- Tuning the Reactivity of Cofacial Porphyrin Prisms for Oxygen Reduction Using Modular Building Blocks
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We assembled eight cofacial porphyrin prisms using MTPyP (M = Co(II) or Zn(II), TPyP = 4-tetrapyridylporphyrin) and functionalized ruthenium-based "molecular clips"using coordination-driven self-assembly. Our approach allows for the rapid synthesis of these architectures in isolated yields as high as 98% for the assembly step. Structural and reactivity studies provided a deeper understanding of the role of the building blocks on the oxygen reduction reaction (ORR). Catalytic efficacy was probed by using cyclic and hydrodynamic voltammetry on heterogeneous catalyst inks in aqueous media. The reported prisms showed outstanding selectivity (>98%) for the kinetically hindered 4e-/4H+ reduction of O2 to H2O over the kinetically more accessible 2e-/2H+ reduction to H2O2. Furthermore, we have demonstrated significant cofacial enhancement in the observed catalytic rate constant ks (μ5 orders of magnitude) over the mononuclear analogue. We conclude that the steric bulk of the clip plays an important role in the structural dynamics of these prisms, which in turn modulates the ORR reactivity with respect to selectivity and kinetics.
- Crawley, Matthew R.,Zhang, Daoyang,Oldacre, Amanda N.,Beavers, Christine M.,Friedman, Alan E.,Cook, Timothy R.
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supporting information
p. 1098 - 1106
(2021/02/03)
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- A new synthesis of bis-enaminones via acylation of ketones
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A short and efficient synthesis for a series of 1,6-diaryl-3,4- diarylaminohexa-2,4-diene-1,6-diones was developed. Based on the acylation-prototropism sequence during the reaction of various aryl methyl ketones with bis-imidoyl chlorides, the products were isolated in good yields. Substituted acetophenones, acetylthiophene, 3-acetylpyridine, and acetylferrocene can be integrated into this reaction as ketone component. Similarly, α-tetralone can be transformed with bis-electrophiles into the corresponding bis-enaminones. Treatment of 2-acetylpyridine with N,N′-bis(4-tolyl)ethanebis(imidoyl) dichloride yielded not only the expected bis-enaminone, but also a new quinolizine derivative which was structurally characterized by single crystal X-ray analysis. Analogously, pinacolone and cyclopropyl methyl ketone can readily be converted into bis-enaminones. Monoimidoyl chlorides showed the same reactivity, providing derivatives in high yields. Georg Thieme Verlag Stuttgart.
- Buehrdel, Gunther,Beckert, Rainer,Petrlikova, Eva,Herzigova, Petra,Klimesova, Vera,Fleischhauer, Jan,Goerls, Helmar
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experimental part
p. 3071 - 3080
(2009/04/06)
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- Heterocycles from Heterocycles. 1,3-Diaryl-4,5-imidazolidinediones from 1,3,5-Triarylhexahydro-1,3,5-triazines and Oxalyl Chloride
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1,3-Diaryl-4,5-imidazolidinediones (6) are easily synthesized from 1,3,5-triarylhexahydro-1,3,5-triazines (1) and oxalyl chloride (5) in a reaction not likely to involve the zwitterionic intermediate (3) of the N-methylenearylamine dimer, but viewing the sequential pick up of two units of the monomer (2) by oxalyl chloride (5).The essential role of ethyl alcohol added to the reaction mixture is recognized.Reaction conditions have been optimized and some ten imidazolidinediones (6) were prepared in good to excellent yields.Geometric parameters of 6 were obtained by X-ray diffraction analysis: all the nuclei are found almost in one plane except for a small twist of the phenyl rings about the C-N bond.
- Verardo, Giancarlo,Giumanini, Angelo G.,Gorassini, Fausto,Tolazzi, Marilena,Strazzolini, Paolo
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p. 10609 - 10628
(2007/10/02)
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- SmI2 Promoted Coupling Reaction of Isocyanates to Oxamides
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Oxamides were obtained in moderate to good yields by the reaction of isocyanates with the SmI2/HMPA/THF system under mild conditions.The system also caused desulfurization of isothiocyanates to give isocyanides in good yields.
- Liu, Yun-Shan,Bei, Mei-Zhi,Zhou, Zhi-Hua,Takaki, Ken,Fujiwara, Yuzo
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p. 1143 - 1144
(2007/10/02)
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