Browsing by Author "Haenel, Matthias"

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Open Access
Electronic interactions between polycyclic arenes in cyclophanes
(1988) Haenel, Matthias; Schweitzer, Dieter
The π-π interaction between polycyclic arenes and the effects of orientation were studied in [2.2]-, [3.3]-, and [3.2]naphthalenophanes, [2]naphthaleno[2]paracyclophanes, and syn- and anti[2.2](2,7)fluorenophane by electron absorption and emission spectroscopy as well as by optically detected magnetic resonance (ODMR) of the excited triplet state. The π-π interaction in the excited singlet and triplet state was found to be highest if a maximal number of sixmembered rings of the interacting arenes in a parallel orientation are completely eclipsed. Similarly, the π-π interaction between the nonbonding nitrogen electron pair and the aromatic π electrons was investigated in isomeric etheno-bridged naphthalenopyridinophanes and an anthracenopyridinophane; in these pyridinophanes, the pyridine rings are fixed perpendicularly above different sites of the naphthalene and anthracene units, respectively.
Open Access
Investigation of the excited triplet states of [2.2]- and [3.3]paracyclophane
(1979) Melzer, Guenter; Schweitzer, Dieter; Hausser, Karl H.; Colpa, Johannes Pieter; Haenel, Matthias
We have studied the excited triplet states of [2-2]- and [3.3]paracyclophane by emission spectroscopy and by ODMR and have compared the results with the corresponding monomer paraxylene. The most striking result is that both phanes exhibit two sets of zero field splitting parameters indicating the existence of two nearly degenerate low lying excited triplet states. Furthermore, we find in distinction to expection a stronger reduction of the zero field splitting parameters as compared to the monomers for [3.3]paracyclophane than for [2.2]paracyclophane. The causes of these surprising experimental findings are discussed.
Open Access
Modelle für Amin-Aromaten-Exciplexe: π-π- versus n-π-Wechselwirkung bei isomeren [2]Naphthalino[2](2,6)pyridinophanen und [2]Naphthalino[2](2,6)pyridinophan-1,11-dienen (Transanulare Wechselwirkung bei [m.n]Phanen ; 29)
(1985) Haenel, Matthias; Lintner, Birgit; Benn, Reinhard; Rufinska, Anna; Schroth, Gerhard; Krüger, Carl; Hirsch, Susanne; Irngartinger, Hermann; Schweitzer, Dieter
Als Exciplex-Modelle wurden die [2.2]Naphthalinopyridinophane 5, 6 und die entsprechenden Diene 3, 4 synthetisiert. Die Molekülstrukturen von 3, 5 und 6 wurden durch Röntgenstrukturanalyse bestimmt. Absorptionsspektren und vor allem die für Exciplexe typisch rot verschobenen und strukturlosen Fluoreszenz-Emissionen von 3 - 6 zeigen Orientierungsabhängigkeiten und werden mit n-π-Wechselwirkung zwischen dem Pyridin-Stickstoff und Naphthalin in 3,4 und π-π-Wechselwirkung zwischen den Aromaten-Einheiten in 5, 6 interpretiert.
Open Access
Modelle für Amin-Aromaten-Exciplexe: [2](1,4)Anthraceno[2](2,6)pyridinophan-1,13-dien (Transanulare Wechselwirkung bei [m.n]Phanen ; 32)
(1986) Haenel, Matthias; Lintner, Birgit; Schweitzer, Dieter
The [2](1,4)Anthraceno[2](2.6)pyridinophan-1,13-dien and the corresponding [2,2]phane were synthesized as models for exciplexes. The dithia[3,3]phanes and were prepared by cyclisation of the dithiols with the dibromide 19. Oxidation of 9 to the disulfone 10 and vapour phase pyrolysis led to 7. Ring contraction of 9 by S-analogous Wittig ether rearrangement led to 20 which was converted to the diene 5 via oxidation to the disulfoxide 21 and pyrolytic elimination of methane sulfenic acid. Attempts to prepare 6 and 8 via similar routes from 11 failed. Electron absorption spectra and fluorescence spectra of 5 and 7 are discussed in terms of n-π interaction in 5 and π-π interaction in 7.
