Unusual emissions from low-concentrated porphyrin solutions

This contribution presents fluorescence measurements from highly diluted tetratolylporphyrin (TTP) solutions where acetone has been chosen as solvent. The concentrations of the solutions ranged from 10(-8) to 10(-14) M. Apart the normal S1-S0 fluorescence a new broad emission was recorded below 10(-8) M. This new emission blue-shifted to the S1-S0 fluorescence covered the spectral range between 19000 and 14000 cm(-1). Within the dilution series, both the S1-S0 porphyrin fluorescence and the new emission exhibited a remarkably non-linear concentration-dependence. In the case in which the aggregate emission was strong, little S1-S0 emission could be detected and vice versa. The intensity maximum of the broad emission was detected from a 10(-13) M solution. The supplementary fluorescence was attributed to the presence of assembled molecules. This assumption was established by comparing the measurements with those obtained from 1:1 acetone water solvent mixtures in which the formation of aggregates had been formerly proven. The emission originating from the formation of aggregates was interpreted by a qualitative model considering the energy levels of J-aggregated porphyrins.     

Coleone C,D, I,I′ aus einer madegassischen Plectranthus sp. nov. Interkonversion von cis- und trans-A/B-6,7-Diketoditerpenen

Coleons C, D, I, I′, obtained from a Madagascan Plectranthus sp. nov.. Interconversion of cis- and trans-A/B-6,7-Diketoditerpenes. Fairly large amounts of Coleons C and D, as well as Coleons I and I′ (3-O-formyl derivative of Coleon I) can bc isolated from the orange glands of an unclassified North Madagascan Plectranthus sp. A reversible transformation of cis- and trans-A/B-6,7-dioxo-abietane via its diosphenol has been achieved for the first time. CD.-Spectra of these compounds are presented. Hydrogenolysis of Coleon D leads to 6β,16-dihydroxy-royleanone.     

The detection of oxygen in magneto-optical layers with SIMS

The detection of oxygen in magneto-optical layers is of fundamental importance for the characterization of the stability of RE-TM material. The magnetic properties are directly influenced by oxide formation. Oxygen depth profiles are carried out by using the SIMS technique. A comparison with magnetic measurements showed a clear conformity. We were able to study the oxidation behaviour of various layers at room temperature and at higher values up to 250° C for several hours. It could be shown that aluminum is a successful material for the protection of RE-films against oxidation. The difficulties of translating SIMS counting rates into concentration values were overcome by using EPMA. Specially prepared reference samples were measured by this technique and could then be used as standard samples for SIMS.     

A parallel implementation of the COLUMBUS multireference configuration interaction program

Summary In this work a parallel implementation of the COLUMBUS MRSDCI program system is presented. A coarse grain parallelization approach using message passing via the portable toolkit TCGMSG is used. The program is very well portable and runs on shared memory machines like the Cray Y-MP, Alliant FX/2800 or Convex C2 and on distributed memory machines like the iPSC/860. Further implementations on a network of workstations and on the Intel Touchstone Delta are in progress. Overall, results are quite satisfactory considering the complexity and the prodigious requirements, especially the I/O bandwidth, of MRCI programs in general. For our largest test case we obtain a speedup of a factor of 7.2 on an eight processor Cray Y-MP for that section of the program (hamiltonian matrix times trial vector product) which has been parallelized. The speedup for one complete diagonalization iteration amounts to 5.9. An absolute speed close to 1 GFLOPS is found. Results for the iPSC/860 show that ordinary disk I/O is certainly not sufficient in order to guarantee a satisfactory performance. As a solution for that problem, the implementation of a fully asynchronous distributed-memory model for certain data files is in preparation. On leave from: Bereich Informatik, Universität Leipzig, Augustusplatz 10/11, O-7010 Leipzig, Germany     

5-(N-Arylnortropan-3-yl)- and 5-(N-Arylpiperidin-4-yl)-2,4-diaminopyrimidines. Novel Inhibitors of Dihydrofolate Reductase

Based on a computer-assisted analysis of the three-dimensional structure of the binary complex of E.coli dihydrofolate reductase (DHFR) with methotrexate, 5-(N-arylnortropan-3-yl)- and 5-(N-arylpiperidin-4-yl)-2,4-diaminopyrimidines 2 and 4 were designed as inhibitors of DHFR. Syntheses of the designed compounds have been carried out. The most potent compound 2a inhibited E. coli DHFR with K_i = 0.49.10^?9M. The activities within the series of compounds synthesized could be rationalized by molecular-modelling experiments which served as the basis of this work. Several compounds within the presented series exhibit antimalarial activities in vitro and in vivo.     

