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Coordination‐Driven Macrocyclization for Locking of Photo‐ and Thermal cis → trans Isomerization of Azobenzene

2014; Wiley; Volume: 20; Issue: 49 Linguagem: Inglês

10.1002/chem.201404620

1521-3765

Masaki Yamamura, Kōji Yamakawa, Yuki Okazaki, Tatsuya Nabeshima,

Supramolecular Chemistry and Complexes

Abstract Both trans and cis isomers of azobenzene‐linked bis‐terpyridine ligand L1 were incorporated in rigid macrocycles linked by Fe II (tpy) 2 (tpy: terpyridine) units. The complex of the longer trans ‐ L1 is dinuclear [( trans ‐ L1 ) 2 ⋅ Fe II 2 ], whereas the complex of the shorter cis ‐ L1 is mononuclear [ cis ‐ L1⋅ Fe II ]. The complex cis ‐ L1⋅ Fe II was not only thermally stable but also photochemically inactive. These results indicate a perfectly locked state of cis ‐azobenzene. The stable macrocyclic structure of cis ‐ L1⋅ Fe II causes locking of the isomerization. To the best of our knowledge, this is first example of dual locking of photo‐ and thermal isomerization of cis ‐azobenzene.