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Isomerization and Dimerization of Indocyanine Green and a Related Heptamethine Dye
Author(s) -
Rüttger Franziska,
Mindt Sonani,
Golz Christopher,
Alcarazo Manuel,
John Michael
Publication year - 2019
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201900715
Subject(s) - cyanine , chemistry , isomerization , indocyanine green , photochemistry , spectroscopy , fluorescence , catalysis , organic chemistry , physics , quantum mechanics , medicine , surgery
Indocyanine green (ICG) and a second heptamethine cyanine dye were studied in detail using 2D NMR spectroscopy at multiple temperatures. In addition to the all‐ trans conformation, we found in both cases a small percentage of a specific β‐γ cis isomer. Exchange rates extrapolated from 2D EXSY spectra under slow exchange conditions are in agreement with that estimated from methine 1 H linewidths near coalescence and with previous photo‐isomerization studies. We could also confirm our previous hypothesis that, under aerobic conditions in combination with exposure to daylight, ICG undergoes radical dimerization specifically at the γ position.