Long-Wavelength-Absorbing and -Emitting Carbostyrils with High Fluorescence Quantum Yields

Synthesis, absorption and fluorescence spectra, as well as quantum yields of a series of donor-acceptor-substituted carbostyrils (=quinolin-2(1H)-ones), are reported. Unprecedented strong absorption maxima (ε=10000 – 20000) close to the visible spectrum, large Stokes shifts up to 130 nm, and quantum yields up to 0.7 are obtained with derivatives containing donor substituents at C(6) and C(7), and either one Ph substituent at C(3) or one CF₃ residue at C(4). For analytical applications in biochemistry and medicine, N(1)-functionalization, or amidoacylation at C(3) in the case of the CF₃ derivatives, is possible without a concomitant hypsochromic shift of their absorption and emission maxima. Semiempirical molecular-orbital calculations (AM1 for structures, ZINDO for electronic transition energies) prove to be a suitable tool for the prediction of absorption properties of these compounds. The crystal-structure analysis of 6,7-dimethoxy-1-methyl-3-nitro-4-(trifluoromethyl)quinolin-2-(1H)-one ( 7 ) (C₁₃H₁₁F₃N₂O₅, monoclinic, P2₁/c, a=12.372(2), b=12.154(2), c=10.119(2)Å, β=112.95(2)°) shows that the NO₂ group, squeezed between the CF₃ and the C=O group, is oriented almost perpendicularly (87.8(4)°) to the ring plane. The intramolecular F⋅⋅⋅N distance between the CF₃ and the NO₂ group is only 2.513(4)Å.     

The Crystal Structures of a Lower Order and a “Higher Order” Cyanocuprate: [tBuCu(CN)Li(OEt2)2]∞ and [tBuCutBu{Li(thf)(pmdeta)}2CN]

Different types of bonding are present in cyanocuprates 1 and 2 , whose crystal structures could be determined (the drawings below show the important structural characteristics). Accordingly, 1 is a lower order cyanocuprate of the type RCu(CN)Li, whereas 2 , which is of the type R₂Cu(CN)Li₂, does not exist as a “higher order” cyanocuprate with Cu–CN bonds, but rather as a cyano-Gilman cuprate.     

On the reaction of 3,4‐dihydropyrimidones with nitric acid. Preparation and x‐ray structure analysis of a stable nitrolic acid

A series of substituted 3,4‐dihydro‐2‐pyrimidones (DHPMs) was reacted with nitric acid under different reaction conditions. Treatment of DHPMs with 50‐65% nitric acid at 0 °C led to the formation of the corresponding dehydrogenated 2‐pyrimidones in moderate to good yields. In contrast, reaction of one representative DHPM with 60% nitric acid at 50 °C led to an unusually stable nitrolic acid, involving a formal nitration, nitrosation, and dehydrogenation step. The molecular structure of this product was determined by X‐ray crystallographic analysis     

Synthese des racemats eines seco-furoeremophilans aus euryops hebecarpus [1]

Starting with 6-amino-5-cyano-3-methyl benzofuran the structure of a seco-furoeremophilane has been established by synthesis.     

Zur Gültigkeit desZenschen Gesetzes und desLe Chatelierschen Prinzips in einigen Phasen mitGrimm-Sommerfeld-Bindung

By extremely rapid cooling of the liquid alloys, solid solutions in the AlSb-GaSb, GaSb-Ge, and InSb-Sn systems are obtained. In order to attain the high cooling rates (10⁷–10⁸ Ks^–1) a shock wave tube has been used. The AlSb-GaSb and GaSb-InSb systems, repectively, form continuous series of stable solid solutions, whereas in the GaSb-Ge and InSb-Ge systems solid solutions occur only within limited regions. They are partly metastable. In all cases,Zen's law is fulfilled. High pressure modifications in the systems investigated here behave according to theLe Chatelier principle with respect to their transformation volumes.

Herrn Prof. Dr.Kurt Komarek zum 60. Geburtstag gewidmet.     

ansa-Metallocene Derivatives : IV. Synthesis and molecular structures of chiral ansa-titanocene derivatives with bridged tetrahydroindenyl ligands

A synthesis for racemic ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride is described. The molecular structures of this compound, of its meso- isomer and of a binaphtholate complex of the (S,S)-enantiomer have been determined. Cleavage of this binaphtholate complex gives the pure (S,tS)-enentiomer.