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  • 1
    Electronic Resource
    Electronic Resource
    Concave Macrobicycles: Absorption Spectra, Luminescence Properties, and Endocavital Complexation of Neutral Organic Guests (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1697-1704 
    Details
    ISSN: 0947-3440
    Keywords: Alkyne bridges ; Charge transfer ; Host compounds ; Molecular cavities ; Toposelectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By a mild modified Eglinton coupling a series of diynebridged macrobicyclic hosts capable of endocavital complexation were synthesized and their structures and complexation properties investigated by X-ray analysis. The inclusion of DMSO in 7 suggests a direct correlation between steric fit and orientation of the guest. On the basis of this hypothesis, the orientation of acetone in an endocavital inclusion of 2 was predicted and verified by X-ray analysis. Comparison of the single-crystal X-ray structures of the vacant macrobicycle 3 and of a family of macrobicycles showing endocavital or “pocket” complexation of neutral organic guests suggests that torsion of the cavities upon complexation results from induced fit. Hydrogenation of the triple bonds leads to the more flexible macrobicycles 10-12 with collapsable cavities. The absorption and emission spectra of the diynebridged macrobicyclic hosts 1 and 3, of their hydrogenated analogues 11 and 12, and of a hemicage parent compound of 2 (14) were investigated. The macrobicyclic compounds 3, 11, 12 and 14 exhibit a strong fluorescence in CH2Cl2 solution at room temperature. The lack of fluorescence of 2 under such conditions is attributed to the presence of low-energy charge-transfer excited states, as indicated by the charge-transfer bands in the absorption spectrum. In a rigid CH2Cl2 matrix at 77 K all the examined compounds are fluorescent.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961102
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  • 2
    Electronic Resource
    Electronic Resource
    Macrocyclic Ethers and Their Inclusion Complexes (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 749-754 
    Details
    ISSN: 0947-6539
    Keywords: clathrates ; host-guest chemistry ; hydrogen bonds ; macrocyclic ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterisation of eleven new macrocyclic ethers (up to 96-membered [6+6] gigantocycle) with well-defined cavities are described. Syntheses of the macrocycles M1-M7 were performed under high-dilution conditions. A “supramolecular” purification method was used for the small [2+2] macrocycles M3-M7, which separated selectively from the reaction mixture on recrystallisation from a dichloromethane/diethyl ether solution mixture. This proved to be an excellent method for purifying [2+2] macrocyclic ethers containing 1,1-diphenylmethane moieties, and the separation was nearly quantitative. Molecular inclusion of dichloromethane in the cavities of noncovalently bonded macrocyclic ethers M2-M5 was studied by X-ray diffraction in the solid state. Additionally, clathrate formation was found for macrocycles M1 (including diethyl ether), M2 (including water), M6 (including benzene) and M7 (including benzene).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030515
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  • 3
    Electronic Resource
    Electronic Resource
    Regioselective Complexation of New Multiple Piperazine/Pyridine Ligands: Differentiation by 113Cd-NMR Spectroscopy (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1353-1359 
    Details
    ISSN: 0009-2940
    Keywords: 113Cd NMR ; Multidentate ligand ; Multinuclear metal complex ; Piperazine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eleven novel piperazine containing open-chain ligands L1-L11 were designed to offer symmetrical and asymmetrical complexation sites for metal ions and were synthesized by repetitive synthetic method. The divergent use of aromatic bishalomethyl and mono-N-alkylated piperazine compounds as spaces led toa series of long (up to M. W. = 836) oligomeric multidentate N-ligands. Due to the lack of solid state methods for structure analysis, an NMR technique using 113 Cd nucleus as a probe in solution state was utilised. 113 Cd chemical shifts were observed to be dependend on the coordination site and similar coordination sites in different ligands gave characteristically similar 113 Cd chemical shifts. As a result 113 Cd-NMR spectroscopy proved to be an excellent tool to distinguish between the structures of the different complexation sites on a nearly quantitative level.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300929
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  • 4
    Electronic Resource
    Electronic Resource
    Syntheses and Reactivity of Aminobis(diorganylamino)phosphanesDedicated to Prof. Dr. Drs. h.c. H. G. von Schnering on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 911-917 
    Details
    ISSN: 0009-2940
    Keywords: Aminobis(diorganylamino)phosphanes ; P-Hydrophosphane imine ; Complexation reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminobis(diorganylamino)phosphanes (R2N)2PNH2 (R = iPr, c-Hex, Ph) (2a-c), were obtained by treatment of the corresponding chlorobis(diorganylamino)phosphanes 1a-c with lithium amide in liquid ammonia. The transition metal phosphane complex (R2N)2(H2N)PNi(CO)3 (3) was prepared by reaction of 2a with tetracarbonylnickel. N-Complexation of 2a with trimethylalane affords the iminophosphorane-alane adduct (R2N)2HP=N(H)AlMe3 (4) by 1,2-H shift from the nitrogen to the phosphorus atom. The corresponding reaction with aluminium trichloride leads to the formation of the salt [(R2N)2HP=N(H)]2AlC12+[AlC14]- (5), in which two iminophosphorane moieties are linked by an AlCl2 bridge. Lithiation of 2a and subsequent reaction with titanocene dichloride result in nucleophilic replacement of one chlorine atom to give the phosphanylamido-substituted titanocene compound (R2N)2P-N(H)Ti(Cl)Cp2 (6a), which rearranges to its P-hydroiminophosphorane tautomer (R2N)2P(H)=NTi(Cl)Cp2 (6b) on gentle heating. No isomerisation was observed in the case of N-borylated aminophosphane (R2N)2P-NH-(9-BBN) (7), obtained by reaction of lithiated 2a with B-Cl-9-BBN. The X-ray structure analyses of compounds 2b, c, 3, 4, 5, and 6a are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290806
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