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Photocatalytic CO 2 Reduction by Periodic Mesoporous Organosilica (PMO) Containing Two Different Ruthenium Complexes as Photosensitizing and Catalytic Sites
Author(s) -
Kuramochi Yusuke,
Sekine Masato,
Kitamura Kyohei,
Maegawa Yoshifumi,
Goto Yasutomo,
Shirai Soichi,
Inagaki Shinji,
Ishida Hitoshi
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701466
Subject(s) - ruthenium , catalysis , chemistry , formate , mesoporous material , photocatalysis , bipyridine , inorganic chemistry , photochemistry , crystallography , organic chemistry , crystal structure
A periodic mesoporous organosilica (PMO) containing 2,2′‐bipyridine (bpy) ligands within the framework (BPy‐PMO) has great potential for designing novel catalysts by modifying metal complexes. A photosensitizing site (Ru(PS)) was introduced by treating cis ‐[Ru(bpy) 2 (dimethylsulfoxide)Cl]Cl with BPy‐PMO. Then a catalytic site (Ru(Cat)) was brought in Ru(PS) x ‐BPy‐PMO by reaction with a ruthenium polymer [Ru(CO) 2 Cl 2 ] n . The stepwise modification of BPy‐PMO successfully affords a novel photocatalyst Ru(PS) x ‐Ru(Cat) y ‐BPy‐PMO. The molar fractions ( x , y ) of Ru(PS) and Ru(Cat) were determined by energy dispersive X‐ray (EDX) measurement and quantification of the amount of CO emitted in the photo‐decarbonylation of Ru(Cat), respectively. Photochemical CO 2 reduction ( λ ex >430 nm) by Ru(PS) x ‐Ru(Cat) y ‐BPy‐PMO in a CO 2 ‐saturated N , N ‐dimethylacetamide/water solution containing 1‐benzyl‐1,4‐dihydronicotinamide catalytically produced CO and formate. The total turnover frequency of CO and formate reached more than 162 h −1 on x= 0.11 and y= 0.0055. The product selectivity (CO/formate) became large when the ratio of Ru(PS)‐to‐Ru(Cat) ( x / y ) was increased. The photocatalysts can be recycled at least three times without losing their catalytic activity, demonstrating that the Ru(PS) and Ru(Cat) units were strongly immobilized on the BPy‐PMO framework.