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Shape-persistant macrocycles with terpyridine units: synthesis, characterization, and structure in the crystal
Christian Grave1, Dieter Lentz, Andreas Schäfer
1Institut für Chemie, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany.
Journal of the American Chemical Society
|June 5, 2003
Summary
Researchers synthesized large, shape-persistent macrocycles with terpyridine units up to 2 nm wide using cross-coupling reactions. These molecules, featuring flexible side chains, were characterized by various spectroscopic and diffraction methods.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Materials Science
Background:
- Shape-persistent macrocycles are crucial building blocks in supramolecular chemistry.
- Terpyridine units are valuable ligands for constructing metal-organic frameworks and coordination polymers.
- Controlling macrocycle size and properties is essential for advanced material design.
Purpose of the Study:
- To synthesize novel shape-persistent macrocycles incorporating one or two terpyridine units.
- To achieve macrocycles with large inner diameters (up to 2 nm).
- To investigate the influence of side chains on solubility, processing, and crystal packing.
Main Methods:
- Transition metal-catalyzed cross-coupling reactions for macrocycle assembly.
- Decoration of precursors with flexible hexyloxy or hexyloxymethyl side chains.
- Characterization using MALDI-TOF mass spectrometry, 2D NMR spectroscopy, and single-crystal X-ray diffraction.
- Scanning tunneling microscopy (STM) for interface studies.
Main Results:
- Successful synthesis of macrocycles with one or two terpyridine units and inner diameters up to 2 nm.
- Overall yields ranged from 8% to 27%, with amounts prepared up to 290 mg.
- Side chain engineering improved solubility and processing.
- Crystal packing analysis revealed dependence on side chain number and length.
- Ordered physisorption of a macrocycle at the solution-HOPG interface was observed via STM.
Conclusions:
- The study demonstrates a viable synthetic route to large, shape-persistent terpyridine-containing macrocycles.
- Flexible side chains are effective for enhancing processability and controlling solid-state structure.
- The synthesized macrocycles show potential for applications in supramolecular chemistry and materials science.
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