Expanding π-Conjugation in Chlorins Using Ethenyl Linker.
J Org Chem
; 83(16): 9076-9087, 2018 08 17.
Article
em En
| MEDLINE
| ID: mdl-30033724
ABSTRACT
A series of chlorin monomers and dyads has been prepared to probe the effect of ethenyl vs ethynyl linkers on the electronic conjugation and optical properties in resulting derivatives. Styryl-substituted chlorins have been prepared either by a Heck reaction or by microwave-assisted olefin metathesis, while ß-ß ethenyl-linked dyads have been synthesized from the corresponding vinyl-substituted chlorin monomer using microwave-assisted olefin metathesis. It has been found that when an ethenyl linker is connected at the ß-position of chlorin it provides stronger electronic conjugation than an ethynyl one, which is manifested by a greater bathochromic shift of the longest wavelength absorption (Q y) and emission bands. Stronger electronic coupling is particularly evident for dyads, where ethenyl-linked dyad exhibits a strong near-IR absorption band emission (λabs = 707 nm, λem = 712 nm, Φf = 0.45), compared to the deep-red absorption and emission of a corresponding ethynyl-linked dyad (λabs = 689 nm, λem = 691 nm, Φf = 0.48). The reactivity of ethenyl-linked dyads with singlet oxygen is discussed as well. The results reported here provide further guidelines for molecular design of deep-red and near-IR absorbing and intensely emitting chlorin derivatives and chlorins with extended π-electronic conjugation for a variety of photonic applications.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2018
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Article