- Steric hindrance of photoswitching in self-assembled monolayers of azobenzene and alkane thiols
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Surface-bound azobenzenes exhibit reversible photoswitching via trans-cis photoisomerization and have been proposed for a variety of applications such as photowritable optical media, liquid crystal displays, molecular electronics, and smart wetting surfac
- Valley, David T.,Onstott, Matthew,Malyk, Sergey,Benderskii, Alexander V.
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- Phenylimino Indolinone: A Green-Light-Responsive T-Type Photoswitch Exhibiting Negative Photochromism
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Imines are photoaddressable motifs useful in the development of new generations of molecular switches, but their operation with low-energy photons and control over isomer stability remain challenging. Based on a computational design, we developed phenylimino indolinone (PIO), a green-light-addressable T-type photoswitch showing negative photochromism. The isomerization behavior of this photoactuator of the iminothioindoxyl (ITI) class was studied using time-resolved spectroscopies on time scales from femtoseconds to the steady state and by quantum-chemical analyses. The understanding of the isomerization properties and substituent effects governing these photoswitches opens new avenues for the development of novel T-type visible-light-addressable photoactuators based on C=N bonds.
- Buma, Wybren Jan,Crespi, Stefano,Di Donato, Mariangela,Doria, Sandra,Feringa, Ben L.,Hilbers, Michiel F.,Kiss, Ferdinand L.,Simeth, Nadja A.,Stindt, Charlotte N.,Szymański, Wiktor,Toyoda, Ryojun,Wesseling, Sammo
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supporting information
p. 25290 - 25295
(2021/10/25)
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- Continuous Flow Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzenes with Gel-Bound Catalysts
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In the search for a new synthetic pathway for azoxybenzenes with different substitution patterns, an approach using a microfluidic reactor with gel-bound proline organocatalysts under continuous flow is presented. Herein the formation of differently substituted azoxybezenes by reductive dimerization of nitrosobenzenes within minutes at mild conditions in good to almost quantitative yields is described. The conversion within the microfluidic reactor is analyzed and used for optimizing and validating different parameters. The effects of the different functionalities on conversion, yield, and reaction times are analyzed in detail by NMR. The applicability of this reductive dimerization is demonstrated for a wide range of differently substituted nitrosobenzenes. The effects of these different functionalities on the structure of the obtained azoxyarenes are analyzed in detail by NMR and single-crystal X-ray diffraction. Based on these results, the turnover number and the turnover frequency were determined.
- Schmiegel, Carsten J.,Berg, Patrik,Obst, Franziska,Schoch, Roland,Appelhans, Dietmar,Kuckling, Dirk
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p. 1628 - 1636
(2021/03/15)
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- Understanding Mechanistic Differences between 3-Diazoindolin-2-Imines and N-Sulfonyl-1,2,3-Triazoles in the Rh2(II)-Catalyzed Reactions with Nitrosoarenes
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The employment of α-iminometallocarbenes to construct valuable N-containing compounds has attracted significant research interest. Herein, the nucleophilic addition of nitrosoarenes with the α-imino rhodium carbene species (I), which is derived from Rh2(II)-catalyzed denitrogenation of 3-diazoindolin-2-imines, to produce synthetically useful 2-iminoindolin-nitrones is described. Mechanistically, the N-attack of nitrosoarenes with the carbene site of I is proposed. For the analogous Rh2(II)-catalyzed reaction of nitrosoarenes with N-sulfonyl-1,2,3-triazoles reported by Li and co-workers (Org. Lett. 2014, 16, 6394), however, the O-attack of nitrosoarenes with the carbene site of α-imino rhodium carbene species (II) is more favorable to occur than the N-attack. The subsequent transformation to yield the product of N-acylamidines is rationalized based on computational studies. The mechanistic differences for the reactions of nitrosoarenes with α-imino rhodium carbene species I and II are discussed.
