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  • 1980-1984  (26)
  • Chemistry  (23)
  • Physics  (3)
  • Theoretical, Physical and Computational Chemistry
  • 1
    Electronic Resource
    Electronic Resource
    Key references in biomaterials: Bone/biomaterial interface in orthopedic joint implants (1984)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 18 (1984), S. 577-599 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820180511
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  • 2
    Electronic Resource
    Electronic Resource
    Adsorption of proteins from plasma to a series of hydrophilic-hydrophobic copolymers. I. Analysis with the in situ radioiodination technique (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 403-423 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adsorption of proteins affects cellular interactions with foreign surfaces and thus plays an important role in determining the biocompatibility of implants. Previous studies have indicated differences in the affinity of various proteins for a given polymer, and differences in the affinity of fibrinogen for a series of polymers varying in hydrophilicity. These studies suggest that differences in the composition of the protein layer adsorbed to polymers from plasma might exist. To examine this hypothesis, the proteins adsorbed from plasma to a series of polymers varying in hydrophilicity were analyzed with the iodogram technique. Copolymers of hydroxyethyl methacrylate and ethyl methacrylate made by the radiation grafting technique were exposed to plasma for 0.5 or 150 min. The adsorbed proteins were iodinated, eluted with SDS, and separated with polyacrylamide gel electrophoresis. Fibrinogen, immunoglobulin G, hemoglobin, and a peak tentatively ascribed to prothrombin were the major proteins detected. Very little iodine was incorporated into adsorbed albumin, even though it was shown to be present by a separate experiment using dye binding. The fraction of total radioactivity associated with each of nine proteins was found to vary markedly and systematically among the surfaces. The distribution of radioactivity into the proteins was very different on 0.5 and 150-min plasma exposed polymers. The results reflect both compositional differences in the adsorbed protein layer on the polymers and differences in the accessibility of proteins to the labeling reagent in the adsorbed state. Differences in the organization of the adsorbed protein layer may play a key role in determining whether cell surface receptors can come in contact with the specific plasma protein able to further stimulate the cell.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150311
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  • 3
    Electronic Resource
    Electronic Resource
    Adsorption of proteins from plasma to a series of hydrophilic-hydrophobic copolymers. II. Compositional analysis with the prelabeled protein techniqueSome of the results of this paper were presented at the World Biomaterials Congress held at Baden, Austria in April 1980. (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 673-695 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Plasma protein adsorption is an important initial event in the response of tissue to foreign materials. Little is known about the way in which the chemical properties of materials influence the nature of the adsorbed layer and thus the later cellular responses. In this study, the amounts of fibrinogen, immunoglobulin G, albumin, and hemoglobin adsorbed from plasma to a series of HEMA-EMA random copolymers varying in hydrophilicity was measured. The adsorption of each protein varied in a characteristic way with copolymer composition probably reflecting a different affinity of the proteins for the various copolymers. A complex variation in the composition of the adsorbed protein layer on polymers varying in hydrophilicity was thus evident. Surface enrichment of the proteins, calculated as the ratio of the surface and bulk fraction of each protein, also varied with copolymer composition, and indicated substantial differences in the composition of the surface and bulk phases. Surface area variations among the copolymers, preferential adsorption of 125I proteins, and the possibility of structural degradation of 125I proteins in plasma were investigated but did not appear to influence the adsorption results. The ability of polymers to fractionate plasma proteins and concentrate them at their surface is concluded to be a key factor in the complex processes which determine the compatibility of polymers in vivo.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150506
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  • 4
    Electronic Resource
    Electronic Resource
