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  • 1
    ISSN: 0935-9648
    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
    Additional Material: 3 Ill.
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  • 2
    ISSN: 0935-9648
    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
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 1 (1995), S. 111-117 
    ISSN: 0947-6539
    Keywords: alkyne complexes ; carbon networks ; macrocycles ; platinum compounds ; tetraethynylethene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of the first organometallic mono- and dinuclear platinum complexes bearing the tetraethynylethene unit as an η1-ligand are reported. Structural characterization of two of the trans σ-bis(acetylide) derivatives by X-ray crystallography reveals coplanarity of the acetylenic π-ligands and indicates possible electronic delocalization across the metal center. This notion is further supported by comparing the electronic absorption spectra of the platinum-containing compounds with those of related tetraethynylethene derivatives without metals. The solidstate structure of a dinuclear complex with two iodoplatinum fragments attached to one set of geminal acetylenes of tetraethynylethene was also investigated by X-ray diffraction. Hay coupling of a mononuclear species leads to the incorporation of the σ-bis(acetylide) moiety into a diplatinated metallacycle. This macrocyclic compound represents a novel structural motif in the design of a transition metal linked carbon network based on tetraethynylethene.
    Additional Material: 6 Ill.
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  • 4
    ISSN: 0947-6539
    Keywords: amphiphiles ; C-glycosides ; cryptates ; fullerenes ; ionophores ; Langmuir-Blodgett films ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the first fullerene cryptate 7 with a sodium ion bound to a benzo[2.2.2]cryptand covalently attached to a methanofullerene[60] is described. The amphiphilic properties of 7 as well as of a variety of other covalent fullerene derivatives with polar functional groups and the ability of these compounds to form Langmuir monolayers at the air-water interface were investigated in a systematic study. Among these derivatives are Diels-Alder adducts of C60 and methanofullerenes, four of which are fullerene C-glycosides. The films at the water surface were characterized by their surface pressure versus molecular area isotherms, compression and expansion cycles, and optical light microscopy. UV/Vis spectroscopy and small-angle X-ray diffraction (SAXS) were employed for LB film characterization on solid substrates. Parameters influencing the spreading and monolayer character include (a) polarity, (b) balance of hydrophobicity to hydrophilicity, (c) size and bulkiness of the polar groups attached to the fullerene, and (d) presence of aromatic residues in these groups.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0947-6539
    Keywords: fullerenes ; endohedral helium complexes ; NMR spectroscopy ; ring currents ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis- to hexakisadducts of C60 (1-6) and mono- to tetrakisadducts of C70 (7-13) containing 3He atoms (endo-hedral helium complexes) were prepared and studied by 3He NMR spectroscopy to determine the influence of degree of functionalization and addition pattern on the chemical shift of the 3He atom. In the series of C60 derivatives, which included the previously measured 6-6 monoadduct 3He@C61H2, the 3He resonance was shifted considerably upfield relative to that of 3He@C60 (δ = -6.36) up to the bisadduct 1 (δ = -11.45). The resonances of the higher adducts 3-6, however, were shifted only slightly further up-field and all appeared in a rather narrow spectral range between δ = -11.84 and -12.26. The absence of further substantial upfield shifts was rationalized in terms of the compensation of deshielding due to the functionalization-induced decrease in the diamagnetic π-electron ring currents that extend around the fullerene sphere by the shielding that results from the weaker pentagonal-ring paramagnetic currents and the increased number of localized benzenoid substructures in 3-6. In contrast, all 3He resonances of the C70 adducts are shifted downfield relative to the signal of 3He@C70 (δ = -28.81). A monotonic relationship exists between the chemical shift and the degree of functionalization, whereby the 3He chemical shifts steadily decrease from monoadduct 7 (δ = -27.53) to the isomeric tetrakisadducts 12 (δ = -21.09) and 13 (δ = -20.68). This deshielding was explained by the reduction of the strong diamagnetic ring currents extending along the polar corannulene perimeters as a result of the functionalization at α- and β-type polar bonds in 7-13. In both series, the addition pattern was also found to have a distinct influence on the 3He chemical shift.
    Additional Material: 6 Ill.
