A novel tricationic Zn(II)phthalocyanine derivative, (NCH 3 ) 3 ZnPc 3+ , was synthesized by ring expansion reaction of boron(III) [2,9(10),16(17)-trinitrosubphthalocyaninato]chloride. First, the reaction of this subphthalocyanine with 2,3-naphthalenedicarbonitrile and Zn(CH 3 COO) 2 catalyzed by 8-diazabicyclo[5.4.0]undec-7-ene was used to obtain the A 3 B-type nitrophthalocyanine. After reduction of nitro groups with Na 2 S and exhaustive methylation of amino groups, (NCH 3 ) 3 ZnPc 3+ was formed in good yields. In addition, the tetracationic analog (NCH 3 ) 4 ZnPc 4+ was synthesized to compare their properties. The absorption and fluorescence spectra showed the Q-bands and the red emission, respectively, which are characteristic of the Zn(II)phthalocyanine derivatives in N,N-dimethylformamide. Furthermore, photodynamic activity sensitized by these compounds was studied in the presence of different molecular probes to sense the formation of reactive oxygen species. (NCH 3 ) 3 ZnPc 3+ efficiently produced singlet molecular oxygen and also it sensitized the formation of superoxide anion radical in the presence of NADH, while the photodynamic activity of (NCH 3 ) 4 ZnPc 4+ was very poor, possibly due to the partial formation of aggregates. Furthermore, the decomposition of L-tryptophan induced by (NCH 3 ) 3 ZnPc 3+ was mainly mediated by a type II mechanism. Antimicrobial photodynamic inactivation sensitized by these phthalocyanines was evaluated in Staphylococcus aureus, Escherichia coli, and Candida albicans, as representative microbial cells. In cell suspensions, (NCH 3 ) 3 ZnPc 3+ was rapidly bound to microbial cells, showing bioimages with red fluorescence emission. After 5 min of irradiation with visible light, (NCH 3 ) 3 ZnPc 3+ was able to completely eliminate S. aureus, E. coli and C. albicans, using 1.0, 2.5 and 5.0 μM phthalocyanine, respectively. In contrast, a low photoinactivation activity was found with (NCH 3 ) 4 ZnPc 4+ as a photosensitizer. Therefore, the amphiphilic tricationic phthalocyanine (NCH 3 ) 3 ZnPc 3+ is a promising photosensitizing structure for application as a broad-spectrum antimicrobial phototherapeutic agent.

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The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc(4+) ) was studied in Candida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5 μM ZnPPc(4+) produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species (ROS) in cell suspensions (~10(6) CFU mL(-1) ). Singlet molecular oxygen, O2 ((1) Δg ), was observed by the reaction with 9,10-dimethylanthracene (DMA) and tetrasodium 2,2-(anthracene-9,10-diyl)bis(methylmalonate) (ABMM), whereas the nitro blue tetrazolium (NBT) method was used to sense superoxide anion radical (O2·-). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D2 O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans. These investigation indicates that O2 ((1) Δg ) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by ZnPPc(4+) .