    A Class of Trinuclear Clusters with Carbonyl Bridging (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 29-49 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The impetus for this work was the structure of a trinuclear complex with two carbonyl groups showing incipient triple bridging - Cp2Rh3(CO)4-. Its structure, barrier to rotation of one Rh(CO)2- piece vs. the rest of the molecule, and the nature of the bridging carbonyl interaction are analyzed. Isolobal analogies form an interesting connection between this complex and a bridged isomer of the recently synthesized carbene complexes, Cp2Rh2(CO)2CR2, one isomer of Cp2Rh3(CO)3, and hypothetical carbyne complexes Cp2Rh2(CO)2CH+,-. A general bonding model for Cp2Rh2(μ-CO)2X complexes is constructed. The model, rich in geometrical detail, allows minima for the bridging carbonyl groups bending toward and away from the bonded ligand X.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630105
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  • 5
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. XVIPart XV, see [1].. Spectrophotometric and thermodynamic studies of solvents and unidentate ligands interaction with the pentacoordinate Co2+-, Ni2+- and Cu2+-complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 587-594 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of solvents and of unidentate ligands such as N3-, SCN-, OCN- and OH- with the Co2+-, Ni2+ and Cu2+-complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMC) have been studied by Spectrophotometric and calorimetric techniques. The spectra in different solvents (Table 2) show that the Ni2+- and probably also the Cu2+-complex with TMC exist as square planar or pentacoordinate species or as a mixture of both, depending on the donor properties of the solvent. The [Co(TMC)]2+-complex is pentacoordinate in all the solvents studied.Ternary complexes [M(TMC)X]n+ are also formed by the unidentate ligands X = N3-, OCN-, OH-, F- and NH3 and their stability constants have been determined. Interesting is the high selectivity of [Ni(TMC)]2+ towards the addition of a further donor (Table 3). Only small ligands such as those listed above form stable adducts, whereas the larger ones such as imidazole or pyridine do not. This is a consequence of the special structure of the complex and of the trans-I-(RSRS)- conformation of the ligand in these complexes. Since the four methyl groups are all on the side of the macrocycle to which the additional unidentate ligand binds, steric interaction between the four methyl groups and the larger ligands prevents the formation of the adducts.The calorimetric measurements show that the stability of the complexes [M(TMC)X]n+ is due to both an enthalpic and entropic contribution which differ in their magnitude (Table 4). This indicates that several antagonistic factors are important in determining the overall stability.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650218
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  • 6
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands, XVIIPart XVI, see [1].. Synthesis of two key intermediates for the preparation of mono-N-functionalized tetraazamacrocycles and their metal complexes (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 861-870 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With a modification of the cyclization procedure of Richman & Atkins [8] the two macrocycles 1,4,7-tritosyl-11-benzyl-1,4,7,11-tetraazacyclotetradecane (8) and 1,7,11-tritosyl-4-trityl-1,4,7,11-tetraazacyclotetradecane (15) were prepared. After selective cleavage of the benzyl and trityl group, respectively, one obtains the two key products 1,4,7-tritosyl-11-benzyl-1,4,7,11-tetraazacyclotetradecane (9) and 1,7,11-tritosyl-4-trityl-1,4,7,11-tetraazacyclotetradecane (16) which have three N-atoms protected by tosyl groups and one accessible for further reactions.To test some of the possibilities we have alkylated 9 and 16 with iodoacetamide, 1-tosyl-aziridine and acrylonitrile. After detosylation with HBr in glacial acetic acid in the presence of phenol mono-N-functionalized tetraazamacrocycles were thus obtained. The advantage of this synthesis is that the cyclization which is the most difficult step of the whole procedure, has to be done only once, regardless of the nature of the pendant arm. In addition a large number of derivatives can be prepared by varying the alkylation component.With Ni2+, Cu2+ and Zn2+ metal complexes of these new ligands were prepared and their IR. and VIS. spectra studied. In the case of the carbamoyl derivatives 12, 14 and 18 the Cu2+-complexes exist in two forms. Whereas at low pH the carboxamide group of the pendant arm is probably not bound to the metal ion, at high pH after deprotonation it coordinates in one of the axial positions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660319
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  • 7
    Electronic Resource
    Electronic Resource
    Zur Stabilität der Metallkomplexe von Methantriessigsäure und cis, cis-1,3,5-Cyclohexantricarbonsäure (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 1588-1592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stabilities of the Mn2+-, Co2+-, Ni2+-, Cu2+- and Zn2+-complexes with 2-(carboxymethyl)glutaric acid (2) and cis,cis-1,3,5-cyclohexanetricarboxylic acid (3) were measured potentiometrically at 25° and I = 0.5 (KNO3). Beside the complexes ML- protonated species MLH and MLH2+ are also formed. Their stability constants are given in Table 1. A comparison between the stabilities of 2 or 3 and those of acetate, as a model for a monocarboxylate, or succinate and glutarate, as examples for dicarboxylates, indicates that in all species only one carboxylate is strongly bound whereas the second and third ones are probably not.The observation that Δlog K1 = log KMLHLH - log KMLH2LH2 as well as Δlog K2 = log KMLL - log KMLHLH are practically constants with values of 0.34 ± 0.05 and 0.49 ± 0.07, respectively, for both ligands and the five metal ions studied is also in line with the proposed monodentate structures of the complexes ML-, MLH and MLH+2.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660527
