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Meso ‐Biphenyl‐Linked, Near‐ and Far‐Infrared Emitting, Chlorin and Bacteriochlorin Dimers: Synthesis, Excitation Transfer, and Singlet Oxygen Production
Author(s) -
Seetharaman Sairaman,
Dukh Mykhaylo,
Tabaczynski Walter A.,
Ou Zhongping,
Karr Paul A.,
Kadish Karl M.,
Pandey Ravindra K.,
D'Souza Francis
Publication year - 2021
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202100120
Subject(s) - photochemistry , ultrafast laser spectroscopy , singlet oxygen , chemistry , excited state , chlorin , bacteriochlorophyll , chromophore , singlet state , absorption (acoustics) , porphyrin , materials science , oxygen , photosynthesis , spectroscopy , atomic physics , biochemistry , physics , organic chemistry , quantum mechanics , composite material
A series of meso ‐biphenyl linked chlorin and bacteriochlorin dimers, derived from naturally occurring chlorophyll (Chl‐ a ) and bacteriochlorophyll (BChl‐ a ) were synthesized in 32 % to 44 % yields and characterized, as photosynthetic antenna mimics, and a new class of singlet oxygen producing agents. The dimers are characterized by absorption, fluorescence, electrochemical, spectroelectrochemical and computational methods to evaluate their physico‐chemical properties, and to identify ground and excited state interactions. Evidence of excited energy exchange among the chromophores in the dimer is derived from femtosecond transient absorption spectral studies. Rate constants for excitation hopping were in the order of 10 11 s −1 , indicating occurrence of efficient processes. Nanosecond transient absorption studies confirmed relaxation of the singlet excited chlorin and bacteriochlorin dimers to their corresponding triplet states ( 3 Chl* and 3 Bchl*). As predicted by the established energy level diagrams, both 3 Chl* and 3 Bchl* are shown to be capable of producing singlet oxygen with appreciable quantum yields ( ϕ SO ∼0.3).