- Bao, Xiaoguang,Fu, Rui,Gao, Ke,Kou, Luyao,Zhou, Shaofang
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supporting information
p. 1565 - 1572
(2021/05/28)
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- Thioether-linked liquid crystal dimers and trimers: The twist-bend nematic phase
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Systematic synthesis of thioether-linked dimers and trimers was carried out to reveal molecular designs for inducing mesophases and twist-bend nematic (NTB) phases. A five-fold approach based on molecular structural parameters including the ter
- Arakawa, Yuki,Komatsu, Kenta,Inui, Satoyoshi,Tsuji, Hideto
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- Novel Phenyldiazenyl Fibrate Analogues as PPAR α/γ/δ Pan-Agonists for the Amelioration of Metabolic Syndrome
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The development of PPARα/γ dual or PPARα/γ/δ pan-agonists could represent an efficacious approach for a simultaneous pharmacological intervention on carbohydrate and lipid metabolism. Two series of new phenyldiazenyl fibrate derivatives of GL479, a previously reported PPARα/γ dual agonist, were synthesized and tested. Compound 12a was identified as a PPAR pan-agonist with moderate and balanced activity on the three PPAR isoforms (α, γ, δ). Moreover, docking experiments showed that 12a adopts a different binding mode in PPARγ compared to PPARα or PPARδ, providing a structural basis for further structure-guided design of PPAR pan-agonists. The beneficial effects of 12a were evaluated both in vitro, on the expression of PPAR target key metabolic genes, and ex vivo in two rat tissue inflammatory models. The obtained results allow considering this compound as an interesting lead for the development of a new class of PPAR pan-agonists endowed with an activation profile exploitable for therapy of metabolic syndrome.
- Giampietro, Letizia,Laghezza, Antonio,Cerchia, Carmen,Florio, Rosalba,Recinella, Lucia,Capone, Fabio,Ammazzalorso, Alessandra,Bruno, Isabella,De Filippis, Barbara,Fantacuzzi, Marialuigia,Ferrante, Claudio,MacCallini, Cristina,Tortorella, Paolo,Verginelli, Fabio,Brunetti, Luigi,Cama, Alessandro,Amoroso, Rosa,Loiodice, Fulvio,Lavecchia, Antonio
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supporting information
p. 545 - 551
(2019/03/19)
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- Enantioselective Oxidative Coupling of β-Ketocarbonyls and Anilines by Joint Chiral Primary Amine and Selenium Catalysis
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An enantioselective primary amine-catalyzed total N-selective nitroso aldol reaction (N-NA) was achieved through the oxidation of primary aromatic amines to the corresponding nitrosoarenes catalyzed by selenium reagents and 30% H2O2. This protocol provides a facile and highly efficient access to α-hydroxyamino carbonyls bearing chiral quaternary centers under exceedingly mild and green reaction conditions with high chemo-and enantiocontrol.
- Chen, Wanting,Wang, Yanni,Mi, Xueling,Luo, Sanzhong
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supporting information
p. 8178 - 8182
(2019/10/16)
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- Photochemical investigation of cyanoazobenzene derivatives as components of artificial supramolecular pumps
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Among the plethora of photochromes reported so far, azobenzene has been proven to be the most suitable photoswitch for molecular systems and materials, due to its highly efficient and clean E-Z photoisomerization. Here we report two ammonium-based molecul
- Casimiro, Lorenzo,Groppi, Jessica,Baroncini, Massimo,La Rosa, Marcello,Credi, Alberto,Silvi, Serena
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p. 734 - 740
(2018/06/21)
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- A novel synthesis of N-hydroxy-3-aroylindoles and 3-aroylindoles
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A straightforward indole synthesis via annulation of C-nitrosoaromatics with conjugated terminal alkynones was realised achieving a simple, highly regioselective, atom- and step economical access to 3-aroylindoles in moderate to good yields. Further functionalizations of indole scaffolds were investigated and an easy way to JWH-018, a synthetic cannabinoid, was achieved.
- Ieronimo, Gabriella,Palmisano, Giovanni,Maspero, Angelo,Marzorati, Alessandro,Scapinello, Luca,Masciocchi, Norberto,Cravotto, Giancarlo,Barge, Alessandro,Simonetti, Marco,Ameta, Keshav Lalit,Nicholas, Kenneth M.,Penoni, Andrea
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supporting information
p. 6853 - 6859
(2018/10/20)
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- Synthesis of Di(hetero)arylamines from Nitrosoarenes and Boronic Acids: A General, Mild, and Transition-Metal-Free Coupling
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The synthesis of di(hetero)arylamines by a transition-metal-free cross-coupling between nitrosoarenes and boronic acids is reported. The procedure is experimentally simple, fast, mild, and scalable and has a wide functional group tolerance, including carbonyls, nitro, halogens, free OH and NH groups. It also permits the synthesis of sterically hindered compounds.
- Roscales, Silvia,Csák?, Aurelio G.
