ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Reactivity of [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)], a Complex Containing the Tridentate Ligand [HC(PPh2)2]- (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 121-124 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Acetylacetonate ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)] (1) is obtained by various procedures: a) by reaction of [Ph3PAuCH (PPh2AuPPh2)2CHAuPPh3](ClO4) 2 with NBu4[Au(acac)Cl], b) by reaction of [ClAuCH(PPh2AuPPh2)2CHAuCl] with [Au(acac)PPh3] or with Tl(acac) and c) by reaction of [ClAuPPh2CH2PPh2AuCl] with Tl(acac). The acetylacetonato ligand can act as deprotonating agent; thus, complex 1 reacts with (phosphane)gold complexes, [Au(C6F5)2{(PPh2)2-CH2)]ClO4, [Au(C6F5)3(PPh2CH2PPh2)] or [Au(PPh3)2]ClO4, to give the hexanuclear complexes [(C6F5)2Au{(PPh2)2CH} AuCH(PPh2AuPPh2)2CHAu{CH(PPh2)2) Au(C6F5)2](ClO4)2, [(C6F5)3Au(PPh2CHPPh2)AuCH (PPh2AuPPh2)2CHAu-(PPh2CHPPh2)Au(C6F5)3] or [(Ph3PAu)2C(PPh2AuPPh2)2C-(AuPPh3)2](ClO4)2, respectively. The crystal structure of 1 has been established by X-ray crystallography and displays two independent eight-membered rings with inversion symmetry and short transannular gold-gold contacts. The first ab initio results for a transannular AuI-AuI interaction are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Further calculations on the internal rotation spectrum of phenol (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 22 (1982), S. 681-690 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of a small deformation of CĈO angle in phenol (tilt), into the rotational far-infrared (FIR) spectrum is analyzed using several approaches. In all of them, the CNDO/2 method is used to determine the potential energy functions. In a first step, the C—O bond and the rotation axis are both supposed to coincide with the C2 symmetry axis of the phenyl group. With this assumption the torsional frequencies are calculated in both the symmetric and asymmetric rotor approximations. In a second step, the tilt of the C—OH bond is determined theoretically and found to be -3°, measured from the C2 symmetry axis, the C—OH bond crossing this axis, Using this second geometry, and taking as the rotation axis the C2 axis, the torsional frequencies are again determined in both approximations. An improvement of the calculated transition energies is encountered at each stage of the calculation, when compared with experimental data. Finally the importance of the introduction of a tilt into the FIR torsional frequency calculations is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560220403
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Classical and quantum mechanical calculations of conformational probability density distributions. Two-rotor molecules (1986)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 29 (1986), S. 553-562 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study the dynamical structure of a two-rotor molecule, such as acetone, as a function of temperature, conformational probability density distributions are computed by using three different approaches: the so-called current approach, the classical approach, and the quantum mechanical oscillator approach. It is found that the three procedures yield comparable results, at least at normal temperature (25°C), although the current and, especially, the classical approaches give rise to too sharp distributions when compared with the quantum mechanical results. Owing to its simplicity, the current approach may be used advantageously, and it is easily extendible to many-rotor systems. Finally, it is verified that deuteration does not affect appreciably the conformation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560290327
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Exploring the potential energy hypersurface of histamine monocation: Tautomerism in gas phase (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 727-740 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential energy hypersurface of the histamine monocation is determined by ab initio methods at the STO-4G level using analytical gradient techniques. Three transition states and two minima have been found for the Nτ—H tautomer. One of the transition states connects the trans conformational region with a minimum gauche structure, where the proton of the ammonium group is approximately halfway between the Nπ of the imidazole group and the N of the ammonium group, but nearer to the Nπ. This minimum connects the potential energy surface of the Nτ—H tautomer with the imidazolium one. In the latter region, three transition states and two minima have been found. Critical points are discussed in relation with experimental data and histamine H2 receptor models.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560380513
