A Direct Comparison of the Aggregation Behavior of Phthalocyanines and 2,3-Naphthalocyanines

Two pairs of analogous zinc(II) phthalocyanines and 2,3-naphthalocyanines with eight butylthio or 3,6-dioxa-1-decylthio substituents have been synthesized and shown to exhibit a substantial aggregation tendency in organic solvents. The visible spectra of the octakis(3,6-dioxa-1-decylthio) naphthalocyanine 7 have been recorded in THF with different concentrations and the data have been analyzed using a nonlinear least-squares fitting procedure giving ϵm (777 nm), ϵd (777 nm), and Kd at 1.95×106 M−1 cm−1, 1.29×105 M−1 cm−1, and 2.72×105 M−1, respectively. Simulated visible spectra for the pure monomeric and dimeric 7 have also been obtained. By variable-concentration and variable-temperature visible spectroscopic studies, the heats of aggregation of all these macrocycles in toluene have also been determined (−17.1 to −105.0 kJ mol−1). These values depend largely on the additional interactions due to the substituents.