Tuneable Intramolecular Intermetallic Interactions as a New Tool for Programming Linear Heterometallic 4f−4f Complexes

Abstract

Statistical mechanics predicts that the design of pure organized heteropolymetallic chains of metal ions bound to linear receptors depends on controlled deviations from the mixing rule DeltaE(MiMj) = 1/2 (DeltaE(MiMi) + DeltaE(MjMj)), whereby DeltaE(MiMj) is the intramolecular intermetallic interaction between neighboring metal i and metal j along the receptor. A thorough investigation of linear polymetallic trivalent lanthanide triple-stranded helicates shows that such deviations are amplified by an increase in the nuclearity of the final complexes and are thus easily evidenced in the tetranuclear heterobimetallic helicates [La(4-y)Lu(y)(L6)3](12+) (y = 0-4). The chemical and physical origins of this unprecedented behavior are discussed together with its practical consequences for programming pure heteropolymetallic 4f-4f complexes.

Thermodynamic Stability of Heterodimetallic [LnLn′] Complexes: Synthesis and DFT Studies

“…A combination of 1 H NMR spectroscopy and spectrophotometry allowed us to determine the formation constants of the various possible trinuclear species ( x= 0, 1, 2, 3) and assess the free energy that favors deviations from statistical distributions. These deviations are ascribed to differences in intramolecular electrostatic interactions and solvation effects (the latter are only relevant in solution) . In a different approach, the serendipitous self‐assembly of Ln III ions with the bridging and chelating quinolato ligand, Q − , produces clusters with the formula [Ln 3 Q 9 ], which shows two slightly different coordination sites that favor larger ions at the central position of the molecule and smaller ions at the sides .…”

“…These deviations are ascribed to differences in intramolecular electrostatic interactions and solvation effects (the latter are only relevant in solution). [26][27] In ad ifferenta pproach, the serendipitous selfassembly of Ln III ions with the bridging and chelating quinolato ligand, Q À ,p roduces clusters with the formula [Ln 3 Q 9 ], which shows two slightly different coordination sites that favor larger ions at the central positiono ft he molecule and smalleri ons at the sides. [28] In all these cases, the purity of the heterometallic analogues has not been reported to exceed 90 %.…”

Looking for the Origin of Allosteric Cooperativity in Metallopolymers

“…A large domain of stability is generated for half‐filled polymers, in which every second site is occupied (Figure b, right) . This ordering phenomenon is analogous to order–disorder phase transition in antiferromagnetic materials and it has been exploited for the formation of organized heteropolymetallic lanthanide complexes . However, a true thermodynamic phase transition is not expected due to the one‐dimensional character of the system and its finite size .…”

Perfluorinated Aromatic Spacers for Sensitizing Europium(III) Centers in Dinuclear Oligomers: Better than the Best by Chemical Design?

“…[2] A statistical mechanics (Ising model) analysis suggests that standard repulsive nearest neighbor intermetallic interactions operating in linear polymers with regularly spaced binding sites should provide the targeted ordered …-Ln 1 -Ln 2 -Ln 1 -Ln 2 -… microstates. [3,4] Pioneering work in this field has relied on the bulk electropolymerization of didentate 1,10-phenanthroline with thienyl spacers [5] and the acyclic diene metathesis of tridentate 2,6-bis(benzimidazol-2-yl)pyridine, [6] followed by reaction with Eu(β-diketonate) 3 or Eu(NO 3 ) 3 to yield red-emitting metallopolymers. A reliable exploitation of this concept for the development of luminescent materials, however, requires the efficient sensitization of the luminophore via the rational optimization of each photophysical step by using chemical tools.…”