Synthesis and characterization of new aromatic tweezers and complex formation with tropylium ion in 1,2-dichloroethane

A series of benzene and pyridine tweezers bearing phenyl, naphthyl and anth ryl receptor units was prepared and characterized. The x-ray crystal struct ure of the 1,3-bis(9-methanolanthracene)methylbenzene ligand (5) is reporte d. UV-visible and NMR spectroscopy were used to investigate the host-guest chemistry of the new ligands in complexation with tropylium tetrafluorobora te as a model aromatic cationic guest in 1,2-dichloroethane. The appearance of coloured charge-transfer absorption bands demonstrates the complex form ation with a tropylium, ion. The enlargement of aryl receptor size from phe nyl and naphthyl to anthryl increases the stability of complexes. Electron donor-acceptor interactions are an important driving force for complexation by molecular tweezers. The results are discussed and compared with those o f previously studied systems containing crown ethers and podands. The bisan thracenes 5 and 1,3-bis(9-methanolanthracene)methylpyridine (6) are especia lly interesting in displaying both complexation ability and intramolecular cycloaddition via charge-transfer excitation. Copyright (C) 2001 John Wiley & Sons, Ltd.