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Improving Continuous Flow Singlet Oxygen Photooxygenation Reactions with Functionalized Mesoporous Silica Nanoparticles
Author(s) -
Mendoza Carlos,
Emmanuel Noémie,
Páez Carlos A.,
Dreesen Laurent,
Monbaliu JeanChristophe M.,
Heinrichs Benoît
Publication year - 2018
Publication title -
chemphotochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 18
ISSN - 2367-0932
DOI - 10.1002/cptc.201800148
Subject(s) - photooxygenation , singlet oxygen , rose bengal , photobleaching , photosensitizer , photochemistry , chemistry , photodegradation , mesoporous silica , mesoporous material , catalysis , oxygen , organic chemistry , photocatalysis , fluorescence , physics , quantum mechanics
Continuous flow photochemistry relying on photosensitizers faces two main challenges: 1) Photodegradation (bleaching) and 2) the downstream removal of the photosensitizer. Rose bengal (RB) is a common photosensitizer utilized for photooxygenation reactions with singlet oxygen ( 1 O 2 ), but is notoriously sensitive to photobleaching and difficult to remove from reactor effluents. The heterogenization of photosensitizers on mesoporous silica nanoparticles (MSNs) is arguably a viable option for such applications. Herein, we report on the use of RB covalently incorporated into MSNs (RB@MSNs) for photooxygenation reactions under continuous flow conditions. RB@MSNs enable the 1 O 2 photooxygenation of various organic substrates upon irradiation with 540 nm LEDs. A series of organic substrates were evaluated including methionine, α‐terpinene, 2‐furoic acid, triphenylphosphine, citronellol and cyclopentadiene. These results emphasize an improved resistance to photobleaching, and the possibility to use RB@MSNs as an easily recoverable catalyst, which could be removed from the reactor effluent either a) by centrifugation or b) by in‐line membrane filtration.