Die Strommer-Zykliden des Flaggenraumes

According to H. BRAUNER a flag space is a three-dimensional affine space with an absolute {,f,F}, wheref is a line in the plane of infinity andF a point onf. A cyclide is a surface of order 4 that intersects only atf. A STROMMER-cyclide is a cyclide generated by translation of a circle in an isotropic plane. In this paper we proof that all STROMMER-cyclides can be generated by translation of an isotropic circle along a divergent Newton-parabola or a conic in a full isotropic plane. We give normal-forms and CAD-pictures of these surfaces. Finaly some geometrical results about STROMMER-cyclides are developed.

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Herrn o.Prof. Dr. Gy. Strommer zum 70. Geburtstag gewidmet.     

Zur Kennzeichnung von Lorentztransformationen in Endlichen Ebenen

Given a commutative field K we define d(A,B):= (a₁–b₁)²–(a₂–b₂)² for A=(a₁,a₂), B=(b₁,b₂) K². Given moreover a fixed k K^O, W. Benz has asked for all mappings : K²K² such that d(A,B)=k implies. This paper gives an answer if K=GF(p), p=5,7,11: must be a bijective collineation in case p = 7,11; there are non-injective mappings in case p=5. To obtain some of these results we have mads use of a computer.

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Prof. R. Artzy zum 70. Geburtstag gewidmet.     

Confirmation of the Structures of Lutein and Zeaxanthin

A series of new esters of lutein ( 1a ) have been prepared with the aim of confirming the structure of lutein via an X‐ray crystal‐structure analysis. Although well crystallized, only one of the derivatives, the (?)‐(1R)‐menthyl carbonate ( 1i ) proved to be useful for a complete structure analysis. The same derivative of zeaxanthin ( 2a ) also allowed its crystal structure to be determined. Both analyses represent the first successful X‐ray crystal structure analyses of the most important xanthophylls. At the same time, they confirm both the constitution and absolute configuration of 1a and 2a that had been deduced earlier by classical methods.     

Interaction of nonionic detergents and swelling clays

Summary The 25° sorption isotherms of a polyoxyethylated n-dodecanol with 14 ethylene oxide units (C₁₂EO₁₄) on sodium and calcium montmorillonite were determined. Sorption complexes of the two clays were also prepared with C₁₂EO₃₀, n-dodecanol, polyethylene glycol and polypropylene glycol. X-ray powder diagrams show that the sorbed organic molecules are intercalated with their chains parallel to the montmorillonite lamellae, in layers one or two molecules thick. Sodium montmorillonite sorbs C₁₂ EO₁₄ and C₁₂EO₃₀ in excess of close-packed double layers: the excess detergent is occluded in interstices and absorbs moisture at 85% relative humidity to the same extent as the bulk detergents. The double layer complexes are not swelled by water; the single layer complexes sorb a single layer of water molecules at 85% relative humidity.Apparent densities of the sorbed organic molecules decrease with increasing EO content while bulk densities increase. This is explained in terms of chain flexibility and polarity.

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Zusammenfassung Die 25°-Absorptions-Isothermen von polyoxyäthyliertem n-Dodekanol mit 14Äthylenoxyd-Einheiten(C₁₂EO₁₄) an Na- und Ca-Montmorillonit wurden bestimmt. Sorptions-Komplexe der 2 Tone wurden ebenfalls mit nDodekanol, Polyäthylenglykol und Polypropylenglykol präpariert. Pulverdiagramme zeigen, daß die sorbierten organischen Moleküle mit ihren Ketten parallel zu den Montmorillonitlamellen eingelagert sind, in Schichten 1 oder 2 Moleküle dick. Na-Montmorillonit sorbiert C₁₂EO₁₄ und C₁₂EO₃₀ im Überschuß zur dichtgepackten Doppelschicht. Der Überschuß ist in Hohlräumen eingelagert und absorbiert Wasser bei 85° relativer Feuchtigkeit im selben Ausmaß wie die reinen Detergentien. Die Doppelschichtkomplexe werden nicht durch Wasser gequollen. Die Einschichtkomplexe sorbieren eine Monoschicht von Wasser-Molekülen bei 85° relativer Luftfeuchtigkeit.Scheinbare Dichten der sorbierten organischen Moleküle nehmen mit steigendem Äthylenoxydgehalt ab, während die Dichten der reinen Substanz ansteigen. Dies läßt sich auf Grund der Kettenbeweglichkeit und Polarität erklären.

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Presented at the 145^th Meeting of the American Chemical Society, New York, N. Y., September 1963.