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  • 1
    Electronic Resource
    Electronic Resource
    Ligands for EuIII, FeIII, SrII, and UO2II Based on CMPO-Functionalized Resorcinarene Cavitands; Synthesis and Extraction (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2247-2254 
    Details
    ISSN: 0947-3440
    Keywords: Cavitands ; P ligands ; CMPO ; Europium extraction ; Radio tracers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partially functionalized cavitands (7a-d) have been synthesized starting from the tetrakis(bromomethyl)cavitand 6. New cavitand-based cation ligands, with one to three carbamoylmethylphosphane oxide (CMPO) moieties (11a-d), were prepared in good (66-90%) yields. The ligands 11a-d extract EuIII, but do so less effectively than the tetra-CMPO cavitand 1. The decreasing number of CMPO groups which result in decreasing extraction percentages for EuIII, also decrease the selectivity of EuIII over that of FeIII, SrII, and UO2II. There is a difference in extraction behavior, determined by radio-tracer experiments, between the distal and proximal disubstituted ligands, 11b and 11c, respectively. The extraction constants for the 1:1 complex of 11b and 11c with Eu(picrate)3 are Kex = 6.7 · 108 M-4 and 3.7 · 109 M-4, respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971111
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Application of Iso(thio)cyanate-Functionalized Calix[4]arenes (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2235-2245 
    Details
    ISSN: 0947-3440
    Keywords: Calix[4]arenes ; Cavitands ; Iso(thio)cyanates ; Carbamates ; (Thio)ureas ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminocalix[4]arenes 7-12 react with triphosgene and thiophosgene to the corresponding iso(thio)cyanate-functionalized calix[4]arenes 13-20. Carbamate- (21-25) and ureasubstituted calix[4]arenes (26,27) can be obtained via isocyanatocalix[4]arenes using a one-pot synthesis starting from the corresponding aminocalix[4]arenes in moderate to good yields. Isothiocyanate-functionalized calix[4]arenes 16, 18 react selectively with amines to the corresponding thioureas 28-31 in 59-83% yield. Reaction of isothiocyanate-functionalized calix[4]arenes 16, 19, 20 with cavitands 34, 38 gives 2:2 products 42-45 in 35-42% yield.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971110
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  • 3
    Electronic Resource
    Electronic Resource
    A Modular Approach to Potential Synthetic Receptors with Large Surfaces Based on Crown[n]cavitands (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1597-1607 
    Details
    ISSN: 1434-193X
    Keywords: Cavitands ; Crown compounds ; Calix[4]arenes ; Building blocks ; Modular approach ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crown[n]cavitands were synthesized by alkylation of tetrahydroxycavitands with polyethyleneglycol ditosylates. The bridging of two hydroxy groups at adjacent aromatic rings by a pentaethyleneglycol unit is favored over the bridging of two hydroxy groups at opposite aromatic rings. The presence of a sodium base enhances the formation of the 1,2-crown[n]cavitand and improves the yield. The combination of 1,2-crown[6]cavitands with calix[4]arenes or resorcin[4]arenes resulted in potential receptor molecules with large hydrophobic surfaces.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of (Hemi)Carceplex Adsorbates for Self-Assembly on Gold (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 269-274 
    Details
    ISSN: 1434-193X
    Keywords: Cage compounds ; Calixarenes ; Cavitands ; Carcerands ; Gold ; Interfaces ; Monolayers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of sulfide-functionalized (hemi)carceplexes suitable for self-assembly on gold is described. A noncentrosymmetrical carceplex 9 (guest DMF) was synthesized by the combination of calix[4]arene 4 and resorcin[4]arene 3, while a noncentrosymmetrical hemicarceplex 12 (guest NMP) was prepared by the combination of two different resorcin[4]arenes, 3 and 10. These adsorbates form ordered self-assembled monolayers on gold with their quasi C4v axis perpendicular to the surface. The two positions possible for the incarcerated guest lead to diastereotopic surfaces.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Novel Ligands for the Separation of Trivalent Lanthanides and Actinides - Tetrakis(phosphane sulfide) and -(phosphinic acid) Cavitands (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 665-674 
    Details
    ISSN: 1434-193X
    Keywords: Cavitands ; Nuclear waste ; Actinide/lanthanide separation ; Solvent extraction ; Sulfur atoms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Cavitands with phosphane sulfide moieties 4 and 8a,b were prepared in good yields from their phosphane oxide analogues, as more stable alternatives for the dithiophosphinic acids used at present. The cavitands 7a and 7b with flexible butoxyphosphane oxide ligating sites are more efficient than cavitand 3 having rigid methylphosphane oxide groups as was studied with EuIII picrate extractions. Due to the absence of an ionic functionality in the phosphane sulfides 4 and 8a,b AmIII and EuIII are not extracted, not even in the presence of synergents (e.g. TBP, TOPO, HDNNS). Cavitand 10 with phosphinic acid groups efficiently extracts EuIII in 1:1 or 2:1 complexes, depending on the metal-to-ligand concentration ratio (extraction constants Kex1 = 3.9·10-5M2 and Kex2 = 1.9·102M, respectively). Furthermore, in the case of 10 EuIII is preferentially extracted over AmIII with a separation factor SEu/Am up to 5.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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