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Coordination Compounds of Coinage Metals with Vinylidenebis(diphenyl-phosphane) and Its Disulfide and Their Reactivity towards NucleophilesDedicated to Professor P. Royo on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1513-1517 
    Details
    ISSN: 0009-2940
    Keywords: Gold ; Silver ; Diphosphane ; Diphosphane Disulfide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylidenebis(diphenylphosphane) reacts with gold(I) or gold(III) compounds to give dinuclear {[{Au(C6F5)]2[(PPh2)2C=CH2{] or [Au{PPh2C(=CH2)Ph2P)]2(ClO4)2] or mononuclear complexes ([Au(C6F5)3(PPh2C(=CH2)Ph2P)]}, respectively. The latter reacts with gold(I) or silver(I) compounds to afford dinuclear [[Au(C6F5)3[PPh2C(=CH2)Ph2P}AuX], X=Cl or C6F5) or trinuclear species {[{Au(C6F5)3{PPh2C(=CH2)Ph2P{]2M]ClO4, M=Au or Ag}. No addition of nucleophiles to the C=C double bond is observed in these complexes, which contain the diphosphane acting as bridging or monodentate ligand. (SPPh2)2C=CH2 reacts with AgClO4 to give [Ag{SPPh2C(=CH2)Ph2PS}]2-(ClO4)2or[Ag[PPh2C(=CH2)Ph2P]2]ClO4. The crystal structure of [Au(C6F5)3{PPh2C(=CH2)Ph2P}Au(C6F5)] has been established by X-ray crystallography, and confirms the expected square planar and linear geometry for the Au111 and Au1 centres, respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301026
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of Silver(I) Complexes with the Bis(diphenylphosphanyl)-o-carborane Ligand. Crystal Structure of [Ag(phen){(PPh2)2C2B10H10}]ClO4 and [Ag{(SPPh2)2CH2}{(PPh2)2C2B10H10}]ClO4 · CH2Cl2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 835-840 
    Details
    ISSN: 0009-2940
    Keywords: Silver(I) complexes ; Bis(diphenylphosphanyl)-o-carborane ; o-Carborane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silver(I) perchlorate or nitrate react readily with bis(di-phenylphosphanyl)-o-carborane to give the complexes [AgX{(PPh2)2C2B10H10}] [X = ClO4 (1), NO3, (2)]. The perchlorate ligand is weakly bound to the silver atom and thus can be displaced by other ligands affording the three-coordinated complexes [AgL{(PPh2)2C2B10H10}]ClO4 [L = PPh3 (3), PPh2Me (4), AsPh3 (5), C5H4NCOOH (6), C9H6NCOOH (7), SPPh3 (8)]. Compounds 3 and 4 can also be obtained by reaction of [Ag(OClO3)PR3] with the diphosphane. Treatment of complex 1 with bidentate ligands leads to the cationic four-coordinated [Ag(L—L){(PPh2)2C2B10H10}]ClO4 [L—L = (PPh2)2C2B10H10 (9), bipy (10), phen (11), (SPPh2)2CH2 (12)] or to the neutral [Ag(S2CNR2){(PPh2)2C2B10H10}] [NR2 = NEt2 (13), NC4H8 (14)]. The crystal structures of 11 and 12 have been established by X-ray crystallography. In both complexes the silver(I) atoms exhibit tetrahedral coordination by two phosphorus and two nitrogen or two sulfur atoms, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270508
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Gold(I) and Silver(I) Complexes with Methanide Ligands [C{PPh2(X)}3]- (X = O, S). Crystal Structures of [M{C(PPh2(X))3}(PPh3)] (M — Au, X — O; M — Ag, X — S) (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 585-588 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Silver complexes ; Triphosphane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal complexes (M(acac)(PPh3)] act as deprotonating agents in the reaction with equimolar amounts of [CH{PPh2(X)}3)] to give the neutral complexes [M{C(PPh2(X))3}(PPh3)] [M = Ag, X = O (1) or S (2); M = Au; X = O (3) or S (4)]. The crystal structures of 2 and 3 have been established by X-ray crystallography. In the structure of 2 (two independent molecules) the silver(I) atoms display a distorted tetrahedral coordination by phosphorus (of PPh3) and three sulfur atoms. In complex 3 the gold(I) atom exhibits linear coordination by phosphorus of PPh3 and the carbon atom of [C{PPh2 (O)}3]-. The reaction of [CH{PPh2(X)}3] with [Ag(CF3SO3)] or [Ag(CF3SO3)(PPh3)] (molar ratio 1:1) leads to [Ag(CF3SO3){CH(PPh2(X))3}] [X = O (5), S (6)] or [Ag(CH(PPh2 (S))3}(PPh3)](CF3SO3) (7), respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290518
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    facet.materialart.
