Effective concentration as a tool for quantitatively adressing preorganization in multicomponent assemblies : application to the selective complexation of lanthanide cations
|Published in||Journal of the American Chemical Society. 2008, vol. 130, no. 3, p. 1025-1040|
|Abstract||The beneficial entropic effect, which may be expected from the connection of three tridentate binding units to a strain-free covalent tripod for complexing nine-coordinate cations (Mz+ = Ca2+, La3+, Eu3+, Lu3+), is quantitatively analyzed by using a simple thermodynamic additive model. The switch from pure intermolecular binding processes, characterizing the formation of the triple-helical complexes [M(L2)3]z+, to a combination of inter- and intramolecular complexation events in [M(L8)]z+ shows that the ideal structural fit observed in [M(L8)]z+ indeed masks large energetic constraints. This limitation is evidenced by the faint effective concentrations, ceff, which control the intramolecular ring-closing reactions operating in [M(L8)]z+. This predominence of the thermodynamic approach over the usual structural analysis agrees with the hierarchical relationships linking energetics and structures. Its simple estimation by using a single microscopic parameter, ceff, opens novel perspectives for the molecular tuning of specific receptors for the recognition of large cations, a crucial point for the programming of heterometallic f-f complexes under thermodynamic control.|
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|CANARD, Gabriel et al. Effective concentration as a tool for quantitatively adressing preorganization in multicomponent assemblies : application to the selective complexation of lanthanide cations. In: Journal of the American Chemical Society, 2008, vol. 130, n° 3, p. 1025-1040. https://archive-ouverte.unige.ch/unige:77|