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61.
D. Braun 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):379-387
Indole-containing bifunctional monomers (diacids, dialcohols, and dialdehydes) were synthesized by using as the basic nucleus two indoles attached by a tetraethylene glycol chain. These monomers were used for the preparation of polyesters, poly-amides, and polyazomethines. 相似文献
62.
I. A. Rodin A. N. Stavrianidi A. V. Braun O. A. Shpigun 《Moscow University Chemistry Bulletin》2013,68(3):127-142
Ginsenosides are the main bioactive compounds of the Panax plant genus. Ginseng and its analogues are widely used to produce traditional medicines in China, Korea, Japan, United States, and the Russian Far East. For more than 40 years, many researchers developed methods of identifying and determining and ginsenosides in plant tissues, extracts, and commercial products. Various extraction methods were used to isolate these compounds from plant materials. The separation of ginsenosides was conducted with methods such as gas chromatography, thin-layer chromatography, and high-performance liquid chromatography (HPLC). The HPLC method was used predominantly. Spectrophotometric and fluorescent monitoring and, later, light scattering and mass-spectrometry coupled with HPLC were used to determine ginsenosides. The most recent variants of these methods are presented in this review, together with a critical evaluation of the published results. 相似文献
63.
Let U(g) be the enveloping algebra of a finite dimensional reductive Lie algebra g over an algebraically closed field of prime characteristic. Let U?,P(s:) be the simply connected quantum enveloping algebra at the root of unity ? , of a complex semi-simple finite dimensional Lie algebra s:. We show, by similar proofs, that the centers of both are factorial. While the first result was established by R. Tange [32] (by different methods), the second one confirms a conjecture in [4]. We also provide a general criterion for the factoriality of the centers of enveloping algebras in prime characteristic. 相似文献
64.
Sabrina I. Kallne Thomas Braun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(35):9465-9469
An unprecedented reaction pathway for the borylation of SCF3‐containing arenes using [Rh(Bpin)(PEt3)3] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C H activations occur with a unique regioselectivity for the position ortho to the SCF3 group, which apparently serves as directing group. Borylated SCF3 compounds can serve as versatile building blocks. 相似文献
65.
Solomon Tesfaye Hannah Braun Kaleab Asres Ephrem Engidawork Anteneh Belete Ilias Muhammad Christian Schulze Nadin Schultze Sebastian Guenther Patrick J. Bednarski 《Molecules (Basel, Switzerland)》2021,26(12)
Medicinal plants have been traditionally used to treat cancer in Ethiopia. However, very few studies have reported the in vitro anticancer activities of medicinal plants that are collected from different agro-ecological zones of Ethiopia. Hence, the main aim of this study was to screen the cytotoxic activities of 80% methanol extracts of 22 plants against human peripheral blood mononuclear cells (PBMCs), as well as human breast (MCF-7), lung (A427), bladder (RT-4), and cervical (SiSo) cancer cell lines. Active extracts were further screened against human large cell lung carcinoma (LCLC-103H), pancreatic cancer (DAN-G), ovarian cancer (A2780), and squamous cell carcinoma of the esophagus (KYSE-70) by using the crystal violet cell proliferation assay, while the vitality of the acute myeloid leukemia (HL-60) and histiocytic lymphoma (U-937) cell lines was monitored in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) microtiter assay. Euphorbia schimperiana, Acokanthera schimperi, Kniphofia foliosa, and Kalanchoe petitiana exhibited potent antiproliferative activity against A427, RT-4, MCF-7, and SiSo cell lines, with IC50 values ranging from 1.85 ± 0.44 to 17.8 ± 2.31 µg/mL. Furthermore, these four extracts also showed potent antiproliferative activities against LCLC-103H, DAN-G, A2780, KYSE-70, HL-60, and U-937 cell lines, with IC50 values ranging from 0.086 to 27.06 ± 10.8 µg/mL. Hence, further studies focusing on bio-assay-guided isolation and structural elucidation of active cytotoxic compounds from these plants are warranted. 相似文献
66.
As a first step towards computing instanton-generated superpotentials in heterotic standard model vacua, we determine the Gromov–Witten invariants for a Calabi–Yau threefold with fundamental group π1(X)=Z3×Z3. We find that the curves fall into homology classes in H2(X,Z)=Z3⊕(Z3⊕Z3). The unexpected appearance of the finite torsion subgroup in the homology group complicates our analysis. However, we succeed in computing the complete genus-0 prepotential. Expanding it as a power series, the number of instantons in any integral homology class can be read off. This is the first explicit calculation of the Gromov–Witten invariants of homology classes with torsion. We find that some curve classes contain only a single instanton. This ensures that the contribution to the superpotential from each such instanton cannot cancel. 相似文献
67.
