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Model Systems for Fluorescence and Singlet Oxygen Quenching by Metalloporphyrins
Author(s) -
McCarthy Jason R.,
Weissleder Ralph
Publication year - 2007
Publication title -
chemmedchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.817
H-Index - 100
eISSN - 1860-7187
pISSN - 1860-7179
DOI - 10.1002/cmdc.200600244
Subject(s) - porphyrin , photochemistry , singlet oxygen , quenching (fluorescence) , chemistry , free base , fluorescence , phototoxicity , singlet state , metal ions in aqueous solution , excited state , metal , alkyl , covalent bond , quantum yield , oxygen , organic chemistry , physics , salt (chemistry) , quantum mechanics , nuclear physics , in vitro , biochemistry
Next‐generation photodynamic therapy agents will minimize extraneous phototoxicity by being active only at the target site. To this end, we have developed a model system to systematically investigate the excited‐state quenching ability of a number of metalloporphyrins. Central metal ions that prefer four‐coordinate, square planar orientations (Ag II , Cu II , Ni II , Pd II , and Zn II ) were used. Porphyrin dimers based on 5‐(4‐aminophenyl)‐10,15,20‐triphenylporphyrin and comprising both a free base porphyrin and a metalloporphyrin covalently linked through a five‐carbon alkyl chain were synthesized. The fluorescence and singlet oxygen quantum yields for the dimers were probed at 630 and 650 nm, respectively, resulting in the excitation of only the free base porphyrin and allowing a comparison of the quenching efficacy of each central metal ion. These results demonstrate that metalloporphyrins can serve as efficient quenchers, and may be useful in the design of novel light‐activated therapeutic agents.