- Syn and anti conformations in 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl] benzoic acid and two related salts
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The crystal structures of 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoic acid, C13H9N3O5, (I), ammonium 2-hydroxy-5-[(E)-phenyldiazenyl]benzoate, NH4 + C13H 9N2O3 -, (II), and sodium 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate trihydrate, Na+ C13H8N3O5 - 3H2O, (III), have been determined using single-crystal X-ray diffraction. In (I) and (III), the phenyldiazenyl and carboxylic acid/carboxylate groups are in an anti orientation with respect to each other, which is in accord with the results of density functional theory (DFT) calculations, whereas in (II), the anion adopts a syn conformation. In (I), molecules form slanted stacks along the [100] direction. In (II), anions form bilayers parallel to (010), the inner part of the bilayers being formed by the benzene rings, with the -OH and -COO - substituents on the bilayer surface. The NH4+ cations in (II) are located between the bilayers and are engaged in numerous N-H?O hydrogen bonds. In (III), anions form layers parallel to (001). Both Na+ cations have a distorted octahedral environment, with four octahedra edge-shared by bridging water O atoms, forming [Na4(H 2O)12]4+ units.
- Yatsenko, Alexandr V.,Paseshnichenko, Ksenia A.
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- Hydrophilicity and Microsolvation of an Organic Molecule Resolved on the Sub-molecular Level by Scanning Tunneling Microscopy
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Low-temperature scanning tunneling microscopy was used to follow the formation of a solvation shell around an adsorbed functionalized azo dye from the attachment of the first water molecule to a fully solvated molecule. Specific functional groups bind initially one water molecule each, which act as anchor points for additional water molecules. Further water attachment occurs in areas close to these functional groups even when the functional groups themselves are already saturated. In contrast, water molecules surround the hydrophobic parts of the molecule only when the two-dimensional solvation shell closes around them. This study thus traces hydrophilic and hydrophobic properties of an organic molecule down to a sub-molecular length scale.
- Lucht, Karsten,Loose, Dirk,Ruschmeier, Maximilian,Strotk?tter, Valerie,Dyker, Gerald,Morgenstern, Karina
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- Identification of the subtype-selective Sirt5 inhibitor balsalazide through systematic SAR analysis and rationalization via theoretical investigations
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We report here an extensive structure-activity relationship study of balsalazide, which was previously identified in a high-throughput screening as an inhibitor of Sirt5. To get a closer understanding why this compound is able to inhibit Sirt5, we initially performed docking experiments comparing the binding mode of a succinylated peptide as the natural substrate and balsalazide with Sirt5 in the presence of NAD+. Based on the evidence gathered here, we designed and synthesized 13 analogues of balsalazide, in which single functional groups were either deleted or slightly altered to investigate which of them are mandatory for high inhibitory activity. Our study confirms that balsalazide with all its given functional groups is an inhibitor of Sirt5 in the low micromolar concentration range and structural modifications presented in this study did not increase potency. While changes on the N-aroyl-β-alanine side chain eliminated potency, the introduction of a truncated salicylic acid part minimally altered potency. Calculations of the associated reaction paths showed that the inhibition potency is very likely dominated by the stability of the inhibitor-enzyme complex and not the type of inhibition (covalent vs. non-covalent). Further in-vitro characterization in a trypsin coupled assay determined that the tested inhibitors showed no competition towards NAD+ or the synthetic substrate analogue ZKsA. In addition, investigations for subtype selectivity revealed that balsalazide is a subtype-selective Sirt5 inhibitor, and our initial SAR and docking studies pave the way for further optimization.
- Bracher, Franz,Dietschreit, Johannes C. B.,Ghazy, Ehab,Glas, Carina,Jung, Manfred,Ochsenfeld, Christian,Sippl, Wolfgang,Urban, Lars,W?ssner, Nathalie
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supporting information
(2020/08/28)
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- Radical arylation of triphenyl phosphite catalyzed by salicylic acid: Mechanistic investigations and synthetic applications
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A straightforward and scalable methodology to synthesize diphenyl arylphosphonates at 20 °C within 1-2 h is reported using inexpensive SA as the catalytic promoter of the reaction. Mechanistic investigations suggest that the reaction proceeds via radical-radical coupling, consistent with the so-called persistent radical effect. The reaction tolerated a wide range of functional groups and heteroaromatic moieties. The synthetic usefulness and the unique reactivity of the obtained phosphonates were demonstrated in different one-step transformations.
