Electron transfer initiated Diels-Alder reaction with allenes as dienophiles

The first examples of using aryl allenes as dienophiles in the electron transfer induced Diels-Alder reaction are described. According to mechanistic tests the reaction proceeds via a cycloaddition of the diene^+· to the allene.     

Unsymmetrically Substituted Benzonaphthoporphyrazines: A New Class of Cationic Photosensitizers for the Photodynamic Therapy of Cancer*

Abstract— Unsymmetrical zinc(II) complexes of benzonaphthoporphyrazines 5 a-12a bearing between one and eight pyri-dyloxy substituents are synthesized by statistical tetra-merization of 6-(l,l-dimethylethyl)-2,3-naphthalenedi-carbonitrile (1) with 4-(3-pyridyloxy)- or 4,5-bis-(3-pyri-dyloxy)-1,2-benzenedicarbonitrile (2, 3). Methylation of 5a-12a leads to the cationic pyridyloxybenzonaphtho-porphyrazines 5b- 12b having between one to eight positive charges. The Q-band transition in the visible spectra exhibits a bathochromic shift from 680 to 760 nm dependent upon the number of annelated naphthalene rings. The singlet oxygen quantum yields of the benzonaphthoporphyrazines determined by the dye-sensitized photoox-idation of 1,3-diphenylisobenzofurane is surprisingly high (in the range of zinc phthalocyanine). The photoox-idative stabilities of the photosensitizers described quantitatively by first-order kinetics decrease with the number of annelated naphtho groups. A linear correlation between the logarithm of the decomposition rate constant and the position of the highest occupied molecular orbital (HOMO)-level of the photosensitizers is found. Destabi-lization of the HOMO leads to a decrease of the pho-tostability. Due to their adjustable long wavelength absorption, their intramolecular polarity axis and their different hydrophilic/hydrophobic character, these novel compounds may be suitable photosensitizers for the photodynamic therapy of cancer.     

SYNTHESIS OF POSITIVELY CHARGED PHTHALOCYANINES and THEIR ACTIVITY IN THE PHOTODYNAMIC THERAPY OF CANCER CELLS

Positively charged zinc containing or metal free phthalocyanines 6a-c and 7a-c were prepared via a three step procedure starting from 4-nitrophthalonitrile. The phthalocyanines contain alkyl chains of different length in order to influence the hydrophilic vs lipophilic character of the compounds. The partition between a hydrophilic (water) and lipophilic (octanol-1) phase was determined, and the photoredox activities were investigated. Initial results on the photodynamic activity of these compounds were compared with those of Dougherty's Photofrin II on different malignant and non-malignant cell lines (XP 29MAmal, CX1, HeLa, S180 and NO17). Positively charged phthalocyanines in vitro showed a higher photodynamic activity than Photofrin II.     

Polymere mit dem Zentralatom eines Makrocyclus in der Hauptkette. 1. Mitt. Polykondensationsreaktionen mit Phthalocyaninsilicium-und Hemiporphyrazingermaniun-Verbindungen

Ohne Zusammenfassung     

Fritz Haber und Clara Immerwahr. Lernen aus der Geschichte

This contribution about Fritz Haber (1868–1934) and his wife Clara Immerwahr (1870–1915) shows us not only the changeful life of these two personalities which began their life full of hope and finished it then in tragedy. Their time is embedded into the history about the break‐up and then come‐down by the First World War of the first period of the German Empire, and also points out exemplarily science and industry of this time.