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A novel extended covalent tripod for assembling triple-helical nine-co-ordinated lanthanide ( III ) podates : the rational design of a single conformer †
| Content Provider | Semantic Scholar |
|---|---|
| Author | Koeller, Sylvain Bernardinelli, Gérald Piguet, Claude |
| Copyright Year | 2003 |
| Abstract | The connection of a methyl group to the apical carbon atom of a semi-rigid extended tripod provides the novel podand 1,1,1-tris-{2-[2-(6-diethylcarbamoyl-pyridin-2-yl)-1-ethyl-1H-benzoimidazol-5-ylmethoxy]-ethyl}-ethane (L13). Reaction with lanthanide() in acetonitrile produces stable and dynamically inert C3-symmetrical podates [Ln(L13)] (Ln = La–Lu) in which Ln is nine-co-ordinate in a pseudo-tricapped trigonal prismatic site. Electroninduced nuclear relaxation in the paramagnetic complex [Nd(L13)] shows that the capping carbon atom adopts the exo conformation with the methyl group pointing outside the cavity of the podand. The crystal structure of [Eu(L13)](ClO4)3 confirms the exclusive formation of the exo conformer, which contrasts with the mixture of two endo conformers reported for the non-methylated analogue. Structural analysis combined with photophysical data in [Ln(L13)](ClO4)3 (Ln = La, Eu, Gd, Tb) point to negligible mechanical coupling mediated by the flexible four-atoms aliphatic chains between the apical carbon atom and the unsymmetrical tridentate binding units. However, the exo conformation of the tripod in [Eu(L13)] removes some interactions between the high-frequency CH oscillators and the metal-centred excited electronic levels, thus leading to larger lifetime and improved quantum yield in solution. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.unige.ch/sciences/chiam/piguet/files/1014/9546/5443/Universaltripod.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Analog Covalent Interaction Crystal structure Dental caries Frequency capping Gadolinium LU decomposition Lactic acid Lanthanoid Series Elements Large Linear algebra Linear programming relaxation MANEA gene Methyl Group Muscle Rigidity Pseudo brand of pseudoephedrine Semiconductor industry Structural analysis Tripod acetonitrile late nucleophagy |
| Content Type | Text |
| Resource Type | Article |
