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Design, synthesis, and photophysical characterization of novel pentacyclic red shifted azine dyes
Author(s) -
Gloster Daniel F.,
Cincotta Louis,
Foley James W.
Publication year - 1999
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570360105
Subject(s) - chemistry , azine , singlet oxygen , iodide , quantum yield , photochemistry , fluorescence , organic chemistry , oxygen , physics , quantum mechanics
As part of our continuing efforts to develop second generation photodynamic therapeutic agents [1], we synthesized three pentacyclic azine dyes that were designed with the aid of MNDO calculations to absorb visible light having wavelengths longer than 600 nm. Photophysical measurements for the azine dyes 1,4,8,11‐tetraethyl‐1,2,3,4,8,9,10,11,13‐nonahydrodipyrazino[2,3‐ b :2′, 3′‐ i ] phenazinium acetate, 13 , 1,4,8,11‐tetraethyl‐2,3,4,8,9,10,11,12,13‐octahydro‐13‐methyldipyrazino[2,3‐ b :2,3′‐ i ]phenazinium iodide, 14 , and l,4,8,11,13‐pentaethyl‐2,3,4,8,9,10,11,12,13‐octahydrodipyrazino[2,3‐ b :2′,3′‐ i ]phenazinium iodide, 15 , are highlighted by a 35 nm red shift in their absorption spectra and a 5–7 fold increase in their singlet oxygen quantum yield relative to tricyclic model compounds 3,7‐bis(diethylamino)phenazinium chloride, 20 , and 3,7‐bis(diethylamino)‐5‐ethyl‐phenazinium iodide, 21 , which were also synthesized for this study. Incorporation of rigid peripheral tetrahydropyrazino ring systems in the pentacyclic azines 13 , 14 , and 15 are responsible for the improved fluorescence and singlet oxygen quantum yields relative to the tricyclic azines 20 and 21 .