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supporting information
p. 1667 - 1671
(2018/03/23)
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- CHROMOPHORES FOR PHOTOCHROMIC COMPOSITIONS USEFUL FOR THREE DIMENSIONAL DISPLAY APPLICATIONS
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Described herein are novel azo-benzene type chromophores. The chromophores are useful in photochromic compositions comprising a polymer matrix and a chromophore, wherein the chromophore is a novel azo-benzene type structure. The photochromic composition i
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Paragraph 0203; 0204
(2017/04/11)
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- Structure requirements for anaerobe processing of azo compounds: Implications for prodrug design
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This Letter generalizes the metabolism of the azo class of compounds by Clostridium perfringens, an anaerobe found in the human colon. A recently reported 5-aminosalicylic acid-based prednisolone prodrug was shown to release the drug when incubated with the bacteria, while the para-aminobenzoic acid (PABA) based analogue did not. Instead, it showed a new HPLC peak with a relatively close retention time to the parent which was identified by LCMS as the partially reduced hydrazine product. This Letter investigates azoreduction across a panel of substrates with varying degrees of electronic and steric similarity to the PABA-based compound. Azo compounds with an electron donating group on the azo-containing aromatic ring showed immediate disproportionation to their parent amines without any detection of hydrazine intermediates by HPLC. Compounds containing only electron withdrawing groups are partially and reversibly reduced to produce a stable detectable hydrazine. They do not disproportionate to their parent amines, but regenerate the parent azo compound. This incomplete reduction is relevant to the design of azo-based prodrugs and the toxicology of azo-based dyes.
- Gavin, Jason,Ruiz, Juan F. Marquez,Kedziora, Kinga,Windle, Henry,Kelleher, Dermot P.,Gilmer, John F.
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p. 7647 - 7652
(2013/02/21)
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- Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate
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Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 4402 - 4413
(2012/06/18)
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- One-pot synthesis of meridianins and meridianin analogues via indolization of nitrosoarenes
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Meridianins, marine alkaloids known as kinase inhibitors with an indole skeleton, and meridianin analogues were produced regioselectively and in moderate to good yields by thermal annulation of nitrosoarenes with 2-amino-4-ethynylpyrimidine and 2-chloro-4-ethynylpyrimidine, respectively, through a novel and atom-economical indolization process.
- Tibiletti, Francesco,Simonetti, Marco,Nicholas, Kenneth M.,Palmisano, Giovanni,Parravicini, Matteo,Imbesi, Federico,Tollari, Stefano,Penoni, Andrea
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experimental part
p. 1280 - 1288
(2010/04/02)
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- Synthesis of functionalized triazatriangulenes for application in photo- Switchable self-assembled monolayers
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Various triazatriangulenes are synthesized by nucleophilic attack at the central C atom of triazatriangulenium ions. The molecular functions, especially azobenzenes, are fixed via an ethynyl linker by in situ deprotection of trimethylsilylalkynes. The structure of two of these molecules is further investigated by X-ray crystallography. The photo-inducedtrans/cis-isomerization of the azobenzene substituted derivatives is analyzed in solution and shows great promise for the preparation of switchable functionalized monolayers, as the triazatriangulenes are known for their self-assembly on gold surfaces. [1].
- Kubitschke, Jens,Naether, Christian,Herges, Rainer
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experimental part
p. 5041 - 5055
(2010/11/05)
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- Preparation of azobenzenealkanethiols for self-assembled monolayers with photoswitchable properties
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A series of azobenzenealkanethiol compounds with the structure p-RC 6H4N=NC6H4(CH2) nSH (n = 3, 4) was synthesized using a divergent strategy with the two anilines H2NC6H4(CH2) nSAc as central compounds. This strategy provides fast access to a broad variety of the respective azobenzenethiols without (note!) an oxygen atom in the alkyl chain, thus permitting the self-assembly of these compounds onto gold in a predictable conformation, also taking advantage of the previously found odd-even effect in aromatic-aliphatic hybrid systems. Initial experiments indicate that all of these molecules indeed form dense monolayers, in which the orientation of the azobenzene unit is determined by the number of methylene groups in the aliphatic part of the molecules. CSIRO 2010.
- Krakert, Simone,Terfort, Andreas
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body text
p. 303 - 314
(2011/06/23)
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- A photoresponsive liquid crystal based on (1-cyclohexenyl)phenyldiazene as a close analogue of azobenzene
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A new photoresponsive calamitic liquid crystal molecule possessing (1-cyclohexenyl)phenyldiazene as a close analogue of azobenzene was synthesized and a comparative study with the corresponding azobenzene analogue carried out.
