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  • 1975-1979  (27)
  • Chemistry  (23)
  • Polymer and Materials Science  (7)
  • Cell & Developmental Biology  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Conformational preferences of substituted cyclopentadienyl and heterocyclopentadienyl complexes (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1578-1590 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die konformative Präferenz in substituierten Cyclopentadienyl- und Heterocyclopentadienyl-KomplexenMO-Berechnungen ergeben erhebliche Barrieren für die internen Rotationen in Thiadiborolen-Fe(CO)3- und Diazaborolen-Cr(CO)3-Komplexen. Die Gleichgewichtsgeometrien der zwei Moleküle sollten verschieden sein. Eine MO-Fragmentanalyse erklärt diese Ergebnisse und führt darüberhinaus zu einer ganz allgemeinen Analyse der Rotationsbarrieren in Heterocyclopentadienyl- und substituierten Cyclopentadienyl-ML3- und -ML2-Komplexen. Für letztere wird ein gleitender Übergang von η5- nach η2-Koordination vorhergesagt.
    Notes: Molecular orbital calculations indicate substantial barriers to internal rotation in thiadiborolene-Fe(CO)3 and diazaborolene-Cr(CO)3 complexes. The equilibrium geometry of the two molecules should also differ. A fragment analysis explains these results and leads to a general analysis of rotational barriers in heterocyclopentadienyl and substituted cyclopentadienyl-ML3 and -ML2 complexes. In the latter an interesting “slipping” from η5 toward η2 coordination is predicted.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110439
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  • 2
    Electronic Resource
    Electronic Resource
    Cycloheptatriene and fulvene Cr(CO)3 complexes (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1591-1602 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloheptatrien- und Fulven-Cr(CO)3-KomplexeIm Tricarbonylchrom(0)-Komplex von 1,6-Methano[10]annulen und in einigen verwandten Komplexen nimmt die Cr(CO)3-Einheit verglichen mit allen anderen Hexatrien-Cr(CO)3-Systemen eine anomale Orientierung relativ zum Polyen ein. Eine theoretische Analyse dieses Problems zeigt, daß diese Vorzugskonformation eng mit der Cycloheptatrien-Norcaradien-Valenztautomerie zusammenhängt. Mögliche Wege, die Rotationsbarriere in derartigen Komplexen zu beeinflussen, werden aufgezeigt. Vorzugskonformation, Rotationsbarriere und Abknicken der exocyclischen Methylengruppe in Tricarbonyl(η6-fulven)chrom(0) werden diskutiert und die Analyse wird auf die analogen Benzyl-Cr(CO)3- und Cyclobutadiencarbinyl-Fe(CO)3-Kationen ausgedehnt. Die Konformation dieser Komplexe wird solchen gegenübergestellt, die zwei Elektronen mehr enthalten.
    Notes: 1,6-Methano[10]annulene-Cr(CO)3 and several related complexes adopt an anomalous orientation of the Cr(CO)3 unit with respect to the polyene, compared to all other hexatriene-Cr(CO)3 complexes. A theoretical analysis of this problem shows that these conformational preferences are closely related to the cycloheptatriene-norcaradiene valence tautomerism. Several strategies for influencing the barrier to internal rotation in these complexes are presented. An analysis of the conformational preference, rotational barrier, and bending of the exocyclic methylene group in fulvene-Cr(CO)3 is also discussed. This is extended to the analogous benzyl-Cr(CO)3 and cyclobutadiene-carbinyl-Fe(CO)3 cations. Finally, the orientations of these complexes are contrasted to those containing two more electrons.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110440
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  • 3
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. XIIIPart XII, see [1].. The complexation of Cu2+ with triazacycloalkanesHerrn Prof. Dr. E. Giovannini zum 70. Geburtstag gewidmet (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 1089-1096 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentiometric study of the complexation of Cu2+ with 1,4,7-triazacyclononane (1), 1,4,8-triazacyclodecane (2) 1,5,9-triazacyclododecane (3) has shown that CuL, CuL2 and (CuLOH)2 are the main species present in solution. Their stabilities (Table 1) and their absorption spectra (Table 2) indicate facial coordination of the cyclic triamines in a distorted octahedral geometry.The formation and dissociation kinetics have been measured by stopped-flow techniques. The formation in acetate buffer can be described by the reaction of Cu2+ and CuAcO+ with the monoprotonated species of the ligand. The bimolecular rate constants for these complexations (Table 3) decrease when the ring size increases. In contrast the dissociation induced by acid is only little affected by the ring size. Thus for these complexes the rate of formation and not that of the dissociation determines the overall stability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620417
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  • 4