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  • 8
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. Part XIXPart XVIII: [1].. Synthesis and Cu2+-complexes of a series of 12-, 14- and 16-membered cis- and trans-N2S2-macrocycles (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 29-38 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of 12-, 14-, and 16-membered N2S2-macrocycles (9-11 and 19-21) with cis and trans-arrangement of the heteroatoms have been synthesized by high-dilution cyclization and subsequent reduction of the amides with B2H6. With these ligands the corresponding Cu2+-complexes were prepared and their UV/VIS spectra, their electrochemistry and their EPR properties have been studied. Generally three absorption bands at 270-320 nm, 330-370 nm and 530-620 nm can be observed in aqueous solution and these have been assigned to the N→Cu2+ and S→Cu2+ charge-transfer bands and to the d-d* transition, respectively. The cyclic voltammetry in CH3CN shows in all cases a reversible or quasi-reversible Cu2+/Cu+-transition at potentials of 10-480 mV against SHE. The values of g‖ and A‖ obtained from EPR spectra indicate that the geometry of the Cu2+-complex of the 14-membered cis-N2S2-macrocycle is less distorted than that of the other complexes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670105
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  • 9
    Electronic Resource
    Electronic Resource
    Stabilities and Redox Properties of Cu(I) and Cu(II) Complexes with Macrocyclic Ligands Containing the N2S2 donor Set (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1060-1069 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexation of Cu(I) and Cu(II) by a series of 12-, 14- and 16-membered macrocyclic ligands 1-6 containing the N2S2 donor set has been studied potentiometrically, spectrophotometrically and voltammetrically.In the case of Cu(II), mononuclear complexes CuL2+ with stability constants of 1010-1015 are formed. In addition, partially hydrolyzed species Cu(L)OH+ are observed at pH 〉 10 for the 12-membered ligands. For Cu(I), beside the specis CuL+ with stabilities of 1012-1014, the unexpected formation of protonated species CuLH2+ was detected. In contrast to the well-known general trends in coordination chemistry, the stability of these protonated species increases relative to that of the complexes with the neutral ligand when the ring size and concomitantly the distance between neighbouring donor atoms is decreased. From the stability constants of the Cu(I)- and Cu(II)-complexes the redox potentials have been calculated and are compared to the values of E1/2 obtained by cyclic voltammetry. Despite the identical donor set the Cu(II)/Cu(I) redox potentials of the complexes are spanning a range of 340 mV or six orders of magnitude in relative stability, reflecting the importance of subtle differences in steric requirements.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670419
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  • 10
    Electronic Resource
    Electronic Resource
    Formation and dissociation mechanism of amide complexes. VPart IV, see [1]. Interconversion of dimeric and monomeric Cu2+-complexes with 1,8-diamino-3,6-diaza-2,7-octanedione: Comparison between the reactivity of terminal and internal amide groups (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 753-761 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The protonation and deprotonation rates of the coordinated amide groups in the Cu2+-complexes of 1,8-diamino-3,6-diaza-2,7-octanedione (DED = L) have been studied by stopped-flow techniques. Starting at low pH from Cu2+ and DED the dimeric Cu2L24+-complex, fully formed within the mixing time of the stopped-flow instrument, reacts in two consecutive steps to yield the final product CuLH-2. The rate constants of the forward and backward reactions have been determined and are given in Table 1. The intermediate was identified as Cu2L2H-22+ by measuring its VIS.-absorption spectrum.The rate constants for the interconversion of the amide groups from the O- to the N-coordinated form in the Cu2+-complexes of DED, 2,10-dioxo-1, 4, 8, 11 tetraazaundecane (DANA) and triglycine (TRIGLY) are compared with each other. It is shown that these rate constants are similar, no matter whether the amide group is terminal or internal as long as the rotation is easily possible as is the case in the dimeric species Cu2L24+ and Cu2L2H-22+. However, for CuLH-2 the inter-conversion only takes place after opening of one of the chelate rings in a rapid protonation preequilibrium.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650313
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