Aggregative Properties of Water-soluble Metal Phthalocyanines in a Borate Buffer Solution

Abstract

Thermodynamic characteristics of dimerization of water-soluble zinc, copper, and cobalt complexes of sulfo-and carboxy-substituted phthalocyanines were obtained. A correlation of the aggregative capacity of the metal phthalocyanines with the nature of the central metal atoms and the number and position of peripheral substituents was revealed.

Self-association of sulfo derivatives of cobalt phthalocyanine in aqueous solution

“…The latter absorbs at λ 615-630 nm against λ 670-675 nm for the monomeric species. The molar absorption coefficient of the dimer at λ 630 is 15 200±50 L mol -1 cm -1 , which is consistent with published data [13,[20][21][22]. No relaxation effects (which are commonly related to change of the aggregate state of the macrocycle) were observed in the electronic absorption spectra [16,20]; this provides an additional proof for the prevalence of dimeric species in solution.…”

“…The dissociation constants K dim decrease in the series III > II > I (K diss = 2.2 × 10 -4 , 1.54 × 10 -4 , and 1.08 × 10 -4 M [13,21], respectively), which characterizes the effect of peripheral substitution on the aggregation of sulfo derivatives of cobalt phthalocyanines in aqueous solution.…”

Synthesis and selected properties of metallo and metal-free 2,3,9,10,16,17,23,24 –octacarboxyphthalocyanines

“…concentration of phthalocyanine, solvents, peripheral substituents, the type of complexated metal ion, ionic strength of the solution and temperature. [49][50][51] Aggregation usually influences application properties of these compounds negatively. Aggregated compounds develop mainly due to interactions of delocalized  electrons of macrocycles.…”