Schleyer, Paul von Rague T1 - Ab Initio Study of Structures and Stabilities of Substituted Lead Compounds. Why is Inorganic Lead Chemistry Dominated by Pb\(^{II}\) but Organolead Chemistry by Pb\(^{IV}\)? N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60069 ER - TY - JOUR A1 - Lambert, Christoph A1 - Kaupp, Martin A1 - Schleyer, Paul von Rague T1 - “Inverted” Sodium-Lithium Electronegativity: Polarity and Metalation Energies of Organic and Inorganic Alkali-Metal Compounds N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60054 ER - TY - JOUR A1 - Kaupp, Martin A1 - Schleyer, Paul von Rague T1 - The Peculiar Coordination of Brium: Ab Initio Study of the Molecular and Electronic Structures of the Group 2 Dihydride Dimers M\(_2\)H\(_4\) (M=Mg, Ca, Sr, Ba) N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60048 ER - TY - JOUR A1 - Kaupp, Martin A1 - Schnering, Hans Georg von T1 - Gaseous Mercury(IV) Fluoride, HgF\(_4\): An ab Initio Study N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60038 ER - TY - JOUR A1 - Kaupp, Martin A1 - Schnering, Hans Georg von T1 - Molekulares Quecksilber(IV)-fluorid, HgF\(_4\): eine ab-initio-Untersuchung N2 - No abstract available KW - Anorganische Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60021 ER - TY - JOUR A1 - Burschka, Christian T1 - Erfahrungen mit einem Modelling-Paket T1 - Experience with a program package for molecular modeling N2 - Als Newcomer im Kreise der Anwender IIOn Molecular Modelling Software sieht man sich mit einer verwirrenden und ständig wachsenden Vielfalt von einschlägigen Programmen konfrontiert. die alle viel versprechen. Oie meisten bieten Grafik 110m Feinsten und eine beeindruckende Benutzeroberfläche. Unterschiede gibt es in der Funlctionalität, der Fehlerhäufigkeit, beim Support und natürlich im Preis. Seit ca. einem Jahr haben wir MOLEK 9000 auf einer IRIS 40351G im Einsatz. Hier ein erster Erfahrungsbericht. KW - Chemie Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-47169 ER - TY - JOUR A1 - Kaupp, Martin A1 - Zyubin, A. S. A1 - Charkin, O. P. A1 - Schleyer, P. v. R T1 - Non-Empirical Calculation of the Structure and Stability of Borohydrides of Zinc, Cadmium and Mercury of the Types MBH4 and HMBH4 N2 - No abstract available Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46339 ER - TY - JOUR A1 - Arbuznikov, Alexey V. A1 - Plakhutin, A. B. T1 - Symmetric vector coupling coefficients for atomic non-Roothaan states in the d\(^N\) configuration N2 - No abstract available Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-47062 ER - TY - JOUR A1 - Plakhutin, B. N. A1 - Arbuznikov, Alexei V. A1 - Trofimov, A. B. T1 - Coupling coefficients for systems with two open electronic shells: transition metal ions with p\(^M\)d\(^N\) configuration N2 - No abstract available Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30736 ER -