Stefan Sander Dr. Robert Müller Dr. Mike Ahrens Prof. Dr. Martin Kaupp Prof. Dr. Thomas Braun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(57):14287-14298
The reaction of [PtCl2(COD)] (COD=1,5-cyclooctadiene) with diisopropyl-2-(3-methyl)indolylphosphine (iPr2P(C9H8N)) led to the formation of the platinum(ii ) chlorido complexes, cis-[PtCl2{iPr2P(C9H8N)}2] ( 1 ) and trans-[PtCl2{iPr2P(C9H8N)}2] ( 2 ). The cis-complex 1 reacted with NEt3 yielding the complex cis-[PtCl{κ2-(P,N)-iPr2P(C9H7N)}{iPr2P(C9H8N)}] ( 3 ) bearing a cyclometalated κ2-(P,N)-phosphine ligand, while the isomer 2 with a trans-configuration did not show any reactivity towards NEt3. Treatment of 1 or 3 with (CH3)4NF (TMAF) resulted in the formation of the twofold cyclometalated complex cis-[Pt{κ2-(P,N)-iPr2P(C9H7N)}2] ( 4 ). The molecular structures of the complexes 1–4 were determined by single-crystal X-ray diffraction. The fluorido complex cis-[PtF{κ2-(P,N)-iPr2P(C9H7N)}{iPr2P(C9H8N)}] ⋅ (HF)4 ( 5 ⋅ (HF)4) was formed when complex 4 was treated with different hydrogen fluoride sources. The Pt(ii ) fluorido complex 5 ⋅ (HF)4 exhibits intramolecular hydrogen bonding in its outer coordination sphere between the fluorido ligand and the NH group of the 3-methylindolyl moiety. In contrast to its chlorido analogue 3 , complex 5 ⋅ (HF)4 reacted with CO or the ynamide 1-(2-phenylethynyl)-2-pyrrolidinone to yield the complexes trans-[Pt(CO){κ2-(P,C)-iPr2P(C9H7NCO)}{iPr2P(C9H8N)}][F(HF)4] ( 7 ) and a complex, which we suggest to be cis-[Pt{C=C(Ph)OCN(C3H6)}{κ2-(P,N)-iPr2P(C9H7N)}{iPr2P(C9H8N)}][F(HF)4] ( 9 ), respectively. The structure of 9 was assigned on the basis of DFT calculations as well as NMR and IR data. Hydrogen bonding of HF and NH to fluoride was proven to be crucial for the existence of 7 and 9 . 相似文献
68.
Matthias Brendel Carolin Braun Dr. Frank Rominger Prof. Dr. Peter Hofmann 《Angewandte Chemie (International ed. in English)》2014,53(33):8741-8745
For a long time d10‐ML2 fragments have been known for their potential to activate unreactive bonds by oxidative addition. In the development of more active species, two approaches have proven successful: the use of strong σ‐donating ligands leading to electron‐rich metal centers and the employment of chelating ligands resulting in a bent coordination geometry. Combining these two strategies, we synthesized bis‐NHC chelate complexes of nickel(0) and platinum(0). Bis(1,5‐cyclooctadiene)nickel(0) and ‐platinum(0) react with bisimidazolium salts, deprotonated in situ at room temperature, to yield tetrahedral or trigonal‐planar bis‐NHC chelate olefin complexes. The synthesis and characterization of these complexes as well as a first example of C? C bond activation with these systems are reported. Due to the enforced cis arrangement of two NHCs, these compounds should open interesting perspectives for bond‐activation chemistry and catalysis. 相似文献
69.
Dilcan Dirican Nils Pfister Martin Wozniak Prof. Dr. Thomas Braun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(31):6945-6963
Binary sulfur fluorides exhibit an interesting reactivity towards transition metal complexes. They open up routes for the generation of sulfur-containing building blocks. Often ligands with particular properties can be constructed. This includes their ability to transfer sulfur atoms or polysulfide units as well as fluorination reactions. This Minireview provides an insight into the reactivity of the binary and ternary sulfur halides S2Cl2, SCl2, SF4, SF6 and SF5Cl towards transition-metal compounds. 相似文献
70.