CCELAS · Charge compensation effects in Lanthanide assisted self-assembly

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Project objective

The rational design and synthesis of pure hetero-polymetallic f-f complexes remains an unsolved chemical challenge, despite the numerous potential applications offered by their appealing electronic, photo-physical and magnetic properties for developing novel luminescent materials and sensors. The use of neutral N-donor ligands, which self-assemble into poly-lanthanide helicates on combination with appropriate Ln(III) salts, has shown substantial promise for selectively introducing different lanthanide ions into extended polymetallic arrays. However, the sequential binding of different Ln(III) ions during the self-assembly process is hindered by electrostatic repulsion between the highly charged Ln(III) centres and the overall process is thus limited by negative cooperativity. Furthermore, the thermodynamic stability of the resulting complexes are somewhat compromised by the labile nature of Ln(III) ions, and the complex formation is thus highly sensitive to external conditions such as effective concentration, solvent polarity, pH etc.The proposed project will therefore address these issues by exploring the potential offered by negatively charged ligand strands for:(i) isolating pure homo- and hetero-polymetallic helicates and(ii) gaining further understanding of the fundamental factors which control the formation of and selectivity in such multi-component systems. For this purpose, a series of polydentate ligands containing both neutral and charged tridentate donor sites will be prepared.Aside from reducing intermetallic repulsion in the final complex, the negatively charged ligands are also expected to:(i) encourage positive cooperativity in sequential assembly steps,(ii) thermo-dynamically stabilize the final supra molecular assembly and(iii) increase the affinity of the charged binding sites for correspondingly smaller Ln(III) ions, thereby enhancing f-f ion recognition between different sites.

Original text from CORDIS.

Participants

• UNIVERSITE DE GENEVE · GENEVE 4CoordinatorSwitzerland

Links

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