<p>Aluminum phthalocyanine chloride (AlPcCl) is a photoactive compound which has been used as a photosensitizer (PS) in photodynamic therapy (PDT). Its spectroscopic properties have been studied in solvents of different polarities (ethanol, acetone, dimethylsulfoxide and chloroform). Its solubility has been found to decrease with increasing solvent polarity, together with full self-aggregation in aqueous solution. The binding of AlPcCl to the copolymer Pluronic^TM micellar class P-123 and F-127 used as solubilizer/carriers was studied. Greater interaction between the more hydrophobic copolymer P-123 and AlPcCl was observed, besides a complex interaction profile involving different AlPcCl forms (self-aggregate/monomeric form) in the copolymers. Time- and temperature-dependent structural organization of AlPcCl in the copolymers was also observed. Thus, AlPcCl has a strong tendency to self-aggregate with increasing solvent polarity, an effect also observed in micellar media.</p>

Ftalocianinas (Pc) são compostos sintéticos de interesse em diversas áreas. Contudo, sua elevada hidrofobicidade favorece o indesejável processo de agregação em meio aquoso. Estudos realizados com a Pc de hidroxi-alumínio (AlPcOH) em diferentes misturas água/etanol (v/v) mostraram que esta encontra-se na forma monomérica em proporções de água inferiores a 30%. Em 40 e 50% água/etanol tem-se a formação de dímeros unidos por ligação hidrogênio ou em ponte Al-O-Al, enquanto que em porcentagens de água superiores a 60% o processo de agregação é complexo, envolvendo múltiplos equilíbrios e agregados de tamanhos grandes (tipo J).

Phthalocyanines (Pc) are synthetic compounds of interest in various fields. However, their high hydrophobicity promotes the undesirable aggregation process in aqueous media. Studies carried out with aluminum phthalocyanine hydroxide (AlPcOH) in different water/ethanol mixtures (v/v) have shown that in proportions of water lower than 30% the Pc is in the monomeric form. At 40 and 50% water/ethanol there was formation of dimers linked by hydrogen bonding or Al-O-Al bridged, while in percentages of water higher than 60% the aggregation process is complex, with multiple equilibria and higher-order aggregates (J-type).

In this work, the spectroscopic properties of 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (TMPP) in solvents of different polarities and water/ethanol mixtures were studied by electronic absorption spectroscopy and resonance light scattering associated with statistical analysis. The molar absorption coefficient and emission maximum of TMPP were dependent on solvent polarity. In the water/ethanol mixture, TMPP remained monomeric up to 25% of water, when it reaches its critical aggregation percentage. Oblique head-to-tail aggregate was found at intermediate water content (35 - 55%), while formation of a J-type aggregate was observed at higher water content (> 60%).

The physicochemical properties (solubilization, structural organization and stability) of meso-tetrakis(p-methoxyphenyl)porphyrin (TMPP), a promising photosensitizer for photodynamic therapy, solubilized in polymeric micelles of tri-block copolymers PluronicTM P-123 and F-127, were studied. The formulations obtained by the solid dispersion method led to monomerization of TMPP in these copolymers. Solubility studies showed that P-123 solubilizes double the photosensitizer than F-127. The self-aggregation phenomenon was affected by the [TMPP]/[poloxamer] ratio and medium temperature. The decrease in the temperature of these systems promoted the formation of different kinds of TMPP aggregates intrinsically connected with the structural changes occurring in the micelles.