    Unknown
    Polar Alkaloids from the Caribbean Marine Sponge Niphates digitalis (2011)
    Details
    Publication Date: 2021-05-19
    Description: A method involving flash chromatography, semi-preparative phenylhexyl RP HPLC-DAD-ELSD combined with analytic polar-RP HPLC-DAD, was applied to separate and purify six highly nitrogenated bases and a bicyclic amidine alkaloid, the major components of the marine sponge Niphates digitalis. Their structures were identified as 1,8-diazabicyclo[5.4.0]undec-7- ene (1), deoxycytidine (2), phenylalanine (3), adenosine (4), deoxyguanosine (5), adenine (6) and thymidine (7) on the basis of spectroscopic data analyses. This is the first report of these compounds in a marine sponge belonging to the Niphates genus and the first evidence of the presence of 1 from a natural source.
    Description: Published
    Description: Marine sponge, Niphates digitalis, nucleosides, nucleobases, antimalarial activity, cytotoxicity
    Keywords: Cytotoxicity ; Sponges ; Sponges ; Cytotoxicity
    Repository Name: AquaDocs
    Type: Journal Contribution
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 9
    facet.materialart.
    Unknown
    Las esponjas marinas como fuente de nuevas sustancias bioactivas. (2011)
    Details
    Publication Date: 2021-05-19
    Description: Marine sponges (Porifera) have drawn the attention from a broad number of researchers all over the world. These animals and their simbionts are specialized in chemical warfare, producing biologically active chemical substances as an effective defense against predators. They have been considered a goldmine to chemists, from which have been discovered more than 6000 novel structures; many of them, with enormous biomedical applications, mainly against cancer, but also against bacteria, viruses and other diseases. Some of the sponge-derived drugs are available in the market, such as: Ara-A (antiviral) and Ara-C (anticancer), but there are diverse bioactive compounds under clinical trials. In Cuba, the researches related to the isolation of compounds from marine sponges are scarce and the initial studies were about pharmacological evaluations of extracts and fractions. In recent studies, three sponges were investigated (Agelas cerebrum, Niphates digitalis and Pandaros acanthifolium), from which were isolated and identified 45 metabolites, two of them were isolated for the first time as natural products, including the discovery of 30 novel metabolites, dividing in two new families of steroidal saponins with uncommon chemical characteristics and potential against several parasitic protozoa and tumor human cell lines.
    Description: Published
    Description: marine sponges, novel compounds, bioactive metabolites, antiparasitic, antitumoral
    Keywords: Sponges ; Organic compounds ; Antiparasitic agents
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 10
    facet.materialart.
    Unknown
    Bromopyrrole alkaloids from the Caribbean sponge Agelas cerebrum (2011)
    Sociedade Brasileira de Química
    Details
    Publication Date: 2021-05-19
    Description: Bioguided fractionation of Agelas cerebrum crude extract resulted in isolation of four bromopyrrole and four bromopyrrole aminoimidazole alkaloids, identified as 5-bromopyrrole-2-carboxylic acid (1), 4-bromopyrrole-2-carboxylic acid (2), 3,4-bromopyrrole-2-carboxylic acid (3), 4,5-bromopyrrole-2-carboxylic acid (4), oroidin (5), bromoageliferin (6), dibromoageliferin (7) and dibromosceptrin (8) on the basis of spectroscopic data analyses (UV, IR, HRMS, 1D and 2D NMR) and comparison with literature data. This is the first report of compounds 2 and 3 in a marine sponge belonging to the Agelas genus and the first evidence of the presence of 1 from a natural source.
    Description: Published
    Description: Agelas cerebrum, bromopyrrole alkaloids, antitumoral, antiprotozoal activity
    Keywords: Chemistry ; Alkaloids ; Sponges ; Alkaloids ; Sponges ; Chemistry
    Repository Name: AquaDocs
    Type: Journal Contribution
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...