Frustration of condensed phase aggregation of naphthalocyanine by dendritic site-isolation

The synthesis and aggregation studies of a pair of 3, 4,12,13,21,22,30,31- octasubstituted 2,3-Naphthalocyanine (Ncs) 1 and 2 was reported. The synthetic route leading to these naphthalonitriles started from dimethyl 4,5-dihydroxyphthalate onto which the previously synthesized dendritic alcohols 3 and 4 were introduced through the Mitsunobu protocol. The obtained diesters 6 and 7 were reduced to the corresponding 1,2-dimethanols (8 and 9), and subsequent Swern oxidation provided the disubstituted dendritic phthalaldehydes 10 and 11. Finally, 10 and 11 were converted to naphthalonitriles 12 and 13 through base-promoted condensation with succinonitrile in DMSO. Compounds 1 and 2 were purified by flash column chromatography. Initial molecular aggregation studies were performed in solution as a function of increasing volume fraction of EtOH. The B-bands at 332 and 402 nm exhibited only slight hypochromicity during this change in solvent conditions.