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  • 6
    ISSN: 0947-6539
    Keywords: conjugation length ; electrochemistry ; nonlinear optics ; oligomers ; poly-(triacetylene)s ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(triacetylene)s [PTAs, —(C≡C—CR=CR—C≡C)n-] are a new class of linearly conjugated polymers with a nonaromatic all-carbon backbone. To explore structure-property relationships in PTAs, we prepared a series of monodisperse oligomers ranging from monomer to hexamer by oxidative Glaser-Hay coupling of a bifunctional („chain-forming“) (E)-hex-3-ene-1,5-diyne in the presence of an endcapping unit. All six oligomers are amazingly stable towards exposure to light, air, and temperatures beyond their melting points. They have been fully characterized and are readily soluble in a wide range of solvents. The conjugated rods are reversibly reduced in one-electron transfer steps and cannot be oxidized below +1.23 V vs. Fc/Fc+. The effective conjugation length in PTAs was estimated from the electronic absorption (UV/Vis) data, and various evaluation methods yielded convergence of the optical properties in the range of 7 to 10 monomer units. The nonresonant second-order molecular hyperpolarizability γ was measured in CHCl3 by means of the third harmonic generation (THG) at Δ = 1.907 μm. A plot of γ/n vs. n revealed a power law γ ≈ na for γ with a fitted exponent a = 2.5 ∓ 0.1. From the THG measurements, an effective conjugation length of about 10 monomer units was found, in surprisingly good agreement with the value obtained from UV/Vis spectroscopy data.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3504-3512 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloarene, eine neue Klasse aromatischer Verbindungen, II. Molekülstruktur und spepktroskopische eigenschaften von KekulenDie Molekülstruktur von Kekulen (1) wurde durch Röntgen-Strukturanalyse bestimmt. Aus den Bindungslängen von 1 wird auf eine bemerkenswerte Lokalisation von aromatischen Sextetts und Doppelbindungen im Sinne der Formulierung 1b geschlossen. - Das Problem der annulenoiden oder benzoiden Diatropie von 1 wird an Hand der 1H-NMR-Spektren diskutiert. Die experimentellen Ergebnisse stützen in Übereinstimmung mit neueren theoretischen Berechnungen die Annahme einer vorherrschenden Ringstrom-Induktion in den benzoiden-Untereinheiten von 1 und schließen einen wesentlichen Beitrag annulenoider Strukturen wie 1a aus. - Absorptions-und Emissionsspektren von 1 sowie Nullfeld-Aufspaltungsparameter des angeregten Triplettzustands von 1 werden diskutiert.
    Notes: The molecular structure of kekulene (1) was determined by X-ray structure analysis. From the bond lengths of 1 a remarkable localisation of aromatic sextets and double bonds is concluded (cf. formula 1b). - The problem of annulenoid versus benzenoid diatropicity in 1 is discussed on the basis of 1H NMR absorptions. These data, in agreement with recent theoretical calculations, support a predominant ring-current induction in the benzenoid subunits of 1 and rule out a significant contribution of annulenoid structures like 1a. - Absorption and emission spectra of 1 are discussed as are the zero-field splitting parameters of the excited triplet state of 1.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 246-259 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [3.3]- und [4.4](2,7)Pyrenophane als Excimeren-Modelle: Synthese, Molekülstruktur und spektroskopische EigenschaftenAls Excimeren-Modelle wurden die [3.3]- und [4.4]Pyrenophane 1 und 2 synthetisiert. Als Vorstufe für die Synthese von 1 wurde das Octahydro-dithia[4.4]pyrenophan 9 durch Cyclisierung von 4 und 8 erhalten, deren Synthese beschrieben wird. Das von 9 abgeleitete Disulfon 10 ergab durch Gasphasen-Pyrolyse 11, das durch Dehydrierung in 1 übergeführt wurde. Auf analogem Wege wurde 2 über 16, 17 und 18 ausgehend von 4 und 15 (dargestellt in der Reaktionsfolge 12 → 13 → 14 → 15) erhalten. - Die Molekülstrukturen von 1 und 2 wurden durch Röntgen-Strukturanalyse bestimmt; sie werden im Hinblick auf transanulare Abstände und Abweichungen von der Planarität der Pyren-Einheiten diskutiert. - Die Absorptionsspektren von 1 und 2 werden im Zusammenhang mit der transanularen Wechselwirkung diskutiert. Die Fluoreszenz-Emission von 1 und 2 entspricht dem Excimeren-Charakter dieser Verbindungen. Ergebnisse, die durch ODMR-Messungen an 1 erhalten wurden, werden mitgeteilt.
