Abstract:Through a rapid screening of Cp*Ir complexes based on a turnon type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2',3'-c] phenazine)Cl] + complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H 2 O 2 generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.
“…Previously, our group reported that the photocatalytic dehydrogenation of N-heterocycles proceeds on the dppz ligand of [Cp*Ir(Cl)dppz] + . 32 More recently, photocatalytic NADH oxidation by 1 has been reported. 33 In both cases, the dppz ligand has been proposed to act as an electron acceptor to form reduced dppz (dppzH 2 ).…”
Section: ■ Results and Discussionmentioning
confidence: 99%
“…In addition to these interesting features of the dppz ligand, it has also been reported to act as a redox center in photocatalysis. Previously, our group reported that the photocatalytic dehydrogenation of N -heterocycles proceeds on the dppz ligand of [Cp*Ir(Cl)dppz] + . More recently, photocatalytic NADH oxidation by 1 has been reported .…”
While photocatalysts have been recognized as powerful
and environmentally
friendly catalysts, harnessing their reactivity still remains challenging.
On account of the distinctive reaction compartment that their protein
scaffolds provide for the incorporated metal complex, artificial metalloenzymes
(ArMs) can improve catalytic reaction rates and stereochemical selectivity.
In the present study, we have developed a photo-driven ArM by incorporating
a DNA photo-switch metal complex, [Ru(bpy)2dppz]2+ (1), into an apo-form riboflavin-binding protein (RFBP).
We report that two potentially competing photocatalytic reaction pathways,
i.e., a photoredox reaction and an energy transfer reaction, can be
switched by 1 alone and by the ArM. This reaction switching
was exploited in selective protein labeling; 1 alone
preferentially promotes tyrosine modification, while the ArM promotes
histidine modification. The present study thus opens the door for
the potential use of ArMs to control the reactivity of photocatalysts.
“…Previously, our group reported that the photocatalytic dehydrogenation of N-heterocycles proceeds on the dppz ligand of [Cp*Ir(Cl)dppz] + . 32 More recently, photocatalytic NADH oxidation by 1 has been reported. 33 In both cases, the dppz ligand has been proposed to act as an electron acceptor to form reduced dppz (dppzH 2 ).…”
Section: ■ Results and Discussionmentioning
confidence: 99%
“…In addition to these interesting features of the dppz ligand, it has also been reported to act as a redox center in photocatalysis. Previously, our group reported that the photocatalytic dehydrogenation of N -heterocycles proceeds on the dppz ligand of [Cp*Ir(Cl)dppz] + . More recently, photocatalytic NADH oxidation by 1 has been reported .…”
While photocatalysts have been recognized as powerful
and environmentally
friendly catalysts, harnessing their reactivity still remains challenging.
On account of the distinctive reaction compartment that their protein
scaffolds provide for the incorporated metal complex, artificial metalloenzymes
(ArMs) can improve catalytic reaction rates and stereochemical selectivity.
In the present study, we have developed a photo-driven ArM by incorporating
a DNA photo-switch metal complex, [Ru(bpy)2dppz]2+ (1), into an apo-form riboflavin-binding protein (RFBP).
We report that two potentially competing photocatalytic reaction pathways,
i.e., a photoredox reaction and an energy transfer reaction, can be
switched by 1 alone and by the ArM. This reaction switching
was exploited in selective protein labeling; 1 alone
preferentially promotes tyrosine modification, while the ArM promotes
histidine modification. The present study thus opens the door for
the potential use of ArMs to control the reactivity of photocatalysts.
“…Given the sustained interest in photocatalysis over the last decade, [16][17][18][19] a growing number of examples for greener metal-free photocatalytic transformation of amines to imines were revealed to promote this transformation as a synthetically robust reaction manifold. [20][21][22][23][24][25] In this context, we came across an amine that was spontaneously converted to the corresponding imine under ambient conditions with dioxygen (Fig. 1C).…”
An iterative hydride reduction/oxidation process was promoted under ambient conditions by a quasi-planar iminium cation rigidified by two concatenated quinoline units. The iminium proton was fixed by hydrogen bonding from neighboring quinoline nitrogen atoms, rendering the imine highly susceptible to hydride reduction with weak reductants, e.g., 1,4-dihydropyridines. The thus-formed amine was readily oxidized by molecular oxygen to regenerate the quasi-planar iminium cation under ambient conditions. This process was exploited for catalytic oxidation of 1,4-dihydropyridines as well as 9,10-dihydroacridine to highlight an intriguing rigidity-driven catalysis.
“…In this sense, artificial metalloenzymes based on the insertion of organometallic complexes on the protein structure has been recently synthesized. [13][14][15][16][17][18][19] However, this required a timeconsuming in the preparation of the organometallic compound or required different modification of the protein for site-selective insertion of the metal. Another issue in this aspect is that mainly this artificial enzyme is water soluble as natural enzyme, presenting similar problems of compatibility in some experimental conditions or being required additional steps.…”
Section: Introductionmentioning
confidence: 99%
“…Therefore, alternative strategies, where both systems conserved full activity, are necessary. In this sense, artificial metalloenzymes based on the insertion of organometallic complexes on the protein structure has been recently synthesized [13–19] . However, this required a time‐consuming in the preparation of the organometallic compound or required different modification of the protein for site‐selective insertion of the metal.…”
The fabrication of novel systems where enzymatic and metallic actives sites can be directly interacting represent a very fancy strategy for sustainable processes. One of the new strategies goes to the direct formation of metal nanoparticles in situ on a protein network as scaffold. This biological entity is the key element because conserved its biological catalytic efficiency but induced the final metallic nanoparticles generation on their structure. This method allows to obtain bifunctional enzyme‐metallic catalysts with excellent versatility and efficiency in a different kind of reaction and experimental conditions. In this concept article, the relevant aspect in term of the fabrication of this enzyme‐metal nanoparticles hybrids and specific recent reported examples where they have been successfully applied in significant cascade processes will be described.
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