The first homologous series of self-assembled aryl bromo- and aryl cyanocuprates, -argentates,and -aurates; MLi(2)XAr(2) (M = Cu(I), Ag(I), Au(I); X = Br,C(triple bond)N; Ar = [C(6)H(4)CH(2)N(Et)CH(2)CH(2)NEt(2)-2]-)

Reaction of 2 molar equiv of the diamine chelated aryllithium dimers Li(2)(C(6)H(4)[CH(2)N(Et)CH(2)CH(2)NEt(2)]-2)(2) (Li(2)Ar(2)) with the appropriate metal bromide allows the synthesis of the first homologous series of monomeric group 11 bromoate complexes of type MLi(2)BrAr(2) (M = Cu (7), Ag (8), Au (9)). Both in the solid state and in solution, the bromocuprate 7 is isostructural with the bromoargentate 8. The crystal structures of 7 and 8 consist of a MLi(2) core, and each of the two aryl ligands bridges via electron-deficient bonding between the group 11 metal and one Li atom (d(C(ipso)-M) = 1.941(4) (mean) and 2.122(4) (mean) A, for 7 and 8, respectively). The bromine atom exclusively bridges between the two lithium atoms. Each of the ortho-CH(2)N(Et)CH(2)CH(2)NEt(2) moieties is N,N'-chelate bonded to one lithium (d(N-Li) = 2.195(5) and 2.182(0) (mean) A for 7 and 2.154(8) and 2.220(1) (mean) A for 8). Although the MLi(2)BrAr(2) compounds are neutral higher-order -ate species, the structure can also be regarded as consisting of a contact ion pair consisting of two ionic fragments, [Li-Br-Li](+) and [Ar(2)M](-), which are interconnected by both Li-N,N'-chelate bonding and a highly polar C(ipso)-Li interaction. On the basis of NMR and cryoscopic studies, the structural features of the bromoaurate 9 are similar to those of 7 and 8. A multinuclear NMR investigation shows that the bonding between the [Li-Br-Li] and [Ar(2)M] moieties is intermediate between ionic and neutral with an almost equally polarized C(ipso)-Li bond in 7, 8, and 9. Similar reactions between M(C(triple bond)N) and 2 molar equiv of LiAr yield the analogous 2:1 cyanoate complexes of type MLi(2)(C(triple bond)N)Ar(2) (M = Ag (10), Au (11)). Multinuclear NMR studies show that the cyanoate complexes 10 and 11 are isostructural with the bromoate complexes 7, 8, and 9. This paper illustrates that these cyanoaurates may serve as excellent model complexes to gain more insight into the structure of 2:1 cyanocuprates in solution.     

A non-selfdual automorphic representation of GL3 and a Galois representation

Oblatum 13-XI-1992 & 22-X-1993     

Global optimization with a limited solution time

In this paper the box constrained global optimization problem in presence of a limited solution time is considered. A method is studied based on a combination of multistart and singlestart which implies a decision sequence on the number of random points to be generated. Search strategies are numerically illustrated. Criteria are introduced to measure the performance of solution methods for the problem class. Moreover, the performance of search strategies, specifically the efficiency of generating random points is analyzed.     

A New Paramagnetic Pd(dmit)2 Salt: Tris(2,2′-Bipyridine)Nickel(II) Bis(1,3-Dithiole-2-Thione-4,5-Dithiolato)Palladate(II) Mono-Acetonitrile; [Ni(bpy)3][Pd(dmit)2]·CH3CN

Combination of the [Ni(bpy)₃]²⁺ cation complex and the [Pd(dmit)₂]⁻ anion (dmit=C₃S₅²⁻=1,3-dithiole-2thione-4,5-dithiolate) has resulted in the paramagnetic [Ni(bpy)₃][Pd(dmit)₂]·CH₃CN compound, a suitable precursor for a molecular magnetic conductor. Its crystal structure consists of a Pd(dmit)₂ anion arrangement that is quite different from segregated stack layers often found for M(dmit)₂−based compounds. The reduction of the [Pd(dmit)₂]^- to the 2− charged anion in the title compound most probably is the result of a charge disproportionation between Pd(dmit)₂ anions.     

Interference of flavonoids with enzymatic assays for the determination of free fatty acid and triglyceride levels

Flavonoids are bioactive food compounds with potential lipid-lowering effects. Commercially available enzymatic assays are widely used to determine free fatty acid (FFA) and triglyceride (TG) levels both in vivo in plasma or serum and in vitro in cell culture medium or cell lysate. However, we have observed that various flavonoids interfere with peroxidases used in these enzymatic assays, resulting in incorrect lower FFA and TG levels than actually present. Furthermore, addition of isorhamnetin or the major metabolite of the flavonoid quercetin in human and rat plasma, quercetin-3-O-glucuronide, to murine serum also resulted in a significant reduction of the detected TG levels, while a trend was seen for FFA levels. It is concluded that when applying these assays, vigilance is needed and alternative analytical methods, directly assessing FFA or TG levels, should be used for studying the biological effects of flavonoids on FFA and TG levels.     

INTERACTION OF PHOTODYNAMICALLY INDUCED CELL KILLING and DARK CYTOTOXICITY OF RHODAMINE 123

Abstract— Loss of clonogenicity of Chinese hamster ovary (CHO) cells, murine L929 fibroblasts and human bladder carcinoma T24 cells caused by photodynamic treatment (PDT) with hematoporphyrin derivative (HPD) is synergistically enhanced by subsequent incubation with rhodamine 123 in the dark. For CHO and L929 cells this synergistic interaction can be explained by an increased uptake of rhodamine 123 as the result of the photodynamic treatment. With aluminum phthalocyanine (AIPc) as photosensitizer only additive effects were observed in the three cell lines. Incubation in the dark with rhodamine 123, followed by a photodynamic treatment with HPD, resulted in an antagonistic interaction with regard to loss of colony formation. With AIPc the combination of treatments resulted in an additive effect with L929 and T24 cells, whereas with CHO cells a slight antagonistic interaction was observed. An antagonistic effect was also observed in model experiments, treating histidine photodynamically with HPD and measuring oxygen consumption. A possible explanation of these results could be an interaction or complex formation of rhodamine 123 with HPD resulting in a diminished singlet oxygen production. With AIPc this does not take place.