Synthesis of covalently-linked phthalocyanine-phthalocyanine and porphyrin-phthalocyanine dimers

The synthesis of the dimeric homonuclear phthalocyanines ( Pc) 4a, 4b, 5a and 5b and the dimeric heteronuclear Pc 4c and 5c is reported. The reactions are carried out by coupling the monomeric Pc 1a and 1b each containing a phenolic OH group in one of its substituents with the bromoalkyl-substituted Pc 2a, b or 3a, b respectively. From the spectral data of 4a-c and 5a-c, it can be concluded that in dichloromethane and toluene as solvents, these binuclear Pc are equilibrating between cofacial and open conformations with the open form predominating. Changing the solvent polarity, e. g. by adding methanol, the equilibrium is shifted towards a cofacial conformation. Treatment of the Pc 2a, b and 3a, b with 5-(4'-oxyphenyl)-10,15,20-triphenylporphin ( 6) in a basic solution gives the porphyrins ( P)-Pc dimers 7a, b and 8a, b respectively. In dichloromethane, the open conformation is preferred for the P-Pc dimers.