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. IXFor part VIII see [1].. Synthesis and properties of a new class of branched N4-macrocycles with an additional ligating group in the side chain (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1376-1387 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of Ni2+ the template reaction between 2,6-diacetylpyridine and 4-(2-dimethylaminoethyl)- or 4-(2-hydroxyethyl)-1, 7-diamino-4-azaheptane yields the complexes of either the open-chain ligand (3 and 11) or of the macrocycle (4 and 12). Reduction of the imino group in 4 and 12 with PtO2/H2 gives 5 and 13, respectively. In the case of the dimethylamino derivative 5 a mixture of at least four isomers was obtained. These were partially separated by chromatography on Sephadex SP-25 cation exchanger. Through demetalation of the Ni2+ complexes by cyanide the new macrocycles 7 and 14 were isolated, from which the corresponding Zn2+ and Cu2+ complexes were prepared.The macrocyclic Ni2+-complexes 4, 12, 5 and 13 can exist in two forms depending on the pH of the solution. At low pH protonation of the dimethylamino or hydroxy group in the side chain occurs. The metal ion is then bound to the four nitrogen atoms of the macrocycle in a square planar ligand field. At higher pH, however, the dimethylamino or hydroxy group (the last one also in its deprotonated form) can coordinate to one of the axial positions, whereby pseudooctahedral coordination geometry is induced. This reaction can be quantitatively described by a reversible acid-base equilibrium, the pKH of which greatly depends on the nature of the functional group, the degree of unsaturation of the macrocycle and the metal ion.The acid-base reaction and the concomitant structural change are a direct consequence of the unique combination of the rigid and kinetically stable structure of the macrocycle and of the flexible and kinetically labile functional group of the side chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610421
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  • 5
    Electronic Resource
    Electronic Resource
    Metal Complexes of Macrocyclic Ligands. XIIPart XI, see [1].. A Complexone-like Tetraazamacrocycle (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 683-688 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexone-like tetraazamacrocycle 1 (LH4) forms a series of metal complexes with Co2+, Ni2+, Cu2+ and Zn2+ (M2+) of the type MLH2, ML2- and M2L, which have been isolated and characterized by VIS., IR. and NMR. spectroscopy. Based on these results tentative structures for the different species are proposed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620306
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  • 6
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. XIV. Formation, dissociation and metal exchange with an N2S2-macrocyclePart XIII, see [1]. (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 2562-2568 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 10, 10, 12-Trimethyl-3,4-benzo-1,6-dithia-9,13-diazacyclopentadecen-dihydrochloride (LH22+, 2) and its Ni2+ complex were synthesized and their reactivity studied. The formation kinetics of 2 with Cu2+ were found to be a second order reaction between Cu2+ or CuACO+ and the monoprotonated form of the ligand LH+. The rate constant kCuLH = 29 M-1S-1 is 105-106 times smaller than those of monoprotonated tetraazamacrocycles either because of second bond formation or because of a strong electrostatic interaction between the positive charges of the Cu2+ and the ammonium group. The metal-metal exchange between NiL+ and Cu2+ was also investigated. The reaction is independent of [Cu2+] and has the same rate and activation parameters as the dissociation of NiL2+. In contrast to open chain ligands, no mixed complex CuNiL4+ as intermediate was observed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620809
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  • 7
    Electronic Resource
    Electronic Resource
    Pharmacologically active polymers, 13Part 12, cf. G. Franzmann, H. Ringsdorf, Makromol. Chem. 177, 2547 (1976).. Elucidation of the tumour affinity of poly[sulfadiazineacrylamide] (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 2669-2674 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly[sulfadiazinacrylamid] (5) mit 14C-Hauptkettenmarkierung wurde synthetisiert und sein Molekulargewicht viskosimetrisch durch Vergleich mit inaktiven Proben von Poly-[sulfadiazinacrylamid] mit membranosmometrisch ermittelten Molekulargewichten ähnlicher Größe bestimmt.In seinem systemischen Verhalten bei Mäusen zeigte die Verbindung einen polymerspezifisch protahierten Verlauf. Die Ausscheidungsraten des Polymeren waren vernachlässigbar gering, seine Toxizität erheblich. Es wurde im Untersuchungszeitraum in der Leber akkumuliert, aber eine Tumoraffinität zum PC6 Plasmazelltumor bei Mäusen war nicht feststellbar.