- Sato, Masanao,Nagano, Shusaku,Seki, Takahiro
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supporting information; experimental part
p. 3792 - 3794
(2009/12/01)
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- Synthesis of an azobenzene-linker-conjugate with tetrahedrical shape
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The synthesis of a tripodal linker system with an adamantane core unit and an azobenzene headgroup is reported for the preparation of photochromic SAMs on gold surfaces. For the final Sonogashira-coupling of the ethynylene-linker precursor 4 with the p-io
- Zarwell, Sebastian,Rück-Braun, Karola
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p. 4020 - 4025
(2008/09/20)
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- Two-photon fluorescent holographic rewritable micropatterning
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Monomeric amorphous systems involving an upper azo-based layer and a lower fluorophore layer have been carefully designed to enable holographic formation of micrometric emissive photopatterns through reversible photoinduced mass migration of azoderivatives. The fluorescent patterns evidenced by NIR biphotonic excitation match the micrometric surface relief. After successful erasure by using a circularly polarized visible light, new patterns can be written again. Copyright
- Ishow, Elena,Brosseau, Arnaud,Clavier, Gilles,Nakatani, Keitaro,Pansu, Robert B.,Vachon, Jean-Jacques,Tauc, Patrick,Chauvat, Dominique,Mendonca, Cleber R.,Piovesan, Erick
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p. 8970 - 8971
(2008/02/09)
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- N-Arylhydroxamic acids as novel oxidoreductase substrates
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N-Arylhydroxamic acids (AHAs) are promising novel N-OH mediators for oxidoreductase catalysis. They are electrochemically active compounds with a redox potential of 0.31-0.41 V vs. SCE. Representative oxidoreductases, e.g. fungal peroxidase from Coprinus
- Kulys, Juozas,Deussen, Heinz-Josef,Krikstopaitis, Kastis,Lolck, Rikke,Schneider, Palle,Ziemys, Arturas
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p. 3475 - 3484
(2007/10/03)
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- Oxidation vs. fragmentation in radiosensitization. Reactions of α-alkoxyalkyl radicals with 4-nitrobenzonitrile and oxygen. A pulse radiolysis and product analysis study
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α-Monoalkoxyalkyl radicals produced from 1,4-dioxane (100percent), 1,3-dioxane (56percent), tetrahydrofuran (92percent) and dimethyl ether (100percent) by H-abstraction by hydroxyl radicals generated in the radiolysis of water were found to react with 4-nitrobenzonitrile (NBN) by addition to give N-alkoxyaminoxyl-type radicals, which have absorption maxima at about 310 nm and decay very slowly (k = 0.4 - 1.0 s-1).On the other hand, the reaction of the α-dialkoxyalkyl radical, 1,3-dioxan-2-yl 3 with NBN leads to the rapid formation of the radical anion NBN.The N-alkoxyaminoxyl-type radicals (A in the case of 1,4-dioxane and D in the case of dimethyl ether) react with ascorbate (k ca. 2*104 dm3 mol-1 s-1).They have a very low reactivity with oxygen (k 3 dm3 mol-1 s-1 in the case of tetrahydrofuran).On the other hand, they are rapidly reduced by NBN radical anion (k ca. 109 dm3 mol-1 s-1 as observed with A and with B derived from 1,3-dioxane).The products -7 mol J-1> in the γ-radiolysis of N2O-saturated solution of 1,4-dioxane in the presence of NBN are 1,4-dioxan-2-one (0.3), 2-hydroxy-1,4-dioxane (2.5), ethane-1,2-diol monoformate (2.1), ethane-1,2-diol diformate (0.7), formaldehyde (2.1), 4-nitrosobenzonitrile and other reduction products of 4-nitrobenzonitrile.These products are accounted for as resulting from the fragmentation of the aminoxyl radical A by (a) heterolysis of the C-O bond (45percent leading to the one-electron oxidation of the 1,4-dioxan-2-yl radical) and (b) homolysis of the N-O bond (55percent leading to the formation of the 1,4-dioxan-2-oxyl radical which undergoes further fragmentation.The products from the reaction of methoxymethyl radicals with NBN under γ-radiolysis conditions are formaldehyde (5.7), methanol (2.5) and methyl formate (1.3).It is concluded that also in this case the decay of the aminoxyl radical D occurs by two pathways: the heterolysis route (46percent) and the homolysis route (54percent).In the presence of oxygen the 1,4-dioxan-2-yl radicals are converted into the corresponding peroxyl radicals.Their bimolecular decay (2k = 2.0*108 dm3 mol-1 s-1) yields the same products as in the case of NBN (albeit with a different product distribution and the formation of some peroxides): 1,4-dioxan-2-one (0.4), 2-hydroxy-1,4-dioxane (0.4), ethane-1,2-diol monoformate (0.6), ethane-1,2-diol diformate (2.8) and formaldehyde (0.6).These results indicate that fragmentation reactions involving the carbon-skeleton of organic radicals are important not only in the case of peroxyl radicals but they can also be induced by nitroaromatic sensitizers.In cells, reduction of the long-lived sensitizer adduct radicals by reducing agents such as ascorbate to give (toxic) hydroxylamine type products may compete with the homolytic or heterolytic fragmentation of the N-alkoxyaminoxyl radicals.