    Notes: As excimer models the [3.3]- and [4.4]pyrenophanes 1 and 2 were synthesized. As the key precursor for the synthesis of 1 the octahydro-dithia[4.4]pyrenophane 9 was obtained by cyclisation of 4 and 8, the syntheses of which are described. Disulfone 10, derived from 9, on vapour-phase pyrolysis yielded 11 which by dehydrogenation was converted into 1. In an analogous route 2 was obtained via 16, 17, and 18 starting from 4 and 15 (prepared in the reaction sequence 12 → 13 → 14 → 15). - The molecular structures of 1 and 2, determined by X-ray structure analyses, are discussed with regard to transanular distances and deviations from planarity of the pyrene units. - Absorption spectra of 1 and 2 are discussed with reference to transanular interactions. The fluorescence emissions of 1 and 2 are found to be ‘excimer-like’. Results obtained by ODMR measurements of 1 are reported.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3817-3829 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ein wasserlösliches Tetraoxa[7.1.7.1]paracyclophan: Synthese und Wirt-Gast-Wechselwirkungen mit alicyclischen und kationischen aromatischen Gastmolekülen in wäßriger LösungAls wasserlöslicher makrocyclischer Wirt für unpolare Gastmoleküle wurde das Tetraoxa[7.1.7.1]paracyclophan 1 synthetisiert. In der Schlüsselreaktion der Synthese von 1 wurden zwei Äquivalente 1-Acetyl-4,4-bis(4-hydroxy-3,5-dimethylphenyl)piperidin (4) mit zwei Äquivalenten 1-Acetyl-4,4-bis[2-(p-tolylsulfonyl)ethyl]piperidin (8) zum Tetraoxa[7.1.7.1]-paracyclophan 9 cyclisiert. Die Synthese von 8, ausgehend von 1-Acetyl-4-piperidon, wird beschrieben. 1 wurde in der Reaktionsfolge 9 → 10 → 11 → 2 → 1 erhalten. Die Temperaturabhängigkeit der 1H-NMR-Spektren von 1, wird diskutiert. - 1H-NMR-Untersuchungen der Wirt-Gast-Wechselwirkungen in wäßriger Lösung zwischen 1 und aromatischen Gastmolekülen mit kationischen Resten und zwischen 1 und alicyclischen Gastmolekülen werden beschrieben. Die Assoziationskonstanten Ka (1 · mol-1) der Komplexe wurden entweder durch Fest-Flüssig-Extraktion und über kompetitive Inhibitionsexperimente bestimmt oder anhand der NMR-Komplexierungsverschiebungen Δδ abgeschätzt.
    Notes: As water-soluble macrocyclic host for apolar guest molecules, the tetraoxa[7.1.7.1]paracyclophane 1 was synthesized. In the key reaction of the synthesis, two equivalents of 1-acetyl-4,4-bis(4-hydroxy-3,5-dimethylphenyl)piperidine (4) and two equivalents of 1-acetyl-4,4-bis[2-(p-tolylsulfonyl)ethyl]piperidine (8) were cyclized to the tetraoxa[7.1.7.1]paracyclophane 9. The synthesis of 8 starting from 1-acetyl-4-piperidone is described. 1 was obtained following the reaction sequence 9 → 10 → 11 → 2 → 1. The temperature dependency of the 1H NMR spectra of 1 is discussed. -1H NMR studies of host-guest interactions in aqueous solutions between 1 and aromatic guest molecules bearing cationic residues and between 1 and alicyclic guest molecules are described. The association constants Ka (1 · mol-1) of the complexes were either determined by solid-liquid extraction and from competitive inhibition experiments, or estimated from NMR complexation shifts Δδ.
    Additional Material: 1 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3487-3503 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloarene, eine neue Klasse aromatischer Verbindungen, I. Synthese von KekulenDefinition und Nomenklatur der Cycloarene, einer neuen Klasse aromatischer Verbindungen, werden diskutiert. Als erster Vertreter der Cycloarene wurde Cyclo [d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzen („Kekulen“, 1) synthetisiert. - Aus dem Dithiaphan 11 wurde durch doppelte Schwefel-Extrusion, entweder photochemisch oder durch Pyrolyse des Disulfons 12, das carbocyclische System 13 erhalten, dessen Dehydrierung 14 ergab. Durch Stevens-Umlagerung von 11 mit anschließender Eliminierung entstand das Phan-dien 15, das zu 18 dehydriert wurde. Durch Photo-Cyclodehydrierung von 15 wurde das Octahydrokekulen 19 in ausgezeichneter Ausbeute erhalten. Die verschiedene Reaktivität von 15 und 18 bei der Photo-Cyclodehydrierung wird in Bezug zu elektronischen und sterischen Effekten diskutiert. Durch Dehydrierung von 19 wurde 1 erhalten.
    Notes: Definition and nomenclature of cycloarenes, a new class of aromatic compounds, are discussed. Cyclo[d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzene (“kekulene”, 1) has been synthesized as the first representative of cycloarenes. - From the dithiaphane 11 by double sulfur extrusion, either photochemically or by pyrolysis of disulfone 12, the carbocyclic system 13 was formed which by dehydrogenation yielded 14. By Stevens rearrangement of 11 followed by elimination the phanediene 15 was obtained which was dehydrogenated to 18. From 15 by photo-cyclodehydrogenation in excellent yield the octahydrokekulene 19 was obtained. The different reactivity of 15 and 18 in the photo-cyclodehydrogenation is discussed in terms of electronic and steric effects. Dehydrogenation of 19 yielded 1.
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