22029-44-3Relevant academic research and scientific papers
Triethylenetetramine penta- and hexa-acetamide ligands and their ytterbium complexes as paraCEST contrast agents for MRI
Burdinski, Dirk,Lub, Johan,Pikkemaat, Jeroen A.,Jalón, Diana Moreno,Martial, Sophie,Del Pozo Ochoa, Carolina
experimental part, p. 4138 - 4151 (2009/03/11)
The ligand triethylenetetramine-N,N,N′,N″,N′″, N′″-hexaacetamide (ttham) was synthesized with the aim of forming lanthanide complexes suitable as contrast agents for magnetic resonance imaging applications utilizing the chemical exchange-dependent saturation transfer (CEST) effect. It was designed to exclude water molecules from the first coordination sphere and provide a high number of CEST active amide protons per lanthanide ion. The ligand was characterized by its protonation behavior and its complexation properties with ytterbium ions in aqueous solution. The basicity of the ttham backbone amine protons decreases in the order N central(1) > Nterminal(1) > Nterminal(2) > Ncentral(2), as deduced from NMR titration experiments and from a comparison of its protonation constants with those of two ttham derivatives, in which either a terminal (N-benzyl-triethylenetetramine-N,N′,N″, N′″,N′″-pentaacetamide, 1bttpam) or a central acetamide group (N′-benzyl-triethylenetetramine-N,N,N″,N′″, N′″-pentaacetamide, 4bttpam) is substituted with a benzyl group. This protonation sequence results from the combined influence of inductive effects, the intramolecular hydrogen bonding network, and the Coulomb repulsion between protonated ammonium groups. The ytterbium complex of ttham, [Yb(ttham)]Cl3, is coordinatively frustrated. Due to steric constraints, in addition to the four backbone nitrogen atoms, only three of the four symmetry-equivalent terminal acetamide donors can coordinate simultaneously to the ytterbium ion, and the dangling fourth one exchanges quickly with the other three. The ytterbium complexes of a total of five ligands (ttham, 1bttpam, 4bttpam, 2,2′,2″-triaminotriethylaminehexaacetamide (ttaham), and diethylenetriamine-N,N,N′,N″,N″-pentaacetamide (dtpam)) were studied with respect to their CEST properties. In solution, all of these complexes have a low symmetry. The presence of multiple magnetically different amide groups in each complex prevents the realization of very high CEST effects. These results nevertheless form an excellent basis for a further optimization of this class of ligands.
Powerful N-monoalkylation of linear tetraamines via bisaminal intermediates
Claudon, Geraldine,Le Bris, Nathalie,Bernard, Helene,Handel, Henri
, p. 5027 - 5030 (2007/10/03)
The bisaminals obtained through the condensation of two linear tetraamines with glyoxal or pyruvic aldehyde were selectively alkylated with bromo- or α,ω-dibromoalkanes in good yields at one of the secondary amino functions to give rise to N-monoalkylated tetraamines or linear octaamines. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
ω-Mono N-Alkylation of Linear Tetraamines through the Reaction of Aldehydes and Ketones on their Tricarbonyl Chromium, Molybdenum or Tungsten Complexes
Yaouanc, Jean-Jacques,Bris, Nathalie Le,Clement, Jean-Claude,Handel, Henri,Abbayes, Herve des
, p. 696 - 698 (2007/10/02)
The reductive amination of carbonyl compounds by the non-coordinated amino function of the fac-LM(CO)3 tridentate complexes of 1,4,7,10-tetraazadecane, 1,5,8,12-tetraazadodecane and 1,5,9,13-tetraazatridecane has been selectively achieved giving rise to ω
