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 epsilon(m) (777 nm), epsilon(d) (777 nm), and K-d at 1.95x10(6) M-1 cm(-1), 1.29x10(5) M-1 cm(-1), and 2.72x10(5) 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). These values depend largely on the additional interactions due to the substituents. (C) 2000 Elsevier Science Ltd. All rights reserved.