Open Access
Modelle für Amin-Aromaten-Exciplexe: isomere [2]Naphthalino[2](2,6)pyrazinophane und [2]Naphthalino[2](2,6)pyrazinophan-1,11-diene (Transanulare Wechselwirkung bei [m.n]Phanen ; 30)
(1985) Lintner, Birgit; Schweitzer, Dieter; Benn, Reinhard; Rufinska, Anna; Haenel, Matthias
Als Exciplex-Modelle wurden die [2.2]Naphthalinopyrazinophane 7, 8 und die entsprechenden Diene 3, 4 synthetisiert. Die Dithia[3.3]phane 20 und 22, dargestellt durch Cyclisierung von 11 mit 12 und 11 mit 16, wurden zu den Disulfonen 21, 23 oxidiert, deren Pyrolyse in der Gasphase 7, 8 ergab. Ringverengung von 20, 22 durch S-analoge Wittig-Etherumlagerung ergab 24 bzw. 26, deren Oxidation zu den Sulfoxiden 25, 27 und pyrolytische Eliminierung von Methansulfensäure zu den Dienen 3 und 4 führte. Absorptions- und Fluoreszenzspektren von 3, 4, 7, 8 sowie die für 7 und 8 beobachtete Phosphoreszenz-Emission werden im Hinblick auf n-π-Wechselwirkung zwischen einem Pyrazin-Stickstoff und Naphthalin in 3,4 und π-π-Wechselwirkung zwischen den Aromaten-Einheiten in 7, 8 diskutiert. Von 7 und 8 wurden die Nullfeld-Aufspaltungsparameter |D| und |E| des angeregten Triplettzustandes über ODMR-Messungen bestimmt.
Open Access
Modelle für Excimere und Exciplexe : Absorptions- und Emissionsspektren von [2.2]Phanen des Fluorens und 9-Fluorenons (Transanulare Wechselwirkung bei [m.n]Phanen ; 28)
(1985) Schweitzer, Dieter; Haenel, Matthias
Die Absorptions-, Fluoreszenz- und Phosphoreszenzspektren von anti- und syn-[2.2](2,7)Fluorenophan (1 und 2) sowie ihre durch ODMR-Messungen bestimmten Nullfeldaufspaltungsparameter [D] des angeregten Triplettzustandes werden im Hinblick auf die Elektronenwechselwirkung und deren Orientierungsabhängigkeit diskutiert. Die entsprechenden [2.2]Phane 3, 5 und 6, die 9-Fluorenon-Einheiten enthalten, zeigen wie 9-Fluorenon keine Emission aus dem angeregten Triplettzustand. Von beiden syn-anti-Isomerenpaaren 2/1 und 6/5 zeigen jeweils die syn-Isomeren 2 und 6 mit "ekliptischer" Anordnung der Fluoren-Kohlenstoffatome die stärkere Elektronenwechselwirkung.
Open Access
Optical detection of magnetic resonance (ODMR) of naphthalenophanes
(1981) Schweitzer, Dieter; Hausser, Karl H.; Blank, Norman E.; Haenel, Matthias
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Open Access
Transannular interactions in [2.2] phanes as studied by luminescence and optical detection of magnetic resonance
(1976) Schweitzer, Dieter; Colpa, Johannes Pieter; Hausser, Karl H.; Haenel, Matthias; Staab, Heinz A.
Emission spectra of different types of [2.2] naphthalenophanes were measured at 1.25 K in glasses as well as in small single crystals. In addition, the D and E values of the excited triplet states were studied by optical detection of magnetic resonance in zero field and the results compared with the corresponding monomeres.
Open Access
Transannular interactions in [2.2] phanes as studied by magnetic resonance and optical spectra
(1975) Schweitzer, Dieter; Colpa, Johannes Pieter; Behnke, J.; Hausser, Karl H.; Haenel, Matthias; Staab, Heinz A.
The interaction of π-electrons in [2.2] phanes was studied both experimentally and theoretically. The fluorescence and phosphorescence spectra were measured at liquid helium temperature; in addition, the zero field splitting parameters D and E were determined by ODMR in zero field and by ordinary ESR at X-band. The results for the phanes with two identical aromatic units can be summarized as follows: The rather small reduction of the D and E values of the order of 10% with respect to the monomers indicates, in agreement with the theoretical treatment given in part II, that the two unpaired electrons of the excited triplet state have a high probability to be at a given time in the same half of the molecule. While the fluorescence spectra show the typical behaviour of emission spectra of dimers or excimers, the phosphorescence spectra exhibit some remaining structure. This behaviour which indicates a somewhat weaker coupling among the triplet orbitals as compared to the singlet orbitals can also be understood on the basis of theoretical considerations. For a phane with two different aromatic units the behaviour is found to be more similar to the corresponding aromatic monomer with the lower excited states with some perturbation by the other part of the phase also in agreement with theoretical expectation.
Open Access
Transanular interaction in [2.2]phanes: [2.2](4,4')diphenylophane and [2.2](2,7) fluorenophane
(1978) Schweitzer, Dieter; Hausser, Karl H.; Haenel, Matthias
The emission spectra and the zero field splitting parameters D and E of the first excited triplet states of [2.2](4,4′) diphenylophane 3 and of the two stereoisomeric syn- and anti [2.2] (2,7) fluorenophanes 4a and 4b are investigated and compared with those of the corresponding monomers.