- Nese, Chandrasekhar,Schuchmann, Man Nien,Steenken, Steen,Sonntag, Clemens von
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p. 1037 - 1044
(2007/10/02)
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- Chemistry of molybdenaoxaziridines. A study of oxo(N-phenylhydroxylamido-O,N)(pyridine-2,6-dicarboxylato) (hexamethylphosphortriamide)molybdenum(VI) and its catalytic properties
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The chemistry of molybdenaoxaziridines is investigated. Oxo(N-phenylhydroxylamido-O,N)(pyridine-2,6-dicarboxylato) (hexamethylphosphortriamide)molybdenum(VI) complexes 3 are prepared in high yields by different procedures, either by a reaction between anilines and oxoperoxo(pyridine-2,6-dicarboxylato)(hexamethylphosphortriamide)molybdenum(VI) (4) or by an oxidative addition reaction of nitrosobenzenes to oxo(pyridine-2,6dicarboxylato)(hexamethylphosphortriamide)molybdenum(IV) (6). The kinetics of the reactions of a series of para-substituted anilines and 4 are studied, and a Hammett plot showed a correlation between log(k/ko) and ap with a p value of -2.29. A mechanism for the formation of 3 is proposed. The electronic structure of 3 is investigated using extended-Hückel calculations. Based on the frontier orbitals of the system, a brief discussion of the chemical properties of 3 is presented. Complex 3 decomposes to mainly azoxybenzene and dioxo(pyridine-2,6-dicarboxylato)(hexamethylphosphortriamide)molybdenum(VI) (5). A variable-temperature study leads to an Arrhenius plot for this decomposition with a AC value of 16.1 kcal·mol-1. Based on the detected decomposition products and on the observed nitroso ligand exchange reaction, a mechanism for the decomposition of 3 is proposed. Treatment of 3 with hydrogen peroxide leads to a selective formation of nitrosobenzenes and 4. This reaction is further developed to a catalytic process for the selective oxidation of various substituted anilines to the corresponding nitrosobenzenes in high yields. The influences of different solvents and of the temperature on the yields of the oxidation are also examined. Based on the kinetic experiments, mechanisms for the stoichiometric and the catalytic oxidation reactions are suggested.
- M?ller, Eval Rud,J?rgensen, Karl Anker
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p. 11814 - 11822
(2007/10/02)
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- Metathesis and reduction reactions of nitroso compounds with metal carbenes and metal carbonyls
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Reaction of nitroso compounds with metal-carbene complexes and metal carbonyls has been investigated.These reactions lead to reduction of the nitroso compounds, primarily to the corresponding azo- and azoxy compounds.Metal-nitrene complexes have been proposed as intermediates in these reactions.These intermediates couple rapidly with the unreacted nitroso compound, or enter into nitrene-like reactions with external or internal trapping agents.Reaction of metal carbonyls with nitrosoarenes and photolysis has been found to be an effective method for the reduction of nitrosoarenes to azoxyarenes, with few problems resulting from overreduction to amines or azo compounds.
- Herndon, James W.,McMullen, Leonard A.
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- 13C NMR studies of p-substituted nitrosobenzenes
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The 13C NMR spectra of a wide range of monomeric para-substituted nitrosobenzenes have been determined end the results related to a wide range of published data for other para-disubstituted benzenes.It is shown that the nitroso substituent exercises a different pattern of effect for the 13C chemical shifts at the ipso C atom from at least twenty eight other substituents.It is noted that when the para substituent is a ?-donor, the nitroso group functions in a different manner from that operative when the para substituent is a ?-acceptor, a general possibility that has already been suggested in the recent literature.
- Al-Tahou, Baheeja M.,Gowenlock, Brian G.
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p. 353 - 355
(2007/10/02)
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