- A Donor-Acceptor [2]Catenane for Visible Light Photocatalysis
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Colored charge-transfer complexes can be formed by the association between electron-rich donor and electron-deficient acceptor molecules, bringing about the narrowing of HOMO-LUMO energy gaps so that they become capable of harnessing visible light. In an effort to facilitate the use of these widespread, but nonetheless weak, interactions for visible light photocatalysis, it is important to render the interactions strong and robust. Herein, we employ a well-known donor-acceptor [2]catenane - formed by the mechanical interlocking of cyclobis(paraquat-p-phenylene) and 1,5-dinaphtho[38]crown-10 - in which the charge-transfer interactions between two 4,4′-bipyridinium and two 1,5-dioxynaphthalene units are enhanced by mechanical bonding, leading to increased absorption of visible light, even at low concentrations in solution. As a result, since this [2]catenane can generate persistent bipyridinium radical cations under continuous visible-light irradiation without the need for additional photosensitizers, it can display good catalytic activity in both photo-reductions and -oxidations, as demonstrated by hydrogen production - in the presence of platinum nanoparticles - and aerobic oxidation of organic sulfides, such as l-methionine, respectively. This research, which highlights the usefulness of nanoconfinement present in mechanically interlocked molecules for the reinforcement of weak interactions, can not only expand the potential of charge-transfer interactions in solar energy conversion and synthetic photocatalysis but also open up new possibilities for the development of active artificial molecular shuttles, switches, and machines.
- ?or?evi?, Luka,Cai, Kang,Chen, Hongliang,Chen, Xiao-Yang,Feng, Yuanning,Jaynes, Tyler,Jiao, Yang,Mao, Haochuan,Qiu, Yunyan,Stoddart, J. Fraser,Stupp, Samuel I.,Wasielewski, Michael R.,Young, Ryan M.,Zhang, Long
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supporting information
p. 8000 - 8010
(2021/06/27)
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- Direct monitoring of biocatalytic deacetylation of amino acid substrates by1H NMR reveals fine details of substrate specificity
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Amino acids are key synthetic building blocks that can be prepared in an enantiopure form by biocatalytic methods. We show that thel-selective ornithine deacetylase ArgE catalyses hydrolysis of a wide-range ofN-acyl-amino acid substrates. This activity was revealed by1H NMR spectroscopy that monitored the appearance of the well resolved signal of the acetate product. Furthermore, the assay was used to probe the subtle structural selectivity of the biocatalyst using a substrate that could adopt different rotameric conformations.
- De Cesare, Silvia,McKenna, Catherine A.,Mulholland, Nicholas,Murray, Lorna,Bella, Juraj,Campopiano, Dominic J.
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supporting information
p. 4904 - 4909
(2021/06/16)
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- Mo(VI) complex catalysed synthesis of sulfonees and their modification for anti-HIV activities
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An efficient method for the synthesis of sulfones has been developed using sugar derived cis-dioxo molybdenum(VI) complex as catalyst and urea hydrogen peroxide as oxygen source. Present method is highly specific for sulfide oxidation irrespective of presence of alkene and aldehyde groups in the same molecule. Synthesis of fifteen sulfones have been reported with 82–98% isolated yields and the catalyst has been reused five times without any loss in its activity. 2-(Phenylsulfonyl)aniline has been condensed with eight different aromatic aldehydes and the products are being explored for HIV-1 reverse transcriptase inhibition activities.
- Madduluri, Vimal Kumar,Baig, Noorullah,Chander, Subhash,Murugesan, Sankaranarayanan,Sah, Ajay K.
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- “Dark” Singlet Oxygen Made Easy
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An operationally simple continuous flow generator of “dark” singlet oxygen has been developed. The singlet oxygen was efficiently reacted with several chemical traps to give the corresponding oxygenated products in high yields. The developed “dark” singlet oxygen generator has been successfully applied in the synthesis of the antimalarial drug artemisinin.
- Elsherbini, Mohamed,Allemann, Rudolf K.,Wirth, Thomas
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supporting information
p. 12486 - 12490
(2019/08/26)
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- Halogenated fatty acid amides and cyclic depsipeptides from an eastern Caribbean collection of the cyanobacterium Lyngbya majuscula
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A lipophilic extract of an eastern Caribbean collection of Lyngbya majuscula yielded two new halogenated fatty acid amides, grenadamides B (1) and C (2), and two new depsipeptides, itralamides A (3) and B (4), along with the known compounds hectochlorin a
- Jimenez, Jorge I.,Vansach, Tifanie,Yoshida, Wesley Y.,Sakamoto, Bryan,Poerzgen, Peter,Horgen, F. David
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supporting information; experimental part
p. 1573 - 1578
(2010/03/31)
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- Flame-induced reactions of sulfur-containing amino acids in an aqueous solution
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Hydrogen-oxygen flames, when blown against an aqueous solution of methionine, induced conversion reactions to homoserine, 2-aminobutyric acid and glutamic acid. Besides the already-known reactions by a hydroxyl radical, a contribution of a hydrogen atom from hydrogen-rich flames to the reaction was recognized. We successfully controlled the vigorous oxidation of the system using a radical scavenger.
