Template effects of metal ions on photodimerization of bis-1-anthracenecarboxamide linked by the oxyethylene chain

A bis-fluorophore linked by an oxyethylene chain, N,N′-(4,7,10-trioxatridecane-1,13-diyl)bis(1-anthracenecarboxamide) 1, was synthesized, and intramolecular photodimerization of the anthracene units in acetonitrile was carried out. The photoproduct ratio of intramolecular regioisomers in the absence and presence of metal ions in acetonitrile was evaluated. Upon photoirradiation of 1, three photodimers formed, trans head-to-head dimer D1, cis head-to-head D2, cis head-to-tail D3, and the product ratio was D1:D2:D3=32:57:11. On the other hand, photodimerization of 1·Ba2+ gave the product ratio as 46:54:0.1, respectively. In the case of 1·Mg2+, the regioisomer ratio was determined as 17:81:2. These isomer ratios strongly depended on the structure of the complex induced by metal ions.