    Notes: Poly[sulfadiazineacrylamide] (5), labeled with 14C in the main chain, was synthesized and its molecular weight viscosimetrically determined by comparison with unlabeled samples of poly[sulfadiazineacrylamide] with similar molecular weights which were determined by membrane osmometry.The material showed a polymer-specific prolongation of its systemic behaviour in mice. Rates of excretion of the polymer were negligibly low, whereas the toxicity was considerable. It was concentrated in the liver during the course of the experiment, but no affinity toward the PC6 plasmacytoma in mice could be detected.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770909
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  • 8
    Electronic Resource
    Electronic Resource
    Diffusion of gases through polyurethane block polymers (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 201-214 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diffusivities of simple gases through a series of polyurethane block copolymers of differing aromatic urethane content and type of soft segment were measured using a quadrapole mass spectrometer as a detecting device. Although an Arrhenius expression generally described the temperature dependence of diffusion in this system, a discontinuity was observed in the Arrhenius plots for some materials, and the discontinuity was found to be related to the onset of the glass transition in the hard domains. Increasing the hard segment content of the materials decreased the diffusivity due to the increase in the activation energy of diffusion. Increasing the soft segment length brought about a decrease in the activation energy with an increase in diffusivity. Polyster urethanes had lower activation energies for diffusion than polyether urethanes of similar hard segment composition. Finally, as the penetrant diameter was increased, a decrease in the diffusivity and an increase in the activation energy was noted.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230118
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  • 9
    Electronic Resource
    Electronic Resource
    Observations on the development of the human atrioventricular node and bundleSupported by N.I.H. Grant HL07047. (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 192 (1978), S. 337-350 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This light microscopic study of the cardiac junctional tissues was based on 27 human embryos, fetuses and postnatal hearts. Evidence was presented that superficial and deep portions of the postnatal AV node were derived from two cellular primordia in the posterior wall of the common atrium at the 6-mm stage. The small right primordia was associated with the right venous valve and gave rise to the loosely organized superficial AV node that extended posteriorly to the coronary sinus ostium. A larger left primordia formed the more compact deep subdivision of the AV node located against the anulus fibrosus. In most postnatal hearts the two subdivisions are partially or completely fused to form the adult AV node. Failure of the nodal primordia to fuse during cardiogenesis may result in two separate nodal cell aggregates above the anulus. The present observations provide a rational explanation for the two AV nodal masses described in the literature and an additional specimen that is illustrated in this communication.An AV bundle was first identified in a 13-mm embryo and appeared to be derived from large clear cells of the posterior AV canal. At 25 mm the bundle formed a broad band across the top of the IV septum and continued into both ventricles. At this stage multiple cell strands penetrated the endocardial cushion to connect the AV bundle to the two nodal primordia. Failure of normal fusion between the AV node primordia and AV bundle can result in a variety of junctional anomalies including congenital heart block.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091920302
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  • 10
    Electronic Resource
    Electronic Resource
    The atrioventricular node and bundle in the ferret heart: A light and quantitative electron microscopic studyThis work was supported in part by N.I.H. grants HL07047, HL19425, HL19606, CA08231. (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 365-391 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cells of the atrioventricular (AV) junction in the ferret heart were examined using light microscopy, a wax-model reconstruction and quantitative electron microscopy to determine their organization and characteristics. A series of subdivisions of the specialized tissues of the AV junction was apparent at both the light and electron microscopic levels. A transitional zone was observed interposed between the atrial muscle cells and the AV node. The AV node consisted of a coronary sinus portion, a superficial portion and a deep portion. The AV bundle had a segment above the anulus fibrosus, a segment which penetrated the right fibrous trigone, a non-branching segment below the anulus fibrosus and a branched segment. At the ultrastructural level the AV junctional conduction tissues had fewer irregularly oriented myofibrils than did working atrial myocardial cells. T-tubules, present in atrial muscle cells, were not observed in the modified muscle cells of the AV node and bundle. Conventional intercalated discs also were not observed between the cells of the AV node or the AV bundle.Atrial myocardial cells had the highest percentage of the plasma membrane occupied by desmosomes, fasciae adherentes and gap junctions. The AV bundle cells had the highest percentage of appositional surface membrane and a relatively large fraction of plasma membrane occupied by gap junctions. Cells of the superficial portion of the AV node had the smallest percentage of the plasma membrane composed of gap junctions, desmosomes or fasciae adherentes, as well as the smallest fraction of the cell membrane apposed to adjacent cells. The stereological data indicate that the most useful distinguishing characteristic between atrial muscle cells and conduction cells was that a smaller percentage of the conduction cell sarcoplasm was occupied by mitochondria and myofibrils. The most useful characteristics that could be used to differentiate between the regions of the AV junctional conduction tissues were the amounts and types of surface membrane specializations in the respective cell types.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001540305
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