- Nomoto, Shinya,Shimoyama, Akira,Shiraishi, Susumu
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p. 1009 - 1012
(2007/10/03)
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- Under-flame Reaction of Sulfur-containing Amino Acids by a Hydrogen-Oxygen Flame
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Methionine was subjected to a flame-induced reaction in water or in an aqueous formic acid solution by using a hydrogen (50%)-oxygen (50%), hydrogen (87%)-oxygen (13%) and hydrogen diffusion flame. Besides the already-known stepwise oxidation by a hydroxyl radical, the contribution of a hydrogen atom from the flame to the reaction was recognized when the hydrogen-rich mixtures were employed. Homoserine was obtained under all the reaction conditions employed here, and glutamic acid when employing aqueous formic acid as a solvent. A common intermediate, the 3-carboxy-3-aminopropyl radical, appeared to exist in the reaction pathway. A coupling reaction of this radical with a hydrogen atom, hydroxyl radical and hydroxycarbonyl radical afforded 2-aminobutyric acid, homoserine and glutamic acid, respectively. Lanthionine and S-methylcysteine underwent the same reactions. Increasing the hydrogen content of the fuel and adding formic acid to the solvent resulted in retarding the reaction rate. The latter modification of the reaction system also brought about greater stability of the reaction products.
- Nomoto, Shinya,Shimoyama, Akira,Shiraishi, Susumu,Seno, Tomoyuki,Sahara, Denzo
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p. 643 - 649
(2007/10/03)
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- L-Methionine related 1-amino acids by acylase cleavage of their corresponding N-acetyl-DL-derivatives
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Acylase I from Aspergillus oryzae is an even more useful enzyme than suggested so far. Besides standard amino acids such as L-Met, L-Val and L-Phe, a number of additional sulfur- and selenium-containing amino acids can be obtained at useful reaction rates and in very high enantiomeric purity by kinetic resolution of the respective N-acetyl-DL-amino acids.
- Bommarius, Andreas S.,Drauz, Karlheinz,Guenther, Kurt,Knaup, Guenter,Schwarm, Michael
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p. 3197 - 3200
(2007/10/03)
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- Sulfonic peracids - III. Heteroatom oxidation and chemoselectivity
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We have investigated the p-toluenesulfonic peracid (2) generated in situ in the oxidation of different types of compounds containing nitrogen and/or sulfur. The sulfonic peracid 2 shows a remarkable chemoselectivity characterized by a preferred oxidation of sulfides to the sulfones in the presence of amines or olefins and a strong dependence on the nature of the amine in the competitive oxidation of olefins and amines.
- Kluge,Schulz,Liebsch
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p. 5773 - 5782
(2007/10/03)
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- Homogeneous Aqueous Oxidation of Organic Molecules by OxoneR and Catalysis by a Water-Soluble Manganese Porphyrin Complex
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Peroxymonosulfate (KHSO5) oxidizes a wide variety of water-soluble organic molecules in aqueous solutions, and the reactions are generally more rapid in phosphate buffer (pH 6-7) than in pure water.A water-soluble porphyrin complex, meso-tetrakis(4-N-methylpyridyl)porphyrinatomanganese(III) chloride, catalyzes epoxidation and hydroxylation under neutral pH conditions.
- Zheng, Tu-Cai,Richardson, David E.
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p. 833 - 836
(2007/10/02)
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- Optical Resolution and Asymmetric Transformation of (RS)-N-Alkyl- and (RS)-N,N-Dialkyl-2-phenylglycines
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Optical resolution of (RS)-N-methyl-2-phenylglycine and (RS)-N-ethyl-2-phenylglycine was carried out by using (1S)-10-camphorsulfonic acid as resolving agents, and that of (RS)-N-ethyl-N-methyl-2-phenylglycine by (R)- and (S)-1-phenylethylamine.Racemization rates of optically active Mpg, Epg, Emp, N,N-dimethyl-2-phenylglycine , and six α-amino acids were measured by heating in carboxylic acids.The electron-donating amino acid side chain and N-substituted alkyl group decreased therate to inhibit the formation of intermediary carbanions, whereas the electron-withdrawing side chain increased it.Asymmetric transformation of (RS)-Mpg, (RS)-Epg, and (RS)-Dmp was carried out on the basis of the results of optical resolution and racemization to give the corresponding enantiomers of approximately 100percent optical purities in over 70percent yield based on the sterting racemates.
- Shiraiwa, Tadashi,Baba, Yoshihisa,Miyazaki, Hideya,Sakata, Shinji,Kawamura, Seiko,et al.
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p. 1430 - 1437
(2007/10/02)
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- Oxidation of Thymines with Hydrogen Peroxide in Hydrochloric Acid
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Oxidation of thymine and 1,3-dimethylthymine with hydrogen peroxide in hydrochloric acid (pH 1.0-2.2) at 35-38 deg C gave the corresponding trans-5-chloro-6-hydroperoxy-5,6-dihydrothymines.The formation of the hydroperoxythymines was dependent on pH of the aqueous solutions.Reaction of the hydroperoxythymine with amino acids and nucleic acids related compounds in deuterium oxide was investigated by NMR spectroscopy.
- Itahara, Toshio
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p. 841 - 844
(2007/10/02)
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