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- Title
Synthesis of Cationic Pyridinium‐(Bacterio)Chlorophyll Conjugates Bearing a Bacteriochlorin, Chlorin, or Porphyrin π‐Skeleton and their Photophysical and Electrochemical Properties.
- Authors
Takahashi, Tatsuya; Ogasawara, Shin; Shinozaki, Yoshinao; Tamiaki, Hitoshi
- Abstract
Fine‐tuning the electronic absorption properties of chlorophylls is important for their use as light‐absorbing pigments. By oxidative coupling, a cationic pyridinium group was selectively introduced at the peripheral vinyl group of three types of synthetic chlorophylls with different degrees of π‐conjugation of the cyclic tetrapyrroles (bacteriochlorin, chlorin, and porphyrin). The substitution with the electron‐withdrawing pyridinium group moved redmost electronic absorption and main fluorescence emission maxima to longer wavelengths. This substitution effect depended on the core π‐system and decreased with increasing the degree of dehydrogenation of the cyclic tetrapyrrole (bacteriochlorin > chlorin > porphyrin). Moreover, fluorescence quenching was observed as a consequence of the introduction of the pyridinium group. The electrochemical measurements and theoretical model calculations showed that the quenching is ascribed to an intramolecular electron transfer from the core π‐skeleton to the peripheral cationic pyridinium group.
- Subjects
PORPHYRINS; VINYL polymers; CHLOROPHYLL; OXIDATIVE coupling; FLUORESCENCE quenching; CHARGE exchange; DIPYRROMETHANES
- Publication
European Journal of Organic Chemistry, 2019, Vol 2019, Issue 37, p6333
- ISSN
1434-193X
- Publication type
Article
- DOI
10.1002/ejoc.201901172