- Estruch-Blasco, Manel,Felipe-Blanco, Diego,Bosque, Irene,Gonzalez-Gomez, Jose C.
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p. 14473 - 14485
(2020/12/29)
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- The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors
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In this paper, a micro-fluidic optimized process for the continuous flow synthesis of azo compounds is presented. The continuous flow synthesis of Sudan II azo dye was used as a model reaction for the study. At found optimal azo coupling reaction temperature and pH an investigation of the optimum flow rates of the reactants for the diazotization and azo coupling reactions in Little Things Factory-MS microreactors was performed. A conversion of 98% was achieved in approximately 2.4 minutes and a small library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic systems. The scaled up synthesis of these compounds in PTFE tubing (i.d. 1.5 mm) was also investigated, where good reaction conversions ranging between 66-91% were attained.
- Akwi, Faith M.,Watts, Paul
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p. 1987 - 2004
(2016/10/05)
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- Synthesis, characterization and radical scavenging activity of aromatic amine conjugates of 5-Aminosalicylic acid
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5-Aminosalicylic acid is an anti-inflammatory drug used in the treatment of inflammatory bowel diseases including ulcerative colitis and Crohn's disease. Due to its rapid and extensive absorption in the upper gastro-intestinal tract, substantial amount of 5-aminosalicylic acid is already lost before reaching the site of action, i.e. the colon. In order to prevent this loss of drug, carrier linked prodrug approach has been used and azo prodrugs have been synthesized with a purpose of colon targeting. The present research describes the synthesis and characterization of azo prodrugs of 5-aminosalicylic acid with aromatic amines. The synthesized prodrugs were tested for antioxidant activity using DPPH (2,2-diphenyl-1-picrylhydrazy1) free radical scavenging activity. All the synthesized compounds were found to possess mild to moderate radical scavenging activity.
- Harveer, Kaur,Jasmeen, Sidana
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p. 475 - 480
(2015/02/02)
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- Synthesis and characterization of triorganotin(IV) complexes of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids. Crystal and molecular structures of a series of triphenyltin 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoates (aryl = phenyl, 2-methylphenyl, 3-methylphenyl and 4-methoxy...)
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The triphenyltin and tri-n-butyltin complexes of some 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids have been synthesized and characterized by 1H-, 13C-, 119Sn-NMR, IR and 119mSn Moessbauer spectroscopic techniques in combination with elemental analysis. The crystal structures of triphenyltin 5-[(E)-2-(aryl-1-diazenyl]-2-hydroxybenzoates (aryl = phenyl, 2-methoxyphenyl, 3-metylphenyl and 4-methoxyphenyl) are reported. Both X-ray and 119Sn Moessbauer data indicate that the triphenyltin complexes adopt a monomeric distorted tetrahedral configuration with the carboxylate ligand coordinating in a monodentate mode. By contrast, 119Sn Moessbauer spectroscopy shows that each tributyltin complex is polymeric and features a trans-trigonal bipyramidal geometry with a planar SnBu3 unit and two apical carboxylate oxygen atoms derived from bidentate bridging carboxylate ligands. This is a solid-state effect, as both 119Sn-NMR and 1(13C-119/117Sn) coupling constant data indicate tetrahedral geometries in solution for the triphenyl and tri-n-butyl complexes.
- Baul, Tushar S. Basu,Dhar, Sushmita,Pyke, Simon M.,Tiekink, Edward R. T.,Rivarola, Eleonora,Butcher, Ray,Smith, Frank E.
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- Evaporator system comprising a stabilized pesticidal phosphoric acid ester and method for stabilizing such ester enclosed in an evaporator
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An evaporator system adapted for emitting insect killing vapors of an insecticide therefrom and comprising a liquid or solid composition enclosed therein, said insecticide consisting in at least one volatile phosphoric acid ester which is stabilized by at least one diazene compound.
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