Corroles are synthetic aromatic macrocycles of the tetrapyrrolic family that share an identical skeleton with corrins but are fully unsaturated like porphyrins. Research attention on corroles has remained low for decades after they first syntheses in 1965; starting from 1999 the discovery and development of synthetic breakthroughs made these compounds readily available and the interest in their applications has largely increased [1]. They have been found to be efficient catalysts and sensors and they show peculiar photophysical and electrochemical properties (high luminescence, ease of oxidation) that distinguish them from the more widely studied porphyrins. Since we are interested in the engineering of multicomponent systems able to perform light-driven actions we studied over the last few years the photophysical properties of free-base corroles and of newly synthesised arrays formed by free-base corroles covalently linked to photo-active partners and the results encourage us to use these compounds as viable alternatives to porphyrins in the construction of supramolecular systems with useful photoinduced properties. Moreover, the detection of high reactivity of both singlet and triplet states of free-base corroles with molecular oxygen prompted us to investigate the yield of singlet oxygen production by these corroles: we found high yields in toluene, ranging from 0.51 to 0.77, and we noticed a correlation between lower yield of singlet oxygen and more facile oxidation of the corrole [2]. This suggests that electron transfer from the lowest singlet excited state of corrole to ground state oxygen, to yield superoxide anion, can compete with energy transfer from the lowest triplet excited state of corrole to yield singlet oxygen. These results point to a possible use of corroles as photosensitizers. Medical applications of corroles up to now have been limited, but few studies demonstrated their efficacy as inhibitors of fibroblast grown factors and as G-quadruplex stabilizers [3,4], indicating good potentialities as anticancer agents. The formation of noncovalent conjugates of corroles with viral proteins and with human serum albumine that allows cellular uptake has already been demonstrated [5,6]. We therefore believe that research on the photophysics of corroles and corrole-based systems can lead to interesting applications in PDT.
Free-base corroles: promising chromophores for singlet oxygen generation
B Ventura;L Flamigni;
2008
Abstract
Corroles are synthetic aromatic macrocycles of the tetrapyrrolic family that share an identical skeleton with corrins but are fully unsaturated like porphyrins. Research attention on corroles has remained low for decades after they first syntheses in 1965; starting from 1999 the discovery and development of synthetic breakthroughs made these compounds readily available and the interest in their applications has largely increased [1]. They have been found to be efficient catalysts and sensors and they show peculiar photophysical and electrochemical properties (high luminescence, ease of oxidation) that distinguish them from the more widely studied porphyrins. Since we are interested in the engineering of multicomponent systems able to perform light-driven actions we studied over the last few years the photophysical properties of free-base corroles and of newly synthesised arrays formed by free-base corroles covalently linked to photo-active partners and the results encourage us to use these compounds as viable alternatives to porphyrins in the construction of supramolecular systems with useful photoinduced properties. Moreover, the detection of high reactivity of both singlet and triplet states of free-base corroles with molecular oxygen prompted us to investigate the yield of singlet oxygen production by these corroles: we found high yields in toluene, ranging from 0.51 to 0.77, and we noticed a correlation between lower yield of singlet oxygen and more facile oxidation of the corrole [2]. This suggests that electron transfer from the lowest singlet excited state of corrole to ground state oxygen, to yield superoxide anion, can compete with energy transfer from the lowest triplet excited state of corrole to yield singlet oxygen. These results point to a possible use of corroles as photosensitizers. Medical applications of corroles up to now have been limited, but few studies demonstrated their efficacy as inhibitors of fibroblast grown factors and as G-quadruplex stabilizers [3,4], indicating good potentialities as anticancer agents. The formation of noncovalent conjugates of corroles with viral proteins and with human serum albumine that allows cellular uptake has already been demonstrated [5,6]. We therefore believe that research on the photophysics of corroles and corrole-based systems can lead to interesting applications in PDT.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
