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Programming heterometallic 4f-4f' helicates under thermodynamic control: the circle is complete.

Charlotte Egger¹, Laure Guénée², Neel Deorukhkar¹

¹Department of Inorganic and Analytical Chemistry, University of Geneva, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland. Claude.Piguet@unige.ch.

Dalton Transactions (Cambridge, England : 2003)

|March 12, 2024

Summary

Researchers created directional triple-stranded helicates using zinc and lanthanide ions. These stable supramolecular structures can be programmed for applications like light-converters and molecular qubits.

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A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Published on: February 16, 2020

Area of Science:

Supramolecular Chemistry
Coordination Chemistry
Materials Science

Background:

Designing complex molecular architectures with precise control over metal ion placement is crucial for advanced materials.
Lanthanide complexes offer unique photophysical properties, but achieving selective incorporation remains a challenge.

Purpose of the Study:

To synthesize and characterize novel triple-stranded helicates with directional properties.
To investigate the thermodynamic behavior and site selectivity of lanthanide ions within the helicate structure.
To explore the potential of these helicates as platforms for light-conversion and molecular qubit applications.

Main Methods:

Synthesis of non-symmetrical segmental ligand strands (L4).
Complexation of ligand strands with zinc (Zn2+) and lanthanide (Ln3+) ions.
Structural and speciation analysis using Nuclear Magnetic Resonance (NMR) spectroscopy in acetonitrile-d3.
Thermodynamic studies of lanthanide permutation and exchange processes.

Main Results:

Quantitatively formed directional [ZnLn2(L4)3]8+ triple-stranded helicates in solid state and solution.
Helicates demonstrated high stability in solution at millimolar concentrations, acting as preorganized C3-symmetrical platforms.
Selective incorporation of lanthanide ions was achieved, with a notable preference for heterolanthanide formation (70% excess) in the challenging La3+:Eu3+ system.
A specific isomer preference was observed, favoring the placement of the larger lanthanum ion in the central binding site.

Conclusions:

The developed rational design allows for programmed control over lanthanide distribution in triple-stranded helicates.
These precisely engineered helicates serve as promising platforms for developing directional light-converters and molecular qubits.
The study highlights the potential for fine-tuning supramolecular properties through selective metal ion incorporation.