33977-38-7Relevant articles and documents
A fullerene helical peptide: synthesis, characterization and formation of self-assembled monolayers on gold surfaces
Nasrallah, Houssein,Rabah, Jad,Bui-Thi-Tuyet, Van,Baczko, Krystyna,Fensterbank, Hélène,Bourdreux, Flavien,Goncalves, Anne-Marie,Declerck, Valérie,Boujday, Souhir,Humblot, Vincent,Wright, Karen,Vallée, Anne,Allard, Emmanuel
supporting information, p. 19423 - 19432 (2018/12/13)
The synthesis of a C60-peptide using “clickable” fullerene and peptide derivatives is described. The peptide is composed of a repeating sequence of α-aminoisobutyric acid (Aib) and two l-alanine (Ala) residues, promoting the formation of a helical conformation, which has been confirmed by IR absorption, NMR and circular dichroism measurements. In addition, the presence of a lipoyl moiety, at the end of the peptide sequence, allows the formation of self-assembled monolayers of the C60-peptide and the parent peptide on a gold surface. A C60-alkyl derivative was also prepared to compare the self-assembly properties of fullerene derivatives containing peptides or alkyl chains. The fullerene assembly on a gold substrate characterized by quartz crystal microbalance and by cyclic voltammetry show that the monolayers containing alkyl chains are slightly less well packed than the peptide monolayers. Finally, polarization modulation reflection adsorption infra-red spectroscopy measurements indicate that the C60-peptide tends to be more vertical than the parent peptide which could originate from complementary C60-C60 and helical-helical interactions.
Influence of calcium-induced aggregation on the sensitivity of aminobis(methylenephosphonate)-containing potential MRI contrast agents
Henig, Joerg,Mamedov, Ilgar,Fouskova, Petra,Toth, Eva,Logothetis, Nikos K.,Angelovski, Goran,Mayer, Hermann A.
body text, p. 6472 - 6481 (2011/08/07)
A novel class of 1,4,7,10-tetraazacyclododecane-1,4,7- tris(methylenecarboxylic) acid (DO3A)-based lanthanide complexes with relaxometric response to Ca2+ was synthesized, and their physicochemical properties were investigated. Four macrocyclic ligands containing an alkyl-aminobis(methylenephosphonate) side chain for Ca 2+-chelation have been studied (alkyl is propyl, butyl, pentyl, and hexyl for L1, L2, L3, and L4, respectively). Upon addition of Ca2+, the r1 relaxivity of their Gd3+ complexes decreased up to 61% of the initial value for the best compounds GdL3 and GdL4. The relaxivity of the complexes was concentration dependent (it decreases with increasing concentration). Diffusion NMR studies on the Y3+ analogues evidenced the formation of agglomerates at higher concentrations; the aggregation becomes even more important in the presence of Ca2+. 31P NMR experiments on EuL1 and EuL4 indicated the coordination of a phosphonate to the Ln3+ for the ligand with a propyl chain, while phosphonate coordination was not observed for the analogue bearing a hexyl linker. Potentiometric titrations yielded protonation constants of the Gd 3+ complexes. log KH1 values for all complexes lie between 6.12 and 7.11 whereas log KH2 values are between 4.61 and 5.87. Luminescence emission spectra recorded on the Eu3+ complexes confirmed the coordination of a phosphonate group to the Ln3+ center in EuL1. Luminescence lifetime measurements showed that Ca-induced agglomeration reduces the hydration number which is the main cause for the change in r1. Variable temperature 17O NMR experiments evidenced high water exchange rates on GdL1, GdL2, and GdL3 comparable to that of the aqua ion.
